97-Bk-250
97-BK-250 JAERI EVAL-MAR87 T.NAKAGAWA
JAERI-M 88-004 DIST-SEP89
----JENDL-3.2 MATERIAL 9755
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
HISTORY
87-03 NEW EVALUATION WAS MADE BY T.NAKAGAWA (JAERI).
DETAILS ARE DESCRIBED IN REF. /1/.
MF=1 GENERAL INFORMATION
MT=451 COMMENTS AND DICTIONARY
MT=452 NUMBER OF NEUTRONS PER FISSION
SUM OF MT=455 AND MT=456
MT=455 DELAYED NEUTRON DATA
BASED ON SEMI-EMPIRICAL FORMULA BY TUTTLE /2/.
MT=456 NUMBER OF PROMPT NEUTRONS PER FISSION
BASED ON SEMI-EMPIRICAL FORMULA BY HOWERTON /3/.
MF=2,MT=151 RESONANCE PARAMETERS
RESOLVED RESONANCE PARAMETERS (MLBW) : 1.0E-5 EV TO 100 EV
RESONANCE PARAMETERS WERE HYPOTHETICALLY GENERATED ADOPTING
THE FOLLOWING AVERAGE VALUES.
D-OBS = 2.09 EV (FROM LEVEL DENSITY PARAMETERS )
S0, S1= 0.83E-4, 3.37E-4 (FROM OPTICAL MODEL CALC.)
RADIATIVE WIDTH = 0.035EV (SAME AS CF-252)
FISSION WIDTH = 0.095 EV (ASSUMED THAT THE RATIO OF
FISSION TO RADIATIVE WIDTH IS EQUAL TO
CROSS SECTION RATIO)
THE ENERGY OF FIRST LEVEL WAS ADJUSTED TO REPRODUCE THE
2200-M/S CROSS SECTIONS OF 350 BARNS /4/ AND 960 BARNS /5/ FOR
CAPTURE AND FISSION, RESPECTIVELY.
UNRESOLVED RESONANCES : 0.1 TO 30 KEV
BY ADOPTING PARAMETERS USED FOR RESOLVED RESONANCE GENERATION
AS INITIAL VALUES, THEY WERE ADJUSTED TO REPRODUCE THE
EVALUATED FISSION AND CAPTURE CROSS SECTIONS BY USING ASREP
/6/. FINAL VALUES OF THE PARAMETERS ARE,
S0 = 0.82E-4, S1 = 3.9E-4, D-OBS = 2.09 EV,
RADIATIVE WIDTH = 0.035 EV, R =9.02 FM,
FISSION WIDTH = 0.104 EV AT 100 EV, 0.208 EV AT 30 KEV.
CALCULATED 2200 M/S CROSS SECTIONS AND RESONANCE INTEGRALS
2200 M/S VALUE RES. INT.
TOTAL 1325.0 B -
ELASTIC 12.22 B -
FISSION 959.3 B 517. B
CAPTURE 353.4 B 199. B
MF=3 NEUTRON CROSS SECTIONS
1) THE OPTICAL MODEL CALCULATION WAS PERFORMED WITH CODE CASTHY
/7/. OPTICAL POTENTIAL PARAMETERS USED WERE OBTAINED /8/ BY
FITTING THE TOTAL CROSS SECTION MEASURED BY PHILLIPS AND HOWE
/9/ FOR AM-241:
V = 43.4 - 0.107*EN (MEV)
WS= 6.95 - 0.339*EN + 0.0531*EN**2 (MEV)
(IN THE DERIVATIVE WOODS-SAXON FORM)
WV= 0 , VSO = 7.0 (MEV)
R = RSO = 1.282 , RS = 1.29 (FM)
A = ASO = 0.60 , B = 0.5 (FM)
2) IN THE STATISTICAL CALCULATION, THE FISSION, (N,2N), (N,3N)
AND (N,4N) CROSS SECTIONS WERE CONSIDERED AS THE COMPETING
PROCCESS CROSS SECTIONS.
3) THE LEVEL DENSITY PARAMETERS WERE DERIVED FROM RESONANCE
LEVEL SPACINGS AND LOW LAYING EXCITED LEVELS ON THE BASIS OF
GILBERT-CAMERON'S FORMULA /10/.
