1. The Physics Case2. Present Status3. Hypersystems in pp Interactions4. The Experiment

Future Experiments on Hypernuclei and

Hyperatoms

_

1. The Physics Case

baryons tagged with a strange quark as a probe of the nuclear structurenuclei as a femto-laboratory for strange baryons

Two Sides of a Coin

mesonic decay of hypernuclei

mesonic decay of hypernuclei

w

N

suppressed by Pauli blocking

pF270MeV/c

w

N

pN100MeV/c

free decayfree decay

0n

+38MeV ( )

+41MeV ( )

2

6

6

4

36

%

%

3ps

p

non-mesonic decay

of hypernuclei

non-mesonic decay

of hypernuclei

w

N

s

N

N

+176MeV

+176MeVnn

p

n

p n

To use nuclei as a QCD-laboratory we have to understand the laboratory

s=1: -, -hypernucleinuclear structure, new symmetries

the presence of a hyperon may modify the size, shape... of nuclei new specific symmetries

Y-N interactionstrange baryons in nuclei weak decay

s=2: -atoms, -, -hypernucleinuclear structurebaryon-baryon interaction in SU(3)f

H-dibaryon

s=3: -atom, (-,-, -hypernuclei ?)quadrupole moment of the

Hypernuclei provide a link between nuclear physics and QCD

Strange Baryons in Nuclear Systems

W

su dusd dd

meson vs. gluon/quark exchange

meson vs. gluon/quark exchange

Weak baryon-baryon interaction non-mesonic weak decay of hypernuclei explore the baryon-baryon weak interaction

N-N scatteringN-N scattering

w

N

N

s

N

N

w

N

s

N

N

S=0 S=1

NN NNN N

only parity violating part of weak interactionparity-conserving part masked by strong interaction

only parity violating part of weak interactionparity-conserving part masked by strong interaction

parity violating and parity-conserving part of weak, strangeness changing, interactionq~400 MeV/c probes short distances

parity violating and parity-conserving part of weak, strangeness changing, interactionq~400 MeV/c probes short distances

T. Sakai, K. Shimizu, K. Yazaki Prog.Theor.Phys.Suppl. 137 (2000) 121-145

H-Particle R.L. Jaffe (1977)

free coalescencet ~ 10-23s

nuclear breeder

t ~ 10-10s

neutron stars

Nuclei as Femto-Laboratory

H-particle in a nucleus free H (see e.g. T. Yamada, NP A691 (2001) 250c; (3q)+(3q) quark cluster model )

free H-dibaryonH-dibaryon in 10

YYBe

B=12.2 MeV B=24.0 MeV

S=-2 Nuclei and H-dibaryon States

Formation of an H-particle in nuclei may modify levels in -nuclei

Contributions to intrinsic quadrupole moment of baryonsOne-gluon exchangeMeson exchange

J=1/2 baryons have no spectroscopic quadrupole moment

- Baryon:J=3/2long mean lifetime 0.82·10-10 sonly one-gluon contributions to quadrupole moment(A.J. Buchmann Z. Naturforsch. 52 (1997) 877-940)

3 2 2( )(3 )iQ d r r z r 3 2 2( )(3 )iQ d r r z r

s

ss

1/ 221/ 2

(3 ( 1)) 0z

Js z J

Q J J J 1/ 221/ 2

(3 ( 1)) 0z

Js z J

Q J J J

Fundamental Properties of Baryons

The quadrupole moment is an unique testcase for the quark-quark interaction

hyperfine splitting in -atom electric quadrupole moment of

prediction Q= (0 - 3.1) 10-2 fm2

E(n=11, l=10 n=10, l=9) ~ 515 keVEQ ~ few keV for Pb

spin-orbit Els ~ (Z)4 l·m

quadrupole EQ ~ (Z)4Qm3

spin-orbit Els ~ (Z)4 l·m

quadrupole EQ ~ (Z)4Qm3

Q= +0.02 fm2

Q= - 0.02 fm2

A very Strange Atom

R.M. Sternheimer, M. Goldhaber PRA 8, 2207 (1973)

