applied gamma-ray spectrometry by c.e crouthamel

APPLIED GAMMA-RAY<br /> SPECTROMETRY<br /> BY<br /> <br /> C. E. CROUTHAMEL<br /> Argonne National Laboratory, U.S.A.<br /> <br /> SECOND E D I T I O N<br /> COMPLETELY REVISED AND E N L A R G E D<br /> BY<br /> <br /> F. ADAMS AND R. DAMS<br /> Institute of Nuclear Sciences,<br /> Ghent State University,<br /> Belgium<br /> <br /> P E R G A M O N PRESS<br /> Oxford · New York · Toronto<br /> Sydney · Braunschweig<br /> <br /> Pergamon Press Offices:<br /> U.K.<br /> U.S.A.<br /> <br /> Pergamon Press Ltd., Headington Hill Hall, Oxford OX3 OBW, England<br /> Pergamon Press Inc., Maxwell House, Fairview Park,<br /> Elmsford, New York 10523, U.S.A.<br /> CANADA<br /> Pergamon of Canada Ltd., 207 Queen's Quay West,<br /> Toronto 1, Canada<br /> AUSTRALIA<br /> Pergamon Press (Aust.) Pty. Ltd., 19a Boundary Street,<br /> Rushcutters Bay, N.S.W. 2011, Australia<br /> FRANCE<br /> Pergamon Press SARL, 24 rue des Ecoles,<br /> 75240 Paris, Cedex 05, France<br /> WEST GERMANY Pergamon Press GmbH, 3300 Braunschweig, Postfach 2923,<br /> Burgplatz 1, West Germany<br /> Copyright (C) 1970 F. Adams and R. Dams<br /> All Rights Reserved. No part of this publication may he<br /> reproduced, stored in a retrieval system, or transmitted, in<br /> any form or by any means, electronic, mechanical,<br /> photocopying, recording or otherwise, without the prior<br /> permission of Pergamon Press Ltd.<br /> First edition 1960<br /> Second revised and enlarged edition 1970<br /> Reprinted 1975<br /> Library of Congress Catalog Card No. 79-114847<br /> <br /> Printed in Great Britain by<br /> Biddies Ltd., Guildford, Surrey<br /> ISBN 0 08 006888 X<br /> <br /> PREFACE TO THE SECOND EDITION<br /> 10 years have passed since the first edition of this book. Much progress has been<br /> made during the past decade, especially in high resolution gamma-ray spectrometry using<br /> semiconductor detectors. The increasing efficiency and the improving energy resolution<br /> made the scientists realize that they had at hand a new and beautiful research tool. Im­<br /> proved amplifying and analyzing equipment were necessary to realize the full abilities of<br /> high resolution detectors.<br /> Like the previous edition, the new one is primarily meant for experimentalists. Chapter 1<br /> contains the various decay processes and the possible interaction mechanisms of gamma<br /> radiation with matter. Chapters 2, 3 and 4 deal with properties and fabrication of respec­<br /> tively scintillation detectors, semiconductor detectors, and proportional gas counters.<br /> Chapter 5 includes the description of basic equipment, i.e. amplifiers, analyzers, special<br /> spectrometer arrangements, and detector shielding. Energy and time resolution is treated<br /> in Chapter 6, whereas Chapter 7 deals with quantitative calibration. The quantitative and<br /> qualitative interpretation of the spectra is treated in Chapter 8. The last chapter describes<br /> the analytical applications of gamma-ray and X-ray spectrometry in tracer studies, activa­<br /> tion analysis, fission product studies, and X-ray fluorescence analysis. Chapters 3, 5 and<br /> 8 are entirely new, while the other chapters were extended and brought up to date.<br /> Appendix II is extended with the gamma-ray spectra of 46, mainly short-lived or neutron<br /> deficient, isotopes. Appendix III contains about 220 gamma-ray spectra taken with a lithium<br /> drifted germanium detector. The calculated intrinsic efficiencies for sodium iodide crystals<br /> are provided in Appendix IV, while a short compilation of internal conversion coefficients<br /> is given in Appendix V. The tabulations of the characteristic X-ray energies (Appendix I)<br /> and of the nuclear data by photon energy and half-life sequences (Appendix VI) have been<br /> supplemented by a sequence of precisely determined photon energies (Appendix VII).<br /> We are deeply indebted to Professor Dr. J. Hoste, Director of the Institute for Nuclear<br /> Sciences, Radio- and Analytical Chemistry Division, for his whole-hearted support and<br /> valuable advice and suggestions. We gratefully acknowledge the help of Dr. A. Speecke for<br /> reading portions of the manuscript and offering many valuable suggestions. During the<br /> preparation of the manuscript we have enjoyed many discussions with friends and colleagues.<br /> We should like to thank, particularly, P. de Regge, J. P. Francois, J. Fuger, J. I. Kim, and R.<br /> Van Inbroukx for providing us with a number of pure gamma sources. For the preparation of<br /> Appendices II, III, and VII, numerous irradiations were performed with the Thetis reactor<br /> and with the linear electron accelerator, both at the Institute of Nuclear Sciences, Ghent.<br /> We are grateful to all those in charge of the exploitation of these machines and especially<br /> to Dr. A. Speecke and Ir. K. Kiesel. We are grateful to Miss M. Helsen and Mrs. J. GorleeZels for preparing the numerous drawings and for their unfailing help in the preparation of<br /> the manuscript.<br /> We thank those who allowed us to use data from their work. We made every endeavor<br /> to acknowledge this help in the text.<br /> <br /> NEARLY<br /> <br /> Ghent, Belgium<br /> <br /> F.<br /> xi<br /> <br /> ADAMS,<br /> <br /> R.<br /> <br /> DAMS<br /> <br /> PREFACE TO THE FIRST EDITION<br /> book is the outgrowth of the rapidly increasing and widespread application of gammaray spectrometry to many fields other than nuclear physics. Chemists, biologists, engineers,<br /> and other research workers applying this valuable tool will face the task of interpreting<br /> the gamma-ray spectra. Each radioactive nuclide and detector combination will present a<br /> virtually unique situation with regard to scattering, energy resolution, and relative inten­<br /> sities in the various energy regions of the spectrum. The accurate qualitative interpretation<br /> of a gamma-ray spectrum requires a careful evaluation of the source and intensity of the<br /> various peaks which may be generated in the spectrum for a given experimental situation.