96-CM-241 JAERI EVAL-MAR89 T.NAKAGAWA
DIST-SEP89
----JENDL-3.2 MATERIAL 9628
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
HISTORY
89-03 EVALUATION FOR JENDL-3 WAS MADE BY T. NAKAGAWA(JAERI)/1/.
MF=1 GENERAL INFORMATION
MT=451 DESCRIPTIVE DATA
MT=452 NUMBER OF NEUTRONS PER FISSION
SUM OF MT=455 AND MT=456
MT=455 DELAYED NEUTRON DATA
ESTIMATED FROM THE SYSTEMATICS BY TUTTLE /2/.
MT=456 NUMBER OF PROMPT NEUTRONS PER FISSION
BASED ON THE EMPIRICAL FORMULA BY HOWERTON /3/.
MF=2 RESONANCE PARAMETERS
MT=151 NO RESONANCE PARAMETERS WERE GIVEN.
CALCULATED 2200M/S CROSS SECTIONS AND RESONANCE INTEGRALS.
2200 M/SEC RES. INTEG.
TOTAL 851.9 B ---
ELASTIC 11.9 B ---
FISSION 700.0 B 969 B
CAPTURE 140.0 B 160 B
MF=3 NEUTRON CROSS SECTIONS
BELOW 1 EV:
THIS ENERGY RANGE WAS ASSUMED TO BE THE THERMAL REGION, AND
FISSION AND CAPTURE CROSS SECTIONS WITH 1/V SHAPE WERE GIVEN
AND ELASTIC SCATTERING WITH A CONSTANT VALUE. THE TOTAL CROSS
SECTION IS A SUM OF THEM.
ABOVE 1 EV:
MT=1,2,4,51-54,91,102,251 TOTAL, ELASTIC AND INELASTIC
SCATTERING, CAPTURE CROSS SECTIONS AND MU-L
CALCULATED WITH OPTICAL AND STATISTICAL MODEL CODE
CASTHY/4/.
THE SPHERICAL OPTICAL POTENTIAL PARAMETERS (MEV,FM):
V =42.0-0.107*EN, R =1.282, A =0.60
WS =6.95-0.339*EN+0.0531*EN**2, RS =1.29, B =0.50
(DERIVATIVE WOODS-SAXON FORM)
VSO=7.0, RSO=1.282, ASO=0.60
THIS SET OF POTENTIAL PARAMETERS WAS DETERMINED /5/ TO
REPRODUCE WELL THE TOTAL CROSS SECTION OF AM-241 BY
PHILLIPS AND HOWE /6/, AND A REAL PART WAS MODIFIED A
LITTLE TO GIVE A SLIGHTLY HIGH REACTION CROSS SECTIONS IN
A LOW ENERGY REGION.
IN THE STATISTICAL MODEL CALCULATION, COMPETING PROCESSES
OF FISSION, (N,2N) AND (N,3N), AND LEVEL FLUCTUATION WERE
CONSIDERED. THE LEVEL SCHEME OF CM-241 WAS TAKEN FROM THE
COMPILATION BY ELLIS-AKOVALI /7/:
NO. ENERGY(MEV) SPIN-PARITY
G.S. 0.0 1/2 +
1 0.0530 3/2 +
2 0.103 5/2 +
3 0.157 7/2 +
4 0.255 9/2 +
OVERLAPPING LEVELS WERE ASSUMED ABOVE 0.35 MEV. THE LEVEL
DENSITY PARAMETERS WERE DETERMINED ON THE BASIS OF NUMBERS
OF EXCITED LEVELS.
CM-242 CM-241
A(1/MEV) 28.0 28.57
T(MEV) 0.40 0.378
C(1/MEV) 2.5771 5.287
E-X(MEV) 4.3163 3.560
SPIN-CUTOFF(1/MEV**0.5) 30.00 30.22
PAIRING E(MEV) 0.15 0.72
AVERAGE RADIATIVE WIDTH = 0.040 EV AND D = 6.6 EV OBTAINED
FROM THE LEVEL DENSITY PARAMETERS WERE USED FOR THE
CAPTURE CROSS SECTION CALCULATION.
MT=16, 17 (N,2N) AND (N,3N) CROSS SECTIONS
CALCULATED WITH THE EVAPORATION MODEL BY PEARLSTEIN /8/.
NEUTRON EMISSION CROSS SECTION WAS ASSUMED TO BE (COMPOUND
NUCLEUS FORMATION CROSS SECTION CALCULATED WITH OPTICAL
MODEL - FISSION).
MT=18 FISSION CROSS SECTION
THE SAME CROSS SECTION AS CM-243 /1/ WAS ASSUMED. BELOW 1
KEV, STRUCTURE WAS REPLACED WITH A SMOOTH CURVE.
MF=4 ANGULAR DISTRIBUTIONS OF SECONDARY NEUTRONS
MT=2,51-54,91
LEGENDRE COEFFICIENTS CALCULATED WITH THE OPTICAL AND
STATISTICAL MODELS WERE GIVEN.
MT=16,17,18
ISOTROPIC DISTRIBUTIONS IN THE LABORATORY SYSTEM.
MF=5 ENERGY DISTRIBUTIONS OF SECONDARY NEUTRONS
MT=16,17,91 EVAPORATION SPECTRUM.
MT=18 ESTIMATED FROM Z**2/A SYSTEMATICS BY SMITH ET AL. /9/,
ASSUMING E(CF-252) = 2.13 MEV.
REFERENCES
1) NAKAGAWA T.: TO BE PUBLISHED AS JAERI-M REPORT.
2) TUTTLE R.J.: INDC(NDS)-107/G+SPECIAL, 29 (1979).
3) HOWERTON R.J.: NUCL. SCI. ENG. 62, 438 (1977).
4) IGARASI S.: J.NUCL.SCI.TECHNOL. 12, 67 (1975).
5) IGARASI S. AND NAKAGAWA T.: JAERI-M 8342 (19879).
6) PHILLIPS T.W. AND HOWE R.E.: NUCL. SCI. ENG., 69, 375 (1979).
7) ELLIS-AKOVALI Y.A.: NUCL. DATA SHEETS, 44, 407 (1985).
8) PEARLSTEIN S.: J. NUCL. ENERGY 27, 81 (1973).
9) A.B. SMITH ET AL. : ANL/NDM-50 (1979).