DOCSLIB.ORG

147- Ternary to Binary Fission Ratio for Neutron Induced

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
147- Ternary to Binary Fission Ratio for Neutron Induced -147- TERNARY TO BINARY FISSION RATIO FOR NEUTRON INDUCED FISSION IN «'Pu IN THE ENERGY REGION FROM 0.02 eV TO 50 eV С WAGEMANS* S.C.K./C.E.N.. B-2400 Mol. Belgium and A.J. DERUYTTER C.B.N.M., EURATOM, 8-2440 Geel, Belgium Abstract The measurements were performed at a 8.1 m flight-path of the C.B.N.M.-Linac at Geel. Binary and ternary fission fragments were consecutively counted with banks of sur­ face - barrier detectors on both sides of a double-faced "9Pu sample. After correction for background and underlying cross-sections, the areas of corresponding resonances in ternary (T) and binary (B) fission and derived ; their ratio yields the T/B value for the resonance considered. Moreover the energy region through the first large resonance from 0.02 eV to 1 eV was subdivided into several zones for which T/B values were also calculated. The T/B ratio seems not to vary significantly in the energy region from 0.02 eV to 50 eV, except for the 15.5 eV resonance where we find about 10 % more ternary fission. Correlations of T/B with the resonance spin J and with other fission characteristics are discussed. *N F WO , University of Ghent and S.C.K./C.E.N. -1Д8- INTRODÜCTIOM Wnen a iLicls_= Missions - spci-ta^eix.sly er ina-ced пу se'"e energetic partiele or j-sciatijn - it generally brsa\s .• i-to twe nes.-. -rag~er.t£ ar,- two or three neu­ trons. This is the so-called Dinary fission. ;- n.v to Q.3 % of the cases these twj- nea-.y fragments are accompanied by a very energetic light particle, mostly an a-particls. This is the ternary or LRA -is- sion. The energy distribution •- these a-particles is compatible with a Gaussian shape, with a peak at 15 MeV a;-j a ^e'i^.jT energy of about 30 ™eV -or the ^^"j Missioning cQ~tpoLir.G r'-Jcla-5. : ,• In the measurements which we are going to cescribe the zl+03u compound nucleus is obtained by bombarding а гз9Ри nucleus iJ"' = 1/2 J with s-wave neutrons ££ = 0, IS + s = 1/2). So compound states with J = D and 1 will be excited. In terms of the classical channel theory of 8ohrz) and Wheeler^) these conpound 0 states cor­ respond either to the ground state or to the 0 quadruools vibration of the nucleus at the saddle point, which are essentially symmetric states. This is not so for the compound 1 state, which is considered to be formed oy the coupling of the octupole vibrations К = G and K. - 1 which are both asymmetric states. These different properties of the 0 ano 1 states will be reflected in the correspon­ ding fission exit channels, which are thus expected to be very different in na­ ture. This implies that also the fission properties are expected to be very dif­ ferent. Baseo on this idea several attempts have been made to classify the neutron resonan- ces into two groups corresponding to J =0 resp. J = 1 by measuring the mass- asymmetry1*) , the total kinetic energy of the heavy fission fragments5), the average nurr-ber of neutrons emitted in fission6) 1(^) and the relative ternary fission yield^). We were especially interested in this last item since recently we were able to clas­ sify the neutron resonances in гз5и neutron induced fission intc two groups corres­ ponding to "low" and "high" ternary to binary fission ratios11). Moreover these T/B-values were correlated with the most reliable direct spin-determinations and with some other fission characteristics. Sir.ce 2ii5U with J ' = 7/2 forms compouno 3 and 4 states under Dompardment with s-wave neutrons, states whicn, according to the channel theory, are thought to have rather similar properties, we expect a priori to obserle an even stronger ef­ fect in the Z39PL neutror. I-^cec fissic . Untii now we have only thought in terms of the Bohr-wheeler picture of transition states on the top of a simple inverted oscillator potential barrier. Although their theory has a lot of merits, actually this picture is e little bit oversim­ plified in view of the discovery of sub-barrier- ana isomeric tission and its ex­ planation on the basis of a "double-humped" fission parrier12j'*)lüS. However -149- ;cr-i-g to Bjdr-Kclm- 5 асе .