The R-Process Nucleosynthesis and Related Challenges
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Nuclear Physics
Nuclear Physics Overview One of the enduring mysteries of the universe is the nature of matter—what are its basic constituents and how do they interact to form the properties we observe? The largest contribution by far to the mass of the visible matter we are familiar with comes from protons and heavier nuclei. The mission of the Nuclear Physics (NP) program is to discover, explore, and understand all forms of nuclear matter. Although the fundamental particles that compose nuclear matter—quarks and gluons—are themselves relatively well understood, exactly how they interact and combine to form the different types of matter observed in the universe today and during its evolution remains largely unknown. Nuclear physicists seek to understand not just the familiar forms of matter we see around us, but also exotic forms such as those that existed in the first moments after the Big Bang and that exist today inside neutron stars, and to understand why matter takes on the specific forms now observed in nature. Nuclear physics addresses three broad, yet tightly interrelated, scientific thrusts: Quantum Chromodynamics (QCD); Nuclei and Nuclear Astrophysics; and Fundamental Symmetries: . QCD seeks to develop a complete understanding of how the fundamental particles that compose nuclear matter, the quarks and gluons, assemble themselves into composite nuclear particles such as protons and neutrons, how nuclear forces arise between these composite particles that lead to nuclei, and how novel forms of bulk, strongly interacting matter behave, such as the quark-gluon plasma that formed in the early universe. Nuclei and Nuclear Astrophysics seeks to understand how protons and neutrons combine to form atomic nuclei, including some now being observed for the first time, and how these nuclei have arisen during the 13.8 billion years since the birth of the cosmos. -
Status and Perspectives of the Neutron Time-Of-Flight Facility N TOF at CERN
Status and perspectives of the neutron time-of-flight facility n_TOF at CERN E. Chiaveri on behalf of the n_TOF Collaboration ([email protected]) Since the start of its operation in 2001, based on an idea of Prof. Carlo Rubbia[1], the neutron time-of-flight facility of CERN, n_TOF, has become one of the most forefront neutron facilities in the world for wide-energy spectrum neutron cross section measurements. Thanks to the combination of excellent neutron energy resolution and high instantaneous neutron flux available in the two experimental areas, the second of which has been constructed in 2014, n_TOF is providing a wealth of new data on neutron-induced reactions of interest for nuclear astrophysics, advanced nuclear technologies and medical applications. The unique features of the facility will continue to be exploited in the future, to perform challenging new measurements addressing the still open issues and long-standing quests in the field of neutron physics. In this document the main characteristics of the n_TOF facility and their relevance for neutron studies in the different areas of research will be outlined, addressing the possible future contribution of n_TOF in the fields of nuclear astrophysics, nuclear technologies and medical applications. In addition, the future perspectives of the facility will be described including the upgrade of the spallation target. 1 Introduction Neutron-induced reactions play a fundamental role for a number of research fields, from the origin of chemical elements in stars, to basic nuclear physics, to applications in advanced nuclear technology for energy, dosimetry, medicine and space science [1]. Thanks to the time-of-flight technique coupled with the characteristics of the CERN n_TOF beam-lines and neutron source, reaction cross-sections can be measured with a very high energy-resolution and in a broad neutron energy range from thermal up to GeV. -
