DOCSLIB.ORG

Calibration of the Production Rates of Cosmogenic 36C1 from Potassium

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

CALIBRATION OF THE PRODUCTION RATES OF COSMOGENIC 36C1 FROM POTASSIUM Jodie Manderson Evans A thesis submitted for the degree of Doctor of Philosophy at The Australian National University July, 2001 daran and Heather Preface This thesis describes the complete calibration of J6C1 produced in-situ from potassium. This project was suggested by Dr John Stone and Dr Keith Fifield, and carried out at the Australian National University (ANU) jointly between the Research School of Earth Sciences (RSES), and the Department of Nuclear Physics, RSPhysSE. The author has taken primary responsibility from the beginning of this project to its conclusion. This has involved collecting the samples, performing mineral separations, preparing them for many different measurements, performing the measurements, and finally, carrying out the analysis and interpreting the data. During this process the author was assisted and advised by many people, as discussed below. With the exception of the samples AT-10, AT-11, AT-12 and AT-13, which were collected by Dr Stone, all the Scottish samples were collected by the author with advice from Dr Colin Ballantyne and assistance from Keith Salt, Matt Franks, Angela Lamb and Dr Greg Lane. The samples for the depth profile from Wyangala were collected by the author with Dr Stone, Dr Fifield, Dr Richard Cresswell, Dr Mariana Di Tada and Dr Kexin Liu. The original trace element measurements were made by ICP-MS at RSES with assistance from Mr Leslie Kinsley. X-ray fluorescence measurements (major element whole rock concentrations and some whole rock uranium and thorium concentrations) were made by Dr Bruce Chappell in the Geology Department at ANU. Later repeat trace element measurements were made by Prompt Gamma Analysis by XRAL in Canada. Potassium concentrations were measured by the author with assistance from Mrs Robyn Maier. Initial calcium measurements were made by the author with the assistance of Mr Mike Shelley. These measurements were then repeated at Ecowise Environmental Laboratories, Australia. All chloride measurements (pyrohydrolysis and isotope dilution) were made by the author following processes developed by Dr Stone. Likewise AgCl samples for the b6Cl analyses were prepared by the author following procedures adapted by Dr Stone from the original work of Conrad et al [Con86] and Zreda et al [Zre91]. AMS measurements were made by the author using the 14UD Pelletron in the Department of Nuclear Physics. Successful 3bCl measurements on the samples relied on the expertise of Dr Fifield and Dr Cresswell, and additional assistance in measuring the samples was provided by Dr Stone, Dr Di Tada and Dr Liu. Acquisition of the multi-parameter data for these measurements employed the software written for the laboratory's data acquisition system by Dr Gordon Foote. The subsequent off-line sorting of these data, which was required to derive the 36C1/Cl values, was carried out by the author using the same software. Analysis and interpretation of the results was performed by the author with initial assistance from Mathematica programs written by Dr Stone and invaluable discussions with Dr Stone, Dr Fifield and Dr Lane. The focus of this work has changed over time. The original intention was to include measurements made on eight samples collected from the Sierra Nevada, USA, by Dr Stone, and three samples collected in the Antarctic by Jeff Klein, but due to uncertainties in their exposure histories that became apparent after this work was underway, they were ultimately omitted from this dissertation. Some of the results obtained on these samples, in addition to four of the Scottish samples included in this work, can, however, be found in the following article: J.M. Evans, J. O. H. Stone, L. K. Fifield and R. G. Cresswell Cosmogenic chlorine-36 production in K-feldspar Nucl. Instr. And Meth. In Phys. Res. B 123, p 334 - 340,1997. No part of this thesis has been submitted for a degree at any other university. Jodie Evans iv Acknowledgemen ts Today is gone. Today was fun. Tomorrow is another one. Everyday, from here to there, funny things are everywhere. Dr Seuss As I put the finishing touches on my thesis I'm amazed at how interested I still am in the subject, and I have a twinge of regret that I won't be continuing the investigation. I don't believe that anyone really enjoys writing up their thesis, but I think I could make a pretty good case that my