DOCSLIB.ORG

Neutrinoless Double-Electron Capture

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Neutrinoless Double-Electron Capture REVIEWS OF MODERN PHYSICS, VOLUME 92, OCTOBER–DECEMBER 2020 Neutrinoless double-electron capture K. Blaum and S. Eliseev Max-Planck-Institut f¨ur Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany F. A. Danevich and V. I. Tretyak Institute for Nuclear Research of NASU, Prospekt Nauky 47, Kyiv 03028, Ukraine Sergey Kovalenko Departamento de Ciencias Físicas, Universidad Andres Bello, Sazi´e 2212, Santiago 8320000, Chile M. I. Krivoruchenko Institute for Theoretical and Experimental Physics, NRC “Kurchatov Institute”, B. Cheremushkinskaya 25, 117218 Moscow, Russia and National Research Centre “Kurchatov Institute”, Ploschad’ Akademika Kurchatova 1, 123182 Moscow, Russia Yu. N. Novikov Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Gatchina, 188300 St. Petersburg, Russia and Department of Physics, St. Petersburg State University, 199034 St. Petersburg, Russia J. Suhonen Department of Physics, University of Jyvaskyla, P.O. Box 35, Jyvaskyla FI-40014, Finland (published 16 December 2020) Double-beta processes play a key role in the exploration of neutrino and weak interaction properties, and in the searches for effects beyond the standard model. During the last half century many attempts were undertaken to search for double-beta decay with emission of two electrons, especially for its neutrinoless mode 0ν2β−, the latter having still not been observed. Double-electron capture (2EC) was not yet in focus because of its in general lower transition probability. However, the rate of neutrinoless double-electron capture 0ν2EC can experience a resonance enhancement by many orders of magnitude when the initial and final states are energetically degenerate. In the resonant case, the sensitivity of the 0ν2EC process can approach the sensitivity of the 0ν2β− decay in the search for the Majorana mass of neutrinos, right-handed currents, and other new physics. An overview of the main experimental and theoretical results obtained during the last decade in this field is presented. The experimental part outlines search results of 2EC processes and measurements of the decay energies for possible resonant 0ν2EC transitions. An unprecedented precision in the determination of decay energies with Penning traps has allowed one to refine the values of the degeneracy parameter for all previously known near-resonant decays and has reduced the rather large uncertainties in the estimate of the 0ν2EC half-lives. The theoretical part contains an updated analysis of the electron shell effects and an overview of the nuclear-structure models, in which the nuclear matrix elements of the 0ν2EC decays are calculated. One can conclude that the decay probability of 0ν2EC can experience a significant enhancement in several nuclides. DOI: 10.1103/RevModPhys.92.045007 CONTENTS III. Phenomenology of Neutrinoless 2EC 9 A. Underlying formalism 10 I. Introduction 2 B. Decay amplitude of the light Majorana neutrino II. Double-Electron Capture and Physics beyond exchange mechanism 10 the Standard Model 4 C. Comparison of 0ν2EC and 0ν2β− decay half-lives 12 0ν2 A. Quark-level mechanisms of EC 5 IV. Electron Shell Effects 13 B. Examples of underlying high-scale models 6 A. Interaction energy of electron holes 15 C. Hadronization of quark-level interactions 8 1. Electrostatic interaction 16 0034-6861=2020=92(4)=045007(61) 045007-1 © 2020 American Physical Society K. Blaum et al.: Neutrinoless double-electron capture 2. Retardation correction in the Feynman gauge 17 astrophysics, and cosmology. The fermions described by the 3. Magnetostatic interaction in the Feynman gauge 17 Dirac equation can also be electrically neutral. However, even 4. Magnetostatic interaction in the Coulomb gauge 18 in this case there is a conserved current in Diracs theory, which 5. Gauge invariance of the interaction energy ensures a constant number of particles (minus antiparticles). of electron holes 18 Majorana fermions, like