95-Am-242 JAEA+ EVAL-FEB10 O.Iwamoto,T.Nakagawa, et al.
DIST-MAY10 20100318
----JENDL-4.0 MATERIAL 9546
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
History
06-04 Resonance parameters were revised.
07-05 New calculation was made with CCONE code.
07-08 New calculation was made with CCONE code.
08-03 Interpolation of (5,18) was changed.
Data were compiled as JENDL/AC-2008/1/.
09-03 (1,452) and (1,455) were revised.
10-02 Data of prompt gamma rays due to fission were given.
10-03 Covariance data were given.
MF= 1 General information
MT=452 Number of Neutrons per fission
Sum of MT's=455 and 456.
MT=455 Delayed neutron data
Determined from nu-d of the following three nuclides and
partial fission cross sections calculated with CCONE code/2/.
Am-243 = 0.006659 *1)
Am-242 = 0.0049 measured by Saleh et al./3/
Am-241 = 0.003154 *1)
*1) an average of systematics by Tuttle/4/,
Benedetti et al./5/ and Waldo et al./6/
Decay constants calculated by Brady and England./7/ were
adopted.
MT=456 Number of prompt neutrons per fission
(same as JENDL-3.3)
Maslov's evaluation /8/ was adopted.
* IDENTICAL TO THAT FOR AM-242M, WHICH WAS OBTAINED WITH
MADLAND-NIX MODEL CALCULATIONS /9/ FITTED TO THE MEASURED
DATA OF HOWE ET AL./10/ ABOVE EMISSIVE FISSION THRESHOLD
SUPERPOSITION OF NEUTRON EMISSION IN (N,XNF) REACTIONS /11/
AND PROMPT FISSION NEUTRONS IS EMPLOYED.
MF= 2 Resonance parameters
MT=151
Resolved resonance parameters (below 100eV)
Hypothetical resonance parameters were determined by Maslov
et al./8/
For the present file, the parameters of -1.9344 and 0.35eV
resonances were modified to reproduce the thermal fission
/12,13/ and capture /14/ cross sections.
Unresolved resonance parameters (100eV - 30keV)
Parameters were determined with ASREP code/15/ so as to
reproduce the cross sections in the energy range from 100 eV
to 30 keV. They are used only for self-shielding calculations.
Thermal cross sections and resonance integrals (at 300K)
-------------------------------------------------------
0.0253 eV reson. integ.(*)
(barns) (barns)
-------------------------------------------------------
total 2758.3
elastic 7.39
fission 2420.7 1050
capture 330.3 205
-------------------------------------------------------
(*) In the energy range from 0.5 eV to 10 MeV.
MF= 3 Neutron cross sections
Cross sections above the resolved resonance region except for
the elastic scattering (MT=2) and fission cross sections (MT=18,
19, 20, 21, 38) were calculated with CCONE code/2/. The same
parameters as those for Am-242m were used in the CCONE
calculation.
MT= 2 Elastic scattering cross section
Calculated as total - non-elastic scattering cross sections.
MT=18 Fission cross section
Below 70 keV, calculated with CCONE code.
Above 70 keV, fission cross section of Am-242m was adopted,
which was based on experimental data.
MT=19, 20, 21, 38 Multi-chance fission cross sections
Calculated with CCONE code, and renormalized to the total
fission cross section (MT=18).
MF= 4 Angular distributions of secondary neutrons
MT=2 Elastic scattering
Calculated with CCONE code.
MT=18 Fission
Isotropic distributions in the laboratory system were assumed.
MF= 5 Energy distributions of secondary neutrons
Assumed to be the same as Am-242m.
MT=18 Fission neutron spectra
Below 6 MeV, calculated with modified Madland-Nix formula
considering multi-mode fission processes (standard-1,
standard-2, superlong).
Above 7 MeV, calculated with CCONE code.
MT=455 Delayed neutron spectra
Summation calculation by Brady and England /7/ was adopted.