Photofission Cross Sections of 238U and 235U from 5.0 Mev to 8.0 Mev Robert Andrew Anderl Iowa State University
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1972 Photofission cross sections of 238U and 235U from 5.0 MeV to 8.0 MeV Robert Andrew Anderl Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Nuclear Commons, and the Oil, Gas, and Energy Commons Recommended Citation Anderl, Robert Andrew, "Photofission cross sections of 238U and 235U from 5.0 MeV to 8.0 MeV " (1972). Retrospective Theses and Dissertations. 4715. https://lib.dr.iastate.edu/rtd/4715 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This dissertation was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction, 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity, 2. -
White Paper on Nuclear Astrophysics and Low Energy Nuclear Physics
WHITE PAPER ON NUCLEAR ASTROPHYSICS AND LOW ENERGY NUCLEAR PHYSICS PART 1: NUCLEAR ASTROPHYSICS FEBRUARY 2016 NUCLEAR ASTROPHYSICS & LOW ENERGY NUCLEAR PHYSICS 1 Edited by: Hendrik Schatz and Michael Wiescher Layout and design: Erin O’Donnell, NSCL, Michigan State University Individual sections have been edited by the section conveners: Almudena Arcones, Dan Bardayan, Lee Bernstein, Jeffrey Blackmon, Edward Brown, Carl Brune, Art Champagne, Alessandro Chieffi, Aaron Couture, Roland Diehl, Jutta Escher, Brian Fields, Carla Froehlich, Falk Herwig, Raphael Hix, Christian Iliadis, Bill Lynch, Gail McLaughlin, Bronson Messer, Bradley Meyer, Filomena Nunes, Brian O'Shea, Madappa Prakash, Boris Pritychenko, Sanjay Reddy, Ernst Rehm, Grisha Rogachev, Bob Ruthledge, Michael Smith, Andrew Steiner, Tod Strohmayer, Frank Timmes, Remco Zegers, Mike Zingale NUCLEAR ASTROPHYSICS & LOW ENERGY NUCLEAR PHYSICS 2 ABSTRACT This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21-23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town meeting of the nuclear astrophysics community organized by the Joint Institute for Nuclear Astrophysics (JINA) on October 9- 10, 2012 Detroit, Michigan, with the purpose of developing a vision for nuclear astrophysics in light of the recent NRC decadal surveys in nuclear physics (NP2010) and astronomy (ASTRO2010). The white paper is furthermore informed by the town meeting of the Association of Research at University Nuclear Accelerators (ARUNA) that took place at the University of Notre Dame on June 12-13, 2014. -
R-Process: Observations, Theory, Experiment
r-process: observations, theory, experiment H. Schatz Michigan State University National Superconducting Cyclotron Laboratory Joint Institute for Nuclear Astrophysics 1. Observations: do we need s,r,p-process and LEPP? 2. r-process (and LEPP?) models 3. r-process experiments SNR 0103-72.6 Credit: NASA/CXC/PSU/S.Park et al. Origin of the heavy elements in the solar system s-process: secondary • nuclei can be studied Æ reliable calculations • site identified • understood? Not quite … r-process: primary • most nuclei out of reach • site unknown p-process: secondary (except for νp-process) Æ Look for metal poor`stars (Pagel, Fig 6.8) To learn about the r-process Heavy elements in Metal Poor Halo Stars CS22892-052 (Sneden et al. 2003, Cowan) 2 1 + solar r CS 22892-052 ) H / X CS22892-052 ( g o red (K) giant oldl stars - formed before e located in halo Galaxyc was mixed n distance: 4.7 kpc theya preserve local d mass ~0.8 M_sol n pollutionu from individual b [Fe/H]= −3.0 nucleosynthesisa events [Dy/Fe]= +1.7 recall: element number[X/Y]=log(X/Y)-log(X/Y)solar What does it mean: for heavy r-process? For light r-process? • stellar abundances show r-process • process is not universal • process is universal • or second process exists (not visible in this star) Conclusions depend on s-process Look at residuals: Star – solar r Solar – s-process – p-process s-processSimmerer from Simmerer (Cowan et etal.) al. /Lodders (Cowan et al.) s-processTravaglio/Lodders from Travaglio et al. -0.50 -0.50 -1.00 -1.00 -1.50 -1.50 log e log e -2.00 -2.00 -2.50 -2.50 30 40 50 60 70 80 90 30 40 50 60 70 80 90 Element number Element number ÆÆNeedNeed reliable reliable s-process s-process (models (models and and nu nuclearclear data, data, incl. -