photons, do not have such a con- B. Double-electron ionization potentials in Auger served current. In Dirac’s theory, particles and antiparticles are spectroscopy 19 independent, while Majorana fermions are their own anti- C. Summary 21 particles and, via CPT, it follows that they must have zero V. Nuclear Matrix Elements 22 charge. Truly neutral spin-1=2 fermions are referred to as A. Overview of the calculated nuclear matrix Majorana fermions, and those with a conserved current are 0ν2 elements in EC 22 referred to as Dirac fermions. Majorana fermions in bispinor B. Overview of the calculation frameworks 23 basis are vectors of the real vector space R4. They can also be 1. Multiple-commutator model 24 described by two-component Weyl spinors in the complex 2. Deformed quasiparticle random-phase space C2. In both representations, the superposition principle approximation 26 3. Microscopic interacting boson model 26 for Majorana fermions holds over the field of real numbers. 4. Energy-density functional method 26 Majorana fermions belong to the fundamental real represen- C. Decays of nuclides with the calculated nuclear tation of the Poincar´e group. A Dirac fermion of mass m can matrix elements 27 be represented as a superposition of two Majorana fermions of − D. Summary 28 masses m and m, respectively. VI. Status of Experimental Searches 28 The neutron has a nonvanishing magnetic moment, so it A. Experimental studies of 2EC processes 28 cannot be a pure Majorana particle. On the other hand, there B. Prospects for possible future experiments 42 is no fundamental reason to claim that it is a pure Dirac C. Neutrinoless 2EC with radioactive nuclides 43 particle. In theories with nonconservation of the baryon D. Summary 43 number, the mass eigenstates include a mixture of baryons and VII. Precise Determination of 2EC Decay Energies 43 antibaryons. At the phenomenological level, the effect is A. Basics of high-precision Penning-trap mass modeled by adding a Majoranian mass term to the spectrometry 43 effective Lagrangian. As a result, the neutron experiences B. Decay energies of 2EC transitions in virtually oscillations n ↔ n¯ whereby the nuclei decay with noncon- stable nuclides 45 servation of the baryon number (Dover, Gal, and Richard, C. Prospects for measurements of decay energies in 1983, 1985; Krivoruchenko, 1996a, 1996b; Gal, 2000; radioactive nuclides 47 Kopeliovich and Potashnikova, 2010; Phillips et al., 2016). VIII. Normalized Half-Lives of Near-Resonant Nuclides 47 Experimental limits for the period of the n ↔ n¯ oscillations A. Decays of virtually stable nuclides 47 τ 2 7 108 in the vacuum vac > . × s(Abe et al., 2015) constrain B. Decays of long-lived radionuclides 51 Δ ∼ 1 τ 0 8 10−33 the neutron Majorana mass to m = vac < . × m, IX. Conclusions 51 2 List of Symbols and Abbreviations 53 where m ¼ 939.57 MeV=c is the neutron Dirac mass. Thus, Acknowledgments 53 under the condition of nonconservation of the baryon number, References 54 Majorana’s idea on the existence of truly neutral fermions can be partially realized in relation to the neutron. In contrast, I. INTRODUCTION neutrinos can be pure Majorana fermions or pure Dirac fermions or a mixture of these two extreme cases. It is In 1937, Ettore Majorana found an evolution equation for a noteworthy that none of the variants of neutrino masses are truly neutral spin-1=2 fermion (Majorana, 1937). His work possible within the SM. The neutrino mass problem leads us to was motivated by the experimental observation of a free physics beyond the SM. Alternative examples of Majorana neutron by James Chadwick in 1932. Majorana also conjec- particles include weakly interacting dark-matter candidates tured that his equation applies to a hypothetical neutrino and Majorana zero modes in solid state systems (Elliott and introduced by Wofgang Pauli to explain the continuous Franz, 2015). − spectrum of electrons in the β decay of nuclei. In the mid- Searches for neutrinoless double-beta (0ν2β ) decay, neu- 1950s, Reines and Cowan (1956, 