^ ^ ANL-6262

MASTER

argonnc Bational Xaboratorg PHYSICS DIVISION

SUMMARY REPORT

December 1960

•%

DISCLAIMER

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ANL-6262 Phys ic s AEG Research and Development Report

ARGONNE NATIONAL LABORATORY 9700 South Cass Avenue

Argonne , Ill inois

PHYSICS DIVISION SUMl^lARY REPORT

December I960

Morton Hame r m e s h , Division Di rec to r

Preceding Summary Repor t s :

ANL-6190 - July^ August I960 ANL-6214 - Sep tember , October I960 ANL-6235 - November I960

Operated by The Univers i ty of Chicago under

Contract W-31-109-eng-38

1

TABLE OF CONTENTS

The date of the last preceding r e po r t i s indicated after the t i t le of each project below. P ro j ec t s which a r e not r epor t ed in th is i s sue a r e l i s ted on subsequent pages .

I. EXPERIMENTAL NUCLEAR PHYSICS PAGE

I-10-1 TANDEM VAN DE GRAAFF ACCELERATOR (New project)

F . P . Mooring and J . R„ Wal lace . . . . . . . o . . . .

The operating pr inciple of the tandem Van de Graaff a c c e l e r a t o r i s d i scussed . The new tandem wing on Building 203 i s de sc r ibed .

1-11-26 INSTALLATION AND OPERATION OF THE VAN DE GRAAFF GENERATOR (ANL-6214, S e p t . - O c t . , I960)

J . R„ Wallace,

The use and operat ion of the 4 . 5 - M e v Van de Graaff genera tor i s desc r ibed for the per iod from July 1 to September 30, I960 .

1-14-21 PULSED BEAMS FOR THE VAN DE GRAAFF GENERATOR (ANL»5978, F e b . - A p r . , 1959)

R. E . Holland, F . J . Lynch, and E . N . Shipley 7

An upper l imit was set for the obse rved mean life of the f i rs t excited s tate of Ca ^ and a lower l imit was set for the pa r t i a l mean life for decay by E2 t r ans i t ion from the same s t a t e .

1-58-8 DELAYED NEUTRON GROUPS FROM N^'^ (ANL-5955, D e c . 1958, J a n . 195 9)

G. J . P e r l o w , A. F . Stehney (CHM), W. J . R a m l e r (CHM), and J . L . Yntema. . . . . . . . . . . 8

1 7 Groups of delayed neut rons f rom a N ^ ' p r e c u r s o r have been observed at energ ies of 1.225 and 0.425 Mev, c o r r e s ­ponding to |3 decay to _ s t a tes in O^''' in a g r e e m e n t with the shel l mode l .

1-116-1 PRINCIPLES OF C Y C H C PARTICLE ACCELERATORS

John J . Livingood (New project) 9

Designed for college s tuden t s , this text a s s u m e s no p r i o r knowledge of the subject and leads to a quanti tat ive unde r ­standing of the va r ious devices in which acce l e r a t i on i s produced by ac vo l tage . The emphas i s i s on pa r t i c l e dynarai c s .

MASS SPECTROSCOPY

II -40-7 FRAGMENTATION OF HYDROCARBONS (ANL-6169, June I960)

H. E . Stanton. 11

E a r l i e r invest igat ions of the f ragmentat ion of h y d r o ­carbons with h igh-energy e lec t rons w e r e extended to benzene and e thylene. The r e s u l t s indicated a depend­ence of fragment yield on bond energy .

PLASMA PHYSICS

I V - l O - i HIGH-FREQUENCY PLASMAS ,

Alber t A. Hatch (New project) 17

The p lasma r e s e a r c h p r o g r a m a t Argonne i s outlined and re la ted to the o v e r - a l l field of p l a s m a p h y s i c s . The major r e s e a r c h de sc r i be d is an exper imenta l study of bas ic p r o p e r t i e s of p l a s m a s produced in homogeneous high-frequency e l ec t r i c fields at low p r e s s u r e s . The minor r e s e a r c h de s c r i be d is a t heo re t i ca l study of the in terac t ion of p l a s m a s with nonhomogeneous h igh-frequency e l ec t romagne t i c f ie lds .

THEORETICAL PHYSICS, GENERAL

V-13-2 SPIN-ORBIT SPLITTING AND PION THEORETIC L-S POTENTIAL (ANL-6130, March I960)

Akito A r i m a , Masao Sugawara , and Tokuo T e r a s a w a . . 29

The doublet spl i t t ings in He^ , N^^ , and O^^ (closed shel ls plus or minus one nucleon) a r e adequately explained in t e r m s of the combinat ion of the s econd-o rde r effect due to the t ensor force and the f i r s t - o r d e r effect due to the L-S po ten t ia l .

i i i

PAGE V-42-1 GEOMETRIC THEORY O F CHARGE

H. Ekste in (New project) 34

The paper a t t empts to explain some bas i c p r o p e r t i e s of e l ec t r i c charge from space- t ime s y m m e t r y con­s idera t ions a lone . As a surpr i s ing by -p roduc t , it is found that the assumpt ion of full space - inve r s ion symmet ry p red ic t s the kind of "par i ty nonconservat ion" effects that a r e usual ly considered to prove the absence of this s y m m e t r y .

PUBLICATIONS 44

PERSONNEL CHANGES IN THE ANL PHYSICS DIVISION 47

PROJECTS NOT REPORTED IN THIS ISSUE

A re fe rence to the las t preceding r e p o r t i s given in p a r e n -ses for each p ro jec t .

EXPERIMENTAL NUCLEAR PHYSICS

I - l - Neutron De tec to r s (ANL-6072, O c t . - N o v . , 1959), G. E . T h o m a s .

1-3- C r o s s Section M e a s u r e m e n t s with the F a s t Neutron Velocity Selector (ANL-6072, O c t . - N o v . , 1959), L . Boll inger and R. C o t e ' .

1-7- G a m m a - R a y Spect ra from Capture in Neutron Resonances (ANL-6146, A p r i l - M a y , I960) , L . M. Boll inger and R. T . C a r p e n t e r .

1-18- Different ial C r o s s Section for Neutron Resonance Scat ter ing (ANL-6169, June I960), Raymond O. Lane .

I "19- Nuclear Resonance Absorpt ion of Gamma Rays (ANL-6169, June I960), L . L . L e e , J r . , L . M e y e r - S c h u t z m e i s t e r , J . P . Schiffer, and D. Vincent .

1-22- Scat ter ing of Charged P a r t i c l e s (ANL-6130, March I960) , Jan Yntema, B , Ze ldman, T . H. Bra id .

1-28- Angular Cor re la t ions in C h a r g e d - P a r t i c l e React ions (ANL-5978, F e b . - A p r i l , 1959), T . H. B r a i d .

1-30- Decay of ^g^r^^^ (3 .1 hr) (ANL-6190, Ju ly-August , I960) , H. A. Grench and S. B . B u r s o n .

1-33- Decay of Tm^^^ (ANL-6235, November I960), S. B . Burson and R. G. H e l m e r .

1-43- Stopping Power of Carbon for Po^^° Alpha P a r t i c l e s (ANL-6235, November i960) , S. B a r k a n .

1-44- Branching Ratio of a and P E m i s s i o n from Bi-212 (ThC) (ANL-6235, November I960) , S. B a r k a n .

1-55- Capture G a m m a - R a y Spect ra for Neutrons with E n e r g i e s f rom 0 .1 to 10 ev (ANL-6052, Sep tember 1959), Sol Raboy and C a r r o l l C. T r a i l .

1-60- 7 . 7 - M e t e r Bent=Crys ta l Spec t rome te r (ANL-6235, November I960), Rober t S m i t h e r .

1-80- Molecular B e a m Studies (ANL-6214, Sept . - O c t . , I960) , Leonard S. Goodman and W. J . Ch i lds .

m

v

1-90- Cros s Sections for 14-Mev Neutrons (ANL-6072, Oct . - N o v . , 1959), Harvey Casson and L. A. Rayburn.

1-98- Neutron Total C r o s s Sections in the Kev Region (ANL-6235, November i960) , Ca r l T . Hibdon.

1-102- Neutron Cross Sections by Self-Detection (ANL-6214, Sept. - O c t . , I960), J a m e s E . Monahan.

I - l l O - Storage of Pulse-Height Data on Magnetic Tape (ANL-6072, O c t . -Nov . , 1959), J a m e s B a u m g a r d n e r .

I - I U - Sol id-s ta te Radiat ion De tec to r s (ANL-6235, November I960) , T. H. Bra id and J . T. Heinr ich .

1-144- Investigation of Scint i l la tors (ANL-6235, November i960) , W a r r e n Buck, Louis Bas i l e . and R. Swank.

MASS SPECTROSCOPY

11-18- Lead Ages of Meteor i tes (ANL-6169, June i960) , D. C. H e s s .

11-28- Kinet ics of Chemical Reac t ions in the Gas P h a s e (ANL-58 i8 , Oct . -D e c , 1957), Will iam A. Chupka.

11-29- Gaseous Species in Equi l ibr ium a t High T e m p e r a t u r e s (ANL-6105, January I960), Wm. A. Chupka.

11-34- A ^ ° - K ^ ° Dating of Meteor i tes (ANL-6 i90 , J u l y - A u g . , I960), David C. H e s s .

11-38- Mass Spec t rome t r i c Study of Charged Atomic and Molecular P roduc t s of Nuclear Trans fo rmat ion (ANL-6214, Sept . - O c t . , I960), Sol Wexler .

CR YST ALLOGRAPHY

I I I -4 - Crys ta l S t ructure Studies of Compounds of E l emen t s A c - A m (ANL-6038, Ju ly-Augus t , 1959), Wm. H. Z a c h a r i a s e n .

I I I - IO- The Crys ta l S t ruc ture of lui^Y/O^ (ANL-6169, June I960) , H. A. Ple t t inger and W. H. Z a c h a r i a s e n .

V. THEORETICAL PHYSICS, GENERAL

V - 3 - Dynamics of Nuclear Collective Motion (ANL-6214, Sep tember -October , I960) , David R. Inglis and Kiuck Lee .

V - 8 - Relat ionships of Collective Effects and the Shell Model (ANL-6235, November I960), Kie ter Kura th .

V - 1 5 - Sta t i s t ica l P r o p e r t i e s of Nuclear Energy States (ANL-6088, December 1959), Norber t Rosenzweig .

V - 1 8 - E l emen ta ry P a r t i c l e s in DeSi t ter Space (ANL-60 38, Ju ly-August , 195 9), Will iam C. Davidon.

I - l O - l

I . EXPERIMENTAL NUCLEAR PHYSICS

I - l O - l Tandem Van de Graaff Acce le ra to r (51210-01)

F . Paul Mooring and Jack R. Wallace Reported by Jack R. Wallace

A new r e s e a r c h tool will soon be in use by the menmbers of

the Van de Graaff Section of the Phys ics Division. It is the 12-Mev Tandem

Van de Graaff Acce le ra to r designed and built by High Voltage Engineer ing

Corpora t ion , Burl ington, M a s s a c h u s e t t s .

The tandem a c c e l e r a t o r design has evolved d i rec t ly from

that of a conventional Van de Graaff e l ec t ros ta t i c g e n e r a t o r . A Van de

Graaff e lec t ros ta t ic acce l e ra to r has cer ta in advantages in invest igat ion of

the p roper t i e s of the nucleus . Some of these a r e : (1) This type of accel=

e ra to r i s capable of producing a t ightly col l imated b e a m of charged pa r t i c l e s

(2) The energy of the pa r t i c l e s emerging from such an a c c e l e r a t o r can be

va r i ed continuously over a l a rge range . (3) The energy sp read of these

pa r t i c l e s can be kept very sma l l ( a 0 .05%).

The tandem a c c e l e r a t o r ' s method of achieving higher

par t ic le energies from the s a m e t e r m i n a l voltage became poss ib le when

sc ien t i s t s learned how to produce nega t ive ly-charged hydrogen ions (p ro­

tons to which two e lec t rons have been a t t a c h e d ) . The pr inc ip le of a tandem

acce l e r a to r is to produce an in tense beam of p r o t o n s , a c c e l e r a t e them by

passing them through a potent ial drop of about 40 k v , then pas s them through

hydrogen gas where they pick up two e l ec t rons . Th is source of negative

ions i s ex terna l to the Van de Graaff a c c e l e r a t o r and at ground potent ia l ,

but connected to i ts acce le ra t ion tube . These negative ions a r e a c c e l e r a t e d

from ground to the high-voltage t e r m i n a l which is charged to a posit ive

I - l O - l

voltage (1 to 6 mil l ion vo l t s ) . In fliis high-voltage shel l these ions a r e pas sed

through a gas cel l which r emoves the two e lec t rons and changes the charge

of the ion f rom negative to pos i t ive . They a r e again a c c e l e r a t e d by pass ing

through another acce le ra t ing tube col l inear with the f i r s t , which runs froiri

this t e r m i n a l shel l to ground. So in this way the pa r t i c l e has acqu i red an en­

ergy twice that a s soc i a t ed with the potential difference of the t e r m i n a l voltage

and ground. The emerging protons a r e then p a s s e d through a 90° magne t ic

ana lyzer whose magne t ic field i s ve ry carefully s tabi l ized and control led . A

signal from the output s l i t s of th is magnet ic ana lyzer i s used to s tabi l ize the

voltage of the t e r m i n a l shel l of the t andem. The pro tons p roceed to a swi tch­

ing magnet which can d i r e c t them to the va r ious p ieces of exper imenta l equip­

ment located in the t a r g e t a r e a .

