RSICC DATA PACKAGE DLC-233
1. NAME AND TITLE OF DATA LIBRARY
CLES: Cross Section Library of Moderator Materials for Low-Energy Neutron Sources.
2. NAME AND TITLE OF DATA RETRIEVAL PROGRAMS
Department of Nuclear Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan through the OECD Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France.
4. HISTORICAL BACKGROUND AND INFORMATION
CLES is a cross section library that consists of 36 sets of multigroup constants (energy-averaged cross sections) for liquid 4He, H2, D2, CH4, H2O and D2O and solid CH4 at many different temperatures. The neutron energy range between 0.1 micro-eV and 10 MeV is discretized into 140 energy groups at equal logarithmic intervals. The angular distribution of scattered neutrons is represented by the expansion in Legendre polynomials up to order 3. The group constants are generated using physical models of a double-differential scattering cross section for the moderator materials, which are newly developed for describing low-energy neutron scattering in terms of the general considerations of molecular dynamics inherent in liquid and solid phases. Most of the calculated cross-section results are compared with many experimental measurements, both double-differential and total, for various material temperatures and neutron energies. Availability of CLES is demonstrated by the multigroup transport analyses of neutron source models for production of ultra cold (» 0:3micro-eV), cold (» 2 meV) and thermal (» 25 meV) neutrons.
5. APPLICATION OF THE DATA
The high-energy part for E>=1 eV (energy group g<70) and the low-energy part for E<=10 eV(g>= 60) are made up separately and then combined into one set. The overlapping energy region between 1 and 10 eV is prepared to make a gradual transition between the two parts. The high-energy part is produced using the Japanese evaluated nuclear data library JENDL-3.3/2/ and the nuclear data processing program NJOY/3/. The low-energy part is created by use of double-differential scattering cross section models developed theoretically for liquid and solid moderator materials. Low-energy neutron scattering by molecular dynamics inherent to each material is fully taken into account and the calculated cross-section results are compared with many experimental measurements, both double-differential and total, at liquid and solid temperatures. Slowing-down and thermalization properties are also examined with neutron energy spectra calculated numerically for moderator models.
All the results are reported in research papers on scientific journals, which are given for each material by paper(s) on cross section model and spectral analysis: liquid He-4/4/5/, liquid molecular H/6/7/, liquid molecular D/8/9/, solid methane/10/11/, liquid methane/10/11/, liquid light water/12/13/, and liquid heavy water/14/13/. Numerical methods for calculation of low-energy neutron scattering cross sections are described in detail and illustrated with physical cross section models/1/.
6. SOURCE AND SCOPE OF DATA
CLES consists of 36 sets of 140-group-constants (energy-averaged cross sections) for seven different moderator materials in liquid and solid phases at given temperatures:
· Liquid He-4 at 0.1, 0.3, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5 K,
· Liquid ortho-, para- and normal- molecular hydrogen at 14.0, 20.4 K
· Liquid ortho-, para- and normal- molecular deuterium at 18.7, 23.6 K,
· Solid methane at 20.4, 50.0, 90.7 K,
· Liquid methane at 90.7, 111.7 K,
· Liquid light water at 278, 300, 325, 350 K,
· Liquid heavy water at 278, 300, 325, 350 K.
All the sets are generated in the following form/1/:
· Neutron energy range between 0.1 micro-eV and 10 MeV,
· Total of 140 energy groups at equal logarithmic energy intervals(i.e. 10 groups per energy decade),
· Expansion of the angular distribution of scattered neutrons in Legendre polynomials up to order 3,
· Weighting energy spectrum by a combination of Maxwellian, 1/E and fission spectra for neutron energy E,
· Microscopic cross sections (b/molecule) in terms of text format(2 MB/set) and ANISN-type cross section table (length IHM=282, position IHT=3, groups IGM=140) though not multiplied by the Legendre factor (2*l+1).
7. DISCUSSION OF THE DATA RETRIEVAL PROGRAM
A Fortran program,
CLES.trans.for, is available to produce cross section tables for specific
neutron transport calculations, both deterministic and Monte Carlo. The major
recipes are as follows:
· Listing the total cross sections of scattering and absorption, the group-to-group transfer cross sections, and the upper- and lower-energy boundaries for all groups,
· Multiplying microscopic scattering cross sections (b/molecule) by the factor (2*l+1) to construct an ANISN-type cross section table,
· Calculating macroscopic scattering cross sections (1/cm) by the input value for number density N (molecules/cm**3): although an equilibrium or theoretical value of N for each material at given temperature is preset, it may be necessary to give any other values in practical cases such as boiling liquid and non-crystalline solid/7,11/,
· Varying the magnitudes of absorption cross section sigma_a(b/molecule) according to the expression p*sigma_a=+ q(v_th/v) with two arbitrary constants p (as a factor) and q (b/molecule) for neutron speeds v at E and v_th at E = 25 meV/13/,
· Merging two group-constant sets in a new one for mixed materials such as, for instance, liquid normal molecular hydrogen with a para:ortho ratio of 1:3/7/, liquid normal molecular D with a para:ortho ratio of 1:2/9/ and liquid heavy water contaminated with liquid light water/13/.