-. - ". -,f the nuclei deexcite into the first well and only 0.01 % intD the second, whereas about 96 \ lead to normal fission. Moreover for neutron induced fission of 23<3Pu the energy available аооиэ the lowest fission threshold is about 1.6 MeV. In view of these considerations ;t is logical to expect that the channel theory of fission will still oe applicable in resonance neutron fission of 239Pu, although the subsequent interactions ta^inf, place between the saddle- and the scission point should attenuate the chanrel effects taking place at the saddle point. In the measurements which we will describe, we tried to classify the resonances according to their ternary to binary fission ratio T/B. Ir, the energy region from 1 eV to 50 eV we calculated the T/B values for the strongest resolved resonances and in the region from 20 meV to 1 eV we calculated T/B for 40 energy zones. EXPERIMENTAL ARRANGEMENTS The measurements were performed at a 8.1 m flightpath of the C8NM linac. By bombarding a mercury cooled uranium target with the 70 MeV electron Deam of the linac, fast neutrons were produced which were then slowed down by a polyethylene slab. Figure 1 gives the lay-out of the detection and data collection system. The detection chamber is an evacuated cylindrical chamber with thin aluminium entrance and exit windows j its inner diameter is 50 cm. In the center of this chamber a double faced 239Pu layer (99.956 at.% ; 1 mg/cm2 thick) is mounted, viewed on each side by a bank of four large Si(Au) surfsea barrier detectors. These aetectors were calibrated daily based on the pulse-ri^:!.;,ht of the natural plutonium ct-particles. Moreover, aluminium screens of different thicknesses can be inserted (ternary fission) or withdrawn (binary fissicn) from between the layers and the detectors. This detection technique allows rather good resolution of the time-of-flight spectra in the low-energy region, since only one back-to-back deposit of 239Pu is used. Moreover, in this way less scattering material is introduced into the neutron beam than with a multi-plate ionization chamber. Pairs of detectors are connected in parallel and the signals from each pair are amplified by a charge-sensitive preamplifier ?nd a DDL main amplifier. The amplified signals are sent into a fast timing single channel analyser (T3CA). After mixing all the fast timing signals are fed into a 4096-channel time-of-flight analyser with an "accordeon" system. Fronn the analyser memory the data are transferred via an interface unit to an IBM 2311 disk for storage. The data handling is performed afterwards with an IBM 1800 system. -1 50- MEASURING PROCEDURE With the apparatus described before three measurements of the ratio of the ternary to binary fission cross-sections vs. neutron energy were performed. Table 1 gives earns details of the different exDerimental conditions. The first and the second measurement cover the energy region from 0.1 eV to 50 eV ; the third covers the region from 10 meV to 15 eV. The total discrimination level for ths ternary ct-particlss was fixed at about 15 JleV for ail the measurements. Each measurement consists of several binary, ternary and background runs. - In a binary run we register the time-of-flight spectrum of the fission fragments in the analyser memory ; in this case there are no aluminium screens between the detectors and the plutonium layers and the discriminators are set to detect only the fission fragments. - In a ternary run we register the t.o.f. spectrum of the light ternary fission fragments (LRA] in the analyser memory. The ternary a-particles are separated from the heavy fission fragments and from the natural a-particles emitted by the plutonium isotopes in the target by inserting a 20 um thick aluminium screen between the detectors and the target. By appropriate discriminator settings the detection levels were adjusted to 15 MeV. - Figure 2 shows the ternary [upper part] and binary [lower part] fission t.o.f. spectra from measurement I and fig. 3 shows the same from measurement III. - For both binary and ternary runs, background runs were performed by putting appropriate neutron filters into the beam. Moreover, for measurement III runs were also performed with a cadmium filter in the beam to evaluate background due to un-timed epicadmium neutrons in the beam and room neutron background (in the energy region below 0.1 eV). In all the measurements a thorough search for the various possible background sources has been done. A detailed description of this background study is given in i !). As a conclusion of all these background measurements we found that the different background contributions were extremely small, especially in measurement III where the repetition frequency was only 100 Hz. The same detection system as described before was moved to the BR2 high flux reactoi of S.CK./C.E.N., Mol, where it was installed at a beam tube and connected to a pulse-height analyser. With this apparatus several pulse-height spectra of binary fission fragments and of ternary a-particles were performed to control the quality of these spectra and to verify the exact position uf the detection levels.