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. -
1 Lecture Notes in Nuclear Structure Physics B. Alex Brown November
1 Lecture Notes in Nuclear Structure Physics B. Alex Brown November 2005 National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy Michigan State University, E. Lansing, MI 48824 CONTENTS 2 Contents 1 Nuclear masses 6 1.1 Masses and binding energies . 6 1.2 Q valuesandseparationenergies . 10 1.3 Theliquid-dropmodel .......................... 18 2 Rms charge radii 25 3 Charge densities and form factors 31 4 Overview of nuclear decays 40 4.1 Decaywidthsandlifetimes. 41 4.2 Alphaandclusterdecay ......................... 42 4.3 Betadecay................................. 51 4.3.1 BetadecayQvalues ....................... 52 4.3.2 Allowedbetadecay ........................ 53 4.3.3 Phase-space for allowed beta decay . 57 4.3.4 Weak-interaction coupling constants . 59 4.3.5 Doublebetadecay ........................ 59 4.4 Gammadecay............................... 61 4.4.1 Reduced transition probabilities for gamma decay . .... 62 4.4.2 Weisskopf units for gamma decay . 65 5 The Fermi gas model 68 6 Overview of the nuclear shell model 71 7 The one-body potential 77 7.1 Generalproperties ............................ 77 7.2 Theharmonic-oscillatorpotential . ... 79 7.3 Separation of intrinsic and center-of-mass motion . ....... 81 7.3.1 Thekineticenergy ........................ 81 7.3.2 Theharmonic-oscillator . 83 8 The Woods-Saxon potential 87 8.1 Generalform ............................... 87 8.2 Computer program for the Woods-Saxon potential . .... 91 8.2.1 Exampleforboundstates . 92 8.2.2 Changingthepotentialparameters . 93 8.2.3 Widthofanunboundstateresonance . 94 8.2.4 Width of an unbound state resonance at a fixed energy . 95 9 The general many-body problem for fermions 97 CONTENTS 3 10 Conserved quantum numbers 101 10.1 Angularmomentum. 101 10.2Parity .................................. -
Star Factories: Nuclear Fusion and the Creation of the Elements
Star Factories: Nuclear Fusion and the Creation of the Elements Science In the River City workshop 3/22/11 Chris Taylor Department of Physics and Astronomy Sacramento State Introductions! Science Content Standards, Grades 9 - 12 Earth Sciences: Earth's Place in the Universe 1.e ''Students know the Sun is a typical star and is powered by nuclear reactions, primarily the fusion of hydrogen to form helium.'' 2.c '' Students know the evidence indicating that all elements with an atomic number greater than that of lithium have been formed by nuclear fusion in stars.'' Three topics tonight: 1) how do we know all the heavier elements are made in stars? (Big Bang theory) 2) How do stars make elements as heavy as or less heavy than iron? (Stellar nucleosynthesis) 3) How do stars make elements heavier than iron? (Supernovae) Big Bang Nucleosynthesis The Big Bang theory predicts that when the universe first formed, the only matter that existed was hydrogen, helium, and very tiny amounts of lithium. If this is true, then all other elements must have been created in stars. Astronomers use spectroscopy to examine the light emitted by distant stars to determine what kinds of atoms are in them. We've learned that most stars contain nearly every element in the periodic table. The spectrum of the Sun In order to measure measure what kinds of atoms were around in the earliest days of the Universe, we look for stars that were made out of fresh, primordial gas. The closest we can get to this is looking at dwarf galaxies, which show extremely low levels of elements heavier than helium. -
