Atomic Energy of Canada Limited A PROGRAM FOR NUCLEAR PHYSICS IN THE SEVENTIES AND BEYOND Edited by J.C. HARDY, A.B. McDONALD and J.C.D. MILTON Chalk River Nuclear Laboratories Chalk River, Ontario September 1973 v AECL-4596 Atomic Energy of Canada Limited A PROGRAM FOR NUCLEAR PHYSICS Us' THE SEVENTIES AND BEYOND* edited by J.C. Hardy A.B. McDonald and J.C.D. Milton ABSTRACT This report discusses a possible research program for the Nuclear Physics tsror>ch in the second half of this decade and beyondA- a program which,if followed, would undoubtedly expand the boundaries of our knowledge "several fold, but more than that, a program that seems likely to lead to fundamentally new and exciting discoveries. The core of the discussion is contained in Chapter II. which reviews the prospects in nine major areas: li nuclei far from the region of beta stability, 2) superheavy nuclei. 3) fission. 4) in-beam studies of electromagnetic properties, 5| heavy ion scattering. 6| transfer reactions with heavy ions. 7) studies with light ion beams. Hi ranges and stopping powers of heavy ions, ard atomic collisions, and 9| fundamental interactions and symmetries The material from thir. chapter leads to the view that the future looks very bright in fields which could he studied with higher energy beams, particularly of heavy ions, in Chapter III the types of beams, and the energy and resolution required to carry out all aspects of the proposed programs are specified and l^ad to the conclusions that a desirable accelerator would be able to produce beams of all ions from hydrogen to uranium with energies variable up to 300 MeY for hydrogen and 10 MeV/nucleon for uranium, with a resolution of 0.01';. A brief discussion is given in Chapter IV of three possible additions to the MP Tandem that would meet all these requirements. The final Chapter. Chapter V. reviews the experimental equipment and data handling facilities that would be necessary to cany out the proposed program in an efficient manner. Much of this aneilliary equipment already exists at the MP Tandem installation. Chalk River Nuclear Laboratories Chalk River, Ontario September 1973 AECL-4596 * This report is based on the Atomic Energy of Canada Limited unpublished internal report CRNL-714, manuscript prepared February 1972, printed October 1972. Programme de physique nucléaire pour les années 1970 et au-delà* édité par J.C. Hardy A.B. McDonald et J.C.D. Milton Résume On envisage un programme de recherches possibles pour le Département de physique nucléaire dans la deuxième partie de la présente décennie et au-delà, programme qui pourrait certainement enrichir nos connaissances et qui semble susceptible de conduirp à des découvertes passionnantes. L'essentiel de la proposition figure dans le Chapitre II qui passe en revue les possibilités offertes dans neuf domaines principaux: 1) noyaux éloignés de la région de stabilité béta, 2) noyaux extrêmement lourds, 3) fission, 4) étude sous faisceaux des propriétés électromagnétiques, 5) diffusion des ions lourds, 6) réactions de transfert avec des ions lourds, 7) études effectuées avec des faisceaux d'ions légers, 8) gammes et puissances d'arrêt des ions lourds et collisions atomiques et 9) interactions fondamentales et symétries. Les données de ce chapitre permettent de conclure que l'avenir se présente sous un jour très favorable dans les domaines qui pourraient être étudiés avec des faisceaux d'énergie supérieure, particulièrement ceux d'ions lourds. Dans le Chapitre III, les espèces de faisceaux, l'énergie et la résolution requises pour réaliser tous les aspects des programmes proposés sont spécifiées et laissent à penser que l'accélérateur souhaitable devrait pouvoir produire des faisceaux de tous les ions depuis l'hydrogène jusqu'à l'uranium avec des énergies variables allant jusqu'à 300 MeV pour l'hydrogène et 10 MeV/ nucléon pour l'uranium, avec une résolution de 0.01%. On commente brièvement au Chapitre IV les trois additions possibles au Tandem MP qui répondraient à toutes ces exigences. Le dernier chapitre, le Chapitre V, passe en revue le matériel expérimental et les dispositifs de traitement des données qui seraient nécessaires pour réaliser le programme proposé de façon efficace. Une grande partie de cet équipement auxiliaire existe déjà dans l'accélérateur Tandem MP. L'Energie Atomique du Canada, Limitée Laboratoires Nucléaires de Chalk River Chalk River, Ontario Septembre 1973 AECL-4596 * Rapport découlant du document CRNL-714, rapport interne de l'EACL dont le manuscrit a eie préparé en février 1972 et imprimé en octobre 1972 INTRODUCTION SOME AREAS IN WHICH NEW AND EXCITING DEVELOPMENTS ARE LIKELY 0. Summary 9 1. The Study of Nuclei Far from the Region of Beta Stability : Z < Q0 A. Introduction 13 B. Specific Problems of Future Interest 14 a) Beta-delayed Particle Emission 14 b) Beta-delayed Nuclear Fission 14 c) New Radioactivities 15 