This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights.

a

a

OWL-'I'M-3867 (ENDF - 166)

R

Contract No. W-7405-eng-26

Neutron Physics Division

SDTl. IRON BROOMSTICK EXPERIMENT

R. E . Maerker

Reference: E. A. Straker, "Experimental Evaluation of Minima i n the Total Neutron Cross Sections of Several Shielding Materials," OWL-TM- 2242 (1968).

JULY 1972

NOTICE This document contains information of a preliminary nature and was prepared primarily for internal use at the Oak Ridge National Laboratory. It is subject to revision or correctioq and therefore does not represent a final report.

#

I 8

OAK RIDGE NATIONAL LABORATORY Oak Ridge, Tennessee 37830

operated by Union Carbide Corporation

for the

3 4456 0514770 2

t

i P

Abstract

a

d

The experimental and calculatiqnal de t a i l s for a CSEWG integral data

tes t ing shielding experiment a re presented,

iii

E'

a

B

1

Y

Description

This experiment was designed t o test a given set of neutron t o t a l cross

sections fo r iron in the range 0.8-11 MeV. Figure 1 shows a schematic of

the arrangement.

diameter and placed so t ha t i t s axis coincided with the axis of the neutron

The iron sample was a cylinder approximately 4 in. i n

beam.

the distance from the neutron source (the Tower Shielding Reactor 11) t o

the sample was 50 f t and the detector was 50 f t from the sample.

beam was confined to a diameter of 3.5 in. by collimators placed between

the reactor and sample near the sample position. To reduce air-scat ter ing

effects the reactor and detector were shielded with lead and water and the

In order t o reduce the effect of neutron inscattering i n the sample,

The neutron

reactor beam and detector acceptance were t igh t ly collimated.

The detector was a nominal 2 in. x 2 in. NE-213 s c i n t i l l a t o r . Separation

of neutron- and gamma-induced pulses was made by a modified Forte c i r cu i t .

The unfolding of the pulse-height dis t r ibut ions was accomplished using the

FERDoR code.

Data

The uncollided transmitted spectra through two samples of iron, one

8-in. thick and the other 12-in. thick (density = 0.0847 atoms/barn*an),

as measured by the NE-213 spectrometer system a r e shown i n Fig. 2 .

error i n the unfolding is such that the spectrum l i e s somewhere within

the darkened area within 68% confidence limits.

The

The spectrum measured by the NE-213 a t the same location when no i ron

In addition, is in the beam is shown i n Fig. 3 and tabulated i n Table I .

there is an estimated 5-10% error i n the absolute spectrum due to power

calibration uncertainties. The resolution function of the NE-213 spectrometer

ORNL DWG 66-9866R

50 f t - 50 ft c

-9

L ATOR T T

‘H,O + Pb NOT TO SCALE. ALL DIMENSIONS IN INCHES EXCEPT AS NOTED.

BEAM CENTERLINE -78 INCHES ABOVE CONCRETE PAD.

N

Fig. 1. Schematic of Experimental Arrangement.

s u

h e 1

io2

5

'c .- E c

I 3 Y

cu I E 0 -

I

0 c

i

2

10'

5

2

IO0

5

2

io-'

5

2

ro-

ORNL - DWG 72- 7349

io 11 7 4 5 6 I

NEUTRON ENERGY (MeV) 2 3

Fig. 2 . Transmitted Spectrum Through Iron.

4

0

c

d

5

Table I. Tabulated Source Spectrum With No Iron Present in Units of Neutrons/MeV/cm2/Kilowatt/Min

