34-Se- 82
34-SE- 82 JNDC EVAL-MAR90 JNDC FP NUCLEAR DATA W.G.
DIST-NOV90
----JENDL-3.2 MATERIAL 3449
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
HISTORY
90-03 NEW EVALUATION FOR JENDL-3 WAS COMPLETED BY JNDC FPND
W.G./1/
MF = 1 GENERAL INFORMATION
MT=451 COMMENTS AND DICTIONARY
MF = 2 RESONANCE PARAMETERS
MT=151 RESOLVED AND UNRESOLVED RESONANCE PARAMETERS
RESOLVED RESONANCE REGION (MLBW FORMULA) : BELOW 18 KEV
RESONANCE ENERGIES WERE BASED ON THE EXPERIMENTAL DATA BY
BROWNE AND BERMAN/2/. THE VALUES OF NEUTRON ORBITAL ANGULAR
MOMENTUM L AND TOTAL SPIN J WERE ASSUMED TO BE 0 AND 0.5 FOR
ALL RESONANCE LEVELS, RESPECTIVELY.
REDUCED NEUTRON WIDTH OF EACH RESONANCE LEVEL WAS ROUGHLY
ESTIMATED ON THE BASIS OF THE DESCRIPTION FOR RESONANCE
STRUCTURES GIVEN BY BROWNE AND BERMAN, AND OF THE REDUCED
NEUTRON WIDTHS GIVEN BY MUGHABGHAB ET AL./3/ IN THE FIRST
STAGE. NEXT, THERMAL SCATTERING CROSS SECTION WAS CALCULATED
USING THE ROUGHLY ESTIMATED REDUCED NEUTRON WIDTHS, AND A
NORMALIZATION FACTOR WAS OBTAINED SO AS TO REPRODUCE THE
EXPERIMENTAL DATA OF 5.0+-0.2 BARNS GIVEN BY MUGHABGHAB ET AL.
THE FINAL NEUTRON WIDTHS WERE DETERMINED BY USING THIS
NORMALIZATION FACTOR AND THE RESONANCE ENERGIES GIVEN BY
BROWNE AND BERMAN.
SCATTERING RADIUS WAS TAKEN FROM MUGHABGHAB ET AL. AVERAGE
RADIATION WIDTH WAS ALSO DETERMINED SO AS TO REPRODUCE THERMAL
CAPTURE CROSS SECTION OF 44.2 MB GIVEN BY MUGHABGHAB ET AL. A
NEGATIVE RESONANCE WAS ADDED AT -120 EV IN THE PRESENT
ANALYSIS.
UNRESOLVED RESONANCE REGION : 18 KEV - 100 KEV
THE NEUTRON STRENGTH FUNCTION S0 WAS BASED ON THE COMPILATION
OF MUGHABGHAB ET AL., AND S1 WAS BASED ON THE SYSTEMATICS OF
MUGHABGHAB ET AL., AND S2 WAS CALCULATED WITH OPTICAL MODEL
CODE CASTHY/4/. THE OBSERVED LEVEL SPACING WERE DETERMINED TO
REPRODUCE THE CAPTURE CROSS SECTION CALCULATED WITH CASTHY.
THE EFFECTIVE SCATTERING RADIUS WAS OBTAINED FROM FITTING TO
THE CALCULATED TOTAL CROSS SECTION AT 100 KEV. THE RADIATION
WIDTH GG WAS DETERMINED FROM A SYSTEMATIC TREND OF MEASURED
VALUES FOR NEIGHBORING NUCLIDES.
TYPICAL VALUES OF THE PARAMETERS AT 70 KEV:
S0 = 1.210E-4, S1 = 2.100E-4, S2 = 0.680E-4, SG = 0.572E-4,
GG = 0.190 EV, R = 7.074 FM.
CALCULATED 2200-M/S CROSS SECTIONS AND RES. INTEGRALS (BARNS)
2200 M/S RES. INTEG.
TOTAL 5.044 -
ELASTIC 5.000 -
CAPTURE 0.04420 0.799
MF = 3 NEUTRON CROSS SECTIONS
BELOW 100 KEV, RESONANCE PARAMETERS WERE GIVEN.
ABOVE 100 KEV, THE SPHERICAL OPTICAL AND STATISTICAL MODEL
CALCULATION WAS PERFORMED WITH CASTHY, BY TAKING ACCOUNT OF
COMPETING REACTIONS, OF WHICH CROSS SECTIONS WERE CALCULATED
WITH PEGASUS/5/ STANDING ON A PREEQUILIBRIUM AND MULTI-STEP
EVAPORATION MODEL. THE OMP'S FOR NEUTRON GIVEN IN TABLE 1 WERE
DETERMINED TO REPRODUCE A SYSTEMATIC TREND OF THE TOTAL CROSS
SECTION BY CHANGING R0, RS AND RSO OF IIJIMA-KAWAI POTENTIAL/6/.
