Independent Yields of Kr and Хе Fragments in the Photofission Of
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Spontaneous Fission of U234, Pu236, Cm240, and Cm244
Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory Title Spontaneous Fission of U234, Pu236, Cm240, and Cm244 Permalink https://escholarship.org/uc/item/0df1j1qm Authors Ghiorso, A. Higgins, G.H. Larsh, A.E. et al. Publication Date 1952-04-21 eScholarship.org Powered by the California Digital Library University of California TWO-WEEK LOAN COPY This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention copy, call Tech. Info. Division, Ext. 5545 UCRL-1772 Unclassified-Chemistry Distribution UNIVEBSITY OF CALIFCEiNIil Radiation Laboratory Contract No, ti-7405-eng-4.8 24.4 SPONTANEOUS FISSION OF' I'Zu6, ~m~~~~ AND Gm A, Ghiorso, G. H, Higgins, A. E. Larsh, Go To Seaborg, and So G, Thompson April 21, 1752 Berkeley, California A. Ghiorso, G. H. Higgins, A. E. Larsh, G. T. Seaborg, and S. Go Thompson Radiation Laboratory and Department of Chemistry Uni versity of California, Berkeley, Californf a April 21, 1952 In a recent communication commenting on the mechanism of fission we called attention to the simple exponential dependence of spontaneous fission rate on Z~/Aand to the effect of an odd nucleon in slowing the fission process.1 Since it is of interest to test further the simple correlation of the spontaneous fission rate for even-even nuclides wfth z~/A~a further number of such rates have been determined, The spontaneous fission rates were measured by pladng the chemically purified samples on one electrode of a parallel plate ionization chamber, filled with a mixture of argon and carbon dioxide, which was connected with an amplifier f ollawed by a register and a stylus recorder. -
Computing ATOMIC NUCLEI
UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL Computing ATOMIC NUCLEI Petascale computing helps disentangle the nuclear puzzle. The goal of the Universal Nuclear Energy Density Functional (UNEDF) collaboration is to provide a comprehensive description of all nuclei and their reactions based on the most accurate knowledge of the nuclear interaction, the most reliable theoretical approaches, and the massive use of computer power. Science of Nuclei the Hamiltonian matrix. Coupled cluster (CC) Nuclei comprise 99.9% of all baryonic matter in techniques, which were formulated by nuclear sci- the Universe and are the fuel that burns in stars. entists in the 1950s, are essential techniques in The rather complex nature of the nuclear forces chemistry today and have recently been resurgent among protons and neutrons generates a broad in nuclear structure. Quantum Monte Carlo tech- range and diversity in the nuclear phenomena that niques dominate studies of phase transitions in can be observed. As shown during the last decade, spin systems and nuclei. These methods are used developing a comprehensive description of all to understand both the nuclear and electronic nuclei and their reactions requires theoretical and equations of state in condensed systems, and they experimental investigations of rare isotopes with are used to investigate the excitation spectra in unusual neutron-to-proton ratios. These nuclei nuclei, atoms, and molecules. are labeled exotic, or rare, because they are not When applied to systems with many active par- typically found on Earth. They are difficult to pro- ticles, ab initio and configuration interaction duce experimentally because they usually have methods present computational challenges as the extremely short lifetimes. -
CHEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky
CHEM 1412. Chapter 21. Nuclear Chemistry (Homework) Ky Multiple Choice Identify the choice that best completes the statement or answers the question. ____ 1. Consider the following statements about the nucleus. Which of these statements is false? a. The nucleus is a sizable fraction of the total volume of the atom. b. Neutrons and protons together constitute the nucleus. c. Nearly all the mass of an atom resides in the nucleus. d. The nuclei of all elements have approximately the same density. e. Electrons occupy essentially empty space around the nucleus. ____ 2. A term that is used to describe (only) different nuclear forms of the same element is: a. isotopes b. nucleons c. shells d. nuclei e. nuclides ____ 3. Which statement concerning stable nuclides and/or the "magic numbers" (such as 2, 8, 20, 28, 50, 82 or 128) is false? a. Nuclides with their number of neutrons equal to a "magic number" are especially stable. b. The existence of "magic numbers" suggests an energy level (shell) model for the nucleus. c. Nuclides with the sum of the numbers of their protons and neutrons equal to a "magic number" are especially stable. d. Above atomic number 20, the most stable nuclides have more protons than neutrons. e. Nuclides with their number of protons equal to a "magic number" are especially stable. ____ 4. The difference between the sum of the masses of the electrons, protons and neutrons of an atom (calculated mass) and the actual measured mass of the atom is called the ____. a. isotopic mass b. -