Load more

Recommended publications
  • Ternary Fission and Quasi-Fission of Superheavy Nuclei and Giant Nuclear Systems
    June 17, 2010 18:24 Proceedings Trim Size: 9in x 6in zagrebaev_¯ssion_2010b TERNARY FISSION AND QUASI-FISSION OF SUPERHEAVY NUCLEI AND GIANT NUCLEAR SYSTEMS V.I. ZAGREBAEV, A.V. KARPOV Flerov Laboratory of Nuclear Reactions, JINR, Dubna, Moscow Region, Russia WALTER GREINER Frankfurt Institute for Advanced Studies, J.W. Goethe-UniversitÄat,Germany We found that a true ternary ¯ssion with formation of a heavy third fragment (a new kind of radioactivity) is quite possible for superheavy nuclei due to the strong shell e®ects leading to a three-body clusterization with the two doubly magic tin- like cores. The three-body quasi-¯ssion process could be even more pronounced for giant nuclear systems formed in collisions of heavy actinide nuclei. In this case a three-body clusterization might be proved experimentally by detection of two coincident lead-like fragments in low-energy U+U collisions. 1. Introduction Today the term \ternary ¯ssion" is commonly used to denote the process of formation of light charged particle accompanied ¯ssion 1. This is a rare process (less than 1%) relative to binary ¯ssion, see Fig. 1. As can be seen the probability of such a process decreases sharply with increasing mass number of the accompanied third particle. These light particles are emitted almost perpendicularly with respect to the ¯ssion axis (equatorial emission) 1. It is interpreted as an indication that the light ternary particles are emitted from the neck region and are accelerated by the Coulomb ¯elds of both heavy fragments. In contrast to such a process, the term \true ternary ¯ssion" is used for a simultaneous decay of a heavy nucleus into three fragments of not very di®erent mass 1.
    [Show full text]
  • Compilation and Evaluation of Fission Yield Nuclear Data Iaea, Vienna, 2000 Iaea-Tecdoc-1168 Issn 1011–4289
    IAEA-TECDOC-1168 Compilation and evaluation of fission yield nuclear data Final report of a co-ordinated research project 1991–1996 December 2000 The originating Section of this publication in the IAEA was: Nuclear Data Section International Atomic Energy Agency Wagramer Strasse 5 P.O. Box 100 A-1400 Vienna, Austria COMPILATION AND EVALUATION OF FISSION YIELD NUCLEAR DATA IAEA, VIENNA, 2000 IAEA-TECDOC-1168 ISSN 1011–4289 © IAEA, 2000 Printed by the IAEA in Austria December 2000 FOREWORD Fission product yields are required at several stages of the nuclear fuel cycle and are therefore included in all large international data files for reactor calculations and related applications. Such files are maintained and disseminated by the Nuclear Data Section of the IAEA as a member of an international data centres network. Users of these data are from the fields of reactor design and operation, waste management and nuclear materials safeguards, all of which are essential parts of the IAEA programme. In the 1980s, the number of measured fission yields increased so drastically that the manpower available for evaluating them to meet specific user needs was insufficient. To cope with this task, it was concluded in several meetings on fission product nuclear data, some of them convened by the IAEA, that international co-operation was required, and an IAEA co-ordinated research project (CRP) was recommended. This recommendation was endorsed by the International Nuclear Data Committee, an advisory body for the nuclear data programme of the IAEA. As a consequence, the CRP on the Compilation and Evaluation of Fission Yield Nuclear Data was initiated in 1991, after its scope, objectives and tasks had been defined by a preparatory meeting.
    [Show full text]
  • Inis: Terminology Charts
    IAEA-INIS-13A(Rev.0) XA0400071 INIS: TERMINOLOGY CHARTS agree INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, AUGUST 1970 INISs TERMINOLOGY CHARTS TABLE OF CONTENTS FOREWORD ... ......... *.* 1 PREFACE 2 INTRODUCTION ... .... *a ... oo 3 LIST OF SUBJECT FIELDS REPRESENTED BY THE CHARTS ........ 5 GENERAL DESCRIPTOR INDEX ................ 9*999.9o.ooo .... 7 FOREWORD This document is one in a series of publications known as the INIS Reference Series. It is to be used in conjunction with the indexing manual 1) and the thesaurus 2) for the preparation of INIS input by national and regional centrea. The thesaurus and terminology charts in their first edition (Rev.0) were produced as the result of an agreement between the International Atomic Energy Agency (IAEA) and the European Atomic Energy Community (Euratom). Except for minor changesq the terminology and the interrela- tionships btween rms are those of the December 1969 edition of the Euratom Thesaurus 3) In all matters of subject indexing and ontrol, the IAEA followed the recommendations of Euratom for these charts. Credit and responsibility for the present version of these charts must go to Euratom. Suggestions for improvement from all interested parties. particularly those that are contributing to or utilizing the INIS magnetic-tape services are welcomed. These should be addressed to: The Thesaurus Speoialist/INIS Section Division of Scientific and Tohnioal Information International Atomic Energy Agency P.O. Box 590 A-1011 Vienna, Austria International Atomic Energy Agency Division of Sientific and Technical Information INIS Section June 1970 1) IAEA-INIS-12 (INIS: Manual for Indexing) 2) IAEA-INIS-13 (INIS: Thesaurus) 3) EURATOM Thesaurusq, Euratom Nuclear Documentation System.