The tandem gene ra to r will p e r m i t a logical extension of ce r t a in

m e a s u r e m e n t s and invest igat ions now being c a r r i e d on a t our p r e s e n t Van de

Graaff a c c e l e r a t o r . New exper imen t s will a l so be poss ib le at these higher

energ ies now avai lable with the t andem. M e m b e r s of the Phys i c s Division a r e

now planning and designing exper imenta l equipment for use with th is new

a c c e l e r a t o r .

The plan view of the exper imenta l level (F ig . 1 ) of the new t a n ­

dem wing of building 203 shows the location of the a c c e l e r a t o r , ana lyzer

m a g n e t s , and switching m a g n e t s , and the re la t ive s izes of the va r ious a r e a s .

The plan chosen will allow a max imum usefulness of the t andem. The e m e r g ­

ing ion beam from the t andem can be d i rec ted through e i ther of the 90° magnet ic

ana lyze r s and then through a switching magnet which in tu rn d i r ec t s the b e a m

through any one of the five poss ib le be a m lines located in the t a r g e t a r e a s .

This m e a n s that while a given expe r imen t i s being conducted in one t a r g e t a r e a

the other t a rge t a r e a wil l be free of radia t ion and the re fo re the next exper imen t

can s imul taneously be p r e p a r e d and i t s equipment checked. Each t a rge t a r e a

has a da t a - r eco rd ing r o o m as soc ia t ed with it and t h e r e a r e wi reways provided

to c a r r y signal cables between the two a r e a s . E n t r a n c e into the vault and t a rge t

I - l O - l 3

a r e a while an experiment i s in p r o g r e s s will be control led. Doors and

gates through the radiat ion shield will be in ter locked, and radiat ion de tec ­

tion equipment will be instal led to monitor the a r e a s at a l l t i m e s .

The c ro s s section through the t a rge t a r e a s (Fig . 2) c lea r ly

shows the radiat ion shielding of the vault and ta rge t a r e a s , necess i ta ted by

operat ions at these ene rg i e s . The gamma cave in the eas t t a rge t a r e a is a

specia l room provided for exper iments that r equ i re a very low external

LOW LEVEL GAMMA CAVE-{ 14' X 16'

BEAM CATCHER, RECESS

EAST TARGET AREA

(50' X 50')

BEAM CATCHER RECESSES

CONSTRUCTION BUILDING

LOADING " PLATFORM

Fig . 1. Exper imenta l level plan view

(basenaent)

I - l O - i

MECHANICAL ROOM

EARTH EMBANKMENT

EAST TARGET AREA

BEAM CATCHER RECESS

WEST TARGEr AREA

GAMMA CAVE VAULT

I. i I., . I 0 10 20'

EARTH EMBANKMENT

BEAM CATCHER RECESS

Fig , Z. Cross section through target a r e a s .

DN.

^<':,...:^^-...BpkAi

-UPPER PART~ EAST TARGET

AREA

rf ' » f : " p " , i

-MECHANICAL ROOM-COMPRESSOR

GAS STORAGE

m^%:.,f;ji-..,di^'^';^ij.'":r^

UPPER PART-WEST TORGET

AREA

l„,.l.„,l,,„l,,.,l 0 10' 20' CONSTRUCTION BUILDING

Fig , 3 . Service level plan view (1st floor)

background. The m a t e r i a l s used in the concrete of the wa l l s , cei l ing, and

floors of this room have been selected for a minimum content of r a d i o ­

act ive e l emen t s .

The plan view of the serv ice level (Fig, 3) shows the

a r e a above the vault in which the acce le ra to r is located. It will contain

I - l O - l 1-11-26

5

the a c c e s s o r y equipment for the t andem, such a s c o m p r e s s o r , gas s to rage

t anks , gas d r i e r , gas r e c i r c u l a t o r , m o t o r - g e n e r a t o r s e t s , vacuum pump,

power dis t r ibut ion pane l , e t c . The se rv ice ga l le ry a r ea will contain heating

and ventilating equipment , a dis t r ibut ion sys tem for signal and control wi re , ,

and eventually th ree offices on the west s ide .

The p resen t construct ion schedule ca l ls for the tandem wing

to be conapleted June 15, 1961. High Voltage Engineering schedules our t an ­

dem for completion by May 1961. It i s hoped that the tandenn's instal la t ion

will not r e q u i r e more than 3 months after i ts de l ivery to our s i t e .

1-11-26 Instal la t ion and Operat ion of the Van de Graaff Genera to r (51210-01)

J . R. Wallace

This r epo r t covers the operat ion of the Van de Graaff g e n e r a ­

to r in the Phys i c s Division for the per iod from July 1 to September 30, I960

inc lus ive .

T h e g e n e r a t o r w a s u s e d to a c c e l e r a t e p r o t o n s and a l p h a s .

I ts voltage va r i ed from 1.6 to 4 . 4 Mv. The beam c u r r e n t s m e a s u r e d . a t the

t a r g e t va r i ed from 0.1 to> 30 ^ a .

The following l is t shows the type of exper imen t s pe r fo rmed

with the genera tor and the number of hours per exper iment .

1. Neutron polar iza t ion

2. Resonance f luorescence

5 9

3. Total c r o s s section of Co and of N^^

" 5 7

4. Mossbauer effect in Fe by Coulomb excitat ion

Elwyn, Lane 9 . 6 h r

H e b e r l e , Meye r , ^ . emman

Huddleston, ^^ . . ' 264.4

Mooring

Holland, Lynch ^08 . 8

1-11-26

4 0 .

155.

37 .

4 8 .

791 .

4 3 .

365.

1200.

,3 hr

,0

,6

2

,3

,0

,7

, 0 hr

5 . Calibrat ing neutron survey counter Anderson

6. Tota l c r o s s section in kev region Hibdon 2 3 6

7. F i s s ion c r o s s section of U Stupegia 4 8

8. Po l a r i z ed protons from Ti (d,p) S m i t h e r , Weinman

Star tup and daily main tenance

Machine r e p a i r s and expe r imen ta l setup

Total t i m e avai lable (64 days X 16 h r + 22 days X 8 h r )

We a r e now trying in the Van de Graaff gene ra to r a c h a r g e -

car ry ing bel t f rom Fab reeka that has a longer lap joint . It was bel ieved by

thei r engineers that the re la t ive ly sma l l d i ame te r (6 i n . ) of our dr ive pulley

caused m o r e than no rma l flexing of the bel t a t the lap joint . In addition to this

flexing we have conditions (high l ineal be l t speed plus high gas density) that

lead to unusual ly high wind ac t ion on the lap joint in the b e l t . Since the

fa i lures with th is bel t have been exclusively at the l ap , we hope this change

in lap design m a y improve the life of the be l t .

T e s t s with F a b r e e k a endless wrapped bel t have been u n s a t i s ­

factory so f a r . The different method of cons t ruc t ion neces s i t a t ed by th i s

type of bel t in t roduced undes i rab le fea tures for our appl ica t ion.

We were plagued with an i r r e g u l a r pulsing be a m which caused

much unsa t i s fac tory operat ion during th is pe r iod . The cause of th is t rouble

was an i n t e rna l e l ec t r i c a l leakage path (low r e s i s t a n c e path) in the insulating

d r ive pulley of the 400-cycle genera to r in the high-vol tage shel l of the Van

de Graaff a c c e l e r a t o r . This i r r e g u l a r leakage caused fluctuations in the

charge r e m o v a l f rom the charging be l t and r e su l t ed in energy changes of the

beam a t the t a r g e t .

Additional t ime was lost during th is q u a r t e r because of a

breakdown of our a i r c o m p r e s s o r u s e d for gas t r a n s f e r .

1-14=21

I-14-21 Pulsed Beams for the Van de Graaff Genera to r (51210-01)

R. E . Holland, F . J . Lynch, and E . N. Shipley Repor ted by R„ E . Holland

PARTIAL LIFETIMES OF FIRST EXCITED STATE OF Ca*^

1 Because of r ecen t i n t e r e s t in the l i fet ime of the f i r s t exci ted

4 3

state of Ca , we began a meas \ i r emen t of th i s l ifetime by a pu l sed -beam 2

technique. While the work was in p r o g r e s s , we l ea rned of a completed 3

m e a s u r e m e n t by Schwarzchi ld and co l l abora to r s at Brookhaven. Our m e a s -

u r e m e n t s indicate that the mean life i s l e s s than 0. 1 m |xsec , in a g r e e m e n t

with an upper l imit of 0,06 mjxsec es tab l i shed at Brookhaven.

During this work , we a l so observed that this s ta te was not

strongly excited by a -pa r t i c l e bombardment (the m e a s u r e m e n t desc r ibed above

was made by proton bombardment ) , and the re fore that the c r o s s sect ion for

Coulomb excitation was sma l l . We were able to es tab l i sh an upper l imit for

the c r o s s section by comparing the yields of gamma r ays from thick t a r g e t s 4 3

of CaCOg(23% Ca ) , CaCOg (no rma l ) , and V (normal ) . No gamma r a y s of

374-kev were observed from ei ther Ca t a rge t under bombardment by 3 , 2 -1 8 2 1

Mev a p a r t i c l e s . Gamma r a y s of 342 kev from O (a ,n )Ne produced a

background which allowed us only to es tab l i sh that the number of 374-kev 4 3

gainma rays from the Ca t a rge t was less than 4% of the numiber of 323-kev 4

ganama rays from the V t a rge t . Using the value B ( E 2 ) = 0.0056 b a r n

1

T. Komoda, submitted for publicat ion in P r o g r e s s of Theo re t i ca l Phys i c s (Kyoto). 2

R. E . Holland and F . J . Lynch, P h y s i c s Division Summary R e p o r t , ANL-5955, (December , 1958, J a n u a r y , 1959), p« 3.

P r iva te communicat ion.

K. A l d e r , A. Bohr , T . Huus , B . Mot te l son , and A, Winther , R e v s . Modern P h y s . 28 , 432 (1956).

1-14-21 1-58-8

5 1

for the reduced E2 t rans i t ion probabi l i ty for V and cor rec t ing for the

difference in energy of the gamma r a y s and the difference in stopping power

of the t a r g e t s , we find for the reduced t r ans i t ion probabi l i ty for f i rs t excited 4 3

state of Ca

B(E2) < 0.000248 b a r n s .

The corresponding l imit on the pa r t i a l E2 mean life i s

T (E2 ) > 34 m|x sec .

We infer that the shor t observed l ifet ime i s due to a high p a r t i a l t r ans i t ion

r a t e for Ml decay .

1 7 1-58-8 Delayed Neutron Groups from N (51210-01)

G. J . P e r l o w , A . F . Stehney (CHM), W. J . R a m l e r (CHM), and J . L . Yntema

The energy of the neut rons which follow the p -decay of i r 1

4. 1-sec N was m e a s u r e d by m e a n s of a neut ron spec t rome te r in which

the energ ies of proton r eco i l s were de t e rmined in a t r ip le p ropor t iona l -

counter a r r a n g e m e n t . The energy ca l ib ra t ions were made with monoenerget ic 7 7 1 7

neutrons from Li (p ,n )Be at the Van de Graaff g e n e r a t o r . The N was 1 4 17

produced in the reac t ion C ( a , p ) N at a mean energy of about 25 Mev, The 1 4

C was in the fornn of a 14-mg pel le t of 41% en r i chmen t , sandwiched in

aluminuin foil. Bombardment and counting were a l t e rna ted by shut ter ing

1

G. J . P e r l o w , Rev . Sc i . I n s t r . 27 , 460 (1956).

1-58-8 1-116-1

the cyclotron b e a m . Two groups of neut rons were obse rved with ene rg ies of

1.225 ± 0.060 and 0.425 ± 0,020 Mev and re la t ive in tens i t ies in the ra t io

l , 6 r l . Within a smal l energy d i sc repancy , these co r re spond to (3 t r ans i t ions 3 _ 1 7

to the 2 s tates of O at 5,38 Mev and 4. 56 Mev. The h igher energy neut rons 2

reported by Hayward would not have been observed. 1 7 , ,

A paper enti t led "Delayed Neut rons from N has been p r e ­pa red for publication.

2 E . Hayward, P h y s , Rev. 7 5 , 917 (1949).

1-116-1 P r inc ip l e s of Cyclic Pa r t i c l e A c c e l e r a t o r s (51210-01)

John J , Livingood

This book p r e s e n t s a coherent d i scuss ion of existing v a r i e t i e s

of cyclic par t ic le a c c e l e r a t o r s ; cyc lo t rons , synchrocyc lo t rons , s y n c h r o t r o n s ,

b e t a t r o n s , m i c r o t r o n s , sec to r - focused dev i ce s , l inear a c c e l e r a t o r s , and

s tochast ic m a c h i n e s . These a r e desc r ibed in sufficient de ta i l to show the i r

s i m i l a r i t i e s , d i f ferences , and l imi ta t ions .