Arxiv:1901.01410V3 [Astro-Ph.HE] 1 Feb 2021 Mental Information Is Available, and One Has to Rely Strongly on Theoretical Predictions for Nuclear Properties
Origin of the heaviest elements: The rapid neutron-capture process John J. Cowan∗ HLD Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019, USA Christopher Snedeny Department of Astronomy, University of Texas, 2515 Speedway, Austin, TX 78712-1205, USA James E. Lawlerz Physics Department, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706-1390, USA Ani Aprahamianx and Michael Wiescher{ Department of Physics and Joint Institute for Nuclear Astrophysics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556, USA Karlheinz Langanke∗∗ GSI Helmholtzzentrum f¨urSchwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany and Institut f¨urKernphysik (Theoriezentrum), Fachbereich Physik, Technische Universit¨atDarmstadt, Schlossgartenstraße 2, 64298 Darmstadt, Germany Gabriel Mart´ınez-Pinedoyy GSI Helmholtzzentrum f¨urSchwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany; Institut f¨urKernphysik (Theoriezentrum), Fachbereich Physik, Technische Universit¨atDarmstadt, Schlossgartenstraße 2, 64298 Darmstadt, Germany; and Helmholtz Forschungsakademie Hessen f¨urFAIR, GSI Helmholtzzentrum f¨urSchwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany Friedrich-Karl Thielemannzz Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland and GSI Helmholtzzentrum f¨urSchwerionenforschung, Planckstraße 1, 64291 Darmstadt, Germany (Dated: February 2, 2021) The production of about half of the heavy elements found in nature is assigned to a spe- cific astrophysical nucleosynthesis process: the rapid neutron capture process (r-process). Although this idea has been postulated more than six decades ago, the full understand- ing faces two types of uncertainties/open questions: (a) The nucleosynthesis path in the nuclear chart runs close to the neutron-drip line, where presently only limited experi- arXiv:1901.01410v3 [astro-ph.HE] 1 Feb 2021 mental information is available, and one has to rely strongly on theoretical predictions for nuclear properties. -
Heavy Element Nucleosynthesis
Heavy Element Nucleosynthesis A summary of the nucleosynthesis of light elements is as follows 4He Hydrogen burning 3He Incomplete PP chain (H burning) 2H, Li, Be, B Non-thermal processes (spallation) 14N, 13C, 15N, 17O CNO processing 12C, 16O Helium burning 18O, 22Ne α captures on 14N (He burning) 20Ne, Na, Mg, Al, 28Si Partly from carbon burning Mg, Al, Si, P, S Partly from oxygen burning Ar, Ca, Ti, Cr, Fe, Ni Partly from silicon burning Isotopes heavier than iron (as well as some intermediate weight iso- topes) are made through neutron captures. Recall that the prob- ability for a non-resonant reaction contained two components: an exponential reflective of the quantum tunneling needed to overcome electrostatic repulsion, and an inverse energy dependence arising from the de Broglie wavelength of the particles. For neutron cap- tures, there is no electrostatic repulsion, and, in complex nuclei, virtually all particle encounters involve resonances. As a result, neutron capture cross-sections are large, and are very nearly inde- pendent of energy. To appreciate how heavy elements can be built up, we must first consider the lifetime of an isotope against neutron capture. If the cross-section for neutron capture is independent of energy, then the lifetime of the species will be ( )1=2 1 1 1 µn τn = ≈ = Nnhσvi NnhσivT Nnhσi 2kT For a typical neutron cross-section of hσi ∼ 10−25 cm2 and a tem- 8 9 perature of 5 × 10 K, τn ∼ 10 =Nn years. Next consider the stability of a neutron rich isotope. If the ratio of of neutrons to protons in an atomic nucleus becomes too large, the nucleus becomes unstable to beta-decay, and a neutron is changed into a proton via − (Z; A+1) −! (Z+1;A+1) + e +ν ¯e (27:1) The timescale for this decay is typically on the order of hours, or ∼ 10−3 years (with a factor of ∼ 103 scatter). -