Decay Modes of Uranium in the Range 203 <A<299
Indian Journal of Pure & Applied Physics Vol. 58, April 2020, pp. 234-240 Decay modes of Uranium in the range 203 <A<299 H C Manjunathaa*, G R Sridharb,c, P S Damodara Guptab, K N Sridharb, M G Srinivasd & H B Ramalingame aDepartment of Physics, Government College for Women, Kolar 563 101, India bDepartment of Physics, Government First Grade College, Kolar 563 101, India cResearch and Development Centre, Bharathiar University, Coimbatore 641 046, India dDepartment of Physics, Government First Grade College, Mulbagal 563 131, India eDepartment of Physics, Government Arts College, Udumalpet 642 126, India Received 17 February 2020 In the present work, we have considered the total potential as the sum of the coulomb and proximity potential. We have used the recent proximity function to calculate the nuclear potential. The calculated logarithmic half-lives correspond to fission, cluster and alpha decay are compared with that of experiments. We also identified the most probable decay mode by studying branching ratios of these different decay modes. The competition between different decay modes such as fission, cluster radioactivity and alpha decay finds an important role in nuclear structure. Keywords: Nuclear potential, Cluster radioactivity, Alpha decay, Spontaneous fission 1 Introduction Parkhomenko et al.18 studied the alpha decay It is important to study the alpha decay properties properties for odd mass number superheavy nuclei. of superheavy nuclei. Most of the superheavy nuclei Poenaru et al.19 improved the formula for alpha decay are identified through alpha decay process only. halflives around magic numbers by using the SemFIS Many researchers in the nuclear physics field formula. -
Neutrinoless Double Beta Decay
REPORT TO THE NUCLEAR SCIENCE ADVISORY COMMITTEE Neutrinoless Double Beta Decay NOVEMBER 18, 2015 NLDBD Report November 18, 2015 EXECUTIVE SUMMARY In March 2015, DOE and NSF charged NSAC Subcommittee on neutrinoless double beta decay (NLDBD) to provide additional guidance related to the development of next generation experimentation for this field. The new charge (Appendix A) requests a status report on the existing efforts in this subfield, along with an assessment of the necessary R&D required for each candidate technology before a future downselect. The Subcommittee membership was augmented to replace several members who were not able to continue in this phase (the present Subcommittee membership is attached as Appendix B). The Subcommittee solicited additional written input from the present worldwide collaborative efforts on double beta decay projects in order to collect the information necessary to address the new charge. An open meeting was held where these collaborations were invited to present material related to their current projects, conceptual designs for next generation experiments, and the critical R&D required before a potential down-select. We also heard presentations related to nuclear theory and the impact of future cosmological data on the subject of NLDBD. The Subcommittee presented its principal findings and comments in response to the March 2015 charge at the NSAC meeting in October 2015. The March 2015 charge requested the Subcommittee to: Assess the status of ongoing R&D for NLDBD candidate technology demonstrations for a possible future ton-scale NLDBD experiment. For each candidate technology demonstration, identify the major remaining R&D tasks needed ONLY to demonstrate downselect criteria, including the sensitivity goals, outlined in the NSAC report of May 2014. -
RIB Production by Photofission in the Framework of the ALTO Project