1959) discovered a particle trinoless double-electron capture (0ν2EC) by nuclei, and other with neutrino properties. At the time of the establishment of lepton number violating (LNV) processes provide the pos- the standard model (SM) of electroweak interactions, three sibility to shed light on the question of the nature of neutrinos families of neutrinos were known. While the neutron is a whether they are Majorana or Dirac particles. By virtue of the composite fermion consisting of quarks, neutrinos acquired black-box theorem (Schechter and Valle, 1982; Hirsch, the status of elementary particles with zero masses in the Kovalenko, and Schmidt, 2006), observation of the 0ν2β SM framework. The discovery of neutrino oscillations decay would prove that neutrinos have a finite Majorana mass. by the Super-Kamiokande Collaboration (Fukuda et al., The massive Majorana neutrinos lead to a violation of the 1998) showed that neutrinos are mixed and massive. A conservation of the total lepton number L. In the quark sector comprehensive description of the current state of neutrino of the SM, the baryon charge B is a similar quantum number. physics was given by Bilenky (2018). Vector currents of B and L are classically conserved. Left- Whether neutrinos are truly neutral fermions is one handed fermions are coupled to the SUð2Þ electroweak gauge of the fundamental questions in modern particle physics, fields WÆ and Z0 so that vector currents of B and L, Rev. Mod. Phys., Vol. 92, No. 4, October–December 2020 045007-2 K. Blaum et al.: Neutrinoless double-electron capture FIG. 1. Schematic representation of neutrinoless double-beta FIG. 2. Schematic representation of neutrinoless double- decay. Two neutrons in the nucleus experience β decay accom- electron capture. Two protons in the nucleus each capture a panied by the exchange of a Majorana neutrino. Neutrons, bound electron from the electron shell and turn into two neutrons protons, electrons, and neutrinos are represented by solid lines. by the exchange of a Majorana neutrino. Notation is the same as Arrows show the flow of baryon charge of protons and neutrons in Fig.
Load more

Recommended publications
  • What Is the Nature of Neutrinos?
    16th Neutrino Platform Week 2019: Hot Topics in Neutrino Physics CERN, Switzerland, Switzerland, 7– 11 October 2019 Matrix Elements for Neutrinoless Double Beta Decay Fedor Šimkovic OUTLINE I. Introduction (Majorana ν’s) II. The 0νββ-decay scenarios due neutrinos exchange (simpliest, sterile ν, LR-symmetric model) III. DBD NMEs – Current status (deformation, scaling relation?, exp. support, ab initio… ) IV. Quenching of gA (Ikeda sum rule, 2νββ-calc., novel approach for effective gA ) V. Looking for a signal of lepton number violation (LHC study, resonant 0νECEC …) Acknowledgements: A. Faessler (Tuebingen), P. Vogel (Caltech), S. Kovalenko (Valparaiso U.), M. Krivoruchenko (ITEP Moscow), D. Štefánik, R. Dvornický (Comenius10/8/2019 U.), A. Babič, A. SmetanaFedor(IEAP SimkovicCTU Prague), … 2 After 89/63 years Fundamental ν properties No answer yet we know • Are ν Dirac or • 3 families of light Majorana? (V-A) neutrinos: •Is there a CP violation ν , ν , ν ν e µ τ e in ν sector? • ν are massive: • Are neutrinos stable? we know mass • What is the magnetic squared differences moment of ν? • relation between • Sterile neutrinos? flavor states • Statistical properties and mass states ν µ of ν? Fermionic or (neutrino mixing) partly bosonic? Currently main issue Nature, Mass hierarchy, CP-properties, sterile ν The observation of neutrino oscillations has opened a new excited era in neutrino physics and represents a big step forward in our knowledge of neutrino10/8/2019 properties Fedor Simkovic 3 Symmetric Theory of Electron and Positron Nuovo Cim. 14 (1937) 171 CNNP 2018, Catania, October 15-21, 2018 10/8/2019 Fedor Simkovic 4 ν ↔ ν- oscillation (neutrinos are Majorana particles) 1968 Gribov, Pontecorvo [PLB 28(1969) 493] oscillations of neutrinos - a solution of deficit10/8/2019 of solar neutrinos in HomestakeFedor Simkovic exp.