MF= 6 Energy-angle distributions
Calculated with CCONE code.
Distributions from fission (MT=18) are not included.
MF=12 Photon production multiplicities
MT=18 Fission
Calculated from the total energy released by the prompt
gamma-rays due to fission which was estimated from its
systematics, and the average energy of gamma-rays.
MF=14 Photon angular distributions
MT=18 Fission
Isotoropic distributions were assumed.
MF=15 Continuous photon energy spectra
MT=18 Fission
Experimental data measured by Verbinski et al./16/ for
Pu-239 thermal fission were adopted.
MF=31 Covariances of average number of neutrons per fission
MT=452 Number of neutrons per fission
Sum of covariances for MT=455 and MT=456.
MT=455
Error of 20% was assumed.
MT=456
The same Covariance as Am-242m was adopted.
MF=33 Covariances of neutron cross sections
Covariances were given to all the cross sections by using
KALMAN code/17/ and the covariances of model parameters
used in the cross-section calculations.
For the fission cross section, covariances of Am-242m obtained
with the GMA analysis were adopted. Standard deviations were
multiplied by a factor of 3.
In the resolved resonance region, the following standard
deviations were assuned parameters:
Total 10 - 60 %
Elastic scattering 20 %
Fission 10 - 60 %
Capture 20 - 70 %
MF=34 Covariances for Angular Distributions
MT=2 Elastic scattering
Covariances were given only to P1 components.
MF=35 Covariances for Energy Distributions
MT=18 Fission spectra
Estimated with CCONE and KALMAN codes.
*****************************************************************
Calculation with CCONE code
*****************************************************************
Models and parameters used in the CCONE/2/ calculation
1) Coupled channel optical model
Levels in the rotational band were included. Optical model
potential and coupled levels are shown in Table 1.
2) Two-component exciton model/18/
* Global parametrization of Koning-Duijvestijn/19/
was used.
* Gamma emission channel/20/ was added to simulate direct
and semi-direct capture reaction.
3) Hauser-Feshbach statistical model
* Moldauer width fluctuation correction/21/ was included.
* Neutron, gamma and fission decay channel were included.
* Transmission coefficients of neutrons were taken from
coupled channel calculation in Table 1.
* The level scheme of the target is shown in Table 2.
* Level density formula of constant temperature and Fermi-gas
model were used with shell energy correction and collective
enhancement factor. Parameters are shown in Table 3.
* Fission channel:
Double humped fission barriers were assumed.
Fission barrier penetrabilities were calculated with
Hill-Wheler formula/22/. Fission barrier parameters were
shown in Table 4. Transition state model was used and
continuum levels are assumed above the saddles. The level
density parameters for inner and outer saddles are shown in
Tables 5 and 6, respectively.
* Gamma-ray strength function of Kopecky et al/23/,/24/
was used. The prameters are shown in Table 7.