Available online at www.sciencedirect.com NIM B Beam Interactions with Materials & Atoms Nuclear Instruments and Methods in Physics Research B 266 (2008) 4092–4096 www.elsevier.com/locate/nimb RIB production by photofission in the framework of the ALTO project: First experimental measurements and Monte-Carlo simulations M. Cheikh Mhamed *, S. Essabaa, C. Lau, M. Lebois, B. Roussie`re, M. Ducourtieux, S. Franchoo, D. Guillemaud Mueller, F. Ibrahim, J.F. LeDu, J. Lesrel, A.C. Mueller, M. Raynaud, A. Said, D. Verney, S. Wurth Institut de Physique Nucle´aire, IN2P3-CNRS/Universite´ Paris-Sud, F-91406 Orsay Cedex, France Available online 11 June 2008 Abstract The ALTO facility (Acce´le´rateur Line´aire aupre`s du Tandem d’Orsay) has been built and is now under commissioning. The facility is intended for the production of low energy neutron-rich ion-beams by ISOL technique. This will open new perspectives in the study of nuclei very far from the valley of stability. Neutron-rich nuclei are produced by photofission in a thick uranium carbide target (UCx) using a 10 lA, 50 MeV electron beam. The target is the same as that already had been used on the previous deuteron based fission ISOL setup (PARRNE [F. Clapier et al., Phys. Rev. ST-AB (1998) 013501.]). The intended nominal fission rate is about 1011 fissions/s. We have studied the adequacy of a thick carbide uranium target to produce neutron-rich nuclei by photofission by means of Monte-Carlo simulations. We present the production rates in the target and after extraction and mass separation steps. -
Spontaneous Fission Half-Lives of Heavy and Superheavy Nuclei Within a Generalized Liquid Drop Model
Spontaneous fission half-lives of heavy and superheavy nuclei within a generalized liquid drop model Xiaojun Bao1, Hongfei Zhang1,∗ G. Royer2, Junqing Li1,3 June 4, 2018 1. School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China 2. Laboratoire Subatech, UMR: IN2P3/CNRS-Universit´e-Ecole des Mines, 4 rue A. Kastler, 44 Nantes, France 3. Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000, China Abstract We systematically calculate the spontaneous fission half-lives for heavy and superheavy arXiv:1302.7117v1 [nucl-th] 28 Feb 2013 nuclei between U and Fl isotopes. The spontaneous fission process is studied within the semi-empirical WKB approximation. The potential barrier is obtained using a generalized liquid drop model, taking into account the nuclear proximity, the mass asymmetry, the phenomenological pairing correction, and the microscopic shell cor- rection. Macroscopic inertial-mass function has been employed for the calculation of the fission half-life. The results reproduce rather well the experimental data. Rela- tively long half-lives are predicted for many unknown nuclei, sufficient to detect them if synthesized in a laboratory. Keywords: heavy and superheavy nuclei; half-lives; spontaneous fission ∗Corresponding author. Tel.: +86 931 8622306. E-mail address: [email protected] 1 1 Introduction Spontaneous fission of heavy nuclei was first predicted by Bohr and Wheeler in 1939 [1]. Their fission theory was based on the liquid drop model. Interestingly, their work also con- tained an estimate of a lifetime for fission from the ground state. Soon afterwards, Flerov and Petrzak [2] presented the first experimental evidence for spontaneous fission. -
Chapter 3 the Fundamentals of Nuclear Physics Outline Natural
Outline Chapter 3 The Fundamentals of Nuclear • Terms: activity, half life, average life • Nuclear disintegration schemes Physics • Parent-daughter relationships Radiation Dosimetry I • Activation of isotopes Text: H.E Johns and J.R. Cunningham, The physics of radiology, 4th ed. http://www.utoledo.edu/med/depts/radther Natural radioactivity Activity • Activity – number of disintegrations per unit time; • Particles inside a nucleus are in constant motion; directly proportional to the number of atoms can escape if acquire enough energy present • Most lighter atoms with Z<82 (lead) have at least N Average one stable isotope t / ta A N N0e lifetime • All atoms with Z > 82 are radioactive and t disintegrate until a stable isotope is formed ta= 1.44 th • Artificial radioactivity: nucleus can be made A N e0.693t / th A 2t / th unstable upon bombardment with neutrons, high 0 0 Half-life energy protons, etc. • Units: Bq = 1/s, Ci=3.7x 1010 Bq Activity Activity Emitted radiation 1 Example 1 Example 1A • A prostate implant has a half-life of 17 days. • A prostate implant has a half-life of 17 days. If the What percent of the dose is delivered in the first initial dose rate is 10cGy/h, what is the total dose day? N N delivered? t /th t 2 or e Dtotal D0tavg N0 N0 A. 0.5 A. 9 0.693t 0.693t B. 2 t /th 1/17 t 2 2 0.96 B. 29 D D e th dt D h e th C. 4 total 0 0 0.693 0.693t /th 0.6931/17 C. -
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. -
1 PROF. CHHANDA SAMANTA, Phd PAPERS in PEER REVIEWED INTERNATIONAL JOURNALS: 1. C. Samanta, T. A. Schmitt, “Binding, Bonding A