    [Show full text]
  • Ivan V. Ani~In Faculty of Physics, University of Belgrade, Belgrade, Serbia and Montenegro
    THE NEUTRINO Its past, present and future Ivan V. Ani~in Faculty of Physics, University of Belgrade, Belgrade, Serbia and Montenegro The review consists of two parts. In the first part the critical points in the past, present and future of neutrino physics (nuclear, particle and astroparticle) are briefly reviewed. In the second part the contributions of Yugoslav physics to the physics of the neutrino are commented upon. The review is meant as a first reading for the newcomers to the field of neutrino physics. Table of contents Introduction A. GENERAL REVIEW OF NEUTRINO a.2. Electromagnetic properties of the neutrino PHYSICS b. Neutrino in branches of knowledge other A.1. Short history of the neutrino than neutrino physics A.1.1. First epoch: 1930-1956 A.2. The present status of the neutrino A.1.2. Second epoch: 1956-1958 A.3. The future of neutrino physics A.1.3. Third epoch: 1958-1983 A.1.4. Fourth epoch: 1983-2001 B. THE YUGOSLAV CONNECTION a. The properties of the neutrino B.1. The Thallium solar neutrino experiment a.1. Neutrino masses B.2. The neutrinoless double beta decay a.1.1. Direct methods Epilogue a.1.2. Indirect methods References a.1.2.1. Neutrinoless double beta decay a.1.2.2. Neutrino oscillations 1 Introduction The neutrinos appear to constitute by number of species not less than one quarter of the particles which make the world, and even half of the stable ones. By number of particles in the Universe they are perhaps second only to photons.
    [Show full text]
  • Electron Capture in Stars
    Electron capture in stars K Langanke1;2, G Mart´ınez-Pinedo1;2;3 and R.G.T. Zegers4;5;6 1GSI Helmholtzzentrum f¨urSchwerionenforschung, D-64291 Darmstadt, Germany 2Institut f¨urKernphysik (Theoriezentrum), Department of Physics, Technische Universit¨atDarmstadt, D-64298 Darmstadt, Germany 3Helmholtz Forschungsakademie Hessen f¨urFAIR, GSI Helmholtzzentrum f¨ur Schwerionenforschung, D-64291 Darmstadt, Germany 4 National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA 5 Joint Institute for Nuclear Astrophysics: Center for the Evolution of the Elements, Michigan State University, East Lansing, Michigan 48824, USA 6 Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA E-mail: [email protected], [email protected], [email protected] Abstract. Electron captures on nuclei play an essential role for the dynamics of several astrophysical objects, including core-collapse and thermonuclear supernovae, the crust of accreting neutron stars in binary systems and the final core evolution of intermediate mass stars. In these astrophysical objects, the capture occurs at finite temperatures and at densities at which the electrons form a degenerate relativistic electron gas. The capture rates can be derived in perturbation theory where allowed nuclear transitions (Gamow-Teller transitions) dominate, except at the higher temperatures achieved in core-collapse supernovae where also forbidden transitions contribute significantly to the rates. There has been decisive progress in recent years in measuring Gamow-Teller (GT) strength distributions using novel experimental techniques based on charge-exchange reactions. These measurements provide not only data for the GT distributions of ground states for many relevant nuclei, but also serve as valuable constraints for nuclear models which are needed to derive the capture rates for the arXiv:2009.01750v1 [nucl-th] 3 Sep 2020 many nuclei, for which no data exist yet.