------------------------------------------------------------------
Tables
------------------------------------------------------------------
Table 1. Coupled channel calculation
--------------------------------------------------
* rigid rotor model was applied
* coupled levels = 0,3,7 (see Table 2)
* optical potential parameters /25/
Volume:
V_0 = 48 MeV
lambda_HF = 0.004 1/MeV
C_viso = 15.9 MeV
A_v = 12.04 MeV
B_v = 81.36 MeV
E_a = 385 MeV
r_v = 1.255 fm
a_v = 0.58 fm
Surface:
W_0 = 17.2 MeV
B_s = 11.19 MeV
C_s = 0.01361 1/MeV
C_wiso = 23.5 MeV
r_s = 1.15 fm
a_s = 0.601 fm
Spin-orbit:
V_so = 5.75 MeV
lambda_so = 0.005 1/MeV
W_so = -3.1 MeV
B_so = 160 MeV
r_so = 1.1214 fm
a_so = 0.59 fm
Coulomb:
C_coul = 1.3
r_c = 1.2452 fm
a_c = 0.545 fm
Deformation:
beta_2 = 0.243
beta_4 = 0.08
beta_6 = 0.0015
* Calculated strength function
S0= 1.45e-4 S1= 2.28e-4 R'= 9.66 fm (En=1 keV)
--------------------------------------------------
Table 2. Level Scheme of Am-242
-------------------
No. Ex(MeV) J PI
-------------------
0 0.00000 1 - *
1 0.04409 0 -
2 0.04860 5 -
3 0.05270 3 - *
4 0.07582 2 -
5 0.09900 2 +
6 0.11400 6 -
7 0.14800 5 - *
8 0.14969 4 -
9 0.17100 4 -
10 0.19000 7 -
11 0.19770 3 -
12 0.23053 1 +
13 0.24436 3 -
14 0.26300 6 -
15 0.26990 3 +
16 0.27433 1 -
17 0.28350 7 +
18 0.28901 4 -
19 0.29284 2 -
20 0.29641 2 -
21 0.30700 5 +
22 0.32784 3 -
23 0.33071 3 -
24 0.34158 0 +
25 0.34200 5 -
26 0.35569 2 +
27 0.36470 2 +
28 0.37040 4 +
29 0.37247 4 -
-------------------
*) Coupled levels in CC calculation
Table 3. Level density parameters
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Am-243 17.8584 0.7698 2.0985 0.4029 -0.9548 3.1071
Am-242 18.6337 0.0000 1.6845 0.2795 -0.6541 0.9592
Am-241 18.1961 0.7730 1.7328 0.3819 -0.7226 2.8365
Am-240 18.5012 0.0000 1.3474 0.2883 -0.6831 1.0000
Am-239 18.4349 0.7762 1.5592 0.3648 -0.5528 2.6354
--------------------------------------------------------
Table 4. Fission barrier parameters
----------------------------------------
Nuclide V_A hw_A V_B hw_B
MeV MeV MeV MeV
----------------------------------------
Am-243 6.200 0.800 5.150 0.520
Am-242 6.410 0.600 5.800 0.550
Am-241 6.100 0.800 5.500 0.520
Am-240 6.100 0.650 6.000 0.450
Am-239 6.000 0.800 5.400 0.520
----------------------------------------
Table 5. Level density above inner saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Am-243 21.5049 0.8981 2.6000 0.2555 -0.6419 2.0981
Am-242 20.8697 0.0000 2.6000 0.3254 -2.4113 2.0000
Am-241 21.3526 0.9018 2.6000 0.3213 -1.4929 2.9018
Am-240 21.2764 0.0000 2.6000 0.3219 -2.3947 2.0000
Am-239 21.2001 0.9056 2.6000 0.3225 -1.4891 2.9056
--------------------------------------------------------
Table 6. Level density above outer saddle
--------------------------------------------------------
Nuclide a* Pair Eshell T E0 Ematch
1/MeV MeV MeV MeV MeV MeV
--------------------------------------------------------
Am-243 21.5049 0.8981 0.6000 0.3532 -0.8019 2.8981
Am-242 21.4288 0.0000 0.5600 0.3688 -1.8681 2.2000
Am-241 21.3526 0.9018 0.5200 0.3556 -0.7969 2.9018
Am-240 21.2764 0.0000 0.4800 0.3567 -1.6981 2.0000
Am-239 21.2001 0.9056 0.4400 0.3579 -0.7919 2.9056
--------------------------------------------------------
Table 7. Gamma-ray strength function for Am-243
--------------------------------------------------------
* E1: ER = 11.52 (MeV) EG = 2.77 (MeV) SIG = 244.72 (mb)
ER = 14.31 (MeV) EG = 4.19 (MeV) SIG = 489.44 (mb)
* M1: ER = 6.57 (MeV) EG = 4.00 (MeV) SIG = 1.28 (mb)
* E2: ER = 10.10 (MeV) EG = 3.19 (MeV) SIG = 6.92 (mb)
--------------------------------------------------------
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