Investigations of Nuclear Decay Half-Lives Relevant to Nuclear Astrophysics
DE TTK 1949 Investigations of nuclear decay half-lives relevant to nuclear astrophysics PhD Thesis Egyetemi doktori (PhD) ´ertekez´es J´anos Farkas Supervisor / T´emavezet˝o Dr. Zsolt F¨ul¨op University of Debrecen PhD School in Physics Debreceni Egyetem Term´eszettudom´anyi Doktori Tan´acs Fizikai Tudom´anyok Doktori Iskol´aja Debrecen 2011 Prepared at the University of Debrecen PhD School in Physics and the Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI) K´esz¨ult a Debreceni Egyetem Fizikai Tudom´anyok Doktori Iskol´aj´anak magfizikai programja keret´eben a Magyar Tudom´anyos Akad´emia Atommagkutat´o Int´ezet´eben (ATOMKI) Ezen ´ertekez´est a Debreceni Egyetem Term´eszettudom´anyi Doktori Tan´acs Fizikai Tudom´anyok Doktori Iskol´aja magfizika programja keret´eben k´esz´ıtettem a Debreceni Egyetem term´eszettudom´anyi doktori (PhD) fokozat´anak elnyer´ese c´elj´ab´ol. Debrecen, 2011. Farkas J´anos Tan´us´ıtom, hogy Farkas J´anos doktorjel¨olt a 2010/11-es tan´evben a fent megnevezett doktori iskola magfizika programj´anak keret´eben ir´any´ıt´asommal v´egezte munk´aj´at. Az ´ertekez´esben foglalt eredm´e- nyekhez a jel¨olt ¨on´all´oalkot´otev´ekenys´eg´evel meghat´aroz´oan hozz´a- j´arult. Az ´ertekez´es elfogad´as´at javaslom. Debrecen, 2011. Dr. F¨ul¨op Zsolt t´emavezet˝o Investigations of nuclear decay half-lives relevant to nuclear astrophysics Ertekez´es´ a doktori (PhD) fokozat megszerz´ese ´erdek´eben a fizika tudom´any´agban ´Irta: Farkas J´anos, okleveles fizikus ´es programtervez˝omatematikus K´esz¨ult a Debreceni Egyetem Fizikai Tudom´anyok Doktori Iskol´aja magfizika programja keret´eben T´emavezet˝o: Dr. -
Sensitivity of Type Ia Supernovae to Electron Capture Rates E
A&A 624, A139 (2019) Astronomy https://doi.org/10.1051/0004-6361/201935095 & c ESO 2019 Astrophysics Sensitivity of Type Ia supernovae to electron capture rates E. Bravo E.T.S. Arquitectura del Vallès, Universitat Politècnica de Catalunya, Carrer Pere Serra 1-15, 08173 Sant Cugat del Vallès, Spain e-mail: [email protected] Received 22 January 2019 / Accepted 8 March 2019 ABSTRACT The thermonuclear explosion of massive white dwarfs is believed to explain at least a fraction of Type Ia supernovae (SNIa). After thermal runaway, electron captures on the ashes left behind by the burning front determine a loss of pressure, which impacts the dynamics of the explosion and the neutron excess of matter. Indeed, overproduction of neutron-rich species such as 54Cr has been deemed a problem of Chandrasekhar-mass models of SNIa for a long time. I present the results of a sensitivity study of SNIa models to the rates of weak interactions, which have been incorporated directly into the hydrodynamic explosion code. The weak rates have been scaled up or down by a factor ten, either globally for a common bibliographical source, or individually for selected isotopes. In line with previous works, the impact of weak rates uncertainties on sub-Chandrasekhar models of SNIa is almost negligible. The impact on the dynamics of Chandrasekhar-mass models and on the yield of 56Ni is also scarce. The strongest effect is found on the nucleosynthesis of neutron-rich nuclei, such as 48Ca, 54Cr, 58Fe, and 64Ni. The species with the highest influence on nucleosynthesis do not coincide with the isotopes that contribute most to the neutronization of matter.