NEUTRON CROSS SECTIONS Volume 1 Neutron Resonance Parameters and Thermal Cross Sections Part A Ζ = 1 - 60 S. F. Mughabghab, M. Divadeenam, and Ν. E. Holden Part Β Ζ = 61 - 100 S. F. Mughabghab Volume 2 Neutron Cross Section Curves Neutron Cross Sections Volume 1 NEUTRON RESONANCE PARAMETERS AND THERMAL CROSS SECTIONS Part Β Ζ = 61 - 100 S. F. MUGHABGHAB National Nuclear Data Center Brookhaven National Laboratory Upton, New York 1984 ACADEMIC PRESS, INC. (Harcourt Brace Jovanovich, Publishers) Orlando San Diego New York London Toronto Montreal Sydney Tokyo Academic Press Rapid Manuscript Reproduction COPYRIGHT© 1984, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED. NO PART OF THIS PUBLICATION MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR ANY INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT PERMISSION IN WRITING FROM THE PUBLISHER. ACADEMIC PRESS, INC. Orlando, Florida 32887 United Kingdom Edition published by ACADEMIC PRESS, INC. (LONDON) LTD. 24/28 Oval Road, London ΝW1 7DX Library of Congress Cataloging in Publication Data Mughabghab, S. F., Date Neutron cross sections. Contents: v. 1, pt. Α. Ζ = 1-60 — pt. Β. Ζ * 61-100. 1. Neutron cross sections—Tables. I. Oivadeenam, M. II. Holden, Ν. Ε. III. Title. QC793.5.N462N47 539.7*213 s [539.7'213] 82-110824 ISBN 0-12-509701-8 (set) ISBN 0-12-5097Π-5 (v.l, pt. B) PRINTED IN THE UNITED STATES OF AMERICA 84 85 86 87 9 8 7 6 5 4 3 2 1 PREFACE This book represents the fourth edition of what was previously known as BNL-325, Neutron Cross Sections, Volume 1,* Resonance Parameters (Third Edition, 1973) by S. F. Mughabghab and D. I. Garber. The first edition of the BNL-325 reports which appeared in 1955 was prepared by Donald J. Hughes and John A. Harvey. Because of the vast amount of data included, this fourth edition of Volume 1 is published in parts A and Β covering the mass regions represented by Ζ = 1-60 and 61 - 100, respectively. As with the third edition, only recommended parameters are presented. In addition to the extensive list of detailed individual resonance parameters for each isotope, this book contains thermal cross sections and average resonance parameters as well as a short survey of the physics of thermal and resonance neutrons with emphasis on evaluation methods. The introduction to the third edition has been expanded in this edition (Part A) to include commonly used nuclear physics formulas and topics of current interest such as direct or valence capture and the Brink-Axel treatment of electric dipole radiation. The introduc­ tion to Volume 1, Part B, covers the topics of paramagnetic scattering, alpha widths of resonances, and sub-threshold fission, which were not discussed pre­ viously in Part A, as well as the systematics of the average resonance parameters for the whole mass range. New additional features have been added to appeal to a wider spectrum of users. These include (1) spin-dependent scattering lengths that are of interest to solid state as well as nuclear physicists and evaluators, (2) Maxwellian 30-keV capture cross sections that are of importance to astrophysi­ cists in their studies of nucleosynthesis and the age of the universe, and (3) s- and p-wave average radiative widths and 7-ray strength functions that are required in capture cross section measurements by neutron physicists. The figures describing the systematics of the potential scattering lengths, s-, ρ-, and d-wave neutron strength functions, and average radiative widths have been enlarged for easy readability for those users requiring an interpolated value. Of particular interest is the determination of potential scattering lengths for light nuclides and the comparison of the behavior of this quantity with mass number in terms of the optical model. * Volume 2: Neutron Cross Section Curves, in preparation. vii viii PREFACE In the present edition, an attempt has been made to achieve, where possible, a consistency between the individual resonance parameters and the various ther­ mal cross sections. To meet this objective, the parameters of negative energy resonances are postulated where required. Immediately preceding the resonance parameter tables, one can find the contribution to the thermal capture and fission cross sections from positive energy resonances of each spin state (for odd target nuclides) as well as the direct capture component calculated within the framework of the Lane-Lynn theory. This information is required in nuclear structure studies carried out by thermal neutron capture 7-ray spectra measurements. An errata to Volume 1, Part A is included in this volume. The author would appreciate being notified by the users of any errors found in the text. Previous editions of