The p rob lem of orbi t s tabi l i ty r e c e i v e s e m p h a s i s , with d i s ­

cuss ions of weak- , s t r o n g - , and sec tor- focusing techniques and of the means

of calculating the frequencies of the a s soc i a t ed osci l la t ions of the o r b i t s .

The important concepts of momentum compact ion , phase s tabi l i ty , and syn­

chrotron osci l la t ions a r e desc r ibed and ana lyzed , and ce r t a in p rob lems of

injection and ejection a r e cons ide red .

The t r e a t m e n t follows the development of a c c e l e r a t o r s from

the s impler to the more complex . An unini t ia ted r e a d e r (who i s a s s u m e d to

unders tand the calculus) i s led through the advances which have o c c u r r e d

over the y e a r s , up to the point where he has gained a solid unders tanding of

1-116-1

the underlying p r inc ip les and has become equipped to r ead intel l igently

the many a r t i c l e s on the subject which appear in the scientif ic j o u r n a l s .

The book, of approximate ly 370 p a g e s , i s i l lus t ra ted with

136 drawings and 28 photographs . A bibl iography of about 500 i t ems is

a r r a n g e d by type of a c c e l e r a t o r , a s an aid in co l l a t e ra l reading for those who

inay wish to delve deeper into theo re t i ca l a spec t s or to l e a r n construct ional

de ta i l s of pa r t i cu la r in s t a l l a t ions .

The D. Van No s t rand Company expects to r e l e a s e the

volume in June 1961.

I I -40-7 11

II . MASS SPECTROSCOPY

II-40-7 Fragmenta t ion of Hydrocarbons (51300-01)

H. E . Stanton

The e a r l i e r invest igat ions of the f ragmentat ion of h y d r o c a r ­

bons under impact by e lec t rons with energ ies ranging up to a few ki lovolts were

extended to benzene and e thylene . The exper imenta l a r r a n g e m e n t s and t e c h ­

niques of m e a s u r e m e n t s were ident ica l to those used for neopentane and h e p ­

tane which were repor ted e a r l i e r .

The r e s u l t s for benzene a r e shown in F i g , 4 . In F ig , 4 ( a ) ,

the conaparison of the m a s s spec t rum given by MA-17 and the one given in

P ro jec t 44 of the A m e r i c a n P e t r o l e u m Inst i tute (used a s a s t anda rd ) , for an

e lec t ron energy of 70 ev , shows the usxxal p r o g r e s s i v e d i s c r epanc i e s in r e ­

lative yield for the lower m a s s n u m b e r s , but o therwise shows a reasonab le

a g r e e m e n t , except for m a s s 15. The r eason for the g r e a t difference

(amounting to a factor of 10) i s not known, and quite poss ib ly may be pa r t i a l

fai lure of r e sponse in MA-17, The yield for this peak fluctuated r a the r

badly throughout the exper imen t s and any conclusions with r e g a r d to yields

at m a s s 15 would be highly hypothet ica l . The yie lds were a l l no rmal i zed

re la t ive to the yield of the pa ren t ion at m a s s 78 , the l a r g e s t peaJs.

One n o t e s , a s with the a l i pha t i c s , that the re la t ive yield

usual ly shows a p r o g r e s s i v e d e c r e a s e with increas ing energy of the ionizing

e l ec t rons and with decreas ing m a s s n u m b e r . The d e c r e a s e s appear to be

m o r e nea r ly uniform and sonnewhat m o r e pronounced with benzene than

they were with heptane and neopentane . With the l a t t e r molecu les the re

were p r e f e r r e d modes of molecu la r rup tu re between adjacent carbon a t o m s ,

whereas the modes in benzene a r e l e s s obvious , poss ib ly because of the ring

s t ruc tu re and the t ighter binding between the carbon a t o m s .

1

Phys ic s Division Summary Repor t ANL-6169 (June I960) , p . 5 1 ,

+ 2

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38 39 49 50 51 52 61 62 63 73 74 75 76 77 78 79

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15 26 27 3 7 , ^ ^38 39 37.5 49 50 51 52 61 62 63 73 74 75 76 77 78 79

MASS NUMBERS

4(a). Mass spectrum of benzene bombarded by 70-ev electrons. The right-hand peak at each mass number is the result obtained by MA-17. These are to be compared with the left-hand peaks, taken as standards, which were found at the Bureau of Standards and reported in Pro­ject 44 of the American Petrolexun Institute. Ordinates are the logarithms of the relative yields normalized to 100 for mass 78. (b) The mass spectra obtained from MA-17 for ben­zene at electron energies of 70 ev (left members) and at 2400 ev (right members). Both spec­tra were normalized to 100 at mass 78.

II-40-7 13

+2

> 0

z UJ

" - 2 UJ >

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12 13 14 15 24 25 26 27 28 29

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A. 12 13 14 15 24 25 26 27 28 29

MASS NUMBERS

Fig . 5 (a). Comparison of the m a s s spec t rum of ethylene a s obtained on MA-17 with 70-ev e lec t rons with a spec t rum given in P ro jec t 44 of the Amer ican Pe t ro leum Insti tute for e lec t rons of the same energy, (b) Comparison of the m a s s spec t ra obtained with bom­barding energies of 70 ev (left) and 2400 ev (right) for e thylene. All peaks were normal ized to 100 at m a s s 28.

I I -40-7

The compar i son of the m a s s s p e c t r a , shown in F i g . 5 (a) ,

for ethylene a s given by MA-17 and P ro j ec t 44 , r e spec t ive ly , shows that

the d i sc repanc ie s a r e sma l l e r than in any other molecule examined so far

(probably because of the much sma l l e r range of m a s s n u m b e r s r equ i r ed ) .

However the genera l t r end in the differences a p p e a r s to be the usxial one.

The peak yie lds were again no rma l i zed with r e s p e c t to the p a r e n t , m a s s

28+ .

The m a s s spec t r a shown in F i g . 5 (b), tciken on MA-17

with bombardmen t energ ies of 70 ev and 2400 ev , indicate a somewhat J ,

g r e a t e r reduct ion in re la t ive peak intensi ty for m a s s e s 25 and lower than

for the other mo lecu le s . In con t r a s t , the re la t ive in tens i t i e s of m a s s e s

26 and 27 with r e s p e c t to the paren t peak did not change a s m a r k e d l y .

The changes in re la t ive yield for these two peaks were not m o r e than 25%

throughout the range of e l ec t ron ene rg ie s employed. The logar i thmic

a b s c i s s a t e n d s , unfor tunately , to obscure changes of th is o r d e r .

The r e s u l t s obtained up to th is point indicate a r a t h e r s imple

i n t e rp re t a t i on . The reduct ion in r e la t ive yield of a given ionic spec ies

with r e s p e c t to i t s pa ren t ion (or p r inc ipa l f ragment in the c a s e of neopentane)

under h igh-energy e lec t ron ic impac t a p p e a r s to be s imply c o r r e l a t e d with the

bond energy which mus t be b roken to produce i t . While , at th i s point , the

re la t ionsh ip i s only qua l i ta t ive , one notes for n-heptane that the re la t ive

yield of the p r inc ipa l peaks (85 , 71 , e t c ) changes l i t t le in going from +

70-ev to 2400-ev e l e c t r o n s , but the peak a t m a s s 15 a p p e a r s to be g rea t ly

changed. Although many of the f ragments der ived from these p r inc ipa l

peaks by success ive elinaination of hydrogens show minor changes a s a func­

tion of e l ec t ron ene rgy , t h e r e a r e some exceptions: 84"*°, 69'*', 28 , and 26"^.

It a p p e a r s that the format ion of these peaks r e q u i r e s the break ing of a m o r e

energe t ic bond than does the r e m o v a l of a second hydrogen from a sma l l e r

f ragment . Since the C-C single bond i s about 3.5 ev and the s imple C-H

bond around 4 . 3 ev, the e a r l i e r experin:ients did not d is t inguish between

these two v a l u e s .

But on considering the p resen t r e s u l t s , F i g s . 4 and 5 , the

effect of bond energy becomes c l e a r e r . All the peaks in benzene for

m a s s number 63 and below (except the e r r a t i c peak at m a s s 14) showed a

comparat ively large drop in re la t ive yield as the bombarding energy of the

e lec t rons was i n c r e a s e d . The formation of these peaks involved the rup tu re

of at least one C-C bond with an energy of about 5.2 ev. Actually m o r e en­

ergy was involved since production of a fragment involves not only breaking

the ring but a lso r e l e a s e from the r ad ica l so fo rmed . A s imi la r s ta tement

applies for ethylene since the formation of f ragments with m a s s e s 15 and

below requ i r e s the rup ture of a double bond with an energy of about 6. 3 ev.

Again in both m a s s s p e c t r a , the r emova l of one or two hydrogens from the

molecule does not seem to be ve ry sensi t ive to e lec t ron energy; but a s

m o r e hydrogens a r e r emoved , fur ther r e m o v a l becomes re la t ive ly l e s s

probable as the e lec t ron energy i n c r e a s e s .

T h e r e were t h r ee peaks that showed dis t inct h igh-energy

components and o thers that gave strong indicat ions of some kinet ic energy

of formation. At the lower e lec t ron e n e r g i e s , the m a s s - 1 5 ion from

benzene showed a well r e so lved peak at high kinet ic e n e r g i e s , with a m a x i ­

mum at 2 .3 ev, a width at half m a x i m u m of about 0 .5 ev , and an ampli tude

of about two th i rds of the ampli tude of the peak at t h e r m a l ene rg ies for

the same m a s s . This ion can be formed from benzene only by an extensive

r e a r rang emient, since the C H . r ad ica l i s not a p a r t of the s t r uc tu r e of the

parent molecu le . The re r e m a i n s the poss ib i l i ty that an impur i ty was

responsible for the peak, but this s eems doubtful.

Ethylene gave two peaks with h igh-energy p a r t s . One , at

m a s s 14''', which r e p r e s e n t e d a rupture of the double bond, had a m a x i m u m

at about 2 ,5 ev and a width a t half max imum of about 1.5 ev , but v e r y low

intensi ty . It s e e m s unlikely that this is a spur ious r e su l t caused by a

ni t rogen impur i ty . +

The ethylene f ragment peak at m a s s 13 a lso showed a sma l l

6 II-40-7

unreso lved h igh-energy component with a max imum around 2 ev. F ina l ly ,

the peak at 12"*" had a h igh-energy t a i l which indicated some kinet ic en ­

e rgy of format ion . It s e e m s probable that when the fragmentat ion of

ethylene involves the separa t ion of the two carbon a toms the re i s some

kinet ic energy of format ion .

IV-10-1 17

IV. PLASMA PHYSICS

IV-10-1 High-Frequency P l a s m a s (54100-01)

Albe r t J . Hatch

The purpose of this r e p o r t is to outline the p la sma r e s e a r c h

p r o g r a m at Argonne and to show i ts re la t ion to the o v e r - a l l field of p lasma

phys i c s .

There a re two l ines of r e s e a r c h being followed, one m a j o r ,

the other minor . The major r e s e a r c h i s an exper imenta l study of b a s i c

p roper t i e s of l ow-pres su re p l a smas produced in high-frequency e lec t r i c fields

which a r e approximately uni form in space in the absence of p lasma . Most of

the work to date has been on the high-frequency p lasmoid phenomenon. The

minor r e s e a r c h i s a theore t i ca l study of the in terac t ion of p l a smas with non-

homogeneous high-frequency e lec t romagne t ic f ie lds , with specia l emphas i s

on rf containment of p l a s m a s .

OSCILLATORY PHENOMENA IN PLASMAS

A plasma is a dynamic physical sys t em made up of e l e c ­

t r o n s , ionSjand neutra l gas a toms (or molecules) in which the e lec t ron and

ion densi t ies a r e usual ly approximate ly equal . The fraction of ionizat ion _ 8

can extend from as low as about 10 for weakly ionized p l a s m a s to a lmos t

1 for fully ionized p l a s m a s . The c h a r a c t e r i s t i c s of a p l a sma which d i s ­

t inguish it from other physical s y s t e m s a r i s e mainly from two c l a s s e s of

phenomena that involve both the individxial and the collective behavior of

the p lasma const i tuents .

One c lass of phenomena is the s ho r t - r a nge in te rac t ions

between the individual const i tuents of the p l a s m a , especia l ly between the

e lec t rons and a t o m s . These in te rac t ions include s h o r t - r a n g e h a r d - s p h e r e

e las t ic col l i s ions , ine las t ic co l l i s ions , recombina t ion , e lec t ron a t t achment .

IV-10-1

and in terac t ion with solid s u r f a c e s .

The other c lass of phenomena i s the individual and col ­

lective r e sponse of the e lec t rons and ions to long-range e l ec t r i c and m a g ­

netic f o r c e s . These forces may or ig inate e i ther from externa l ly applied

fields or from the in t e rna l collective behavior of e l ec t rons and ions t h e m ­

se lves . Among the phenomena included in th is c l a s s a r e the t r a n s m i s s i o n

and ref lect ion of e lec t romagne t ic radia t ion through p l a s m a s , containment of

p l a smas by magne t i c and e lec t romagne t ic f i e lds , and seve ra l spec ies of

e lec t ron and ion osc i l l a t i ons , including cyclo t ron r e s o n a n c e . It i s to th i s

c lass that the p lasmoid and containment phenomena belong.