d) Nuclear Masses and the Boundary of Stability 15 e) Nucleosynthesis, Exolic Nuclei and Other Astrophysical Considerations 16 0 Double Beta-decay 1(> g) Beta-decay at High Energies 16 h) Mirror Nuclei 1 ft i) Nuclear Structure 17 C. Production Techniques and Requirements 17 a) Compound Nuclear Reactions 17 b) Transfer Reactions i1) c) Heavy-Ion Induced Fission 21 d) Summary' 27 References 22 2. Superheavy Nuclei A. Introduction 27 B. Properties 27 C. Production -'1 D. Detection 53 E. Summary 34 References 34 3. Fission A. Introduction and Survey 3° B. Coulomb Fission 40 C. Intermediate Structure 41 D. Fission Isomers 43 References 43 4 In-beam Studies of Electromagnetic Properties of Nuclei 47 A. Introduction B. Pertinent Problems in Nuclear Structure 47_ a) Vibrational Nuclei ' b) Rotational Nuclei (Even A) 4^ c) Closed Shell Nuclei 48 C. Reaction Mechanisms a) Compound-Nucleus Reactions 48 b) Transfer Reactions 49 D. Experimental Techniques '" a) Nuclear-Lifetime Measurement Using the Recoil-Distance Method (RDM) 50 b) Nuclear-Lifetime Measurement Using the Doppler-Shift-Attenuation Method (DSAM) 51 c) Angluar-Distribution Studies Following Heavy-Ion Reactions 52 d) g-Factors of Excited Nuclear Levels 53 E. Beam Requirements 53 References 53 5. Heavy-Ion Elastic and Inelastic Scattering A. Introduction 57 B. Optical Model Analysis 57 C. Microscopic Theories 58 D. Experimental Requirements 60 References (,3 6. Transfer Reactions with Heavy Ions A. Introduction 67 B. Nucleon Exchange in Heavy-Ion Scattering 67 C. Few-Nucleon Transfer Reactions 68 D. Multi-Nucleon Transfer Reactions 69 E. The Nuclear "Josephson" Effect -ji References 7? 7. Studies with Light-Ion Beams A. Introduction -,-, B. Nudeon-Nucleon Scattering 77 C. Many-Body Final States gO D. Quasi-Free Scattering on Nuclei gi E. Meson Production in Nuclei g-j F. Summary References 84 8. Ranges, Stopping Powers and Atomic Collisions Part 1: Ranges and Stopping Powers of Heavy Ions A. Introduction 89 B. Applications and Inadequacies 89 a) Coulomb Excitation 89 b) Doppler-Shift Measurements 90 C. Future Development 91 Part 2: Properties of United Atoms 92 References 92 9. Fundamental Interactions and Symmetries A. Introduction 95 B. Strong Interactions 95 a) Nucleon-Nucleon Scattering 95 b) Symmetries in Nuclei and Nuclear Reactions 96 C. Nuclear Gamma Decay 99 a) Time-Reversal Invariance 99 b) Parity Violation 100 c) E.M. Studies oflsospin Symmetries 100 d) Exchange Currents 101 D. Nuclear Beta Decay 101 a) Weak Interactions 102 b) Induced Interactions 102 c) Fundamental Nuclear Properties 104 References 105 HI. SUMMARY OF OPTIMUM ACCELERATOR PROPERTIES 1. Introduction 111 2. Mass and Energy Range of Projectiles 111 3. Energy Resolution 111 4. Current and Emittance 113 References "3 IV. SOME HEAVY ION ACCELERATORS 1. Introduction H7 2. The MD Tandem Van de Graaff as a Preaccelerator 117 3. A Helix Linear Accelerator for Heavy Ions 118 4. A Heavy-Ion Cyclotron 118 5. A Heavy-Ion Synchrotron 120 References ! -3 V. EXPERIMENTAL FACILITIES AND TECHNIQUES 1. Introduction '^' 2. Computing Facilities A. Introduction '^8 B. Detailed Description I28 3. Target-Making Facilities <29 A. Solid Targets '29 B. Differentially Pumped Gas Target 130 4. Gamma-Ray Detection 130 5. Beta-Ray Detection 130 6. Charged Particle Detectiun and Identification 13 i A. Introduction 131 B. Solid State Detectors 131 C. QD1 Magnetic Spectrometer 132 D. Particle Identification 133 a) Solid-State Counter Telescopes 133 b) QD3 Magnetic Spectrometer 134 7. Beam-Pulsing Facility ]35 8. Isotope Separator 136 9. Polarized Beams and Targets 136 References j^g A PROGRAM FOR NUCLEAR PHYSICS IN THE SEVENTIES AND BEYOND PREFACE This report is an attempt to answer the question, "What are the most interesting, important and valuable thUigs tha1 could be done by the nuclear Physics Branch in the seventies?" The answer is based soundly on th.> knowledge and interests of the members of the Branch. No attempt has been made to survey fields in nuclear physics outside the existing areas of competence of the Branch. However no further restrictions were placed on the authors. A program following the suggestions in this report would thtrefore be a logical and natural extension of the present program and would be securely based on tht existing expertise and equipment The relevance of such a program to the objectives of AECL and ,he means of implementing it have not been discussed at this time; such things will come later. Nevertheless, to indicate that the program is a realistic one, a brief discussion is given of three possible additions to the MP Tandem, any one of which might satisfy the requirements, which are' the ability to provide beams of all ions from protons to uranium (or heavier) with energies up to 300 MeV for protons, greater than 10 MeV/nucleon for uranium and with intensities greater than ~ 1012 particles per second.