BNL-325 have been widely used and frequently refer­ enced. We hope that this new edition continues to be a prime source book that will satisfy the needs of the casual and serious user of neutron cross sections as well as the student interested in this exciting and rich field. S. F. Mughabghab Brookhaven National Laboratory ACKNOWLEDGMENTS A project of this magnitude is not the work of one individual. The list of people whose help must be acknowledged is necessarily quite long. Four people must be specially thanked. These are Dr. C. L. Dunford, Dr. R. R. Kinsey, F. M. Scheffel, and V. McLane. The scope of the project consists of four parts: (1) preparation of the pertinent up-to-date body of data; (2) computer coding; (3) evaluation and recommenda­ tions; and (4) production and checking. (1) Production of this volume demanded an accurate and complete body of the world's resonance parameter and thermal data. For this publication, the com­ puterized files of the CSISRS library of the National Nuclear Data Center (NNDC) were used. In addition, the other three international neutron data cen­ ters, CCDN (Ν. Ε. Α.), NDS (I. Α. Ε. Α.), and CJD (USSR), compiled and transmitted to us data collected from their areas of responsibility. (2) To operate on the CSISRS library files and produce resonance parameter listings in a usable form for evaluation, computer coding was necessary. This was ably carried out by V. McLane. (3) As an aid in the evaluation stage, computer codes for physics checking and calculations of quantities from the voluminous amount of resonance param­ eters were required. Many people readily extended their help in this regard. The author wishes to express his deep gratitude to Dr. C. L. Dunford, Dr. R. R. Kinsey, and V. McLane. The author also acknowledges the help of B. A. Magur- no in calculating the Westcott factors using ENDF data base. (4) This volume was produced from computer-generated film on an FR80. The program to compose pages, including upper and lowercase symbols and Greek letters, was written by Dr. R. R. Kinsey and afforded very substantial savings of money and of errors. The checking at various stages of this task was diligently done by F. Scheffel and the checking of the final results was carried out by Dr. S. Pearlstein and Dr. M. R. Bhat. The author gratefully acknowledges their suggestions and criticisms. In addition, the author wishes to thank M. Blennau, P. Dixon, J. Roys, S. Santos, Τ Dawson, and A. Fuoco for their diligent, tireless effort in providing the necessary computer services, and D. Faivre for typing the introduction. ix χ ACKNOWLEDGMENTS Many physicists outside the NNDC have aided in this publication. We are grateful to the many experimentalists throughout the world who made special efforts to provide us with their very recent resonance parameter and thermal data prior to publication. In particular, special mention goes to Drs. R. Macklin and J. A. Harvey, J. Dabbs, and D. Horen of Oak Ridge National Laboratory; Professor J. B. Garg of the State University of New York at Albany; Professors R. C. Block and R. W. Hockenbury of Rensselaer Polytechnic Institute; Drs. H. Jackson and R. Holt of Argonne National Laboratory; Professor R. O. Lane and Dr. H. Knox of Ohio State University; Dr. W. R. Kane of Brookhaven National Laboratory; Drs. H. Weigmann, G. Rohr, F. Poortmans, F. Corvi, and Κ. H. Bockoff of Central Bureau of Nuclear Measurements, Belgium; Drs. B.J. Allen, J. W. Boldeman, G. C. Hicks, and A. R. de L. Musgrove of Australian Atomic Energy Commission Research Establishment; Professor F. Firk of Yale Univer­ sity; Dr. D. B. Syme of Harwell; Drs. Yu. Popov and A. B. Popov of Joint Institute of Nuclear Research (DUBNA); Dr. S. M. Kalebin of Research Institute Atom Reactors (USSR); Drs. J. C. Browne, B. Berman, and R. M. White of the University of California Lawrence Livermore Laboratory; Dr. R. W. Benjamin of Savannah River Laboratory; Dr. R. F. Carlton of Middle Tennessee State University; Dr. R. Winters of Denison University; Drs. D. M. Drake, F. O. Purser, and J. A. Farrell of Los Alamos National Laboratory; Dr. V. P. Vertebnyi of the Ukranian SSR Academy of Sciences; Dr. H. G. Priesmeyer of Institut fur Reine und Angewandte Kernphysik der Universitat Kiel; and Dr. M. Ohkubo of Japan Atomic Energy Research Institute. In addition, we are grateful to the physicists who communicated their thermal data prior to publication. These include Professor Dr. L. Koester of Physik Department der Technischen Univer­ sitat Munchen; Drs. H. Glaettli and A. Abragam of Saclay; Drs. F. DeCorte and L. Moens of the Institute for Nuclear Sciences, Belgium; Dr. E. Steiness of Institutt for Atomenergi, Norway; Dr. B. Ryves of