P l a s m a - e l e c t r o n osc i l la t ions a r e one of the long-range

force phenomena which have been the subject of much r e s e a r c h s ince the i r

d i scovery over 30 yea r s ago . Tonks and Langmuir showed in 1929 that

these osci l la t ions occur in a one-d imens iona l sys tem at the r ad ian frequency 2 V^

w = (ne /mtQ ) , where n - e lec t ron dens i ty , e and m a r e the charge

and m a s s of the e lec t ron ,and Cg i s the pe rmi t t iv i ty of f ree space . Such

osci l la t ions in dc-or pu l se -exc i ted p l a s m a s r e s u l t from charge densi ty

g rad ien t s ; in rf*excited p l a s m a s they r e su l t from a combination of o sc i l l a ­

ting charge densi ty g rad ien t s and r e s p o n s e to the rf exci ta t ion. F o r the

range of e lec t ron dens i t ies no rma l ly encountered in l abora to ry p l a s m a s ,

the f requencies of p l a s m a - e l e c t r o n osc i l la t ions a r e in the nonainal range

of 1 to 10 000 M c / s e c .

Most of the expe r imen ta l r e s e a r c h on p l a s m a - e l e c t r o n

osci l la t ions has been pe r fo rmed in dc=excited plasnnas, a spec ies of p l a s ­

ma which i m p o s e s seve re l imi ta t ions on many (but not all) types of such o b -

s e r v a t i o n s , main ly because the osci l la t ions a r e m e r e l y a by-produc t of the

1

L . Tonks and I . Langmui r , P h y s . Rev . 33 , 195(1929) .

IV-10-1 19

more prominent dc p lasma m e c h a n i s m s . One is therefore justified in

the conjecture that th is is a situation which has perhaps ser ious ly hampered

the advance of our knowledge of osc i l l a to ry phenomena in p l a s m a s . Indeed,

it i s genera l ly recognized that p lasma osci l la t ions a r e cu r ren t ly one of the

least unders tood of the impor tan t bas ic phenomena of p lasma behavior .

It i s axiomatic in physics that the study of the osc i l l a to ry

p roper t i e s of a physical med ium can usual ly be pe r fo rmed mos t expedit iously

by exciting the medium at frequencies in the vicini ty of i ts r esonan t a n d / o r

cutoff f requencies . Thus one is led to expect that phenomena involving e lec t ron

oscil lat ions should become ve ry p rominen t , pe rhaps even dominant , in p l a s ­

mas excited by frequencies in the megacycle r a n g e . This expectat ion a p p e a r s

to be at leas t par t i a l ly confirmed by the many types of unusual phenomena

observed in r f -exc i ted p l a smas a t low p r e s s u r e s . F u r t h e r confirmation is

emerging from the detai led exper imenta l study of t he ' i n t e rna l c h a r a c t e r i s t i c s

of the var ious phenomena.

HIGH-FREQUENCY PLASMOIDS

There a r e t h r ee major p lasma m e c h a n i s m s which occur

in high-frequency p l a smas at low p r e s s u r e s , n a m e l y , diffusion, p l a s m o i d s ,

and mul t ipact ing, l i s ted in o rder of decreas ing p r e s s u r e .

The diffusion m e c h a n i s m — s o named because the dominant

mechan i sm of e lec t ron loss is by diffusion to the tube walls and e l ec t rodes—-

occurs throughout a wide range of p l a sma p a r a m e t e r s , i . e . , p r e s s u r e , tube

d imens ions , and applied frequency. Although diffusion has been studied

mainly a s a breakdown m e c h a n i s m , ce r t a in t heo re t i ca l a spec t s of i t s ro le

a s a plasma mechan i sm have a l so been developed and c o r r e l a t e d with e x p e r i ­

menta l observat ion .

F r o m the standpoint of a p p e a r a n c e , the mos t unusual rf

p l a sma phenomena at low p r e s s u r e s a r e the high-frequency p lasmoids f i r s t 2

repor ted by R. W. Wood in 1930. A high-frequency p lasmoid is a region

R. W. Wood, P h y s . Rev . 35, 673 (1930).

IV-10-1

in a high-frequency p lasma that has a definite sharply bounded f o r m — e . g . ,

a spheroid , spindle , d isk , or pear shape , depending mainly on the p lasma

tube configuration and the pressure—with in which the luminous intensi ty of

the p lasma is usual ly noticeably higher than that of the surrounding p l a s m a .

Although Wood suggested that the p lasmoids were a manifestat ion of an o s ­

ci l la tory phenomenon, his observat ions did not include any confirmatory 3 4

evidence for this hypothes is . Recent studies at Harwel l , Saclay, and 5

Argonne , however , now tend to confirm Wood's hypothesis and a r e s t a r t ­

ing to r evea l some of the detai ls of the osc i l la tory m e c h a n i s m .

Multipacting is a l ow-pres su re high-frequency quas i -

osc i l la tory m e c h a n i s m — i . e . , nonharmonic—in which the e lec t ron t rans i t

t ime between e lec t rodes i s nominally

7-cycle and e lec t ron mult ipl icat ion

is by secondary emiss ion due to e l ec ­

t ron im.pact,on the e lec t rode surfaces ,

with energ ies of the o rde r of 50 ev

or m o r e . Although the mechan i sm

lacks cer ta in impor tant a t t r ibu tes

ord inar i ly a s soc ia ted -with p l a s m a s ,

especial ly a random elec t ron d i s ­

tr ibution in phase space , it n e v e r ­

the less has other c h a r a c t e r i s t i c s

that a r e measu rab l e by the same

E . R . H a r r i s o n , J . E lec t ron ics and Control 5 , 319(1958) . (Harwell work . ) "* R. G e l l e r , Compt. rend . 249, 2749(1959). (Saclay work . ) 5 ———

A. J . Hatch, Proceedings of the Four th Internat ional Conference on Ioniza­tion Phenomena in Gases ^ , 314 (North-Holland Publishing Company, A m ­s t e r d a m , I960).

PRESSURE (MICRONS Hg)

Fig . 6. High-frequency p lasma do­mains in dry a i r . These p l a smas a r e es tabl ished between p lane-pa ra l l e l aluminum elect rodes , 23 cm in d iameter and 15 cm a p a r t , a t a frequency of 15 M c / s e c ,

IV-10-1 21

diagnostic techniques as a r e used in " r e a l " p l a s m a s and the re fore is a u s e ­

ful neighboring mechan i sm to the p l a smo ids .

The p resen t r e s e a r c h is a imed at studying high-frequency

p lasma and plasmoid phenomena in the gap between the diffusion domain and the

multipacting domain a s shown in F i g . 6. This map of the plasma domains i s

by no means complete; it has been filled in only enough to provide an orienting

reference for the p r e s e n t s tud ie s , and the re a r e s e v e r a l subdomains which

have been recognized but have not yet been explored in sufficient detai l to be

included.

Some idea of the va r i e ty of high-frequency p l a sma phenomena

at low p r e s s u r e s can be gained from examination of the p la sma photos in

F ig , 7. The p l a smas shown in the top th ree photos a r e in the diffusion do­

main . Of t h e s e , the only one for which the re is a sa t i s fac tory published 6

theore t ica l descr ip t ion is the doubly s t r i a t ed p l a s m a at 50 jx. The plasma

shown in the 13~jx photo is in the vicinity of the t r ans i t ion at the m e a n - f r e e -

path l imi t , shown in F i g . 6, where the e lec t ron m e a n - f r e e - p a t h i s equal to

the cha rac t e r i s t i c diffusion length. Two s tages in the appea rance of the

high-frequency p lasmoids a r e shown in the photos at 1.0 and 0, 3|x. The

spheroidal dark sheath which del ineates the p lasmoid s e e m s to p re sen t a

paradoxica l situation in that although p lasma boundar ies o rd ina r i ly tend to

beconnie l e s s dis t inct as p r e s s u r e is r educed , th is one beconmes m o r e d is t inc t .

In the 0. 3-ji photo the sheath width i s of the o rde r of 0.002 of the e lec t ron

m e a n - f r e e - p a t h . Dens i tomete r m e a s u r e m e n t s of the negat ive from which

this photo was made show that the luminous intensi ty of the dark sheath

(D = 0.295 a r b i t r a r y units) i s l e s s than that of both the immedia te ly adjacent

W. P . A l l i s , S. C. B rown , and E . E v e r h a r t , P h y s . Rev . 84, 519 (1951).

22 IV- lO- i

HIGH FREQUENCY PLASMAS AND PLASMOIDS

Fig. 7. Photographs of high-frequency p la smas and plasmoids

The p a r a m e t e r s a r e the same as in Fig. 6.

IV- lO- i 23

surrounding p lasma (D = 0. 300) and the plasmoid in t e r io r (D = 0. 340). The

increas ing prominence and d i s t inc tness of the p lasmoids as the abrupt ex­

tinction boundary is approached (maintaining voltage in F ig . 6) suggests that

we have h e r e ei ther an isola ted f reakish mechan i sm of no fundamental i m ­

portance ( there a r e many such in p la sma physics) or a beautiful manifestat ion

of a significant and fundamental p l a sma p rope r ty (there a r e a l so s e v e r a l of

these in p la sma phys ics ) .

The exper imenta l study of the high-frequency p lasmoids in­

volves m e a s u r e m e n t s of the axia l va r ia t ion of luminous in tens i ty , dc and

rf potentials in the p l a s m a , and e lec t ron and ion dens i ty , a l l a s functions of

applied rf potent ia l , f requency, e lec t rode separa t ion , and gas p r e s s u r e .

The exper iment i s a clean one in the sense that the p l a smas a r e produced in

the homogeneous e l ec t r i c field between l a r g e - d i a m e t e r p l ane -pa ra l l e l e l e c ­

t rodes ; t h u s , to the f i rs t approximat ion the osc i l la tory phenomena occur

pa ra l l e l to the ax is and the axia l observa t ions can be c o r r e l a t e d d i rec t ly with

one-dimensional axial theory .

The r e su l t s of the s tudies appear to point toward one p a r a ­

mount conclusion, namely , that the mode t rans i t ions in F i g . 6 naark the

changeover from osci l la t ions of free e lec t rons in a "nornnal" p la sma to

osci l lat ions of bound e lec t rons in the p lasmoid domain. The equation of

motion of an e lec t ron in a one-d imens iona l p lasma produced by a field

E exp (jwt) i s

x + v x + o j x = (e /m) E exp (j ojt) , (1)

where v is the collision frequency for naomentunn t ransfer (e las t ic m

col l is ions) . The solution of th is equation is

(e /m) E sin 0 ,. . , . X = exp (jwt) , (2)

0) V m

IV-10-1

where

tan e = —^ J . (3) a3p -co

This solution r e p r e s e n t s a forced osci l la t ion. At sufficiently low p r e s s u r e s the

damping t e r m v^^k in Eq. (1) becomes negligible, and the solution above reduces

to

(e /m)E ,. , = -—^ — e x p (j CD t)

OOp^ -OD^ ( 4 )

When 01^^ < 03 the e lec t rons a r e cons idered as free and osc i l la te under the

major influence of the external ly applied driving force . When OD^ > 00 the

e lec t rons a r e cons idered as bound and osc i l la te under the major influence of a

force developed internal ly by charge separa t ion, although the frequency of

osci l lat ion is sti l l controlled by the ex terna l driving fo rce . The binding

force in the plasmoid is due to i ts posit ive dc potential which a r i s e s from

the re la t ively mobile e lec t rons being lost to the tube walls at a higher ra te

(initially) than a r e the re la t ive ly slow ions . As the t rans i t ion f rom free to

bound osci l la t ions occur s , Eq. (4) shows that the phase of the e lec t ron

motion theore t ica l ly undergoes a shift of 180°. Associa ted with this shift

is a phase shift in the self potential of the osci l la t ing e l e c t r o n s . Such a

phase shift has been observed exper imenta l ly in the vicinity of the t r a n s i ­

tions shown in F i g . 6.

Considerat ions based on this bound e lec t ron m e c h a n i s m

and supported by m e a s u r e m e n t s of the axial profi les of dc and rf potentials

have recent ly led to an explanation of the axial par t of the dark sheath around

the p lasmoids which can be s u m m a r i z e d by r e f e r r ing to F i g . 8. Here a r e

plotted r ep resen ta t ive curves showing the axial profile of the instantaneous

axial rf e l ec t r i c field for the th ree ca ses of no plasma, n o r m a l p lasma, and

the high-frequency plasmoid. In the case of no p lasma the e l ec t r i c field

-10-1

is unifornci. In the no rma l p lasma

the e lec t r ic field has the same

sign al l along the axis even though

i ts magnitude inay v a r y . In

the plasmoid c a s e , however ,

the sign of the e lec t r i c field

inside the plasmoid is opposite

to that outside the plasmoid.

Thus in F ig . 8 the e lec t r ic

field has two ze ros located

approximately at the plasmoid

dark sheath. In the iminediate

vicinity of these two ze ros

there is a smal l zone within

which the rf e lect r ic field i s

l e s s than a "threshold"value

requ i red to cause gaseous

ionization. These two zones

correspond to the axial pa r t

of the plasmoid dark sheath.