2. Present Status

strangeness deposition (stopped K-,-) FINUDA@DANEtagged kaon „beam“low momentum (T=16MeV)low backgroundalso (stopped K-,+) neutron rich nuclei

strangeness production (+, K+) (-, K0) BNL, KEK, (GSI?)

pBEAM 1 GeV/c

high beam intensitylow cross section (1-10 mb/sr)q > 300 MeV/c large p, L

strangeness exchange (K_

, )(K_

, ) BNL, KEK, J-PARClow beam intensitylarger cross section (100 mb/sr)magic momentum low p, L

(e,e´K+) , (,K+) TJNAF, MAMI-Cspin-flip amplitude unnatural parity statesnew nuclei (p : 10

Be)

polarised beamsub-MeV resolution possible (0.3 MeV) for particle unstable states

substitutional state

non-substitutional state

Single Hypernuclei

( 1)A Ae Z e K Z ( 1)A Ae Z e K Z

stoppA

dA

e

KK

Z ZK

e e

stoppA

dA

e

KK

Z ZK

e e

Tamura et al.

Neutron number

                 

                 

             

             

           

         

         

         

       

             

16Λ O 18

Λ O14Λ N 15

Λ N12Λ C 13

Λ C 14Λ C

9ΛB 10

Λ B 11Λ B 12

Λ B7ΛBe 8

ΛBe 9ΛBe10

Λ Be6ΛLi 7

ΛLi 8ΛLi 9

ΛLi4ΛHe 5

ΛHe6ΛHe 7

ΛHe 8ΛHe

4ΛH3

ΛH

1 2 3 4 5 6 7 8 9

4

8

7

6

3

5

2

1

10

9

Pro

ton

nu

mb

er

Status of Single Hypernuclei

high resolution -spectroscopy

with germanium detectors

7 0.5 2 40.4

6 2 4

( 2; : 5 / 2 1/ 2 ) 3.6 0.5 1

( 2; : 3 1 ) 10.9 0.9 3

B E Li e fm

B E Li e fm

B(E2)~R4

shrinkage of 6Li core by ~20%

high resolution -spectroscopy is crucial to understand the structure of hypernculei

KEK, BNL

Multi-Hypernuclei are terra incognita, but they exist !

1963: Danysz et al. 10Be

1966: Prowse 6He

1991: KEK-E176 13B (or 10Be)

2001: AGS-E906 4H (~15);

no binding energies

2001: KEK-E373 6He

(Nagara)

“ 10Be

(Demachi-Yanagi)

NAGARA

6- 12 4

6 5

ΛΛ

-ΛΛ Λ

Ξ + C + He+t

He He+ π

He

p+

H. Takahashi et al., PRL 87, 212502-1 (2001)

Double Hypernuclei

Interpreting B as bond energy one has to consider e.g.

dynamical change of the core nucleusN spin-spin interaction for non-zero spin of coreexcited states possible

if- or intermediate -nuclei are produced in excited statesQ-value difficult to determine (particularly for heavy nuclei)nuclear fragments difficult to identify with usual emulsion technique

new concept required -spectroscopy!

1

1

( ) ( ) ( )

( ) ( ) ( )

A A A

A A A

B Z B Z B Z

B Z B Z B Z

What is known?

6

6 0.18 0.180.11 0.11

10

10

13

Hyperkern ( ) ( )

10.9 0.5 4.7 0.6 Prowse (1966)

7.25 0.19 1.01 0.20 KEK-E373 (2001)

17.7 0.4 4.3 0.4 Danysz (1963)

8.5 0.7 4.9 0.7 KEK-E176 (1991)

27.6 0.7 4.8

B MeV B MeV

He

He

Be

Be

B

10 0.35

0.21

0.7 KEK-E176 (1991)

12.33 KEK-E373 (2001, unpublished)Be

same event

same event

3. Hypersystems in pp Interactions_

-atoms: x-raysconversion

-(dss) p(uud) (uds) (uds)Q = 28 MeV

Conversion probability approximatly 5-10%

Y. Hirata, J. Randrup et al.,

- capture

_

(Kaidalov & Volkovitsky)

quark-gluon string model

s

ud

s

dd

s

ds

s

ss

0

Use pp Interaction to produce a hyperon “beam” (t~10-10 s) which is tagged by the antihyperon or its decay products