as a Function of Energy in MeV*

0.5 2130 2.2 2300 4.4 700 8.2 89 0.55 0.6

0.65

0.7

0.75 0.8 0.85

0.9

0.95 1 .0

1.1

1.2 1.3

1.4 1 .5

1.6

1.7 1.8 1.9 2.0 2.1

2280 2500

2750

2760 2550

2350 2330

2300

2270

2240

2190

2160

2170

2190 2210

2270 2 310

2360 2 380

2400 2330

2.3 2.4 2.5 2.6 2.7 2.8

2.9 3.0

3.1

3.2

3.3

3.4

3.5 3.6

3.7 3.8 3.9

4.0 4.1 4.2 4.3

2230 2180

2100

2030 1930

1810

1670 1530

1350

1180

1030

955

900 870

835 805

795

780 770 750 725

4.5 6 80 4.6 660

4.7 640

4.8 610

4.9 5 85 5 .O 565 5.2 5 10

5.4 460

5.6 4 10

5.8 370 6.0 335

6.2 305

6.4 275

6.6 250

6.8 220 7.0 2 00

7.2 175

7.4 152 7.6 132 7.8 116 8.0 101

8.4 8.6

8.8 9.0 9.2

9.4 9.6 9.8

10.0

10.2

10.4

10.6 10.8

11.0

11.2

11.4 11.6 11.8 12.0

77 67

59

52 45

39.5

34.5 30 26.5

23 20

17.5

15.3 13.3 11.7 10.2

8.9 7.8 6.8

* Interpolation in this table should follow the formula:

E,, - E E - E, L I (E ) , where E < E < E2. No(E> = E2 - E$(E1) -t E2 - E:O 2 1 - -

6

system and unfolding procedure is shown i n Table 11, expressed as f u l l

width a t half maximum (percent of peak energy).

P

Method of Calculation

The calculation consists first of determining a transmitted uncollided

spectrum N (AE') . unc

where No(Ei) is taken or interpolated from Table I , t = 20.32 cm or 30.48

cm, and the energy intervals AEi, which in general may be of variable width,

are chosen suff ic ient ly small tha t a l l of the s t ructure i n the v i c in i ty of

a l l of the minima i n the t o t a l cross section is included.

of energy subintervals, AEi, used in the region 0.5-12 MeV should follow

as closely as possible the number suggested i n the report sheet.

The t o t a l number

The values

(AE') are to be binned into far fewer intervals , @ E t ) , shown i n the Of Nunc attached report sheet.

The second par t o f the calculation consists of folding the values of

( A E ~ ) with the resolution function of the NE-213 spectrometer sys tm:

(E) = 1 Nunc(AE')R(E' + E)AE'. E '

R(E ' + E) is a gaussian centered at E ' , the midpoint of AE , and using the

values appearing in Table 11, becomes

c

R(E' + E) = g32f4 ew - 1 (E - E') E I a x 235.4820J'l,j

d

where a is the FWHM value a t E ' expressed in the uni t s of Table 11.

7

Table 11. Energy Resolution of the Spectrometer System* ~

a a a FWHM/E(%) E (MeV) FWHM/E (%) E (MeV) FWHM/E (%) E (MeV)

0 .5 47.5

0.6 44

0.7

0.8

0.9

1 .0

1.1

1.2

1 .3

1.4

1.5 1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5 2.6

2.7 2.8

2.9 3.0

3.1

3.2

41

38.5

36

33.5

32.5

31

30

29

27.5

26.5

26

25

24.5

24

23.5

23

22.5 22

21.5 21.2

20.8

20.4 20.1

19.7

19.4

19.1

3.5 18.2

3.6 18.0

3.7

3.8’

3.9

4.0

4 .1

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5.0

5 .1

5.2

5.3

5.4

5.5

5.6

5.7

5.8 5.9 6.0

6.2

6.4

17.7

17.4

1 7 . 1

16.9

16.7

16.5

16.3

16 .1

15.9

15.7

15.5

15.3

15.2

15.1

14.9

14.7

7.0 12.6

7.2 12.4

7.4 12.2

7.6 12 .1

7.8 11.9

8.0 11.8

8.2 11.6

8.4 11.5

8.6 11.4

8.8 11.3

9 .o 9.2

9.4

9.6

9.8

10.0

10.2

10.4

11.2

11.1

10.9

10.8

10.7

10.5

10.3

10.2

14.5 10.6 10 .1

14.4 10.8 10.0

14.3 11.0 9.8 14.2 11.4 9.7

14 .1 11.8 9.6 13.9 12.2 9.6 13.8

1 3 . 7

13.5

13.2

3.3 18.8 6.6 13.0

3.4 18.5 6.8 12.8 (ir

*In te rpo la t ion i n t h i s t a b l e should fo l low t h e formula E, - E E - E- L 1

a ( E ) = a(E1) + a ( E 2 ) E2 - -

where El I; E I; E2.