UJ

u. o a: o UJ - J UJ u. oc (/) 3 o UJ

< I -

1

^ V ^ V N O R M A L PLASMA / ^ ^

K NO PLASMA-, /7

I • ^ — ^

^ P L A S M O I D x y

^DARK SHEATH^

1

-

- d / 2 + d/2 AXIAL POSITION

Fig . 8. Axial profi les of rf e l ec t r i c field represen ta t ive of the th ree cases indicated. The d a r k -sheath zones in the plasmoid case occur at the field ze ros which r e su l t f rom the phase r e v e r s a l of the field inside the p lasmoid .

The axial dc field has i ts

maximum value just inside the plasmoid sheath and this is where the e l e c ­

t rons oscillating inside the p lasmoid rece ive thei r tu rn -a round acce le ra t ion .

The sheath can therefore a lso be considered a s the zone within which the

energy of the plasmoid e lec t rons i s below the ionization energy of the g a s .

The osci l la tory motion of the e lec t rons inside the plasmoid is genera l ly

not simple harmonic because mos t of the tu rn-a round acce le ra t ion occurs

only within the na r row sheath. However , a s the conditions of operat ion

in the plasmoid approach the maintaining voltage at low p r e s s u r e and

applied emf as sho-wn in F ig . 6,the ra t io of the sheath width to the p l a s ­

moid -width i n c r e a s e s and the e lec t ron motion i s bel ieved to become m o r e

IV-10-1

nea r ly ha rmon ic .

Equation (1) is applicable to a wide v a r i t y of high-frequency

p l a sma m e c h a n i s m s . At p r e s s u r e s well above the m e a n - f r e e - p a t h l imit

in F ig . 6, the coll is ion damping t e r m v x becomes impor tan t w h e r e a s the 2

q u a s i - e l a s t i c t e r m w x is negligible and the resul t ing equation e n t e r s into P

the theory of the diffusion m e c h a n i s m . At ve ry low p r e s s u r e s , at which

both V X and cj x a r e negl ig ib le , the resul t ing exp re s s ion x = ( e /m) E exp (jwt)

can be used to desc r ibe e i ther undamped free e lec t ron osc i l l a t ions or the

mult ipact ing m e c h a n i s m by appropr i a t e choice of the boundary condi t ions .

The Tonks -Langmui r type of p l a s m a - e l e c t r o n osci l la t ion a s observed in dc-

excited p l a s m a s can be cons idered as another spec ia l case of Eq . (1) in

which E = 0 and v is negl ig ib le . Here the cohering effect of E exp (jut)

d i s a p p e a r s , thus explaining why the osci l la t ions become difficult to o b s e r v e .

By considering both the p lasmoid osci l la t ions and the Tonks -Langmui r o s ­

ci l la t ions a s l imiting ca se s of Eq , (1) which r e su l t main ly f rom sheath

effects , and which differ only to the extent of the p r e s e n c e or absence of a

cohering field, one can now see the just if icat ion of Wood's hypothesis that

the two phenomena a r e ve ry c lose ly r e l a t ed .

PLASMAS IN NONHOMOGENEOUS ELECTROMAGNETIC FIELDS

The achievement of control led the rmonuc lea r r eac t ions

r e q u i r e s — a m o n g other th ings—the isola t ion of an e x t r e m e l y hot dense

p l a sma from the naa te r ia l wal ls of a con ta ine r . The s ta t ic or pulsed m a g ­

net ic fields used for th is pu rpose in mos t expe r imen t s to date have had

the flaw of permi t t ing ins tab i l i t i es to develop with a r i s e t ime of the o r d e r

of a m i c r o s e c o n d . One method of suppress ing the ins tab i l i t i e s i s to r e ­

v e r s e the containing field in a pe r iod shor te r than the r i s e t ime of the i n ­

s t a b i l i t i e s , a method which r e q u i r e s the use of h igh-f requency f ie lds .

Seve ra l poss ib le containment methods using the nonhomo­

geneous fields in r e sonan t cavi t ies have been p roposed . The pr inc ip le of

such containment has an analogy in the format ion of sand p a t t e r n s along the

IV-10-1 27

nodal lines of 2-dimensional vibrat ing p la tes or m e m b r a n e s — t h e Chladni

sand f igures . P l a s m a s a r e l ikewise expected to be concent ra ted or contained

in the vicinity of the nodal points of the e lec t romagnet ic fields in 3-dimensional

cav i t i es .

One type of containment by cavity f ie lds , which has been

known for seve ra l y e a r s , a r i s e s f rom the Lorentz force exe r t ed on an individual

charged par t ic le in an e lec t romagne t i c field. This force on e lec t rons i s de ­

r ivable from a sca la r potential

2 l i e / ^ z \ ,^.

4 mw \ / a v '

where — { E ^ is the t i m e - a v e r a g e d square of the e l ec t r i c f ield, / \ '^^ <E " E / . Such $ potential wel ls a r e known to occur in cavity fields of the

e lec t r i c quadrupole type but the i r containment capabi l i t ies a r e l imi ted to low-7

densi ty p l a smas in which oo < w .

The poss ib i l i ty of containing h igh-dens i ty p l a s m a s in the

nonhomogeneous fields of r e sonan t cavi t ies has r ece ived sporad ic at tention

during the past few y e a r s , but none of the proposed containment s chemes has

shown any firm p romise of scientif ic feas ib i l i ty , to say nothing of economic

feasibi l i ty. An analog exper iment was pe r fo rmed about a yea r ago at

Argonne , however , in which the equi l ibr ium p r o p e r t i e s of dense p l a s m a

cores as sinnulated by copper sphero ids were studied in a r e sonan t cavi ty.

F r o m th is exper iment a new and significant r e su l t e m e r g e d , name ly , that

cavity fields of the magnet ic quadrupole t-ype might have the r equ i s i t e

7 The comparat ive values of co and oo a r e a commonly used c r i t e r ion of

re la t ive p lasma densi ty . When o) < co the applied field will pene t ra te the p lasma; when cop > oj the field is apprec iab ly a t tenuated ins ide the p l a sma . ® A. J . Hatch and J . W. B u t l e r , Bul l . A m . P h y s . Soc. 5 , 324 (I960).

IV-10-1

equi l ibr ium and containment p r o p e r t i e s . More r ecen t ly , t heo re t i ca l

s tudies have demons t ra t ed that for v e r y smal l (point) t e s t s p h e r e s of

rad ius r . the magnet ic quadrupole and h igher magnet ic mult ipole modes

in cavi t ies p o s s e s s potent ial wel ls which can be r e p r e s e n t e d by the s ca l a r

point function

T- 2„„ i „ /y\^ - .„ (E=X^ ). (6)

To the extent that such a t e s t sphere can be cons idered a s r e p r e s e n t a t i v e

of a dense p l a s m a , these modes a r e theore t i ca l ly capable of containing

dense p l a s m a s .

Calculat ions of the rf power n e c e s s a r y to contain t h e r m o ­

nuclear p l a s m a s a t p r e s s u r e s of hundreds of a t m o s p h e r e s in such potent ial

wel ls a r e d i scourag ing . However , p r e s s u r e s of the o r d e r of d y n e s / c m

a r e achievable with re la t ive ly modes t rf power . The effects of such

p r e s s u r e s on p l a s m a s in the m i c r o n p r e s s u r e range should be observab le

provided the i r mani fes ta t ions a r e not o b s c u r e d by competing effects . Thus ,

from the point of view of bas ic p lasma p h y s i c s , the ma in p rob lem i s that

of the in t e rac t ion of p l a s m a s with e l ec t romagne t i c f ields.which now takes

on added i n t e r e s t because of the theore t i ca l ly p red ic ted ex is tence of $

and i h i l l s and wel ls in nonhomogeneous f ie lds . This work i s rece iv ing

continued at tent ion a s a l ikely a r e a for m o r e intensive expe r imen ta l and

theo re t i ca l work in the fu ture .

V-13-1 29

V. THEORETICAL PHYSICS, GENERAL

V-13-1 Spin-Orbit Splitting and Pion Theore t ic L-S Potent ia l (51210-01)

Akito A r i m a , Masao Sugawara , and Tokuo T e r a s a w a '

Concerning the or igin of the sp in-orb i t coupling in nuc le i ,

two of the p resen t authors have recen t ly shown that the s econd-o rde r effect

due to the tensor force i s fair ly l a rge in light nuc le i . The s ame effect has

a l so been shown to give roughly the observed doublet spli t t ings in heavy 2

nucle i . However , the numer i ca l r e s u l t s depend s t rongly on the nuc lea r radi i

a s sumed . If the tensor force suggested by the meson theory i s a s s u m e d

and the nuclear radi i a r e chosen to fit the difference between the Coulomb

energ ies of the m i r r o r nuclei and the e l ec t ron -nuc leus s c a t t e r i n g , the

doublet spli t t ings due to the t enso r force amount to one-fifth to one-half the

observed v a l u e s . If the nuc lear rad i i a r e reduced by 20% or l e s s , the c o r r e s ­

ponding effect can produce the obse rved v a l u e s . T h e r e f o r e , we have s t r e s s e d

the impor tance of the t enso r force and have concluded that the t e n s o r force 1

explains considerable amounts of the obse rved sp l i t t ings .

Depar tment of Nuclear P h y s i c s , Jajjan Atomic Energy R e s e a r c h Ins t i tu te , T o k a i - m u r a , Iba rak i -ken , Japan ,

1

T. T e r a s a w a , P r o g r , T h e o r e t . P h y s . (Kyoto) 2 3 , 87 (I960); A . A r i m a and T . T e r a s a w a , P r o g r , Theore t , P h y s . (Kyoto) 23 , 115 ( i960); A, A r i m a to be published in Nuclear P h y s . 18. This has a l s o been inves t igated by Wigner and Feingold: E . P . Wigner , Symposium on New R e s e a r c h Techniques in P h y s i c s , Rio de J a n e i r o , 1952; A. M. Fe ingold , P h y s , Rev . 101, 258 (1956). 2

S. Takagi , W. W a t a r i , and M. Yasuno, P r o g r . T h e o r e t , P h y s . (Kyoto) 22, 549 (1959); B . Jancovic i , P r o g r . T h e o r e t . P h y s , (Kyoto) ^ , 585 (1959).

L. Hulthen and M, Sugawara , Handbuch der Phys ik (Edwards B r o t h e r s , Ann A r b o r , 1943) Vol. 39. Concerning the pion theore t i c po ten t i a l s , the works b e ­fore 1956 a r e s u m m a r i z e d in Suppl, P r o g r . T h e o r e t . P h y s . Ill (1956), edi ted by M. Take tan i .

* B . C. Car l son and I . T a l m i , P h y s . Rev, 96 , 436 (1954).

^ R. Hofs tadter , R e v s , Modern P h y s . 28 , 214 (1956).

v - 1 3 - 1

The purpose of the p r e sen t note i s to r e p o r t that the pion-

theore t i c L - S potential can give other la rge fractions in such a way that the

o v e r - a l l effects just explain the observed spli t t ings without changing nuc lear

r a d i i .

It ha s been known that a strong L-S potent ia l can produce l a rge

doublet spl i t t ings in nuc le i . Severa l au thors have in fact shown recen t ly that

the phenomeno logical L-S potent ial due to G a m m e l and Tha l e r can give l a rge S 9

sp l i t t ings , even values which a r e much g r e a t e r than obse rved . > Here a r i s e s

the quest ion of how la rge the spl i t t ings due to the p ion- theore t i c L-S potential

can b e . This potential i s weaker than tha t of Gamnnel and T h a l e r , but s t i l l

not negligibly s m a l l . In th is note we a s s u m e the L-S potent ia ls tha t were

der ived recen t ly by Okubo and one of the p r e s e n t a u t h o r s , ' We a l so have

re inves t iga ted the G a m m e l - T h a l e r potent ia l a s a check on the prev ious work .

We consider those light nuclei which a r e c losed shel ls plus

or minus one nucleon: He , N , and O . As for the nuc lea r wave functions,

the ha rmon ic osc i l la tor mode l i s a s s u m e d for s impl ic i ty in ca lcu la t ions .

The f i r s t - o r d e r per tu rba t ion exp re s s ions for the doublet spl i t t ings a r e wr i t ten as

6

J . P . El l io t t and A . M. L a n e , P h y s . Rev . 96 , 1160 (1954); R . J . Bl in-Stoyle , P h i l . Mag . 4 6 , 973 (1955); C. A . P e a r s e , P h y s . Rev . 106, 545(1957); B . P . Nigann and M. K. Sundaresan , P h y s . Rev . I l l , 284 (1958). ^ J . G a m m e l and R, T h a l e r , P h y s . Rev . m , 291 (1957); JL_07, 1337 (1957). ® J . Sawicki and R. Fo lk , Nuclear P h y s . j j ^ , 368 (1959); J . Sawicki , Nuclear P h y s . J ^ , 350 (1959).

G. E . Tauber and T - Y . Wu, Nuclear P h y s . 16 , 545 ( I960) . The au thor s a r e v e r y grateful to P r o f e s s o r s T -Y. Wu and G. E . Taube r for informing them of the r e s u l t s of the i r work before publ icat ion.

^° M. Sugawara and S. Okubo, P h y s . Rev . 117, 605 and 611 ( I960) .

