E. Kowalski Nuclear Electronics With 337 Figures Springer-Verlag New York Heidelberg Berlin 1970
Dr. Emil Kowalski Lecturer, Institute of Applied Physics, University of Berne, Switzerland Nucleonics Division, Landis & Gyr Ltd., Zug, Switzerland ISBN-13: 978-3-642-87664-6 e-isbn-13: 978-3-642-87663-9 DOl: 10.1007/978-3-642-87663-9 The use of general descriptive names, trade names, trade marks etc. in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee to be determined by agreement with the publisher. by Springer-Verlag Berlin' Heidelberg 1970. Library of Congress Catalog Card Number 72-98149. Softcover reprint of the hardcover 1 st edition 1970 Title No. 1632
Preface Electronics is the most important tool in nuclear radiation metrology. Without electronic instruments most of the problems concerned with measurement in pure or applied nuclear research, radiation protection or the use of radioactive isotopes in industrial process control would remain unsolved. Conversely, the radiation metrology was one of the first areas, if not the first, outside communications in which electronic devices were successfully employed. The quantum nature of nuclear radiations determined the need to work with pulse-type signals and thus contributed substantially to the establishment of analog and digital pulse techniques in electronics. It was no coincidence that, as late as 1949, W. C. ELMORE and M. SANDS were able to call the first monograph on nuclear electronics quite simply "Electronics". Despite these close interrelations between electronics and radiation measurement in nuclear physics, there is virtually no modern monograph dealing with the specialized electronic circuits and instruments used in measuring nuclear radiation. ELMORE and SANDS has long since become obsolete and, similarly, the excellent works covering special areas of nuclear electronics (e. g. A. B. GILLESPIE'S "Signal, Noise and Resolution in Nuclear Counter Amplifiers", 1953; I. A. D. LEWIS and F. H. WELLS' "Millimicrosecond Pulse Techniques", 1959; or R. L. CHASE'S "Nuclear Pulse Spectrometry", 1961) now lag well behind the latest advances in technology*). The reason for this state of affairs may well be that nuclear electronics, with about 300 original papers published per year, is enjoying such rapid growth that any summary is bound to be out of date within a year. There are also various works dealing with related fields, in particular digital techniques. When in 1964 I began at the friendly suggestion of Professor K. P. MEYER to lecture on nuclear electronics, I soon felt the lack of any systematic review of the subject, and I started by writing down the script of my lectures. However, I soon found that it was desirable to supplement * However, a most interesting book, published last year, "Instrumentation electronique en physique nuc1eaire", 1968, by J.-J. SAMUEL!, J. PIGNERET and A. SARAZIN, at least plugs the gap with regard to the evaluation of the time and energy information of detector signals. v
Preface the text by a literature review. The present text arose out of a study of a thousand or so original papers; it could be called a monograph with the character of a textbook. The fact that the literature is covered up to the end of 1968 gives it the required up-to-dateness, and the attempt to create a systematic structur should ensure that the book retains its value as a reference work for some years to come. The book is primarily addressed to the experimental physicist who, when designing an experiment, needs to be able to review the possibilities of the available instrumentation so as to instruct his technicians (electronic engineers) accordingly. It can also be of help in the training of electronic engineers and as a work of reference for the technicians whom almost every institute of physics, chemistry, biology, medicine etc. employs and who are expected to construct and maintain nuclear electronic apparatus, often without any special training. To make the text as concise as possible, the general concepts of electronics are taken for granted and a certain basic knowledge is assumed. This should be acceptable to both the types of reader I have mentioned: the technicians have already acquired this knowledge and the physicists do not need it in order to understand the circuit principle. The text follows the order of construction of a piece of electronic apparatus: first the detectors and input circuits, then the analog portion, the analogto-digital and time-to-digital converters and the digital analyzers, and finally the build-up of rather complex total systems are discussed. I must here acknowledge the help and encouragement given me by Professor K. P. MEYER; I thank him most sincerely for his unflagging interest in my work. Dr. R. SIEGENTHALER performed valuable service in the early stages of the work, particularly in reviewing the literature, and I am much indebted to him. I am also grateful to Mr. 1. MERTON for his kindness in helping to revise the English manuscript. My thanks are due, too, to Springer-Verlag and especially to Dr. H. MAYER-KAUPP for accepting my work for publication despite its highly specialized field of interest. Last but not least, I have to thank my wife for her patience at the times when the manuscript received more of my attention than she did. Cham, Switzerland, November 1969 E.K. VI