    [Show full text]
  • Properties of Selected Radioisotopes
    CASE FILE COPY NASA SP-7031 Properties of Selected Radioisotopes A Bibliography PART I: UNCLASSIFIED LITERATURE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA SP-7031 PROPERTIES OF SELECTED RADIOISOTOPES A Bibliography Part I: Unclassified Literature A selection of annotated references to technical papers, journal articles, and books This bibliography was compiled and edited by DALE HARRIS and JOSEPH EPSTEIN Goddard Space Flight Center Greenbelt, Maryland Scientific and Technical Information Division / OFFICE OF TECHNOLOGY UTILIZATION 1968 USP. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Washington, D.C. PREFACE The increasing interest in the application of substantial quantities of radioisotopes for propulsion, energy conversion, and various other thermal concepts emphasizes a need for the most recent and most accurate information available describing the nuclear, chemical, and physical properties of these isotopes. A substantial amount of progress has been achieved in recent years in refining old and developing new techniques of measurement of the properties quoted, and isotope processing. This has resulted in a broad technological base from which both the material and information about the material is available. Un- fortunately, it has also resulted in a multiplicity of sources so that information and data are either untimely or present properties without adequately identifying the measurement techniques or describing the quality of material used. The purpose of this document is to make available, in a single reference, an annotated bibliography and sets of properties for nine of the more attractive isotopes available for use in power production. Part I contains all the unclassified information that was available in the literature surveyed. Part II is the classified counterpart to Part I.
    [Show full text]
  • Etude Des Évolutions Microstructurales Sous Irradiation De L’Alliage D’Aluminium 6061-T6
    THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ GRENOBLE ALPES Spécialité : Matériaux, Mécanique, Génie Civil, Electrochimie (2MGE) Arrêté ministériel : 7 août 2006 Présentée par Camille FLAMENT Thèse dirigée par Alexis DESCHAMPS et codirigée par Jérôme GARNIER et Joël RIBIS préparée au sein du Laboratoire d’étude du Comportement Mécanique des Matériaux (CEA) dans l'École Doctorale Ingénierie, Matériaux, Mécanique, Energétique, Environnement, Procédés, Production (I-MEP2) Etude des évolutions microstructurales sous irradiation de l’alliage d’aluminium 6061-T6 Thèse soutenue publiquement le 01 décembre 2015, devant le jury composé de : M. Alexis DESCHAMPS Professeur à l’INP de Grenoble, Directeur Mme. Myriam DUMONT Maître de conférences à l’Université Aix-Marseille, Rapporteur M. Thierry EPICIER Directeur de recherche au CNRS, Président M. Jérôme GARNIER Ingénieur de recherche au CEA, Co-encadrant M. Alexandre LEGRIS Professeur à l’Université Lille 1, Rapporteur M. Joël RIBIS Ingénieur de recherche au CEA, Co-encadrant REMERCIEMENTS Remerciements Cette thèse a été réalisée au Service de Recherches Métallurgiques Appliquées (SRMA) du Département des Matériaux pour le Nucléaire du CEA Saclay (DMN). Je souhaite donc tout d’abord remercier Messieurs Philippe Chapelot et Pascal Yvon de m’avoir accueillie respectivement au SRMA et DMN. Je remercie également Madame Laetitia Nicolas, ex-chef du Laboratoire d’étude du Comportement Mécanique des Matériaux qui fut mon laboratoire de rattachement et Monsieur Jean- Luc Béchade, ex-chef du Laboratoire d’Analyse Microstructurale des Matériaux (dorénavant chef du Service de Recherche de Métallurgie Physique) au sein duquel j’ai pu m’installer et utiliser les différents outils de caractérisation.