Recent ly M. Taketani ajid S. Machida der ived the L-S potent ia l due to the pion t heo ry . The au thor s would l ike to e x p r e s s the i r thanks to P r o f e s s o r S. Machida for his k indness in informing them of the r e s u l t s .

V - 1 3 - i 31

AEp = - I ( 1 P | V _ | l p ) (1)

(2)

and

AE = 4 ( i p I V_ 1 Ip) -I (Zp I V. I 2p) M (U I V_ I If) -f (id I V I Id) , (3)

where E q s . (1) and (3) refer to the c a s e s of one nucleon outside closed shel ls

in the orbi ts Ip and Id , r e spec t i ve ly , and Eq. (2) r e f e r s to the case of 1 5 1 5

N or O . In these equations

oc

( ^ i | V ^ | n ' i ' ) = J R ^ ^ ( r ) R ^ , ^ , ( r ) V ^ ( r ) r ^ d r , (4) r

c

where R (r) is the re la t ive wave function defined in r e f e r e n c e 1 and V, (r) n i ±

a r e the coefficients of the L-S ope ra to r in the two-body nuc lea r potent ial in

the t r ip l e t even and odd s t a t e s , r e spec t i ve ly , L and S being the r e l a t i ve

orbi ta l and total spin angular momen tum o p e r a t o r s of the two-nucleon

sys t em. Since V^ (r) d iverges v e r y badly as r goes to z e r o , and a l s o the

re la t ive wave function R (r) of the two nucleons should van ish inside the n i

h a r d - c o r e r a d i u s , we have a s sumed a ze ro cutoff in Eq . (4) at r equal to

th ree tenths of the Compton wavelength of the pion.

The r e s u l t s a r e sho-wn in F ig , 9 , as functions of the

paranaeter p which i s p ropor t iona l to the nuclear r ad ius and is defined in

re fe rence i . If the wave functions of the pure ha rmon ic osc i l la tor model

a r e a s s u m e d , an exper imenta l value p can be de t e rmined f rom the differ-4

ence between the Coulomb ene rg ies of the m i r r o r nuclei . We have ex­

tended calculat ions toward the sma l l e r side of the nuc lea r r ad ius s ince one

v - 1 3 - 1

1.9 2.0 2.1 2.2 /> (IO"'^cm)

2.4

Fig . 9. F i r s t - o r d e r doublet splittiiig AE for He^ and L i ^ , N^^ and O , and O"*- and F ^, aga ins t p which is propor t ional to the nuclear r a d i ­us and defined as (2 /v)2 and v = ma)/-ii, m being the nucleon m a s s and u) the angular frequency of a harmonic osc i l l a to r . Ver t ica l l ines indicate the value of p that i s de termined from the difference between the Coulomb energies of the m i r r o r nuc le i . The G-T curves refer to the Gannmel-Thaler potential ( reference 7) and ps and pv curves a r e the effects of the pion theore t i ca l potent ials ( r e ­ference 10) with p s - p s and ps-pv couplings, r espec t ive ly . Dotted lines a r e second-orde r effects due to the pion theore t ica l tensor force and have been taJcen from reference 1 Exper imenta l values a r e indicated by horizontal l ines (or a shaded band).

can argue that taking p < p m a y

be reasonable because of the a d ­

mix tu re of higher s ta tes due to

h i g h e r - o r d e r per turba t ions and

the sho r t - r ange cor re la t ion .

It is v e r y i n t e r ­

esting that the L-S potential sug­

gested by the pion theory can

produce the la rge doublet sp l i t t ings ,

especia l ly in the ps -pv c a s e . Even

in the p s - p s c a s e , the contribution

has the same o rde r of magnitude

a s that due to the tensor fo rce .

T h e G a m m e l - T h a l e r L-S potential

s e e m s to give split t ings that a r e

somewhat too l a rge . The even-

state L-S in teract ion is cons ide r ­

ably l e s s impor tant in producing

doublet spli t t ings than the odd-s ta te

in te rac t ion . There fo re , a s far a s

the odd-s ta te L-S potential is

a t t r a c t i v e , the sign of the splitting

is c o r r e c t , and this is the case in

a l l potentials assunmed. ' B e ­

cause of the shor t - range na ture

of the L-S potent ia ls , one might

think that our zero cut-off procedure

in Eq . (4) might lead to a se r ious

overes t imate compared -with the

case in which a proper corre la t ion

-1 33

function is introduced into the wave function R (r) in Eq . (4). We have , n i

g

t he re fo re , compared our r e su l t with that of Tauber and Wu, who used the

G-T potential and introduced the cor re la t ion function. Our r e su l t is only

about 10% la rge r than the i r r e s u l t in N at the same p. There fore our r e s u l t

cannot be too much of an o v e r e s t i m a t e . We have a l so e s t ima ted the magnitude

of the second-order effect. The effect can be calcula ted in the same way as

is outlined in the previous p a p e r s . A nucleon inside the closed shel l i n t e r ­

ac t s -with the outside nucleon and both can jump into higher Orbits . The

second*order cor rec t ion to the doublet splitting is finally given by

< ' = - | S s d r ('p|v l N . i p ) Y i - ^ j ,

where co is the angular frequency of a ha rmonic osc i l l a to r . The co r r ec t ion 12)

AE is es t imated only for the G-T potent ial and at p = 2 . 4 . It has the

opposite sign to AE given by Eq . (1) and is about 25% of AE , or l e s s . P P

We may hope that the higher o rde r co r r ec t ions would not affect our r e s u l t s

d ras t i ca l ly .

As the conclusion, the doublet spl i t t ings a r e adequately

explained in a l l th ree nuclei cons ide red in t e r m s of the combinat ion of the

s econd-o rde r effect due to the t ensor force and the f i r s t - o r d e r effect due to 3 I D

the L-S potent ial , both of which a r e suggested by the p r e sen t pion t h e o r y ,

if the ps-pv coupling is a s s u m e d and a l so the nuc lear r ad ius i s chosen at p .

The spli t t ings obtained from the p s - p s theory s e e m to be somewhat s m a l l ,

while those from the G a m m e l - T h a l e r potential s e e m too la rge for the s ame

p. However , the sma l l e r p may be m o r e r e a s o n a b l e , a s we have d i scussed

be fo re . T h u s , it i s cer ta in ly p r e m a t u r e to ru le out the p s - p s case on this

b a s i s a lone . We a lso r e c a l l that the der iva t ion of the L-S potent ial in the

p s - p s coupling contains ce r t a in ambigu i t i e s . T h e r e f o r e , we cer ta in ly cannot

d i sc r imina te the p s - p s and p s - p v couplings. Our posi t ive s ta tement is that

the she l l -model doublet spl i t t ings do not indicate any u rgen t need for introducing

v-13 -1 V - 4 2 -

phenomenological L-S potent ials bes ides those a l r eady expected from the

pion theory .

V-42-1 Geome t r i c Theory of Charge (51151-01)

H. Eks te in

The "explanat ion" of e l ec t r i c i ty has been an age-o ld

d r e a m of p h y s i c i s t s . Students of the h i s to ry of phys ics know about one-

fluid and two-fluid t heo r i e s of e lec t r i c i ty and about mechan ica l e ther

t h e o r i e s . The path of phys ics i s s t rewn -with skele tons of such t h e o r i e s .

After many f a i l u r e s , phys ic i s t s have r e s igned t h e m s e l v e s to consider e l e c ­

t r i c i ty a s a phenomenon of i t s o-wn, not reduc ib le to off- explainable in t e r m s

of other phenomena. But , a s cocks cannot stop crowing, so phys ic i s t s

cannot stop trying to simplify the p ic tu re of n a t u r e , i , e , , to d e c r e a s e the

number of sepa ra t e a s sumpt ions needed.

The p r e sen t paper t r i e s to deduce the m o r e b a s i c a spec t s

of e lec t r i c i ty from such p r i m e pr inc ip les a s r e l a t i v i s t i c covar iance and

pr inc ip les of quantum m e c h a n i c s . What a r e these ba s i c a s p e c t s ? F i r s t ,

the exis tence of two dis t inc t t-ypes of p a r t i c l e s , such a s e lec t rons and p o s i ­

t r o n s , tha t have ident ica l mechan ica l p r o p e r t i e s . Second, the exis tence

of a conserved quantity (the charge) which would be jus t the difference

between the n u m b e r s of posi t ive and negative p a r t i c l e s if t h e r e were only

e lec t rons and pos i t rons in the wor ld , but which h a s a m o r e subtle meaning

in the p r e s e n c e of other p a r t i c l e s such a s p ro tons and an t ip ro tons . T h i r d ,

the curious fact tha t the charge never changes a s the r e s u l t of any m e a s u r e ­

men t . This is m o r e than a conservat ion p r o p e r t y , for the energy (which is

conserved) may well be changed by an ex te rna l measu r ing s y s t e m . Th i s

42-1 35

"superconse rva t ion" p roper ty of e l ec t r i c charge is exp res sed by a " s u p e r -

select ion r u l e . "

The main assumpt ion is covar iance of na tu ra l laws under

the full Lorentz group^ including space and t ime r e v e r s a l . This a s sumpt ion ,

together with some of the bas ic pr inc ip les of quantum m e c h a n i c s , i s s u r p r i s i n g ­

ly powerful for the ana lys i s of one-par t i c le s y s t e m s , in that it r e s t r i c t s the

number of poss ib i l i t i e s . One of the oldest examples of this power is the

p red ic t ion that spins can be only in tegra l or ha l f - in tegra l—not of any i n t e r ­

media te va lue . The type of s ta tements in a theory of this kind ("Wigner ism"

for short) i s not mainly "if A , then B , " a s in dynamical t heo r i e s ( e . g . ,

Newton's equat ions) . It is r a t h e r : "A or B may ex i s t , but not C" ( e . g . ,

the spins may exist only with the va lues mentioned above). This can be

provided by p r inc ip les that r e s t r i c t the number of a p r i o r i poss ib i l i t i e s . The

purpose of the game isunot jus t to postulate a scheme that is consis tent with

e x p e r i m e n t , for the s imples t such s ta tement would be: "Anything may e x i s t . "

The s u c c e s s of such a theory is m e a s u r e d by the number of conceivable

objects forbidden by theory provided tha t , in fact , they a r e not obse rved .

This should be a c t o m p l i s h e d by use Of the sma l l e s t poss ib le number of

p r inc ip les or a s s u m p t i o n s . A figure of m e r i t of the theory might be

number of excluded poss ib i l i t i es number of a s sumpt ions (or pr inc ip les )

A l e s s quanti tat ive c r i t e r ion used by judges in theory-beau ty contes ts is

the " s impl i c i ty" or "e legance" or "plausibi l i ty" of the p r i n c i p l e s . It i s

indispensable to make such a r e q u i r e m e n t , because it is technical ly always

possible to s u m m a r i z e any number of s t a tements by the symbolic equation

X = 0.

The set of p r inc ip les which we use can c la im plausibi l i ty

because each of them i s (almost) s epa ra t e ly and d i rec t ly ve r i f i ab le , i . e . ,

the observab le impl ica t ions of the p r inc ip les can be t e s t ed m o r e or l e s s

V-42-1

d i rec t ly . This i s v e r y different from a quantum field theory , for which the

set of a l l a ssumpt ions may (or may not , we do not know) lead by a compl i ­

cated ma themat i ca l p rocedure to predic t ions comparable and consistent with

exper imen t .

F u r t h e r m o r e , a g rea t effort is made to accept only the

m o s t gene ra l assumpt ions that imply observed r e s u l t s . A good example of

th is effort i s the h is tory of the ma thema t i ca l formulat ion of s y m m e t r y in

Hi lber t space . It was or iginal ly a s s u m e d that ope ra to r s mus t form a r e ­

presenta t ion of the s y m m e t r y g roup . This assumpt ion indeed impl ies the

observed s y m m e t r i e s of observable quan t i t i e s , but it i s not the m o s t gene ra l

assumpt ion that accompl i shes this p u r p o s e . T h e r e f o r e , the assumpt ion was

modified to loosen the connection demanded between group and o p e r a t o r s .

The cu r r en t ly accepted r e q u i r e m e n t is that the o p e r a t o r s m u s t form a co-

r e p r e s e n t a t i o n , up to a factor of modulus uni ty , of the s y m m e t r y g roup .

This means (1) that instead of mimicking the group^multiplication table

^ 1 ^ 2 - ^ 1 2

(la)

U(L^) U d . ^ ) = U(L^2)

the o p e r a t o r s U (L) m u s t only satisfy an a lgebra

U ( L , ) U ( L 3 ) = e ^ * < ^ V ' ^ ' - U ( L 3 . 2 ) V (lb)

(2) that the o p e r a t o r s do not have to be un i ta ry but that some of them may

be an t iun i ta ry . That i s , ins tead of having the l inear p rope r ty

U(af + bg ) = a U f + b U g

(where a , b a r e numbers and f, g a r e v e c t o r s in Hi lber t space) , the opera­

t o r s m a y have the ant i l inear p rope r ty

V - 4 2 - i "

U(af + bg)= a Uf + b Ug .