8

The smeared calculated spectra Nunc(E) may then be compared d i rec t ly with

the reported experimental spectra.

Codes

A FORTRAN package is available to perform a l l the manipulation described

in the preceding section. Subroutine XSECT and its subroutines access the

to t a l cross section from an ENDF/B tape and interpolate the cross section

for any energy according to the interpolation scheme specified on the tape.

I t w i l l only access pointwise data so tha t any evaluation a t l ea s t pa r t i a l ly

described by resonance parameters above 500 keV cannot be accessed by this

- code.

pointwise representation of the same tapes from Brookhaven in t h i s instance.

(See Table I11 under comments.) I t w i l l be necessary to obtain a

The main routine calculates the uncollided flux, smoothes the uncollided

flux with the resolution function of the spectrometer system, and outputs

the fluxes both before and a f t e r smoothing in the energy grid suggested in

the report sheet.

The input data consist of the following cards:

Card A. T , ADEN (12F6.3).

meters, and ADEN the atomic density in atoms/barn-an a re shown

in the following table (Table 111).

T , the t h i c h e s s of the cylinder i n cent i -

Card B. ELEM(1) ,1=1,20(20A4). ELEM(1) is the element studied (see

Table 111).

MATNg, WDE, NDFB(1216). MATNO is the MAT number of the

ENDF/B evaluation (see Table 111), WDE = 1 i f binary, = 2

i f BCD, and depends on the par t icular version of the tape an

ins ta l la t ion possesses, and NDFB is the logical tape number

of the ENDF/B tape.

Card C.

c

9

Table 111. Parameters Describing the Iron Broomstick Experiments

ELEM(1) T ADEN MAm# COMMENTS :

I R ~ N 20.32 0.0847 1180 Resonance parameters

and the ENDF/B Evaluations Used to Compare With Experiment

IR$N 30.48 used, but only below 60 keV. OK 0.0847 1180

1 0

Cards D. ERG(1) ,1=ly86(12F6.3). The energy values in MeV a t which the s'

source is tabulated in Table I . ERG(1) = 0.50 and ERG(86) = 12.0. - Cards E. FZERQ)(I) ,1=1,86(12F6.3). The source spectrum in un i t s of -

2 neutrons/MeV/cm /kilowatt/min tabulated in Table I . FZERS) (1) =

2130 and FZERq(86) = 6.8.

Cards F. NINT(1) ,1=1,85(1216). The number of subintervals AEi within

each AE' used in calculating the uncollided flux (see report

sheet) .

NINT(1) = 150 and NINT(85) = 10.

Use the suggested values appearing in the report sheet.

Cards G. ER(1) ,1=1,84(12F6.3). The energy value in MeV a t which the - , ,

resolution function of the spectrometer system is specified in

Table 11. ER(1) = 0.50 and ER(84) = 1 2 . 2 .

Cards H. PCTWID(I),I=1,84(12F6.3). The values of a, the resolution of

the spectrometer system, in uni t s of percent of peak energy of

the f u l l width a t half maximum, also tabulated i n Table 11.

PCTWID(1) = 47.5 and PCTWID(84) = 9.6.

Cards I . ES(I),I=lY75(12F6.3). The energy values in MeV a t which the

smoothed uncollided spectrum is t o be calculated (see the report

sheet) . ES(1) = 0.80 and ES(75) = 11.0.

Each iron thickness must be run separately ( i . e . , two submissions t o

the computer.

(23 K words) on the IBM-360/75 or 360/91 computer with a running time of

approximately 45 sec on the IBM-360/91.

The code requires a storage of approximately 92 K bytes

b'

i

11

Report sheet f o r the iron "broomstick" experiment.

Calculated values of N for each AE' used.