8. DATA FORMAT AND COMPUTER
Fortran 90; Linux or Windows (D00233MNYCP00).
9. TYPICAL RUNNING TIME
a. Documentation available with library
N. Morishima: CLES: Cross Section Library of Moderator Materials for Low-Energy Neutron Sources (November 2006).
b. Other useful documentation
Methods for Calculation of Low-Energy Neutron Scattering Cross Sections J. Neutron Res. 13(2005) 225-240.
K.Shibata et al.: Japanese Evaluated Nuclear Data Library Version 3 Revision-3: JENDL-3.3 J. Nucl. Sci. Technol. 39(2002) 1125-1136.
R.E.MacFarlane, D.W.Muir: The NJOY Nuclear Data Processing System, Version 91 LA-12740-M, Los Alamos National Laboratory, October 1994.
N.Morishima, Y.Abe: Evaluation of Cold-Neutron Scattering Cross Sections for Liquid He-4 at Temperatures between 1 and 4.2 K Nucl. Instr. And Method-A, 397(1997) 354-364;
Y.Abe, N.Morishima: Ultracold and Cold Neutron Cross Sections of Liquid 4He at Low Temperatures down to 0.1 K Nucl. Instr. And Method-A, 459(2001) 256-264;
N.Morishima, M.Sakakibara: Ultracold Neutron Production by the Phonon Excitation in Superfluid 4He at Temperatures below 1 K J. of Neutron Res. 8(2000) 233-243.
Y.Abe, N.Morishima: Neutronic Study of UCN Production and Storage in a Liquid He-4 Source Nucl. Instr. And Method-A, 481(2002) 414-421.
N.Morishima, D.Mizobuchi: Cross Section Models for Cold Neutron Scattering from Liquid H2 and D2 Nucl. Instr. And Method-A, 350(1994) 275-285;
N.Morishima, A.Nishimura: On the Yield of Cold and Ultracold Neutrons for Liquid H2 at Low Temperatures near the Melting Point Nucl. Instr. And Method-A, 426(1999) 638-641.
N.Morishima, Y.Matsuo: Cold Neutron Production in Liquid para- and normal-H2 Moderators Nucl. Instr. And Method-A, 490(2002) 308-315.
N.Morishima: Cold and Thermal Neutron Scattering Cross Sections of Liquid H2 and D2 at Temperatures between Melting and Boiling Points Ann. Nucl. Energy, 27(2000) 505-516;
N.Morishima, Y.Nishikawa: Cold and Thermal Neutron Scattering Cross Sections of Liquid H2 and D2. II: Improvement on Coherent Scattering Ann. Nucl. Energy, 31(2004) 737-745.
Y.Matsuo, N.Morishima, Y.Nagaya: Neutronic Study of Spherical Cold Neutron Sources composed of Liquid H2 and D2 Nucl. Instr. And Method-A, 496(2003) 446-451.
N.Morishima, Y.Sakurai:Cross-Section Model for Cold Neutron Scattering in Solid and Liquid CH4 Nucl. Instr. And Method-A, 490(2002) 527-537.
N.Morishima, T.Mitsuyasu: Cold Neutron Production in Solid and Liquid CH4 Moderators Nucl. Instr. And Method-A, 517(2004) 295-300;
T.Mitsuyasu, N.Morishima, Y.Nagaya:
Cold Neutron Production in Solid and Liquid CH4 Moderators II: on the
Reentrant-Hole Configuration Nucl. Instr. And Method-A, 537(2005) 610-613 (2005).
Y.Edura, N.Morishima: Cold and Thermal Neutron Scattering in Liquid Water: Cross-Section Model and Dynamics of Water Molecules Nucl. Instr. And Method-A, 534(2004) 531-543.
Y.Edura, N.Morishima: Generation of Neutron Multigroup Constants in the Energy Range 0.1 micro-eV-10 MeV for Light and Heavy Water at Four Different Temperatures, Nucl. Instr. And Method-A, 560(2006) 485-493.
Y.Edura, N.Morishima: Cold and Thermal Neutron Scattering in Liquid Water-II: Scattering Laws and Group Constants for H2O and D2O Nucl. Instr. And Method-A, 545(2005) 309-318.
11. CONTENTS OF LIBRARY
The package is transmitted on a CD disc which contains the report listed in section 10.a above, the installation and executable files, data files and test cases.
12. DATE OF ABSTRACT
August 2008, August 2012.
KEYWORDS: CROSS SECTIONS, NEUTRON