This less r e s t r i c t i v e ma themat i ca l r e q u i r e m e n t a l so impl ies the observed

s y m m e t r y p rope r t i e s but , being less r e s t r i c t i v e , al lows for m o r e poss ib i l i ­

t i e s , some of which we know to be r ea l i zed . The cur ren t ly accepted fornaalism

may st i l l be too r e s t r i c t i v e . At any r a t e , one of the main preoccupat ions of

Wigner i s t s (or Wigner ianers ?)is the avoidance of r e s t r i c t i o n s imposed for

ma themat i ca l convenience r a t h e r than by physical p r i nc ip l e s .

One of the main assumpt ions is that one-par t i c l e s ta tes a r e 1

to be d e s c r i b e d b y i r r e d u c i b l e r e p r e s e n t a t i o n s of the L o r e n t z g r o u p . T h e

j u s t i f i c a t i o n for t h i s a s s u m p t i o n i s a s f o l l o w s . It can b e shown (a) t h a t the

o p e r a t o r P P ( w h e r e the P a r e t h e g e n e r a t o r s of t h e s p a c e - t i m e t r a n s -|x p. Il­

l a t i o n s ) c o m m u t e s wi th a l l g r o u p o p e r a t o r s , and (b) t ha t in i r r e d u c i b l e r e ­

p r e s e n t a t i o n s ( S c h u r ' s Lemma) s u c h a n o p e r a t o r i s a c o n s t a n t , i . e . ,

P P = - m .

I t fo l lows t h a t t he t i m e - t r a n s l a t i o n o p e r a t o r P c a n , in an i r r e d u c i b l e r e ­

p r e s e n t a t i o n , b e e x p r e s s e d a s a funct ion of t h e s p a c e - t r a n s l a t i o n o p e r a t o r s

^k = 2 i

^0 = (^k^k ^ - ) 2

In this c a s e , the t i m e - t r a n s l a t i o n is the re fore a function of space - t r ans l a t i ons ,

and the re fore any s ta te

1

A ternminological note: (1) While , as mentioned above , we a r e now looking for co rep resen ta t ions up to a factor r a t h e r than for r e p r e s e n t a t i o n s , we will s t i l l use the shor t word " r e p r e s e n t a t i o n . " To avoid ambigui ty , we may refer to " p r o p e r r ep re sen ta t ion" when we rea l ly mean r ep re sen t a t i on . (2) F r e n c h phys ic i s t s have long r e f e r r e d to the Loren tz group as the Po incare g roup . Fo r N A T O a m i t y a s well a s for h i s to r i c j u s t i c e , we should accept this change of n a m e , for Loren tz had rea l ly nothing to do with the g roup . The c red i t may be split between Po inca re and E ins t e in , but so many things bea r E ins t e in ' s name that it i s only fair to a t t r ibute the group to P o i n c a r e .

V - 4 2 - i

- ^ 0 ^

^

which develops in t ime t from an ini t ia l s tate \\i may be obtained a l so by

an appropr ia te l inear combination of space - t r ans l a t ed vec to r s

e ijj

Stated crudely: an ini t ial s ta te de sc r ibed by an i r r educ ib le r ep resen ta t ion

does not "essen t i a l ly" change during t ime-deve lopmen t , because the la ter

s t a tes a r e just l inear combinations of the space- t rans labes of the ini t iaT

s t a t e . This i s (almost) an experimiental tes t of i r r educ ib i l i ty .

Stable one -pa r t i c l e s ta tes mee t th is specification; two-

par t i c l e s ta tes do not , because—for i n s t a n c e — n o space - t r ans l a t i on of an

e l ec t ron -pos i t ron sys tem will produce gamma r a y s . A l so , unstable

p a r t i c l e s do not r ea l ly m e e t the r e q u i r e m e n t , because (as another example)

no space - t r ans l a t i on of a TT will produce gamma r a y s . N e v e r t h e l e s s ,

it i s u sua l to consider unstable pa r t i c l e s a s being approximate ly desc r ibed

by i r r educ ib le r e p r e s e n t a t i o n s . T h u s , the p r i m a r y subjects of s y m m e t r y

theory a r e the s imples t s y s t e m s (one-par t i c le s ta tes) that a r e de sc r ibed

by i r r educ ib l e r e p r e s e n t a t i o n s . One should expect that the enumera t ion

of the i r r educ ib l e r e p r e s e n t a t i o n s of the Po inca re group will p red ic t the

g e n e r a l p r o p e r t i e s of a l l p a r t i c l e s .

To what extent has th is expectat ion been r ea l i z ed? One

of the str iking facts about e l emen ta ry p a r t i c l e s is that they often occur in

doub le t s—elec t rons and p o s i t r o n s , posi t ive and negative p ions , e t c .

Until r e c e n t l y , the only i r r educ ib l e r e p r e s e n t a t i o n s known a t t r ibuted only

one l inear ly independent s ta te to a sp in less pa r t i c l e with given m a s s and

m o m e n t u m , two to a spin-|^ p a r t i c l e , and , m o r e gene ra l l y , 2s + 1 l inear ly

independent s ta tes to a par t i c le with spin s. If this were t r u e , the in ­

t roduct ion of e l ec t r i c charge a s a s epa ra t e and super imposed entity would

v - 4 2 - 1 39

indeed be indispensable—or e lse how can the exis tence of two mechanica l ly

equal copies for the e lect ron be explained?

Of c o u r s e , pure s-ymmetry theory does not exclude the

possibi l i ty of two i r reduc ib le r ep resen ta t ions with exactly equal m a s s and spin ,

but this would be an acc ident . If we wish to obtain nontri-vial r e s t r i c t i o n s from

s-ymmetry t heo ry , we mus t adopt the pr inc ip le : acc idents don' t happen.

For tuna te ly , the complete theory of s y m m e t r y is r i c h e r ,

and it does provide for the possibi l i ty of two such s t a tes ; in technical language,

there exist i r reduc ib le r ep resen ta t ions in which the re a r e two l inear ly inde­

pendent vec to r s with given m o m e n t u m , mass^and spin project ion on the m o m ­

entum. T h u s , we can explain the exis tence of posi t ive and negat ive pa r t i c l e s

with equal mechan ica l p r o p e r t i e s .

What i s m o r e impor tan t i s that the re a r e only two such

l inear ly independent s ta tes poss ib le in an i r r educ ib le r e p r e s e n t a t i o n . This

(on the assumpt ion that we a r e just if ied in equating the charge doublets to the

doublets predic ted by the theory) p r ed i c t s that the re can be only double ts ,

and not t r i p l e t s , quadrup le t s , e t c . This predic t ion is indeed in ag reemen t

with exper imen t , although approx imate mul t ip le ts of higher o r d e r ex i s t ,

e . g . , the neu t ra l pion in addition to the two charged ones—but i t s m a s s is

not quite the same .

It is encouraging that pure ly geome t r i c cons idera t ions

explain the dual ( ra ther than t r ip le or sextuple) na ture of e l ec t r i c i t y . How­

e v e r , the "doubled" r ep re sen ta t ions of the theory a r e too n u m e r o u s ; they

allow for too many poss ib i l i t i e s .

Another phys ica l pr inc ip le will be needed to obtain non-

t r iv ia l r e s u l t s . After the painful exper ience of pa r i t y -nonconse rva t ion , mos t

phys ic is t s will ag r ee that invar iance p r inc ip les should be t e s t ed exper imenta l ly

before they a r e r a i s e d to the dignity of fundamental pos tu l a t e s . But , before

being ver i f ied ,a pr inciple mus t be e x p r e s s e d in an exper imenta l ly ver i f iable

way. The pr incip le of t i m e - r e v e r s a l i n v a r i a n c e , a s o rd ina r i ly s t a ted , does

v - 4 2 - 1

not satisfy this r e q u i r e m e n t , and an addit ional or m o r e complete formulation

is needed.

To see how t i m e - r e v e r s a l differs from other i n v a r i a n c e s ,

let us r e s t a t e c lea r ly what i s mean t by invar iance or s y m m e t r y of na tu ra l

l aws . This s ta tement will avoid the use of coord ina tes . These a r e somet imes

useful , but always a r b i t r a r y , conventions and thei r introduction at this point

tends to obscure the s imple in t r in s i c meaning of the s t a t e m e n t s .

Given a s ta te ^ specified by a complete set of m e a s u r e ­

men t s at one t ime (say, t = 0) , t h e r e ex i s t s an image state ig =. U (L)TE

induced by an invar iance e lement L. In our s c h e m e , L includes the set of al l

l eng th -p rese rv ing mappings of s p a c e - t i m e into i tself . The s ta te U (L)^ is

obtained from •$ by making a ce r t a in t-ype of change in the equipment which

produced •$, th is change being de te rmined by L a s follows. If L is a

t r a n s l a t i o n , the equipment i s to be t r a n s f e r r e d to another point -without

ro ta t ion . If L i s a space - ro t a t i on , the equipment i s to be ro t a t ed -with r e ­

spect to i t s fo rmer posi t ion. If L i s a " p r o p e r " Lorentz t r a n s f o r m a t i o n ,

the producing equipment i s to be put on a moving suppor t . The predic t ion

of the invar iance pr inciple is then that a l l m e a s u r e m e n t s made a t a l l t imes

on ^ will be r e l a t ed to those made on ^ in the s imple -way impl ied by the

g e o m e t r i c meaning of L, Fo r i n s t ance , the obse rved va lues on U(Tr)TS

(Tr being a space t rans la t ion) will be numer i ca l ly equal at points T r P to

those made a t points P in the or ig ina l exper iments on ^, The impl icat ion

of other invar iance operat ions will be sufficiently c lea r by analogy to t h i s .

The one except ion to th i s opera t ional i n t e rp re t a t i on of

invar iance is t i m e - r e v e r s a l . What i s the ins t ruc t ion for the p r epa ra t i on

of a s ta te U ( T ) T E ? One occas ional ly finds textbook s ta tements about "let t ing

t ime run backward" but th is i s c l ea r ly a m a n n e r of speaking and not an

opera t iona l in s t ruc t ion .

Consider f i r s t the c l a s s i ca l c a s e . The s t a t emen t i s :

given that a c l a s s i ca l s ta te ^ . (specified by pos i t i ons , m o m e n t a , and possibly

in t r in s i c angular momenta of a l l p a r t i c l e s at one t ime) evolves into a s tate

v - 4 2 - 1 41

"ij. after a t ime t , then there ex is t s a s tate T-^. which evolves into a s ta te f f

T^. during t ime t . The s ta tement i s empty un less an ins t ruc t ion for the p r e ­

para t ion of any state T ^ corresponding to a given ^ is provided. The s t a t e ­

ment would be empty if this ins t ruc t ion had to re ly on a specific t h e o r y , since

symmet ry s ta tements should be imposed on a theory , and not be deduced from

i t . In fact, the ins t ruct ion is easy to formulate : T ^ is obtained from <k by

revers ing a l l momenta and angular momenta and leaving the posi t ions unchanged.

In th is pure ly emp i r i c a l f o r m , the s ta tement is ve r i f i ab le ,

and has been verif ied to a la rge extent . The essen t ia l point i s that a d i rec t ly

verif iable s ta tement of t i m e - r e v e r s a l invar iance has to be made in t e r m s of

a geomet r i c operat ion (180° ro ta t ion) .

For at leas t a r e s t r i c t e d set of ( improper) quantum

mechanica l s t a t e s , the c l a s s i ca l s t a tement can be immedia te ly adapted: F o r

a one-par t i c le s tate which is a s imul taneous eigenvector of momen tum p and

of the project ion s of the angular momen tum (s = J -p , / p ) on i t , the t i m e -

r e v e r s a l opera tor is equivalent to a 180 rota t ion -with r e s p e c t to a d i rec t ion

no rma l to p , i . e . ,

U(T)ife = e ' '^U(R ) if (2) p , s p p , s

- p , s .

In this form the s ta tement is in a g r e e m e n t with observa t ions a s well a s

with al l t heor i e s of e l emen ta ry p a r t i c l e s cons idered in the p a s t . In the case

of the "doubled" r e p r e s e n t a t i o n s , however , not a l l s imul taneous e igenvec­

t o r s of p and s satisfy Eq, (2) and the re fo re we have to impose it a s a c o n ­

dition on s t a t e s .

The fact that some v e c t o r s in Hi lber t space do not r e ­

p r e s e n t physical ly rea l i zab le s t a t e s i s not new but s t i l l unfamil iar to m o s t

phys i c i s t s . In conventional quantum m e c h a n i c s a s formula ted by D i r a c or

v - 4 2 - 1

von Neumann, the re was a one- to-one assoc ia t ion between the r a y s of Hi l -i6

be r t space ( i . e . , the vec to r s mul t ip l ied by any phase e , s ince phases

a r e not observable) and observable "pu re s t a t e s . " This i s p a r t of the

conventional set of a x i o m s .

