*•"*' C>" UNIVERSITY OF OSLO SECTION for NUCLKAR PHYSICS AND ENERGY PHYSICS Annual Report January I - December 31 Ot/P ~ 1990 Rcpon 9111 • Received 30 - 04 - 199! ISSN-03.12-S57I DEPARTMENT OF PHYSICS REPORT SERIES SECTION for NUCLEAR PHYSICS AND ENERGY PHYSICS Annual Report j. January I - December 31 Qt/P^ 1990 Report 91-11 • Received 30-04-1991 ISSN-0332-5571 Contents 1 Introduction 5 2 Personnel 7 2.0.1 Research StalT 7 2.0.2 Technical Surf 7 2.1 Coopcralors. Research Staff at Section Tor Electronics and Mea­ surements 8 2.2 Visiting Scientists 8 2.3 Students 8 3 The Cyclotron 9 3.1 Operation and Maintenance 9 3.2 A Universal, Low-level and High Frequency Multiplexer System for Operator Supervision 9 4 Data Acquisilion and Analysis 10 4.1 Introduction 10 4.2 Configuration 11 4.3 DAISY, a VME Based Data Acquisilion System for the Oslo Cyclotron Laboratory 12 4.3.1 Front-end 12 4.3.2 Back-end 12 4.3.3 Data reduction 13 4.4 The Data Acquisilion Program SHIVA 15 4.5 Additional Data Analysis Software 16 5 Nudcsr Indraarnuitoa II 5.1 The CACTUS Project 18 5.2 The NORDHALL Project 19 t ExpcriaMfilal Nurkar Physki 20 6.1 Introduction 20 6.2 Nuclear Properties at High Temperature 21 6.2.1 On the '" Ybf'Hcn) Reaction Mechanism 21 6.2.2 Chaos in Nuclei and the K Quantum Number 23 6.2.3 A i -Ray Signature Tor the K Quantum Number 26 6.2.4 Extraction of Multiplicity Distributions 31 6.2.5 Discrete 7-Transitions from the lmDy(:,Hc.«) Reaction . 37 6.2.6 Gross-Properties of Statistical 7-Dccay in l72Yb 38 6.2.7 Gamma-Decay Properties of odd-A mYb 43 6.2.8 Gamma-Decay Pattern in Transitional Nuclei 44 6.2.9 Feeding- and Entry- Regions in the '''YbCHc.orn) Re­ action 44 6.2.10 Levels, Lifetimes and g-F.iclors in ,0*Po and ""Po ... 48 6.3 High-Spin Properties of Nuclear Stales 50 6.3.1 A study of the doubly magic nucleus'gNi28 50 6.3.2 A Search for Supcrdcformation in 6°7s\ 51 6.3.3 Search for the Negative Signature Partner of the ft,j/2|541)l/2~ Band in ""Tm 51 6.3.4 The Rotational Structure of """Yb 53 6.3.5 A Sncdm.scopic Study of High Spin Discrete- and Con­ tinuum Slates in "ir'Tm 55 7 Theoretical Nuclear Physics 56 7.1 The Nuclear Many-Body Problem and Nuclear Structure 57 7.1.1 Folded-Diagram Theory of the Effective Interaction ... 57 7.1.2 Studies of llic Particle-Particle and Hole-Hole Effective Interactions appropriate for Nuclei in the Mass-16 and Mass-40 Regions 58 7.1.3 Nuclear Structure with the Lanczos Method 60 2 7.1.4 Tensor Decomposition of ihc Effective Interaction .... 61 7.2 Nuclcai Reactions 62 7.2.1 Momentum-Dependent Mean Field Effects on the Nu­ clear Equation of State and on Phase Transition Signals . 62 7.2.2 Proximity Interaction between Deformed Nuclei 63 7.3 The Foundation of Quantum Physics 63 7.3.1 The Non-Separubilily in Quantum Physics 63 7.3.2 Interpretation of Quantum mechanics 64 X Other Fields or Research 66 S. I Natural Environment Ionizing Radiation 66 8.2 Solar Energy 69 8.2.1 Solar Hydrogen - Hydrogen Produced from Renewable Resources 69 8.2.2 Hay Dryers 70 8.3 Wet Breathing Gas 71 9 Seminars 72 10 Committees, Conferences and Visits 73 10.1 Committees and Various Activities 73 10.2 Conferences 75 10.3 Visits 76 11 Theses, Publications and Talks 77 11.1 Theses 77 11.2 Scicnlilic publications 77 11.2.1 Nuclear Itiysics and Instrumentation 77 11.3 Scicnlilic and Technical Reports 79 11.3.1 Nuclear Physics and Instrumentation 79 11.3.2 Solar Energy 81 11.3.3 Educational Physics 81 11.4 Talks ami Conference Reports 81 11.5 Popular Science 84 3 11.6 Science Pulicy 89 4 Chapter 1 Introduction This annual report summarizes the research and development activities of the Section for Nuclear Physics and Energy Physics at The University of Oslo in 1990. It includes experimental and theoretical nuclear physics, as „ci: as other fields of physics in which members of the section have participated. The report describes completed projects and work currently in progress. The experimental activities in nuclear physics have, as in the previous years, mainly been ccnicrcd around the Cyclotron Laboratory with the SCANDITRONIX MC-35 Cyclotron. Using the CACTUS multidctcctor system, several experi­ ments in collaboration with the nuclear physics group at the University of Bergen have been completed. Some results have been published and were also presented at the international conference in Oak Ridge, U.S.A., while more data remains to be analyzed. The cyclotron has continued to work satisfactorily due to the untiring effort of E.A. Olsen. The excellent job done by him, J. Wiknc and T. Ramsøy in keeping the accelerator