    [Show full text]
  • 2.3 Neutrino-Less Double Electron Capture - Potential Tool to Determine the Majorana Neutrino Mass by Z.Sujkowski, S Wycech
    DEPARTMENT OF NUCLEAR SPECTROSCOPY AND TECHNIQUE 39 The above conservatively large systematic hypothesis. TIle quoted uncertainties will be soon uncertainty reflects the fact that we did not finish reduced as our analysis progresses. evaluating the corrections fully in the current analysis We are simultaneously recording a large set of at the time of this writing, a situation that will soon radiative decay events for the processes t e'v y change. This result is to be compared with 1he and pi-+eN v y. The former will be used to extract previous most accurate measurement of McFarlane the ratio FA/Fv of the axial and vector form factors, a et al. (Phys. Rev. D 1984): quantity of great and longstanding interest to low BR = (1.026 ± 0.039)'1 I 0 energy effective QCD theory. Both processes are as well as with the Standard Model (SM) furthermore very sensitive to non- (V-A) admixtures in prediction (Particle Data Group - PDG 2000): the electroweak lagLangian, and thus can reveal BR = (I 038 - 1.041 )*1 0-s (90%C.L.) information on physics beyond the SM. We are currently analyzing these data and expect results soon. (1.005 - 1.008)* 1W') - excl. rad. corr. Tale 1 We see that even working result strongly confirms Current P1IBETA event sxpelilnentstatistics, compared with the the validity of the radiative corrections. Another world data set. interesting comparison is with the prediction based on Decay PIBETA World data set the most accurate evaluation of the CKM matrix n >60k 1.77k element V d based on the CVC hypothesis and ihce >60 1.77_ _ _ results
    [Show full text]
  • Double-Beta Decay of 96Zr and Double-Electron Capture of 156Dy to Excited Final States
    Double-Beta Decay of 96Zr and Double-Electron Capture of 156Dy to Excited Final States by Sean W. Finch Department of Physics Duke University Date: Approved: Werner Tornow, Supervisor Calvin Howell Kate Scholberg Berndt Mueller Albert Chang Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics in the Graduate School of Duke University 2015 Abstract Double-Beta Decay of 96Zr and Double-Electron Capture of 156Dy to Excited Final States by Sean W. Finch Department of Physics Duke University Date: Approved: Werner Tornow, Supervisor Calvin Howell Kate Scholberg Berndt Mueller Albert Chang An abstract of a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics in the Graduate School of Duke University 2015 Copyright c 2015 by Sean W. Finch All rights reserved except the rights granted by the Creative Commons Attribution-Noncommercial License Abstract Two separate experimental searches for second-order weak nuclear decays to excited final states were conducted. Both experiments were carried out at the Kimballton Underground Research Facility to provide shielding from cosmic rays. The first search is for the 2νββ decay of 96Zr to excited final states of the daughter nucleus, 96Mo. As a byproduct of this experiment, the β decay of 96Zr was also investigated. Two coaxial high-purity germanium detectors were used in coincidence to detect γ rays produced by the daughter nucleus as it de-excited to the ground state. After collecting 1.92 years of data with 17.91 g of enriched 96Zr, half-life limits at the level of 1020 yr were produced.
    [Show full text]
  • «Nucleus-2020»
    NRC «Kurchatov Institute» Saint Petersburg State University Joint Institute for Nuclear Research LXX INTERNATIONAL CONFERENCE «NUCLEUS-2020» NUCLEAR PHYSICS AND ELEMENTARY PARTICLE PHYSICS. NUCLEAR PHYSICS TECHNOLOGIES. BOOK OF ABSTRACTS Online part. 12 – 17 October 2020 Saint Petersburg НИЦ «Курчатовский институт» Санкт-Петербургский государственный университет Объединенный институт ядерных исследований LXX МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ «ЯДРО-2020» ЯДЕРНАЯ ФИЗИКА И ФИЗИКА ЭЛЕМЕНТАРНЫХ ЧАСТИЦ. ЯДЕРНО-ФИЗИЧЕСКИЕ ТЕХНОЛОГИИ. СБОРНИК ТЕЗИСОВ Онлайн часть. 12 – 17 октября 2020 Санкт-Петербург Organisers NRC «Kurchatov Institute» Saint Petersburg State University Joint Institute for Nuclear Research Chairs M. Kovalchuk (Chairman, NRC “Kurchatov Institute”) V. Zherebchevsky (Co-Chairman, SPbU) P. Forsh (Vice-Chairman, NRC “Kurchatov Institute”) Yu. Dyakova (Vice-Chairman, NRC “Kurchatov Institute”) A. Vlasnikov (Vice-Chairman, SPbU) S. Torilov (Scientific Secretary, SPbU) The contributions are reproduced directly from the originals. The responsibility for misprints in the report and paper texts is held by the authors of the reports. International Conference “NUCLEUS – 2020. Nuclear physics and elementary particle physics. Nuclear physics technologies” (LXX; 2020; Online part). LXX International conference “NUCLEUS – 2020. Nuclear physics and elementary particle physics. Nuclear physics technologies” (Saint Petersburg, Russia, 12–17 October 2020): Book of Abstracts /Ed. by V. N. Kovalenko and E. V. Andronov. – Saint Petersburg: VVM, 2020. – 324p. ISBN Международная Конференция «ЯДРО – 2020. Ядерная физика и физика элементарных частиц. Ядерно-физические технологии» (LXX; 2020; Онлайн часть). LXX Международная Конференция «ЯДРО – 2020. Ядерная физика и физика элементарных частиц. Ядерно-физические технологии» (Санкт-Петербург, Россия, 12–17 Октября 2020): Аннот. докл./под ред. В.Н. Коваленко, Е.В. Андронова. – Санкт-Петербург: ВВМ , 2020. – 324 c. ISBN 978-5-9651-0587-8 ISBN 978-5-9651-0587-8 ii Program Committee V.