    [Show full text]
  • Ternary and Quaternary Fission
    FEATURES Ternary and quaternary fission Friedrich Gönnenwein 1, Manfred Mutterer2 and Yuri Kopatch 3 1 Physikalisches Institut, Universität Tübingen, Germany 2 Institut für Kernphysik, Technische Universität Darmstadt, Germany 3 Frank Laboratory of Neutron Physics, JINR, Dubna, Russia N uclear fission has become known in the late thirties of the last century as a process where a heavy nucleus such as Ura­ nium or Thorium decays into two fragments of about the same Fig. 5: Time variations of the apex height in dimensionless mass. The process was discovered while irradiating natural Urani­ coordinates for a sessile drop measured during solvent loss um with thermal neutrons [1] and it soon became evident that at low humidity rate (RH=30%; 6o=40°;R0=3.1 mm). After the among the U-isotopes it was 235U to be held responsible for the primary buckling instability leading to an axisymmetric reaction 235U(nth,f ) observed. Shortly afterwards it was found that "peak) a secondary instability takes place and breaks the heavy nuclei such as 238U may also undergo fission spontaneously axisymmetry of the drop. Inset: image taken at 45° of such drop at the final stage of the drying process: radial wrinkles Whether by spontaneous or induced fission, the mother are clearly observable all around the peak formed by the first nucleus disintegrates in the overwhelming fraction of cases just buckling instability (also in Figure 4b). into two fragments. Fragmentation into three or more daughter nuclei of about equal mass has up to the present not been detect­ cascade of buckling events takes place, resulting in a complex ed unambiguously.
    [Show full text]
  • The Economics of Nuclear Power Programmes in the United Kingdom
    THE ECONOMICS OF NUCLEAR POWER PROGRAMMES IN THE UNITED KINGDOM Traditionally, decisions concerning investment in electricity-generating plant in the UK have been based on an evaluation of the direct costs involved, namely capital and operating costs. Examination of many of the wider-ranging impacts such as environmental implications and possible health effects have often been given somewhat less emphasis within the decision-making process. This book attempts to correct this imbalance by integrating estimates of various indirect costs associated with the operation of both coal-fired and nuclear-power generating capacity into a social cost analysis. Moreover, in an attempt to facilitate informed discussion ofsome ofthe more important issues relevant to the nuclear-power debate, this book also provides an interdisciplinary overview of several areas of legitimate public concern. In this respect, particular attention is paid to the technology involved in nuclear-reactor operation, the nature and development ofthe uranium market, the 'economics' ofthe reprocessing option, and the environmental impact of radioactive emissions from nuclear-power plant. It should be stressed that the author does not adopt either a pro- or anti­ nuclear standpoint, but rat her attempts to provide a means to raise the nuclear debate from an emotional to a more informed level. Peter LIoyd Jones is Research Fellow in the Department of Political Economy at the University of Aberdeen. He was employed as a consultant to the Electricity Consumers' Council for the Sizewell inquiry in 1982-3. He has contributed articles to Energy Economics, Financial Times Energy Reviews and the International Journal 0/ Environmental Studies. THE ECONOMICS OF NUCLEAR POWER PROGRAMMES IN THE UNITED KINGDOM Peter Lloyd Jones M MACMILLAN PRESS LONDON © Peter Lloyd Jones 1984 Softcover reprint of the hardcover 1st edition 1984 978-0-333-35095-9 All rights reserved.