_

General Idea

- capture:

- p + 28 MeV-

3 GeV/c

Kaons_

trigger

p_

2. Slowing down and capture

of insecondary

target nucleus

2. Slowing down and capture

of insecondary

target nucleus

1.Hyperon-

antihyperonproductionat threshold

1.Hyperon-

antihyperonproductionat threshold

+23MeV

3. -spectroskopy

with Ge-detectors

3. -spectroskopy

with Ge-detectors

Production of Double Hypernuclei

20000 stopped -K- beam, diamond target

neutron detector arrays

(--,12C) 12B + nBNL-AGS E885

few tens 2 decays of 4

HK- beam lineCylindrical Detector

System2 decaysBNL-AGS

E906

Captured - per day

beam/ targetdevicereactionfacility

several hundreds stopped -

(K-,K+)emulsion(K-,K+)KEK-PS E373

vertex detector + spectrometer

vertex detector

spectrometer, =30 msr

device

3000 „golden events“

~ 300000 KK trigger

(incl. trigger)

=2·1032, thin target,production vertex decay vertex

p p GSI-HESR

2000106 stopped p per sec

p p K*K*

K*N Kcold anti-protons

<70008·106/sec5 cm 12C

(K-,K+)JHF

statusbeam/ targetreactionexperiment

Competition

¯

¯

¯

¯

¯¯

Expected Count Rate

Ingredients (golden events)luminosity 2·1032 cm-2s-1 +- cross section 2mb for pp 700 Hz p(100-500 MeV/c) p500 0.0005 + reconstruction probability 0.5 stopping and capture probability pCAP 0.20 total captured - 3000 / day

- to nucleus conversion probability p 0.05 total hyper nucleus production 4500 / month

gamma emission/event, p 0.5

-ray peak efficiency pGE 0.1

~7/day „golden“ -ray events (+ trigger) ~ 700/day with KK trigger

high resolution -spectroscopy of double hypernuclei will be feasible

- capture:

- p + 28 MeV-

5.5 GeV/c

Kaons_

trigger

p_

2. Slow down

and capture of in

secondary target nucleus

2. Slow down

and capture of in

secondary target nucleus

1.Hyperon-

antihyperonproductionat threshold

1.Hyperon-

antihyperonproductionat threshold

+203MeV

3. -spectroskopy

with Ge-detectors

3. -spectroskopy

with Ge-detectors

Production of -Atoms

( ) 1( ) 20

atoms by produktion (~35/sec)hyperfine splitting in -atom

electric quadrupole moment of

prediction Q= (0 - 3.1) 10-2 fm2

E(n=11, l=10 n=10, l=9) ~ 515 keVEQ ~ few keV for Pb

taking production rate, stopping probability, capture probability and detection probability into account we expect

-

spin-orbit Els ~ (Z)4 l·m

quadrupole EQ ~ (Z)4Qm3

spin-orbit Els ~ (Z)4 l·m

quadrupole EQ ~ (Z)4Qm3

Q= +0.02 fm2

Q= - 0.02 fm2

~10 detected -transitions per daywith high resolution -spectroscopy feasible

A very strange Atom

R.M. Sternheimer, M. Goldhaber PRA 8, 2207 (1973)

Count rate estimate needs more detailed studies!

4. The Experiment

The PANDA Detector

hermetic (4)high ratePID (, e, , , K, p)trigger (e, , K, D, ) compact (€)modular

Elektronenkühler

InjektionKicker Septum

Solid state-micro-trackerthickness ~ 3 cm

High rate germanium detector

Summary

Hypersystems provide a link between nuclear physics and QCD

They allow to study basic properties of strongly interacting systems

These unique experiments will be feasible at the GSI-HESR