    [Show full text]
  • Limit on the Radiative Neutrinoless Double Electron Capture of Ar from GERDA Phase I
    Eur. Phys. J. C (2016) 76:652 DOI 10.1140/epjc/s10052-016-4454-5 Regular Article - Experimental Physics Limit on the radiative neutrinoless double electron capture of 36Ar from GERDA Phase I GERDA Collaboration1,a M. Agostini1, M. Allardt4, A. M. Bakalyarov13, M. Balata1, I. Barabanov11 , N. Barros4,20, L. Baudis19, C. Bauer7, E. Bellotti8,9, S. Belogurov11,12, S. T. Belyaev13, G. Benato19, A. Bettini16,17, L. Bezrukov11, T. Bode15, D. Borowicz3,5, V. Brudanin5, R. Brugnera16,17, A. Caldwell14, C. Cattadori9, A. Chernogorov12, V. D’Andrea1, E. V. Demidova12, A. di Vacri1, A. Domula4, E. Doroshkevich11, V. Egorov5, R. Falkenstein18, O. Fedorova11, K. Freund18, N. Frodyma3, A. Gangapshev7,11, A. Garfagnini16,17, C. Gooch14, P. Grabmayr18, V. Gurentsov11, K. Gusev5,13,15, J. Hakenmüller7, A. Hegai18,M.Heisel7, S. Hemmer17, G. Heusser7, W. Hofmann7,M.Hult6, L. V. Inzhechik11,21, J. Janicskó Csáthy15, J. Jochum18, M. Junker1, V. Kazalov11,T.Kihm7, I. V. Kirpichnikov12 , A. Kirsch7,A.Kish19, A. Klimenko5,7,22, R. Kneißl14, K. T. Knöpfle7, O. Kochetov5, V. N. Kornoukhov11,12, V. V. K u z m i n o v 11, M. Laubenstein1, A. Lazzaro15, V. I. Lebedev13, B. Lehnert4,H.Y.Liao14, M. Lindner7, I. Lippi17, A. Lubashevskiy5,7 , B. Lubsandorzhiev11, G. Lutter6, C. Macolino1,23, B. Majorovits14, W. Maneschg7, E. Medinaceli16,17, M. Miloradovic19, R. Mingazheva19, M. Misiaszek3, P. Moseev11, I. Nemchenok5, D. Palioselitis14, K. Panas3, L. Pandola2, K. Pelczar3, A. Pullia10, S. Riboldi10, N. Rumyantseva5, C. Sada16,17, F. Salamida9, M. Salathe7, C. Schmitt18, B. Schneider4, S. Schönert15, J. Schreiner7, A.-K.