    [Show full text]
  • Fission and Corrosion Product Behaviour in Liquid Metal Fast Breeder Reactors (Lmfbrs)
    IAEA-TECDOC-687 Fission and corrosion product behaviour in liquid metal fast breeder reactors (LMFBRs) INTERNATIONAL ATOMIC ENERGY AGENCY The IAEA does not normally maintain stocks of reports in this series. However, microfiche copie f thesso e reportobtainee b n sca d from INIS Clearinghouse International Atomic Energy Agency Wagramerstrasse5 P.O. Box 100 A-1400 Vienna, Austria Orders should be accompanied by prepayment of Austrian Schillings 100,- fore for e chequa th f m th IAEf m o n i o n i r eAo microfiche service coupons orderee whicb y hdma separately fro INIe mth S Clearinghouse. FISSIO CORROSIOD NAN N PRODUCT BEHAVIOUR IN LIQUID METAL FAST BREEDER REACTORS (LMFBRs) IAEA, VIENNA, 1993 IAEA-TECDOC-687 ISSN 1011-4289 Printed by the IAEA in Austria February 1993 FOREWORD In 1969 e Internationath , l Atomic Energy Agency decide o includt d e th e topic of fission and corrosion product behaviour in liquid metal fast breeder reactors (LMFBRs} in its programme of specialists meetings. It was apparent at the time that with the advent of experimental fast reactor systems in the USAe USSRth , ,e Unite Francth d d an eKingdom e expansioth , f supportino n g research programme e fragmenteth d an s d natur f informatioo e n arising from these various activities, it would be beneficial to co-ordinate certain topics at an international level. Suppor thir tfo s approac provides hwa Membey db r States and, against this background e IAEs helth ,Aha d three international specialists meetingse on , Germanyn i o purpose meetinge tw Th provido USSe th .d t i th n f an R s o e wa se a better understanding of the way various radionuclides behave in operating systemo providt d an se guidance safth e r developmenfo e f prototypo t d an e eventually commercial systems o meeT .t these objective e specialistth s s discussed experiment results, reviewed experimental programme identified san d area further fo s r work.
    [Show full text]
  • National Conference on Radiation Physics NCRP-2017
    A Brief Report on National Conference on Radiation Physics NCRP-2017 23-24 November 2017 Organized by Department of Physics, Bangalore University, Bengaluru In Collaboration with AMD, Bengaluru Submitted to Bangalore University By Dr. N. Nagaiah Convener, NCRP-2017 Professor, Dept. of Physics Jnana Bharathi, Bangalore University Bengaluru – 560056 Karnataka National Conference on Radiation Physics November 23rd -24th, 2017 REPORT ON THE TWO DAY NATIONAL CONFERENCE ON RADIATION PHYSICS (NCRP), 23-24 NOVEMBER 2017, BENGALURU A two day National Conference on Radiation Physics (NCRP 2017), was organized during 23-24, November 2017 by Department of Physics, Bangalore University, Bengaluru (BUB) in collaboration with Atomic Minerals Directorate for Exploration and Research (AMD), Bengaluru. The program was supported by the Bangalore University, Bengaluru, Board of Research in Nuclear Sciences (BRNS), BARC, Mumbai, AMD, Bengaluru and was sponsored by M/s Nucleonix Systems Pvt Ltd, Hyderabad, M/s PLA Electro Appliances (P) Ltd, Mumbai, Acharya Institutes and Indian Academy Degree College (Autonomous) Bengaluru. The National Advisory Committee consisted of Prof. H. N. Ramesh, Vice Chancellor, Bangalore University, Prof. B. K. Ravi, Registrar, Bangalore University, Prof. I. S. Shivakumara, Dean, Faculty of Science, BUB, Dr. K. S. Pradeep Kumar, RSSD, BARC, Mumbai, Prof. P. Venkataramaiah, Ex- VC, Kuvempu University, Shivamogga, Dr. Lalit Varshney, BARC, Mumbai, Shri. L. K. Nanada, Director, AMD, Hyderabad, Shri. A. K. Bhatt, Regional Director, AMD, Bengaluru, Dr. Nagesh N. Bhat, RPAD, BARC, Mumbai, Dr. N. Kumar, FCD, BARC, Mumbai, Dr. Ashutosh Dash, RC & IG, BARC, Mumbai, Shri. B.N. Dileep, ESL, Kaiga, Prof. N. Karunakara, CARER, Mangalore University, Mangaluru, Prof.