However, this axiom cannot be c o r r e c t . It i s known that

a ro ta t ion through 360 produces a vec tor - ^ for a spin-j^ s y s t e m , but a

vector +^ for a sp in less sys tem such a s the vacuum. By i tself , th is i s not

dis turbing since phase fac tors ±1 a r e not observab le . But if we cons ider

a vec tor ^ + it. ,^ , a l inear combination between the vacuum state and a

state of spin j , then a rotat ion through 360° produces ^ - • $ . . - , , which

is not equal to the or iginal vec tor even up to a factor of unit modu lus . Yet,

a rotat ion through 360 cannot poss ib ly change the physica l na tu re of a

system.4 We mus t conclude tha t , although ^ +•>$:. ,^ i s a wel l -def ined

vector in Hi lber t s p a c e , it does not c o r r e s p o n d to a r ea l i zab le s t a t e . This

does not exclude the exis tence of a sy s t em that somet imes gives the resu l t

0, and at o ther t i m e s the r e s u l t j for the obse rved value of the angular

m o m e n t u m . Such a sys tem might be de s c r i be d by a s t a t i s t i ca l ( incoherent)

mix tu re of spin-0 and spin~-|- s t a t e s . Con t r a ry to conventional quantum

m e c h a n i c s , the Hi lber t space of phys ics has holes in which v e c t o r s languish

without the dignity of s t a t e s .

Our p r i nc ip l e , which r e q u i r e s an exper innental ver i f iabi l i ty

of t i m e - r e v e r s a l s y m m e t r y , r e l e g a t e s many vec to r s to th is pu rga to ry of

n o n - s t a t e s . In p a r t i c u l a r , a l l but one of the "doubled" r e p r e s e n t a t i o n s tu rn

out to have no s ta tes a t a l l , and can be d i s c a r d e d . This i s the d e s i r e d r e ­

sult of a phys ica l pr inciple in a s y m m e t r y theory : it r e s t r i c t s the number

of p o s s i b i l i t i e s .

The remain ing "doubled" i r r educ ib l e r e p r e s e n t a t i o n has

some s t a t e s , but mos t of i t i s in p u r g a t o r y . In technica l language , t h e r e

i s a super se lec t ion ru le within the i r r e duc ib l e r e p r e s e n t a t i o n . Two sub-

s p a c e s , each of which i s i r r educ ib l e under the r e s t r i c t e d P o i n c a r e g r o u p .

v - 4 2 - 1 43

a r e separa ted by super se lec t ion, i . e , , l inear combinations of v e c t o r s from

the two subsp)aces a r e not s t a t e s . Obviously, we identify the v e c t o r s in

the two subspaces with posit ive and negative p a r t i c l e s , r e spec t ive ly , and

we have—from genera l pr inc ip les only—deduced or "p red ic ted" the supe r -

select ion which is consistent with obse rva t i ons .

The superse lec t ion ru le can be extended deductively to

many-body s t a t e s . It then s ta tes that sys t ems having different values of

the difference between the number of posi t ive and of negative p a r t i c l e s ( i . e . ,

sys tems for which n - n ?£ n - n ) a r e sepa ra ted by supe r se l ec t ion .

One obtains a l so the " supe rconse rva t ion" of a quantity Q (charge) which is

p ropor t iona l to the difference between the number s of posi t ive and negative

p a r t i c l e s .

The two one -pa r t i c l e subspaces a r e connected by the

opera tor that r e p r e s e n t s space i nve r s ion , i . e . , the m i r r o r image of a

posi t ive pa r t i c l e is a negative p a r t i c l e , and the m i r r o r image of a neut ron

is an an t ineut ron . One should expec t , on the b a s i s of this s y m m e t r y

p rope r ty , that in some exper imen t s the posi t ive par t i c le will r e v e a l i t s lack

of m i r r o r s y m m e t r y .

In one sense then, the pure s y m m e t r y theory p red ic t s

the Wu exper imen t . I t i s i ron ic to ref lec t that if these cons idera t ions on

the bas i s of a s s u m e d full r e l a t i v i s t i c s y m m e t r y had been c a r r i e d out in

1940—and the re is no r e a s o n why this could not have been done—physic is t s

would have expected r e s u l t s of the "pa r i ty -nonconse rva t ion" t-ype just b e ­

cause of invers ion symimetry of n a t u r a l l a w s .

Work on th is p ro jec t has been completed and the r e s u l t s

have been published in a r e p o r t ent i t led: " G e o m e t r i c Theory of C h a r g e , "

H. Eks t e in , P h y s . Rev . 120, 1917 = 1924 (December 1, I960) .

m

PUBLICATIONS SINCE THE LAST REPORT

PAPERS

MEASUREMENTS OF SPATIAL ASYMMETRIES IN THE DECAY OF POLARIZED NEUTRONS

M. T . Burgy , V. E . Krohn , T. B . Novey, G. R.. Ringo, and V. L. Telegdi . (Pro jec t 1-123)

P h y s . Rev . 120, 1829-1838 (December 1, I960) .

GEOMETRIC THEORY O F CHARGE

P h y s . Rev . | ^ , 1917-1925 (December 1, 1960).

NUCLEAR DEFORMATION IN THE SPHEROIDAL SHELL MODEL

Kiuck Lee and D. R. Ing l i s , , . . . . . . . . , . . . , , . , , (Pro jec t V-3) Phys , Rev , jL20, 1298-1302 (November 15, I960) .

LIVING AND WORKING AT HARWELL

Alexander Langsdorf , J r . Phys ics Today 13 (11), 16-19 (November I960) .

NUCLEAR SPIN AND HFS OF Ge^^

W. J . Childs and L . S. Goodman. , , . . (P ro jec t 1-80) Bul l . A m . P h y s . Soc, 5 , 411 (November 25 , I960),

LEFT-RIGHT ASYMMETRY IN THE SCATTERING OF POLARIZED NEU­TRONS FROM LIGHT NUCLEI

A . J . Elwyn and R. O. Lane , . . . , , . . . . . ( P r o j e c t 1-18) Bul l . A m . P h y s . Soc, 5, 410 (November 25, I960) .

MOSSBAUER E F F E C T IN FERROMAGNETIC ALLOYS O F Sn^^^ II

S. S. Hanna, L , M e y e r - S c h u t z m e i s t e r , R. S. P r e s t o n , and

Bul l . A m . Phys , Soc, 5 , 429 (November 25 , I960) .

DECAY OF Tm^"^^

R. G. Helmer and S. B . B u r s o n . (Pro jec t 1-33) Bu l l . A m . P h y s . Soc. _5, 425 (November 25 , i960) .

6 l T 3 T9 R 5 1 2 3 LIFETIMES OF EXCITED STATES O F Ni , Ga , B r , Rb , AND Sb

R. E . Holland, F . J . Lynch, and E . N. Sh ip ley . . (P ro jec t 1-14) Bul l . A m . P h y s . Soc. 5 , 424 (November 25 , i960) .

45

ISOTOPIC IDENTIFICATION OF NEUTRON RESONANCES IN Cd FROM CAPTURE GAMMA-RAY SPECTRA

H. E . Jackson and L. M. Bol l inger . . „ . , (Projec t 1-3) Bul l . A m . Phys . Soc ._5 , 409 (November 25 , I960) .

ANALYSIS OF THE STRUCTURE OF NUCLEI FROM (d,t) REACTIONS

B . J . R a z , B . Ze ldman , and J . L, Y n t e m a . . . . . . (Pro jec t 1-22) Phys . Rev. 120, 1730-1737 (December 1, I960).

REPULSION OF ENERGY LEVELS IN COMPLEX ATOMIC SPECTRA

Norbe r t Rosenzweig and Char l e s E . P o r t e r . . . . . . (Pro jec t V-15) P h y s . Rev . _1_20, 1698-1714 (December 1, 1961).

SYSTEMATIC ERRORS IN THE DIRECT MEASUREMENT O F NUCLEAR LIFETIMES IN THE SUB-MILLIMICROSECOND REGION

E . N. Shipley, F . J . Lynch, and R. E . H o l l a n d . . . (Pro jec t I-14) Bul l . A m , Phys , Soc. _5, 424 (November 25, I960) .

CAPTURE GAMMA RAYS FROM Cd^^^(n,v) Cd^^*

R. K. Smither (Pro jec t 1-60) Bul l . A m , P h y s . S o c . J , 409 (November 25 , I960) .

SIMPLIFICATION OF CARATHEODORY'S TREATMENT O F THERMODYNAMICS

Louis A. Turner A m . J . P h y s . 28, 781-786 (December I960) .

5 7 TEMPERATURE DEPENDENCE OF THE MOSSBAUER SPECTRUM IN Fe

D. H. Vincent , R. S, P r e s t o n , J . H e b e r l e , and S. Hanna (Pro jec t I-19) Bul l . Am, P h y s . Soc. 5_, 428 (November 25 , I960) .

ENERGY DEGRADING-FOCUSING OF CYCLOTRON BEAM

W. J . R a m l e r , J . L„ Yntema , and M. Oselka . . . (P ro jec t 1-22) Nuclear I n s t r . and Methods 8, 217-220 (I960).

(d,t) REACTIONS ON NUCLEI WITH A « 60

B . Ze ldman , J . L . Yntema, a n d B . J . R a z . . . . . . . . . (Pro jec t 1-22) P h y s . Rev. 120, 1723-1730 (December 1, i960) .

ADDITIONAL PAPERS ACCEPTED FOR PUBLICATION

DECAY OF sgEr^®^ (3. 1 hr)

H. A . Grench and S. B . Bur son (Projec t 1-30) P h y s . Rev. in F e b r u a r y 1, 1961 i s s u e .

E F F E C T OF RADIOFREQUENCY RESONANCE ON THE NATURAL LINE FORM

M. N. Hack and M, H a m e r m e s h . , (Pro jec t 1-19) Nuovo c imento .

PROPOSAL FOR DETECTING THE POLARIZATION O F SLOWPROTONS

Juergen Heber le Helv. P h y s . Acta (Internat ional Symposium on Po la r i za t ion Phenomena of Nucleons) in December I960 i s s u e .

THE ANGULAR DISTRIBUTIONS OF NEUTRONS SCATTERED FROM VARIOUS NUCLEI

R. O. Lane , A . Langsdorf, J r . , J . E . Monahan, and A . J . Elwyn (Pro jec t 1-18)

Ann. P h y s . in F e b r u a r y 1961 i$suQ,

PRINCIPLES O F CYCLIC PARTICLE ACCELERATORS

John J . Livingood. D. VanNostrand about June 1961,

THE CRYSTAL STRUCTURE O F LITHIUM TUNGSTATE

W. H. Zacha r i a sen and H. A. P le t t inger (Pro jec t III-10) Acta C rys t . (about January 1961 i s s u e ) .

THE CRYSTAL STRUCTURE OF GADOLINIUM TRICHLORIDE HEXAHYDRATE

M a s s i m o M a r e z i o , H. A. P l e t t i n g e r , and W. H. Z a c h a r i a s e n Acta Cryst*(about January 1961 i s s u e ) .

P E R S O N N E L CHANGES IN T H E A N L PHYSICS DIVISION

D E P A R T U R E S

D r . Ak i to A r i m a jo ined the P h y s i c s D i v i s i o n a s a R e s i d e n t R e s e a r c h

A s s o c i a t e on S e p t e m b e r 14 , 1959 . He h a s b e e n i n t e r e s t e d in

s p i n - o r b i t sp l i t t i ng a n d t e n s o r f o r c e , s p i n - o r b i t s p l i t t i n g and

p ion t h e o r e t i c L - S p o t e n t i a l , a n d the i n f l u e n c e of s h o r t - r a n g e

t w o - b o d y i n t e r a c t i o n s on t h e e q u i l i b r i u m d e f o r m a t i o n of nuc le i

( P r o j e c t V - 1 3 ) . He t e r m i n a t e d a t A N L on D e c e m b e r 7 , I960

t o r e t u r n to the I n s t i t u t e for N u c l e a r S t u d y , U n i v e r s i t y of

T o k y o , T o k y o , J a p a n .

D r s . H e r m a n A . T a s m a n j o i n e d the P h y s i c s D i v i s i o n a s a R e s i d e n t R e ­

s e a r c h A s s o c i a t e on M a y 3 1 , I 9 6 0 . He h a s c o l l a b o r a t e d wi th

W. A . Chupka a n d J . B e r k o w i t z on h i g h - t e m p e r a t u r e t h e r m o ­

d y n a m i c s t u d i e s w i th a m a s s s p e c t r o m e t e r a n d on d e v e l o p m e n t

of a double oven for s tudy ing f r a g m e n t a t i o n a n d d i s s o c i a t i o n

r e s u l t i n g f r o m i o n i z a t i o n by e l e c t r o n i m p a c t . He t e r m i n a t e d

a t A N L on D e c e m b e r 19 , I 960 to r e t u r n to t h e L a b o r a t o r i u m v o o r

M a s s a s p e c t r o g r a f i e , A m s t e r d a m , the N e t h e r l a n d s .

D r . M a l c o l m M a c f a r l a n e j o i n e d t h e P h y s i c s D i v i s i o n a s a R e s i d e n t R e ­

s e a r c h A s s o c i a t e on N o v e m b e r 2 , 1959. He s t u d i e d s t r i p p i n g

r e a c t i o n s a s i n d i c a t o r s of t h e s t r u c t u r e of l igh t and i n t e r m e d i a t e

n u c l e i ( P r o j e c t s V - 9 a n d 1-22) , p a i r i n g f o r c e s in n u c l e i , a n d , in

57 c o l l a b o r a t i o n wi th R . D . L a w s o n , a r o t a t i o n a l m o d e l for F e

He t e r m i n a t e d a t A N L on D e c e m b e r 3 0 , I960 t o jo in the P h y s i c s

D e p a r t m e n t of the U n i v e r s i t y of R o c h e s t e r .