    [Show full text]
  • Nuclear Physics and Astrophysics SPA5302, 2019 Chris Clarkson, School of Physics & Astronomy [email protected]
    Nuclear Physics and Astrophysics SPA5302, 2019 Chris Clarkson, School of Physics & Astronomy [email protected] These notes are evolving, so please let me know of any typos, factual errors etc. They will be updated weekly on QM+ (and may include updates to early parts we have already covered). Note that material in purple ‘Digression’ boxes is not examinable. Updated 16:29, on 05/12/2019. Contents 1 Basic Nuclear Properties4 1.1 Length Scales, Units and Dimensions............................7 2 Nuclear Properties and Models8 2.1 Nuclear Radius and Distribution of Nucleons.......................8 2.1.1 Scattering Cross Section............................... 12 2.1.2 Matter Distribution................................. 18 2.2 Nuclear Binding Energy................................... 20 2.3 The Nuclear Force....................................... 24 2.4 The Liquid Drop Model and the Semi-Empirical Mass Formula............ 26 2.5 The Shell Model........................................ 33 2.5.1 Nuclei Configurations................................ 44 3 Radioactive Decay and Nuclear Instability 48 3.1 Radioactive Decay...................................... 49 CONTENTS CONTENTS 3.2 a Decay............................................. 56 3.2.1 Decay Mechanism and a calculation of t1/2(Q) .................. 58 3.3 b-Decay............................................. 62 3.3.1 The Valley of Stability................................ 64 3.3.2 Neutrinos, Leptons and Weak Force........................ 68 3.4 g-Decay...........................................
    [Show full text]
  • Two-Neutrino Double Electron Capture on 124Xe Based on an Effective
    Physics Letters B 797 (2019) 134885 Contents lists available at ScienceDirect Physics Letters B www.elsevier.com/locate/physletb 124 Two-neutrino double electron capture on Xe based on an effective theory and the nuclear shell model ∗ E.A. Coello Pérez a,b, , J. Menéndez c, A. Schwenk a,b,d a Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany b ExtreMe Matter Institute EMMI, Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany c Center for Nuclear Study, The University of Tokyo, Tokyo 113-0033, Japan d Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany a r t i c l e i n f o a b s t r a c t Article history: We study the two-neutrino double electron capture on 124Xe based on an effective theory (ET) and Received 22 March 2019 large-scale shell model calculations, two modern nuclear structure approaches that have been tested Received in revised form 31 July 2019 against Gamow-Teller and double-beta decay data. In the ET, the low-energy constants are fit to electron Accepted 21 August 2019 − capture and β transitions around xenon. For the nuclear shell model, we use an interaction in a large Available online 23 August 2019 configuration space that reproduces the spectroscopy of nuclei in this mass region. For the dominant Editor: J.-P. Blaizot 124 2νECEC = − × 22 transition to the Te ground state, we find half-lives T1/2 (1.3 18) 10 y for the ET and 2νECEC = − × 22 T1/2 (0.43 2.9) 10 y for the shell model.
    [Show full text]
  • Status and Perspectives of 2, + and 2+ Decays
    Review Status and Perspectives of 2e, eb+ and 2b+ Decays Pierluigi Belli 1,2,*,† , Rita Bernabei 1,2,*,† and Vincenzo Caracciolo 1,2,3,*,† 1 Istituto Nazionale di Fisica Nucleare (INFN), sezione di Roma “Tor Vergata”, I-00133 Rome, Italy 2 Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133 Rome, Italy 3 INFN, Laboratori Nazionali del Gran Sasso, I-67100 Assergi, Italy * Correspondence: [email protected] (P.B.); [email protected] (R.B.); [email protected] (V.C.) † These authors contributed equally to this work. Abstract: This paper reviews the main experimental techniques and the most significant results in the searches for the 2e, eb+ and 2b+ decay modes. Efforts related to the study of these decay modes are important, since they can potentially offer complementary information with respect to the cases of 2b− decays, which allow a better constraint of models for the nuclear structure calculations. Some positive results that have been claimed will be mentioned, and some new perspectives will be addressed shortly. Keywords: positive double beta decay; double electron capture; resonant effect; rare events; neutrino 1. Introduction The double beta decay (DBD) is a powerful tool for studying the nuclear instability, the electroweak interaction, the nature of the neutrinos, and physics beyond the Standard Model (SM) of Particle Physics. The theoretical interpretations of the double beta decay Citation: Belli, P.; Bernabei, R.; with the emission of two neutrinos is well described in the SM; the process is characterized Caracciolo, V. Status and Perspectives by a nuclear transition changing the atomic number Z of two units while leaving the atomic of 2e, eb+ and 2b+ Decays.