(AE' ) and approximate number of subintervals AE un c i

N ( A E ' ) Number of Subintervals un c

(neutrons/cm 2 /MeV/kW/min) BE' /AEi

(MeV) t = 20.32 t = 30.48 Suggested AE'

0.50-0.55

0.55-0.60 0.60-0.65

0.65-0.70

0.70-0.75 0.75-0.80

0.80-0.85 0.85-0.90

0.90-0.95

0.95-1.00

1.0-1.1 1.1-1.2

1.2-1.3 1.3-1.4

1.4-1.5

1.5-1.6 1.6-1.7

1.7-1.8 1.8-1.9 1.9-2 .O

2: 0-2.1 2 .l-2.2

2.2-2.3 2.3-2.4 2.4-2.5

2.5-2.6

2.6-2.7

150 150 150

150 150 150

150 15 0

150

150 200 200 150

150 150

150 15 0

150 15 0 150

50

50 50

50

50

50

50

Report sheet for the iron "broomstick" eyperiment (continued).

N (AE') unc Number of Subintervals

2 AE / AEi (neutrons / cm /MeV/kW/min) AE (MeV) t = 20.32 t = 30.48 Suggested

2.7-2.8

2.8-2.9

2.9-3 .O

3 .0-3.1

3.1-3.2

3.2-3.3

3.3-3.4

3.4-3.5

3.5-3.6

3.6-3.7

3.7-3.8

3.8-3.9

3.9-4.0

4 .0 -4 .1

4.1-4.2

4.2-4.3

4.3-4.4

4.4-4.5

4.5-4.6

4.6-4.7-

4.7-4.8

4.8-4.9

4.9-5.0

5.0-5.2

5.2-5.4

5.4-5.6

5.6-5.8

5.8-6.0

6.0-6,2

6.2-6.4

5 0

5 0

5 0

30

30

30

30

30

30

30

30

30

30

30

30

30

30

10

1 0

10

10

10

10

2 0

20

20

20

20

2 0

20

c

13

Report sheet for the iron "broomstick" experiment (continued).

N (AE') Number of Subintervals unc

(neutrons/cm 2 /MeV/kW/min) AE' /AEi

(MeV) t = 20.32 t = 30.48 Suggested AE'

6.4-6.6

6.6-6.8

6.8-7 .O

7.0-7.2

7.2-7.4

7.4-7L6

7.6-7.8

7.8-8.0

8.0-8.2

8.2-8.4

8.4-8.6

8.6-8.8

8.8-9.0

9.0-9.2

9.2-9.4

9.4-9.6

9.6-9.8

9.8-10.0

10.0-10.2

10.2-10.4

10.4-10.6

10.6-10.8

10.8-11.0

11.0-11.2

11.2-11.4

11.4-11.6

11.6-11.8

11.8-12.0

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

20

10

10

10

10

10

10

10

10

10

10

14

Report sheet for the iron "broomstick"experiment (continued) . Calculafed valves of NUnc(E), i.e., smoothed data to be compared with

experiment . Nunc(E)

2 (neutrons / cm /MeV/kW/min 1 E (MeV) t = 20.32 t = 30.48

0 . 8

0.85

0 . 9

0 .95

1 .0

1.1

1 . 2

1 . 3

1 . 4

1 .5

1 . 6

1 . 7

1 . 8

1 . 9

2.0

2 . 1

2 . 2

2 . 3

2.4

2.5

2.6

2 . 7

2.8

2 .9

3 .0

3.1

3 .2

3 .3

3 .4

.~

--

N (E) unc 2 (neutrons / cm /MeV/kW/min)

t = 20.32 t = 30.48 E (MeV)

3.5

3 .6

3.7

3 .8

3 . 9

4 .0

4 . 1

4.2

4 . 3

4 . 4

4 .5

4.6

4.7

4 .8

4 . 9

5 . 0

5.2

5.4

5 . 6

5 .8

6 . 0

6.2

6 . 4

6 .6

6.8

7 .O

7 . 2

7 . 4

7 . 6

15

Report sheet f o r the iron "broomstick" experiment (continued).

.. .

