37-Rb- 85
37-RB- 85 JNDC EVAL-MAR90 JNDC FP NUCLEAR DATA W.G.
DIST-NOV90
----JENDL-3.2 MATERIAL 3725
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
HISTORY
84-10 EVALUATION FOR JENDL-2 WAS MADE BY JNDC FPND W.G./1/
90-03 MODIFICATION FOR JENDL-3 WAS MADE/2/.
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 8.468 KEV
RESONANCE PARAMETERS OF JENDL-2 WERE MODIFIED AS FOLLOWS :
EVALUATION OF JENDL-2 WAS PERFORMED ON THE BASIS OF THE DATA
MEASURED BY OHKUBO ET AL./3/ AMONG 138 LEVELS MEASURED IN THE
ENERGY REGION UP TO 18.6 KEV, 116 RESONANCE LEVELS WERE
ASSUMED TO BE S-WAVE, AND REMAINING 22 LEVELS WERE ESTIMATED
TO BE P-WAVE. NEUTRON WIDTHS OF ALL LEVELS WERE DETERMINED
FROM THE 2G*(NEUTRON WIDTH) MEASURED BY OHKUBO ET AL.
HOWEVER, THE VALUE OF TOTAL SPIN J FOR EACH RESONANCE LEVEL
WAS UNKNOWN EXCEPT 13 LEVELS ASSIGNED BY OHKUBO ET AL., AND
THE TARGET SPIN OF 2.5 WAS ADOPTED AS J FOR J-UNKNOWN LEVELS.
RADIATION WIDTHS WERE OBTAINED FOR 10 LEVELS BELOW 2.6 KEV
FROM THE MEASUREMENT BY OHKUBO ET AL. AVERAGE RADIATION WIDTH
WAS ALSO ESTIMATED TO BE 328+-18 MEV BY OHKUBO ET AL., AND WAS
ADOPTED FOR THE OTHER LEVELS. A NEGATIVE RESONANCE WAS ADDED
AT -943 EV SO AS TO REPRODUCE THE THERMAL CAPTURE CROSS
SECTION OF 480+-10 MB GIVEN BY MUGHABGHAB ET AL./4/
FOR JENDL-3, THE TOTAL SPIN J OF 125 RESONANCE LEVELS WAS
TENTATIVELY ESTIMATED WITH A RANDOM NUMBER METHOD. NEUTRON
WIDTHS OF THESE LEVELS WERE MODIFIED ON THE BASIS OF THE
ESTIMATED J VALUES. NEUTRON AND RADIATION WIDTHS OF THE
NEGATIVE RESONANCE LEVEL WERE ALSO MODIFIED SO AS TO REPRODUCE
THE THERMAL CAPTURE CROSS SECTION ACCORDING TO THE ABOVE
MODIFICATION OF THE NEUTRON WIDTHS. SCATTERING RADIUS WAS
TAKEN FROM THE GRAPH (FIG. 1, PART A) GIVEN BY MUGHABGHAB ET
AL.
UNRESOLVED RESONANCE REGION : 8.468 KEV - 100 KEV
UNRESOLVED RESONANCE PARAMETERS WERE ADOPTED FROM JENDL-2.
THE NEUTRON STRENGTH FUNCTION, S0, WAS TAKEN FROM THE
RECOMMENDATION IN REF./5/, AND S1 AND S2 WERE CALCULATED WITH
OPTICAL MODEL CODE CASTHY/6/. THE OBSERVED LEVEL SPACING WAS
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.
TYPICAL VALUES OF THE PARAMETERS AT 70 KEV:
S0 = 1.000E-4, S1 = 2.920E-4, S2 = 0.650E-4, SG = 21.4E-4,
GG = 0.205 EV, R = 6.828 FM.
CALCULATED 2200-M/S CROSS SECTIONS AND RES. INTEGRALS (BARNS)
2200 M/S RES. INTEG.
TOTAL 6.334 -
ELASTIC 5.854 -
CAPTURE 0.4800 8.73
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/7/ 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/8/.
THE OMP'S FOR CHARGED PARTICLES ARE AS FOLLOWS:
PROTON = PEREY/9/
ALPHA = HUIZENGA AND IGO/10/
DEUTERON = LOHR AND HAEBERLI/11/
HELIUM-3 AND TRITON = BECCHETTI AND GREENLEES/12/
PARAMETERS FOR THE COMPOSITE LEVEL DENSITY FORMULA OF GILBERT
AND CAMERON/13/ WERE EVALUATED BY IIJIMA ET AL./14/ 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
/15/.
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 TAKEN FROM REF./16/.
NO. ENERGY(MEV) SPIN-PARITY
GR. 0.0 5/2 -
1 0.1513 3/2 -
2 0.2810 1/2 -
3 0.5140 9/2 +
4 0.7350 3/2 -
5 0.8685 7/2 -
6 0.8830 1/2 -
7 0.9500 5/2 +
8 1.1750 7/2 +
LEVELS ABOVE 1.294 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/17/ AND NORMALIZED TO 1 MILLI-BARN AT 14 MEV.
THE GAMMA-RAY STRENGTH FUNCTION (22.0E-04) WAS ADJUSTED TO
REPRODUCE THE CAPTURE CROSS SECTION OF 335 MILLI-BARNS AT 25
KEV MEASURED BY LAKSHMANA ET AL./18/
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 = 32 (N,N'D) CROSS SECTION
MT =103 (N,P) CROSS SECTION
MT =104 (N,D) CROSS SECTION
MT =105 (N,T) CROSS SECTION
MT =106 (N,HE3) 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 (= 281.4) WAS ESTIMATED BY THE
FORMULA DERIVED FROM KIKUCHI-KAWAI'S FORMALISM/19/ AND LEVEL
DENSITY PARAMETERS.
FINALLY, THE (N,2N), (N,P) AND (N,ALPHA) CROSS SECTIONS WERE
NORMALIZED TO THE FOLLOWING VALUES AT 14.5 MEV:
(N,2N) 1050.00 MB (RECOMMENDED BY BYCHKOV+/20/)
(N,P) 17.40 MB (SYSTEMATICS OF FORREST/21/)
(N,ALPHA) 6.65 MB (RECOMMENDED BY FORREST/21/)
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
---------------------------------------------------------------
35-BR- 81 1.290E+01 8.310E-01 3.275E+00 7.733E+00 1.570E+00
35-BR- 82 1.266E+01 6.900E-01 5.789E+00 3.665E+00 0.0
35-BR- 83 1.324E+01 7.830E-01 2.683E+00 6.978E+00 1.460E+00
35-BR- 84 * 1.302E+01 7.738E-01 1.393E+01 5.216E+00 0.0
36-KR- 82 1.319E+01 7.810E-01 4.961E-01 8.191E+00 2.740E+00
36-KR- 83 1.483E+01 6.700E-01 2.532E+00 5.589E+00 1.170E+00
36-KR- 84 9.970E+00 9.600E-01 4.942E-01 8.590E+00 2.630E+00
36-KR- 85 1.024E+01 8.900E-01 1.570E+00 6.261E+00 1.170E+00
37-RB- 83 * 1.400E+01 7.831E-01 3.730E+00 7.579E+00 1.570E+00
37-RB- 84 1.106E+01 8.060E-01 5.598E+00 4.438E+00 0.0
37-RB- 85 1.190E+01 8.690E-01 2.827E+00 7.561E+00 1.460E+00
37-RB- 86 1.002E+01 8.500E-01 3.954E+00 4.312E+00 0.0
---------------------------------------------------------------
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 4.75 FOR RB- 85 AND 5.0 FOR RB- 86.
REFERENCES
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