THE OMP'S FOR CHARGED PARTICLES ARE AS FOLLOWS:
PROTON = PEREY/7/
ALPHA = HUIZENGA AND IGO/8/
DEUTERON = LOHR AND HAEBERLI/9/
HELIUM-3 AND TRITON = BECCHETTI AND GREENLEES/10/
PARAMETERS FOR THE COMPOSITE LEVEL DENSITY FORMULA OF GILBERT
AND CAMERON/11/ WERE EVALUATED BY IIJIMA ET AL./12/ MORE
EXTENSIVE DETERMINATION AND MODIFICATION WERE MADE IN THE
PRESENT WORK. TABLE 2 SHOWS THE LEVEL DENSITY PARAMETERS USED
IN THE PRESENT CALCULATION. ENERGY DEPENDENCE OF SPIN CUT-OFF
PARAMETER IN THE ENERGY RANGE BELOW E-JOINT IS DUE TO GRUPPELAAR
/13/.
MT = 1 TOTAL
SPHERICAL OPTICAL MODEL CALCULATION WAS ADOPTED.
MT = 2 ELASTIC SCATTERING
CALCULATED AS (TOTAL - SUM OF PARTIAL CROSS SECTIONS).
MT = 4, 51 - 91 INELASTIC SCATTERING
SPHERICAL OPTICAL AND STATISTICAL MODEL CALCULATION WAS
ADOPTED. THE LEVEL SCHEME WAS BASED ON EVALUATED NUCLEAR
STRUCTURE DATA FILE (1987 VERSION)/14/ AND NUCLEAR DATA
SHEETS/15/.
NO. ENERGY(MEV) SPIN-PARITY
GR. 0.0 0 +
1 0.6548 2 +
2 1.4200 0 +
3 1.7312 2 +
4 1.7354 4 +
5 2.5508 3 +
6 2.8942 5 -
LEVELS ABOVE 3.015 MEV WERE ASSUMED TO BE OVERLAPPING.
MT = 102 CAPTURE
SPHERICAL OPTICAL AND STATISTICAL MODEL CALCULATION WITH
CASTHY WAS ADOPTED. DIRECT AND SEMI-DIRECT CAPTURE CROSS
SECTIONS WERE ESTIMATED ACCORDING TO THE PROCEDURE OF BENZI
AND REFFO/16/ AND NORMALIZED TO 1 MILLI-BARN AT 14 MEV.
THE GAMMA-RAY STRENGTH FUNCTION (5.46E-05) WAS ADJUSTED TO
REPRODUCE THE CAPTURE CROSS SECTION OF 0.045 BARN AT 25 KEV
WHICH WAS A SOMEWHAT LARGER VALUE THAN A META-STABLE STATE
PRODUCTION CROSS SECTION OF 0.045 BARN AT 24 KEV MEASURED BY
CHAUBEY AND SEHGAL/17/
MT = 16 (N,2N) CROSS SECTION
MT = 17 (N,3N) CROSS SECTION
MT = 22 (N,N'A) CROSS SECTION
MT = 28 (N,N'P) CROSS SECTION
MT =103 (N,P) CROSS SECTION
MT =104 (N,D) CROSS SECTION
MT =105 (N,T) CROSS SECTION
MT =107 (N,ALPHA) CROSS SECTION
THESE REACTION CROSS SECTIONS WERE CALCULATED WITH THE
PREEQUILIBRIUM AND MULTI-STEP EVAPORATION MODEL CODE PEGASUS.
THE KALBACH'S CONSTANT K (= 96.6) WAS ESTIMATED BY THE
FORMULA DERIVED FROM KIKUCHI-KAWAI'S FORMALISM/18/ AND LEVEL
DENSITY PARAMETERS.
FINALLY, THE (N,2N) AND (N,P) CROSS SECTIONS WERE
NORMALIZED TO THE FOLLOWING VALUES AT 14.5 MEV:
(N,2N) 1100.00 MB (MEASURED BY FREHAUT+/19/)
(N,P) 2.40 MB (SYSTEMATICS OF FORREST/20/)
MT = 251 MU-BAR
CALCULATED WITH CASTHY.
MF = 4 ANGULAR DISTRIBUTIONS OF SECONDARY NEUTRONS
LEGENDRE POLYNOMIAL COEFFICIENTS FOR ANGULAR DISTRIBUTIONS ARE
GIVEN IN THE CENTER-OF-MASS SYSTEM FOR MT=2 AND DISCRETE INELAS-
TIC LEVELS, AND IN THE LABORATORY SYSTEM FOR MT=91. THEY WERE
CALCULATED WITH CASTHY. FOR OTHER REACTIONS, ISOTROPIC DISTRI-
BUTIONS IN THE LABORATORY SYSTEM WERE ASSUMED.
MF = 5 ENERGY DISTRIBUTIONS OF SECONDARY NEUTRONS
ENERGY DISTRIBUTIONS OF SECONDARY NEUTRONS WERE CALCULATED WITH
PEGASUS FOR INELASTIC SCATTERING TO OVERLAPPING LEVELS AND FOR
OTHER NEUTRON EMITTING REACTIONS.