-----------------------------------------------------------
ISOTOPE 247 248 249 250 251
-----------------------------------------------------------
A(1/MEV) 28.1 27.8 34.2 30.05 30.0
SPIN-CUTOFF FACT 30.47 30.39 33.79 31.76 31.82
PAIRING E(MEV) 0.39 0.0 0.903 0.0 0.865
TEMP.(MEV) 0.364 0.326 0.366 0.340 0.385
C(1/MEV) 2.90 10.8 12.2 24.6 6.56
EX(MEV) 7.97 1.85 4.30 2.34 4.05
-----------------------------------------------------------
BELOW 30 KEV, CROSS SECTIONS ARE REPRESENTED WITH RESONANCE
PARAMETERS.
MT=1,2 TOTAL AND ELASTIC SCATTERING
THE OPTICAL MODEL CALCULATION WAS ADOPTED.
MT=4, 51 TO 59 AND 91 INELASTIC SCATTERING
THE LEVEL SCHEME WAS TAKEN FROM REF. /11/.
NO. ENERGY(KEV) SPIN-PARITY
--------------------------------------------
GROUND 0.0 2 -
1 34.5 3 -
2 35.6 4 +
3 78.1 5 +
4 86.4 7 +
5 97.0 5 -
6 104.1 1 -
7 125.4 2 -
8 129.0 6 +
9 131.9 3 +
10 157.0 8 +
11 167.0 6 -
12 175.4 1 +
13 191.0 7 +
14 211.8 2 +
15 237.0 3 +
16 242.0 9 +
17 248.0 7 -
18 270.0 4 +
--------------------------------------------
LEVELS ABOVE 296 KEV WERE ASSUMED TO BE OVERLAPPING.
MT=16, 17 AND 37 (N,2N), (N,3N) AND (N,4N)
CALCULATED WITH EVAPORATION MODEL BY TAKING THE COMPOUND
NUCLEUS FORMATION CROSS SECTION CALCULATED WITH OPTICAL MODEL.
MT=18 FISSION
SHAPE OF THE CF-251 FISSION CROSS SECTION /12/ WAS ADOPTED
AND MULTIPLIED BY THE FACTOR OF 0.84.
MT=102 RADIATIVE CAPTURE
CALCULATED WITH CASTHY. THE AVERAGE RADIATIVE WIDTH OF 0.035
EV AND S-WAVE LEVEL SPACING OF 2.09 EV WERE ASSUMED.
MT=251 MU-BAR
CALCULATED WITH CASTHY.
MF=4 ANGULAR DISTRIBUTIONS OF SECONDARY NEUTRONS
MT=2,51-59 CALCULATED WITH OPTICAL MODEL.
MT=16,17,18,37,91 ISOTROPIC DISTRIBUTIONS IN THE LABORATORY
SYSTEM WERE ASSUMED.
MF=5 ENERGY DISTRIBUTIONS OF SECONDARY NEUTRONS
MT=16,17,37,91 EVAPORATION SPECTRUM ASSUMED.
MT=18 MAXWELLIAN FISSION SPECTRUM.
TEMPERATURE ESTIMATED FROM SYSTEMATICS OF
SMITH ET AL./13/.
REFERENCES
1) NAKAGAWA, T.: JAERI-M 88-004 (1987).
2) TUTTLE, R.J.: INDG(NDS)-107/G+SPECIAL, P.29 (1979).
3) HOWERTON, R.J.: NUCL. SCI. ENG., 62, 438 (1977).
4) MUGHABGHAB, S.F.: NEUTRON CROSS SECTIONS, VOL.1, PART B,
ACADEMIC PRESS (1984)
5) DIAMOND, H., ET AL.: J. INORG. NUCL. CHEM., 30, 2553 (1968).
6) IGARASI, S.: J. NUCL. SCI. TECHNOL., 12, 67 (1975).
7) KIKUCHI, Y.: PRIVATE COMMUNICATION.
8) IGARASI, S. AND NAKAGAWA T.: JAERI-M 8342 (1979).
9) PHILLIPS, T.W. AND HOWE, F.R.: NUCL. SCI. ENG., 69, 375(1979).
10) GILBERT A. AND CAMERON A.G.W. : CAN. J. PHYS., 43, 1446(1965).
11) SCHMORAK, M.R.: NUCL. DATA SHEETS, 32, 87 (1981).
12) NAKAGAWA, T: JAERI-M 86-086 (1986).
13) SMITH, A.B. ET AL.: ANL/NDM-50 (1979).