<br /> The discussion in Chapters 1 and 2 deal with the intrinsic and extrinsic variables which<br /> affect the observed gamma-ray and X-ray spectra. Most of the effects of these variables are<br /> illustrated in Appendix II. Appendices I and IV are tabulations of the characteristic X-ray<br /> energies in keV and of the nuclear data by photon energy and half-life sequences. These<br /> data are designed to aid in the rapid qualitative interpretation of the gamma-ray spectra.<br /> The quantitative calibration of the spectra is treated in Chapter 3 with supplementary<br /> data in Appendix III.<br /> Finally, some of the most widely utilized applications are discussed in Chapter 4, with<br /> particular emphasis given to activation analysis.<br /> The authors are indebted to many colleagues at the Argonne National Laboratory for<br /> support and assistance in preparing the manuscript, in particular, Richard C. Vogel and<br /> Victor H. Munnecke for their continued support and valuable suggestions in examining<br /> the manuscript, also to Peter Kafalas, Ellis P. Steinberg, Donald Engelkemeir, Harold A.<br /> May and Charles E. Miller for reading portions of the manuscript and offering valuable<br /> criticisms. Willard H. McCorkle and Joseph I. McMilien have given invaluable assistance<br /> with the many irradiations at CP-5. The authors are also indebted to Dorothy A. Carlson<br /> and her co-workers in the Graphic Arts Department for preparing the numerous drawings;<br /> Gene H. McCloud, Allen A. Madson, and Marion Crouthamel for their many hours of<br /> assistance in the checking and preparation of the manuscript.<br /> THIS<br /> <br /> Lemont, Illinois<br /> C. E. CROUTHAMEL<br /> <br /> INTRODUCTION<br /> SCINTILLATION counting, one of the oldest radiation detection techniques, has gone through<br /> several developmental phases. The visually detected scintillations of energetic alpha parti­<br /> cles absorbed in thin films of zinc sulfide crystals were first noted by Sir William Crookes<br /> and also independently by Elster and Geitel in 1903. Crookes and Regener had developed<br /> an early apparatus, the spinthariscope and its' associated counting techniques, by 1908.<br /> The spinthariscope was made up of a microscope of magnification about thirty with an<br /> objective of large numerical aperture, a zinc sulfide copper-activated screen, a source of<br /> alpha particles, and a gas-tight box which could be evacuated and in which these compo­<br /> nents as well as scatterers and absorbers could be mounted. In the 25 years following its<br /> development the spinthariscope produced many valuable contributions to the field of nuclear<br /> research. Its application made possible detailed studies of the scattering of alpha particles<br /> by thin foils and thus first indicated the presence, and then the size and charge, of the atomic<br /> nucleus. Also, the first evidence of artificial disintegration of stable isotopes was obtained<br /> by Rutherford with this instrument in 1919. Anyone familiar with present-day instrumenta­<br /> tion will appreciate the high quality of the data gathered by means of this early instrument.<br /> An account and analysis of the numerous pioneering experiments which employed the<br /> spinthariscope is given by Rutherford et α/.(1)<br /> The visual scintillation counter became obsolete in the 1930's, and the next 20 years<br /> were characterized by the rapid growth and development of electronic counting techniques.<br /> Gas-filled ionization chambers in which the incident charged particles generate ion pairs<br /> were used as the basic detector. With these gas-filled systems there are three well-defined<br /> operating »methods—the ionization detector, the proportional counter, and the GeigerMüller counter.<br /> In the first method the ionization chamber consists of two electrodes in a gas medium.<br /> When the chamber is placed in a radiation field the gas is ionized. If a steady voltage is<br /> also applied to the electrodes, the ion pairs separate under the influence of the electric field<br /> and current will flow in an external circuit connected to the ionization chamber. As the<br /> chamber voltage is increased, this current quickly reaches a limiting value which is pro­<br /> portional to the rate of production of the ion pairs. In order to measure this saturation<br /> current, however, it is necessary to use extremely sensitive current measuring devices.<br /> Probably the most reliable and sensitive current measuring device applied to ionization<br /> chambers is the vibrating reed electrometer.<br /> The second operating method of the gas-filled systems, the proportional counter, uses a<br /> cylindrical or spherical chamber with a positive electric field originating on a thin wire<br /> electrode. Multiplication of the signal occurs in the vicinity of the wire where the electric<br /> field intensity is great enough to cause the incoming primary electrons to produce miniature<br /> avalanches öf electrons. The gas multiplication is limited so that the final pulse produced is<br /> proportional to the number of primary electrons generated along the track of the incident<br /> ionizing particle. The proportional counter requires carefully designed amplifiers and very<br /> stable, noise-free high voltage and power supplies. This counter is now generally accepted<br /> for alpha and beta counting as one of the most useful and widely applied systems in the<br /> XV<br /> <br />