Contents 1. Introduction 2. Radiation Detectors and Related Circuits. 4 2.1. Ionization Chamber 4 2.1.1. Energy Required for the Generation of One Charge Carrier Pair 5 2.1.2. Mobility of the Charge Carriers 6 2.1.3. The Pulse Shape 6 2.1.4. Preamplifier Circuits 11 2.2. Proportional Counters 14 2.2.1. Detection Mechanism and Pulse Shape in the Proportional Counter. 14 2.2.2. Statistics of the Multiplication Process 16 2.2.3. Preamplifier Circuits 17 2.3. Geiger-Muller-Counters. 20 2.3.1. Detection Mechanism and Pulse Shape in the GM Counter. 20 2.3.2. Quenching Circuits. 24 2.4. Semiconductor Detectors 27 2.4.1. Characteristic Properties of Semiconductor Detectors 27 2.4.2. Energy Required to Form a Hole-Electron Pair 31 2.4.3. The Pulse Shape in the pn and pin Detectors. 34 2.4.4. Preamplifiers and Related Circuits 38 2.5. Scintillation and Cerenkov Counters 48 2.5.1. Principle of a Scintillation Counter. 48 2.5.2. The Pulse Shape 51 2.5.3. Photomultiplier Statistics and the Pulse Height. 55 2.5.4. Thermal Noise. 56 2.5.5. Signal Circuits Used in Scintillation Counters 60 2.5.6. Auxiliary Circuits 66 2.5.7. Scintillation Counter Stabilizer Circuits 70 2.5.8. Cerenkov Counter 74 VII
Contents 3. 3.1. 3.1.1. 3.1.2. 3.1.3. 3.1.4. 3.1.5. 3.1.6. 3.1.7. 3.2. 3.2.1. 3.2.2. 3.2.3. 3.3. 3.4. 3.5. 3.6. 4. 4.1. 4.1.1. 4.1.2. 4.1.3. 4.1.4. 4.1.5. 4.1.6. 4.2. 4.2.1. 4.2.2. 4.3. 5. 5.1. 5.2. 5.3. 5.3.1. 5.3.2. VIII Analog Circuits. Linear Pulse Amplifiers. General Considerations, Linearity The Transient Response of an Amplifier. Pulse Shaping Sum Effects Overload Recovery. Practical Design Criteria Amplifiers with Variable Gain Arithmetic Operations on Analog Signals Operational Amplifiers Arithmetic Operations on Pulse Amplitudes Practical Circuits. Window Amplifiers. Linear Gates. Pulse Stretchers Fast Pulse Amplifiers Analog-to-Digital Converters Pulse Height Discriminators. The Principle of a Multivibrator Integral Discriminators.. Differential Discriminators. Multiple Arrays of Differential Discriminators Conservation of the Time Information in a Discriminator Fast Tunnel Diode Discriminators Digital Encoding of the Pulse Height Converters of the Wilkinson Type Other Converter Systems Pulse Shape Discriminators Evaluation of the Time Information General Considerations, Resolution. Pulse Shapers for Coincidence Circuits and Time-to-Digital Converters Coincidence Circuits.. Ideal Coincidence Stage. Practical Circuits.... 75 75 76 84 90 106 III 114 115 117 117 120 122 128 131 137 142 151 152 152 158 169 177 J79 183 191 192 201 205 213 213 217 227 227 231
Contents 5.3.3. The Chronotron Principle. 240 5.4. Digital Encoding of the Time Interval. 243 5.4.1. Direct Digital Encoding. 244 5.4.2. Principle of a Time-to-Pulse-Height Converter 246 5.4.3. Start-Stop Converter 250 5.4.4. Overlap Converter 256 5.4.5. The Vernier Principle. 261 5.5. Auxiliary Circuits 264 6. Digital Circuits. 268 6.1. Basic Digital Circuits. 269 6.1.1. Fundamentals of Boolean Algebra, Gates 269 6.1.2. Circuitry of Different Logics. 278 6.1.3. The Flip-Flop 286 6.1.4. Practical Flip-Flop Circuits 290 6.1.5. Tunnel Diode Circuits 292 6.2. Scalers and Registers 296 6.2.1. Shift Registers. 296 6.2.2. Pulse Scalers. 299 6.3. Logical and Arithmetical Digital Circuits 308 6.4. Memories. 316 6.5. Data Output. 320 6.6. Count Rate Meters. 324 7. Data Processing 327 7.1. Simple Counting Systems 327 7.2. Multiscaler Arrays 329 7.3. Multichannel Analyzers. 332 7.4. Multiparameter Analyzers. 336 7.5. On-Line Computers. 342 8. Appendix 347 8.1. Laplace Transform Calculus. 347 8.1.1. Networks 347 8.1.2. Naive Operational Calculus 350 8.1.3. Laplace Transformation. 354 8.1.3.1. Rules of the Laplace Transformation 355 IX
Contents 8.1.3.2. Application of the Laplace Transformation in the Network Analysis............... 8.1.3.3. Inverse Transformation of Rational Functions F(P) 8.1.3.4. Stability Considerations. 8.1.3.5. Approximations............... 357 359 361 361 8.2. Noise...... 364 8.2.1. General Considerations, Concept of Equivalent Noise Charge..................... 364 8.2.2. 8.2.3. Noise Sources.................. The Noise of an Amplifier with the Transfer Function G(p)...'.................. 365 366 8.2.4. 8.2.5. Noise in a Charge Sensitive Amplifier........ Properties of Input Stages with Vacuum Tubes, Bipolar Transistors and FET. 368 370 8.2.6. Noise and Resolution. 373 9. 10. References.. 377 Subject Index 399 x