TABLE 1 NEUTRON OPTICAL POTENTIAL PARAMETERS
DEPTH (MEV) RADIUS(FM) DIFFUSENESS(FM)
---------------------- ------------ ---------------
V = 46.0-0.25E R0 = 5.7 A0 = 0.62
WS = 7.0 RS = 6.2 AS = 0.35
VSO= 7.0 RSO= 5.7 ASO= 0.62
THE FORM OF SURFACE ABSORPTION PART IS DER. WOODS-SAXON TYPE.
TABLE 2 LEVEL DENSITY PARAMETERS
NUCLIDE SYST A(1/MEV) T(MEV) C(1/MEV) EX(MEV) PAIRING
---------------------------------------------------------------
32-GE- 78 1.234E+01 8.699E-01 7.304E-01 9.395E+00 2.930E+00
32-GE- 79 1.362E+01 7.523E-01 2.737E+00 6.567E+00 1.360E+00
32-GE- 80 * 1.277E+01 8.125E-01 5.273E-01 8.551E+00 2.820E+00
32-GE- 81 * 1.255E+01 8.025E-01 2.496E+00 6.770E+00 1.360E+00
33-AS- 79 1.290E+01 8.230E-01 3.020E+00 7.585E+00 1.570E+00
33-AS- 80 1.150E+01 7.250E-01 4.181E+00 3.535E+00 0.0
33-AS- 81 * 1.293E+01 8.025E-01 2.772E+00 7.120E+00 1.460E+00
33-AS- 82 * 1.271E+01 7.927E-01 1.371E+01 5.344E+00 0.0
34-SE- 80 1.334E+01 8.130E-01 6.129E-01 9.136E+00 3.000E+00
34-SE- 81 1.368E+01 7.490E-01 2.463E+00 6.614E+00 1.430E+00
34-SE- 82 1.259E+01 7.980E-01 3.563E-01 8.246E+00 2.890E+00
34-SE- 83 1.381E+01 7.500E-01 2.666E+00 6.708E+00 1.430E+00
---------------------------------------------------------------
SYST: * = LDP'S WERE DETERMINED FROM SYSTEMATICS.
SPIN CUTOFF PARAMETERS WERE CALCULATED AS 0.146*SQRT(A)*A**(2/3).
IN THE CASTHY CALCULATION, SPIN CUTOFF FACTORS AT 0 MEV WERE
ASSUMED TO BE 6.291 FOR SE- 82 AND 5.0 FOR SE- 83.
REFERENCES
1) KAWAI, M. ET AL.: PROC. INT. CONF. ON NUCLEAR DATA FOR SCIENCE
AND TECHNOLOGY, MITO, P. 569 (1988).
2) BROWNE,J.C. AND BERMAN, B.L.: PHYS. REV. C26, 969 (1982).
3) MUGHABGHAB, S.F. ET AL.: "NEUTRON CROSS SECTIONS, VOL. I,
PART A", ACADEMIC PRESS (1981).
4) IGARASI, S.: J. NUCL. SCI. TECHNOL., 12, 67 (1975).
5) IIJIMA, S. ET AL.: JAERI-M 87-025, P. 337 (1987).
6) IIJIMA, S. AND KAWAI, M.: J. NUCL. SCI. TECHNOL., 20, 77
(1983).
7) PEREY, F.G: PHYS. REV. 131, 745 (1963).
8) HUIZENGA, J.R. AND IGO, G.: NUCL. PHYS. 29, 462 (1962).
9) LOHR, J.M. AND HAEBERLI, W.: NUCL. PHYS. A232, 381 (1974).
10) BECCHETTI, F.D., JR. AND GREENLEES, G.W.: POLARIZATION
PHENOMENA IN NUCLEAR REACTIONS ((EDS) H.H. BARSHALL AND
W. HAEBERLI), P. 682, THE UNIVERSITY OF WISCONSIN PRESS.
(1971).
11) GILBERT, A. AND CAMERON, A.G.W.: CAN. J. PHYS., 43, 1446
(1965).
12) IIJIMA, S., ET AL.: J. NUCL. SCI. TECHNOL. 21, 10 (1984).
13) GRUPPELAAR, H.: ECN-13 (1977).
14) ENSDF: EVALUATED NUCLEAR STRUCTURE DATA FILE (JUNE 1987).
15) NUCLEAR DATA SHEETS, 50, 1 (1987).
16) BENZI, V. AND REFFO, G.: CCDN-NW/10 (1969).
17) CHAUBEY, A.K. AND SEHGAL, M.L.: PHYS. REV., 152, 1055 (1966).
18) KIKUCHI, K. AND KAWAI, M.: "NUCLEAR MATTER AND NUCLEAR
REACTIONS", NORTH HOLLAND (1968).
19) FREHAUT, J., ET AL.: SYMP. ON NEUTRON CROSS SECTIONS FROM
10-50MEV, BNL, P.399 (1980)
20) FORREST, R.A.: AERE-R 12419 (1986).