    [Show full text]
  • Search for Double Beta Decay of 106Cd with an Enriched 106 Cdwo4 Crystal Scintillator in Coincidence with Cdwo4 Scintillation Counters
    Article Search for double beta decay of 106Cd with an enriched 106 CdWO4 crystal scintillator in coincidence with CdWO4 scintillation counters P. Belli1,2 , R. Bernabei 1,2* , V.B. Brudanin3 , F. Cappella4,5 , V. Caracciolo1,2,6 , R. Cerulli1,2 , F.A. Danevich7 , A. Incicchitti4,5 , D.V. Kasperovych7 , V.R. Klavdiienko7 , V.V. Kobychev7 , V. Merlo1,2 ,O.G. Polischuk7 , V.I. Tretyak7 and M.M. Zarytskyy7 1 INFN, sezione di Roma “Tor Vergata”, I-00133 Rome, Italy 2 Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133 Rome, Italy 3 Joint Institute for Nuclear Research, 141980 Dubna, Russia 4 INFN, sezione Roma “La Sapienza”, I-00185 Rome, Italy 5 Dipartimento di Fisica, Università di Roma “La Sapienza”, I-00185 Rome, Italy 6 INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi (AQ), Italy 7 Institute for Nuclear Research of NASU, 03028 Kyiv, Ukraine * Correspondence: Dipartimento di Fisica, Università di Roma “Tor Vergata”, I-00133 Rome, Italy. E-mail address: [email protected] (Rita Bernabei) Received: date; Accepted: date; Published: date Abstract: Studies on double beta decay processes in 106Cd were performed by using a cadmium tungstate 106 106 scintillator enriched in Cd at 66% ( CdWO4) with two CdWO4 scintillation counters (with natural Cd composition). No effect was observed in the data accumulated over 26033 h. New improved half-life limits were set on the different channels and modes of the 106Cd double beta decay at level of 20 22 106 lim T1/2 ∼ 10 − 10 yr. The limit for the two neutrino electron capture with positron emission in Cd + 106 2nECb ≥ × 21 106 to the ground state of Pd, T1/2 2.1 10 yr, was set by the analysis of the CdWO4 data in coincidence with the energy release 511 keV in both CdWO4 counters.
    [Show full text]
  • Radioactivity
    AccessScience from McGraw-Hill Education Page 1 of 43 www.accessscience.com Radioactivity Contributed by: Joseph H. Hamilton Publication year: 2014 A phenomenon resulting from an instability of the atomic nucleus in certain atoms whereby the nucleus experiences a spontaneous but measurably delayed nuclear transition or transformation with the resulting emission of radiation. The discovery of radioactivity by Henri Becquerel in 1896 was an indirect consequence of the discovery of x-rays a few months earlier by Wilhelm Roentgen, and marked the birth of nuclear physics. See also: X-RAYS. On the other hand, nuclear physics can also be said to begin with the proposal by Ernest Rutherford in 1911 that atoms have a nucleus. On the basis of the scattering of alpha particles (emitted in radioactive decay) by gold foils, Rutherford proposed a solar model of atoms, where negatively charged electrons orbit the tiny nucleus, which contains all the positive charge and essentially all the mass of the atom, as planets orbit around the Sun. The attractive Coulomb electrical force holds the electrons in orbit about the nucleus. Atoms have radii of about 10,−10 m and the nuclei of atoms have radii about 2 × 10,−15 m, so atoms are mostly empty space, like the solar system. Niels Bohr proposed a theoretical model for the atom that removed certain difficulties of the Rutherford model. See also: ATOMIC STRUCTURE AND SPECTRA. However, it was only after the discovery of the neutron in 1932 that a proper understanding was achieved of the particles that compose the nucleus of the atom.
    [Show full text]