National Physical Laboratory, Great Britain; Dr. Ε. T. Jurney of Los Alamos National Laboratory; Dr. Ε. T. Kennett of McMaster University; Dr. F. Kropff of Centre Atomics Bariloche, Argentina; Drs. V. F. Sears and M. A. Lone of Chalk River Nuclear Laborator­ ies, Canada; Dr. K. Abrahams of Reactor Centrum Netherlands; Dr. C. Coceva of CNEN Centre, Bologna, Italy; and Dr. M. Asghar of Institute Max Von Laue-Paul Langevin, Grenoble, France. The criticism and suggestions of the reviewers have been essential. Our thanks go to Dr. R. E. Chrien of Brookhaven National Laboratory; Drs. J. A. Harvey, L. Weston, and R. Macklin of Oak Ridge National Laboratory; Professor R. C. Block of Rensselaer Polytechnic Institute; Professor R. O. Lane and Dr. H. Knox of Ohio State University; and Professor F. Firk of Yale University. Valuable discussions with Drs. G. F. Auchampaugh and M. Moore of Los Alamos Na­ tional Laboratory about their sub-threshold fission results are gratefully acknowledged. ACKNOWLEDGMENTS xi The tabulation of an energy-ordered listing of strong resonances as an aid to experimentalists for identifying impurities in samples was motivated by a sug­ gestion from the late Dr. E. R. Rae. We also gratefully acknowledge Dr. G. D. James for the tabulation of neutron energy standards. These tables appear in Volume 1, Part B. We would like to recognize the past and present members of the NNDC Advisory Committee, Drs. R. Ehrlich, A. B. Smith, H. Goldstein, M. S. Moore, G. Hanna, P. Lazarus, P. Greebler, R. A. Dannels, J. Robertson, and M. Duret and Professors R. O. Lane and C. Maynard for their valuable suggestions and encouragement. The author would like to gratefully acknowledge the financial support of the United States Department of Energy. Neutron Physics of Thermal Cross-Sections and Resonance Parameters In a previous publication, the compilations and evaluations of the thermal cross sections, average resonance properties and resonance param­ eters for elements Ζ = 1-60 were reported. In addition, a short survey of basic neutron physics was presented with emphasis on the systematics of s- and p-wave neutron strength functions, So and Si radiative widths, Γ ο and Γ ι 7 7 and potential scattering lengths, R'. A comparison of optical model calcula­ tions of So, Si, and R' with the relevant experimental data was made for the purpose of testing the reliability of interpolating and extrapolating values in mass regions where experimental data are lacking. Because of the success of the direct capture mechanism in the thermal region and the valence neutron model in the resonance region, these interesting aspects of the capture reaction mechanism were discussed previously in some depth. In this volume, we conclude the evaluations of the thermal cross sec­ tions and neutron resonance parameters of the remaining isotopes covering the mass region Ζ = 61-100. A summary of the systematics for the whole mass region Ζ = 1-100 is illustrated in different graphical forms. Further­ more, some interesting and exciting developments in sub-threshold neutron induced fission and their interpretation 2 3 in terms of Strutinsky's4 double humped fission barrier are briefly covered. For details, the interested reader is referred to the excellent detailed review articles by Bjornholm and Lynn, 5 - 6 78 Lynn and Michaudon. In the appendices, neutron and gamma-ray energy standards, as well as the ten strongest resonances of each isotope are included. To avoid repetition, this introduction is to be viewed as a supplement to Vol. 1, part A. This volume basically follows the same format and approach as that of Vol. 1, part A. I. THERMAL CROSS-SECTIONS In ref. 1, the scattering cross sections, coherent scattering amplitudes and capture cross sections were discussed in some detail. In the present section, the paramagnetic scattering cross sections, the generalized ex­ pression for the direct capture cross^section, and the 2200 m/sec thermal constants for 23U3 , 23U5 , 23P9 u, and 24P1u are presented. A. Paramagnetic Scattering In the rare earth region and for elements in the ionic state such as oxide samples, the interaction between the magnetic moment of the neutron and that of the ion must be taken into account. Such an interaction gives rise to a paramagnetic cross section which has the form: 9 1 40 Ί—ι—ι—ι—ι—ι—ι—ι—ι—ι—ι ι—ι Γ Ί—I—Γ PARAMAGNETIC SCATTERING OF RARE EARTH IONS (E = 0.0253 eV) n EXPERIMENTAL VALUES 30 CALCULATED VALUES 20 oh J L J L 55 65 70 75 ATOMIC NUMBER Ζ Figure 1. Comparison of the paramagnetic scattering cross sections measured at a neutron energy of 0.0253 eV with the theoretical calculations of Mattos . The solid curve is an eyeguide to the theoretical values. 2