PROF. CHHANDA SAMANTA, PhD PAPERS IN PEER REVIEWED INTERNATIONAL JOURNALS: 1. C. Samanta, T. A. Schmitt, “Binding, bonding and charge symmetry breaking in Λ- hypernuclei”, arXiv:1710.08036v2 [nucl-th] (to be published) 2. T. A. Schmitt, C. Samanta, “A-dependence of -bond and charge symmetry energies”, EPJ Web Conf. 182, 03012 (2018) 3. Chhanda Samanta, Superheavy Nuclei to Hypernuclei: A Tribute to Walter Greiner, EPJ Web Conf. 182, 02107 (2018) 4. C. Samanta with X Qiu, L Tang, C Chen, et al., “Direct measurements of the lifetime of medium-heavy hypernuclei”, Nucl. Phys. A973, 116 (2018); arXiv:1212.1133 [nucl-ex] 5. C. Samanta with with S. Mukhopadhyay, D. Atta, K. Imam, D. N. Basu, “Static and rotating hadronic stars mixed with self-interacting fermionic Asymmetric Dark Matter”, The European Physical Journal C.77:440 (2017); arXiv:1612.07093v1 6. C. Samanta with R. Honda, M. Agnello, J. K. Ahn et al, “Missing-mass spectroscopy with 6 − + 6 the Li(π ,K )X reaction to search for ΛH”, Phys. Rev. C 96, 014005 (2017); arXiv:1703.00623v2 [nucl-ex] 7. C. Samanta with T. Gogami, C. Chen, D. Kawama et al., “Spectroscopy of the neutron-rich 7 hypernucleus He from electron scattering”, Phys. Rev. C94, 021302(R) (2016); arXiv:1606.09157 8. C. Samanta with T. Gogami, C. Chen, D. Kawama,et al., ”High Resolution Spectroscopic 10 Study of ΛBe”, Phys. Rev. C93, 034314(2016); arXiv:1511.04801v1[nucl-ex] 9. C. Samanta with L. Tang, C. Chen, T. Gogami et al., “The experiments with the High 12 Resolution Kaon Spectrometer at JLab Hall C and the new spectroscopy of ΛB hypernuclei, Phys. -
Cold Reaction Valleys in the Radioactive Decay of Superheavy 286 112, 292 114 and 296 116 Nuclei
COLD REACTION VALLEYS IN THE RADIOACTIVE DECAY OF SUPERHEAVY 286 112, 292 114 AND 296 116 NUCLEI K. P. Santhosh, S. Sabina School of Pure and Applied Physics, Kannur University, Payyanur Campus, India Cold reaction valleys in the radioactive decay of superheavy nuclei 286 112, 292 114 and 296 116 are studied taking Coulomb and Proximity Potential as the interacting barrier. It is found that in addition to alpha particle, 8Be, 14 C, 28 Mg, 34 Si, 50 Ca, etc. are optimal cases of cluster radioactivity since they lie in the cold valleys. Two other regions of deep minima centered on 208 Pb and 132 Sn are also found. Within our Coulomb and Proximity Potential Model half-life times and other characteristics such as barrier penetrability, decay constant for clusters ranging from alpha particle to 68 Ni are calculated. The computed alpha half-lives match with the values calculated using Viola--Seaborg-- Sobiczewski systematics. The clusters 8Be and 14 C are found to be most probable for 30 emission with T1/2 < 10 s. The alpha-decay chains of the three superheavy nuclei are also studied. The computed alpha decay half-lives are compared with the values predicted by Generalized Liquid Drop Model and they are found to match reasonably well. 1. INTRODUCTION Generally radioactive nuclei decay through alpha and beta decay with subsequent emission of gamma rays in many cases. Again since 1939 it is well known that many radioactive nuclei also decay through spontaneous fission. In 1980 a new type of decay known as cluster radioactivity was predicted by Sandulescu et al. -
Current Status of Equation of State in Nuclear Matter and Neutron Stars
Open Issues in Understanding Core Collapse Supernovae June 22-24, 2004 Current Status of Equation of State in Nuclear Matter and Neutron Stars J.R.Stone1,2, J.C. Miller1,3 and W.G.Newton1 1 Oxford University, Oxford, UK 2Physics Division, ORNL, Oak Ridge, TN 3 SISSA, Trieste, Italy Outline 1. General properties of EOS in nuclear matter 2. Classification according to models of N-N interaction 3. Examples of EOS – sensitivity to the choice of N-N interaction 4. Consequences for supernova simulations 5. Constraints on EOS 6. High density nuclear matter (HDNM) 7. New developments Equation of State is derived from a known dependence of energy per particle of a system on particle number density: EA/(==En) or F/AF(n) I. E ( or Boltzman free energy F = E-TS for system at finite temperature) is constructed in a form of effective energy functional (Hamiltonian, Lagrangian, DFT/EFT functional or an empirical form) II. An equilibrium state of matter is found at each density n by minimization of E (n) or F (n) III. All other related quantities like e.g. pressure P, incompressibility K or entropy s are calculated as derivatives of E or F at equilibrium: 2 ∂E ()n ∂F ()n Pn()= n sn()=− | ∂n ∂T nY, p ∂∂P()nnEE() ∂2 ()n Kn()==9 18n +9n2 ∂∂nn∂n2 IV. Use as input for model simulations (Very) schematic sequence of equilibrium phases of nuclear matter as a function of density: <~2x10-4fm-3 ~2x10-4 fm-3 ~0.06 fm-3 Nuclei in Nuclei in Neutron electron gas + ‘Pasta phase’ Electron gas ~0.1 fm-3 0.3-0.5 fm-3 >0.5 fm-3 Nucleons + n,p,e,µ heavy baryons Quarks ???