    [Show full text]
  • Beta-Delayed Fission in Proton-Rich Nuclei in the Lead Region
    ARENBERG DOCTORAL SCHOOL Faculty of Science Beta-delayed fission in proton-rich nuclei in the lead region CERN-THESIS-2015-234 01/09/2015 Lars Ghys Supervisor: Dissertation presented in partial Prof. Dr. P. Van Duppen fulfillment of the requirements for the Prof. Dr. M. Huyse, co-supervisor degree of Doctor in Science Dr. L. Popescu, co-supervisor (SCK•CEN) September 2015 Beta-delayed fission in proton-rich nuclei in the lead region Lars GHYS Examination committee: Dissertation presented in partial Prof. Dr. N. Severijns, chair fulfillment of the requirements for Prof. Dr. P. Van Duppen, supervisor the degree of Doctor Prof. Dr. M. Huyse, co-supervisor in Science Dr. L. Popescu, co-supervisor (SCK•CEN) Prof. Dr. L. C. Pereira Prof. Dr. R. Raabe Prof. Dr. M. J. Van Bael Prof. Dr. A. N. Andreyev (University of York, UK) September 2015 © 2015 KU Leuven – Faculty of Science Uitgegeven in eigen beheer, Lars Ghys, Celestijnenlaan 200D box 2418, B-3001 Heverlee (Belgium) Alle rechten voorbehouden. Niets uit deze uitgave mag worden vermenigvuldigd en/of openbaar gemaakt worden door middel van druk, fotokopie, microfilm, elektronisch of op welke andere wijze ook zonder voorafgaande schriftelijke toestemming van de uitgever. All rights reserved. No part of the publication may be reproduced in any form by print, photoprint, microfilm, electronic or any other means without written permission from the publisher. Dit werk kwam mede tot stand met steun van het Fonds voor Wetenschappelijk Onderzoek (FWO) Vlaanderen. Dankwoord Deze thesis kon alleen tot stand komen door de hulp en ondersteuning van velen gedurende de afgelopen vier jaar en dit op allerlei verschillende manieren.
    [Show full text]
  • Radionuclides
    Physics of Novel Radiation Modalities: Radionuclides James S. Welsh Stritch School of Medicine Loyola University Chicago Disclosure • Member of the Advisory Committee on the Medical Uses of Isotopes (ACMUI) for the United States Nuclear Regulatory Commission (NRC) • Board of directors: – Coqui Radioisotopes – Colossal Fossils Learning Objectives • Understand the basic physics of alpha, beta, gamma and other types of radioactivity • Gain some familiarity with the various sealed and unsealed radionuclides commonly used in radiation oncology Types of radioactivity • Alpha • Beta – Beta minus – beta plus (positron emission) – electron capture • Gamma – Isomeric transitions – Internal conversion – Internal pair production • Cluster radioactivity • Spontaneous fission – Binary or ternary • Rare types: – Proton radioactivity – b+ delayed proton emission – b- delayed neutron emission – b+ delayed deuteron or triton emission – Beta delayed fission Fun with Isotopes Radioactive decay supposedly follows a mathematically precise exponential function • Supposedly unaffected by temperature, pressure, chemical environment • First declared by Rutherford, Chadwick and Ellis Generally true but… …well-known exceptions do exist …well-known exceptions do exist • Electron Capture (e.g. 7Be, 109In, 110Sn) – If chemical environment make K-shell electrons less accessible, decay rate might be altered …well-known exceptions do exist • Electron Capture (e.g. 7Be, 109In, 110Sn) – If chemical environment make K-shell electrons less accessible, decay rate might be altered
    [Show full text]
  • Ternary Fission
    Journal of Chennai Academy of Sciences 1, 29-53 (2019) 29 Ternary Fission M. Balasubramaniam* Department of Physics Bharathiar University Coimbatore - 641046, Tamil Nadu Received 25 October 2019 Abstract: In this review, an account of the ternary fission phenomenon is discussed. Conventionally, ternary fission refers to the emission of very light charged α-particles from the neck formed between the main fission fragments. Further, the third particle emission is always identified to emit in a direction perpendicular to that of the axis of main fission fragments. However, recently, heavy charged particle accompanied fission has been reported to be emitted collinearly along with other fission fragments. The theoretical understanding of conventional ternary fission and collinear ternary fission based on three cluster model and statistical approach is presented. 1 Historical Perspective 1.1 Fission Nuclear physics bifurcated from the domain of atomic physics after the discovery of radioactivity, a process in which an unstable atomic nucleus disintegrates to result in another isotope by emitting particles spontaneously. The remarkable experiments of Rutherford and his collaborators put forth concrete evidence of the presence of a nucleus at the center of the atom. Since then, the quest has been to understand the sub-atomic structure through various possible reactions. However, the probe to investigate were limited and are available mainly from other radioactive sources. The development of voltage multipliers by Cockcroft and Walton expanded the av- enue of investigation. The discovery of neutron by Chadwick further kindled the *Email: [email protected] 30 M. Balasubramaniam scientific community to probe the nuclear structure as well as to synthesize possible transuranic elements.
    [Show full text]