N (E) unc n

(neutrons /cmL /MeV/ kW/min )

E (MeV) t = 20.32 t = 30.48

7 . 8

8.0

8 . 2

8 . 4

8.6

8 .8

9 . 0

9 .2

9 . 4

N (E)

2 (neutrQns/cm /MeV/kW/min)

unc

E (MeV) t = 20.32 t = 30.48

9 . 6

9 . 8

10.0

1 0 . 2

1 0 . 4

10.6

10.8

11.0

h

P

*

& '

17

INTERNAL DISTRIBUTION

1-3. 4.

5-9. 10. 11. 12 . 13. 14. 15. 16. 17. 18. 19. 20.

85.

86.

87. Q

b

88. 89. 90.

91.

92. 93.

94 I

95.

96. 97.

98. 99.

100. 101. 102.

103.

L , S. Abbott A. R. Buhl C. E . Clifford M. L . Gritzner W. 0. Harms R. E . Maerker F. C . Maienschein B. J . McGregor F. R. Mynatt E. M. Oblow F. G . Perey R. W . Roussin A. H. Snell D. B. Trauger

21. 22.

23-72. 73. 74. 75. 76.

77-78. 79.

80-82. 83. 84.

D . K . Trubey G . E . Whitesides Radiation Shielding Info. C t r . H. Feshbach (consultant) H. Goldstein (consultant) C . R. Mehl (consultant) H. T . Motz (consultant) Central Research Library OWL Y - 1 2 Technical Library Document Reference Section

Laboratory Records Laboratory Records ORNL RC ORNL Patent Office

EXTERNAL DISTRIBUTION

H. Al ter , Atomics International, 8900 Desota S t . , Box 309, Canoga Park, Calif . 91304 Martin Becker, Rensselaer Polytechnical In s t i t u t e , Tibbits Ave., Troy, N. Y . 12181 R. Dannels, Westinghouse Electric Corp., ARD, Waltz M i l l S i t e , P . 0. Box 158, Madison; Pa. 15663 M. Drake, Brookhaven National Laboratory, , Upton, N . Y . 11973 N . Francis, Knolls Atomic Power Laboratory, Schenectady, N. Y . 12301 R. A. Grimesey, Idaho Nuclear Corp., P. 0. Box 1845, Idaho Fal ls , Idaho 83401 W. H. H a m u m , Division of Reactor Development C, Technology, U. S. Atomic Energy Commission, Washington, D. C . L. Harris, Gulf General Atomic, P. 0. Box 608, San Diego, Cal i f . 92112 P. B. Hemmig, Division of Reactor Development C, Technology, U. S. Atomic Energy Commission, Washington, D. C . B. Hutchins, General Electric Co., BRDO, 310 DeGuigne D r . , Sunnyvale, Calif . 94086 M. H. Kalos, Courant In s t i t u t e of Mathematical Sciences, New York University, 251 Mercer S t , , New York, N. Y . 10012 D. C . Kaul, Defense Nuclear Agency, Washington, D. C . R. J . LaBauve, Los Alamos Scient i f ic Laboratory, P. 0. Box 1663, Los Alamos, N. M. 87544 K. 0. Laughon, AEC S i t e Rep., ORNL Duane Marr, WAIXO, P. 0. Box 1970, Richland, Wash. Malcolm McGregor, Lawrence Livermore Laboratory, Berkeley, Calif. 94720 S. Pearlstein, Brookhaven National Laboratory, Upton, N . Y . 11973 T. A. P i t t e r l e , Westinghouse Electr ic Corp., ARD, Waltz M i l l S i t e , P. 0. Box 158, Madison, Pa. D. L . Rigotti , U. S. Army Nuclear Defense Laboratory, P. 0. Box 856 Edgewood Arsenal, Md.

20545

20545

20305

99352

15663

18

104.

105.

106.

E , Specht, Atomics International, 8900 Desota S t . , Box 309, Canoga Park, Calif . 91304 E. A. Straker, Science Applications, Inc., Clinton Bldg., Sui te 700, 2109 W. Clinton Ave., Huntsville, Ala. A. Travel l i , Argonne National Laboratory, 9700 S. Cass Ave., Argonne, I l l .

Research and Technical Support Division

35805

107-108. Technical Information Center (TIC) 109-110.

5

b

b