and data system in operation is highly appreciated by all of us. The collaboration with foreign laboratories has continued in 1990. We participate in the Nordic collaboration, NORDBALL, at the Niels Bohr Tandem Accelerator Laboratory in Risø. Members of the section also participate in experiments at the Darcsbury Laboratory, England, GSI, Darmstadt, Germany, and KVI, Groningen, Netherlands. In the fall Tore Ramsøy was awarded the degree Dr. Scicnt. The title of his thesis is: Spectroscopy High Above the Yrast Line in Rare Earth Nuclei At the end of 1990 10 students (for the degree Cand. Scicnt.) and three post­ graduate students (for the degree Dr. Scicnt.) were associated with the section. While the University covers the basic costs of running the cyclotron laboratory, the experimental activities would not have been possible without the contin­ ued support from the Norwegian Research Council for Science and Humanities (NAVF). Support from the Nordic Committee for Accelerator-Based Research (NOAC) and the Nordic Institute of Theoretical Atomic Physics (NORDITA) is also gratefully acknowledged. The work in energy research is supported by 5 NAVF and the Council Tor Agricultural Research. Finally, the efforts of Torgeir Engeland, h' gne Guttormsen and Tore Ramsey who have served as editors of this report, are appreciated by the other members of the Section. Blindern, April 1991 Svein Mesaelt Leader of the Seclion for Nuclear Physics and Energy Physics 6 Chapter 2 Personnel 2.0.1 Research Staff Sven Lilicdal Andersen Assoc, prof. Harald Andts Research ass. (NAVF) Aysc Alac, Research ass. (until Aug. 1) Bård Bjerke Research ass. (NAVF) Torgeir Engeland Assoc, prof. Ivar Espc Assoc, prof. Kristoffer Gjøtlcnid Assoc, prof. Magne Guttormsen Assoc, prof. Ole Hcrbjørnsen Assoc, prof. Morten Hjorth-Jcnscn Research ass. Trygve Hollebckk Professor (Senior scientist) Finn Ingebrclscn Assoc, prof. Svein Mcsscll Assoc, prof. (Section leader) Eivind Osncs Professor John Rckslad Professor Anders Slorruslc Senior scientist Roald Tangen Prof. cmcr. Per Olav Tjørn Professor Trine Spcdstad Tvcicr Research ass. (NAVF) 2.0.2 Technical Staff Izchak Moore Engineer (until April 1) Eivind Atle Ol.scn Section engineer Tore Ramsøy Section engineer (NAVF) Jon Wiknc Section engineer 7 2.1 Coopcrators, Research Staff at Section for Electronics and Measurements Bernhard Skaali Professor 2.2 Visiting Scientists 25.01.90 E. Hammaren. Jyvåskyla. Finland 25.01.90 B. Hcrskind. Niels Bohr lnslilulcl. Denmark 25.01.90 I. Ollcrlund. Lund, Sweden 25.01.90 H. Ryde, Lund. Sweden 25.01.90 G.Tihcll. Uppsala, Sweden 20.07 90 F.A. Career, Dubna, USSR 12.12.90 D. Strottniann, Los Alamos, USA 2.3 Students As of December 31, 1990. 10 graduate students (for die degree Cand. Scicnt.) and 3 posl-graduatc students (for the degree Dr. Scicni.) were associated with the section. K Chapter 3 The Cyclotron 3.1 Operation and Maintenance E.A. Olscn, J. Wiknc and S. Mcsscll No major replacements or modifications of the cyclotron or the beam lines has been done in 1990. Approximately 80 days have been used for schedu'ed and un­ scheduled maintenance. Problems have mostly been connected with the cooling systems and the KF-sysiems. The total beam lime for nuclear experiments in 1990 was 396 hours, 'He beam was accelerated most of the lime. The cyclotron was also used 23 times, a total of 36 hours, by the nuclear chemistry group for isotope production. 3.2 A Universal, Low-level and High Frequency Multi­ plexer System for Operator Supervision J. Wiknc The increasing complexity of the beam line at the Cyclotron lab gave rise to the need for a new multiplexer system for both beam measurement points and video cameras. Commercial solutions were both costly and not particularly well suited to our requirement. One single design of K-channel multiplexers takes care of both these needs, i.e. currcnu in Ihc sub-nA range and frequencies of several MHz. Several units may be cascaded. Two multiplexers fit onto a 19" rack front pan.! only 30 mm high. The inputs and outputs arc BNC contacts at the rear of the design. The channels arc selected electronically by means of lighted push-buttons on the Cyclotron control desk, same type as those used in most other contexts at the lab. 9 Chapter 4 Data Acquisition and Analysis 4.1 Introduction 'I'hc dala acquisition syMc:,i at the Oslo Cycloirun Laboratory may be divided into two major componcnls: • A fmnl-cnd system responsible fur data digitali/ation, read-out and for­ maning. This system is based on a VMEbus with connections lo CAMAC and NIM devices.