situation has been more difficult than most! I've gone from being single with no kids, to married with 2 (and it's the best thing that's ever happened to me!). I've moved overseas and back again twice. And I won't even go into how difficult it is to discuss your work with your supervisors when all three of you are living thousands of miles apart. But I will soon be finished and I have many people I would like to thank for helping me get from here to there. First I would like to thank my "tag team" supervisors, John Stone and Keith Fifield. John's enthusiasm for the work has been inspiring, and I'm very grateful for his time and patience in teaching a physicist enough of the geology and chemistry to carry out the project. Keith's expertise with the accelerator, his efforts reading and rereading what I'm sure seemed like endless chapters so promptly, and keeping me focussed when I started stressing out at the end, were a godsend. Thanks to all my official and unofficial advisers during my time here: Garry Allan, Richard Cresswell, Alan Chivas, Trevor Ophel and the person who is really responsible for me finishing, Greg Lane. George Dracoulis has supported me throughout my time at nuclear and I greatly appreciate his efforts at the very end as my default supervisor and critically reading my entire thesis in final form. (I'd also like to thank George for making sure the girls finally got a shower in the refurbishment of the building!). On the RSES side of the road, I'd also like to thank Kurt Lambeck for his support of my Ph.D. I'd like to thank Mariana Di Tada and Kexin Liu for all their special help making my final AMS measurements when I was nine months pregnant with Ciaran. Their support really meant a lot to me. I'd also like to thank Sam King and Phil Day for being great people! As I said, I'm not a geologist, so I have to thank Colin Ballantyne, Keith Salt, Matt Franks and Angela Lamb for all their advice and assistance with collecting samples in Scotland. I'd also like to thank everyone who helped me with various measurements at RSES: Robin Maier, Ian McDougall, John Chappell, Leslie Kinsley, Mike Shelley, John Mya, Shane Paxton and Joe Cali. I'd like to express my appreciation to everyone at nuclear physics for being so supportive over the last 8 years, particularly Gordon Foote and Aidan Byrne, who have been my cheerleaders in the last 6 months, giving me words of encouragement every time they go past my desk to their offices, and Anna Wilson, Nanda Dasgupta and Susan Helyar for reading parts of my thesis. I'd also like to thank Clyde and Susan for being such great friends in Stony Brook! I also really appreciate the help I got from both sets of grandparents when Greg went away for two weeks during the last month of writing up. I'd like to thank my brother for the words of encouragement I'm sure everyone else was thinking, but only he could give ("Just finish the bloody thing!"). I'd like to thank my Dad for his support and doing that last check for typos. And I'd like to thank my Mum for her support and, particularly, for finishing her thesis X years ago with three young kids! Finally, I'd like to thank my two precious children, Ciaran and Heather, for their tolerance of mum disappearing to work all the time for the last couple of weeks, and being stressed and grumpy when she was at home. But mostly I'd like to thank my husband Greg, without whom there is no way I would have finished. He listened to me go on and on about various aspects of my thesis when we were living too far away from my supervisors to talk to them about it properly. He read pages and pages of rubbish I'd written, but most importantly he always believed I'd get there. Thank you! Abstract Chlorine-36 production rates from potassium have been calibrated for the top 10m of the lithosphere, where "6C1 is produced by two main reaction channels: i) spallation, which dominates 3bCl production in the top 2 metres below the earth's surface, and ii) negative muon capture, which dominates at depths of between 2 and ~20 metres below the earth's surface. Rock samples were collected from two sites: i) rock surfaces exposed by the end of the Loch Lomond Readvance glaciation in Scotland 11,600 years ago, and ii) a 6.1m depth profile at a granite quarry in south eastern Australia, for which a steady state J6C1 concentration dictated by a history of constant erosion was assumed. In addition, the 36C1 measurements were made on pure K-feldspar mineral separates to remove the b0Cl contributions from calcium, iron and titanium, and to minimise the 36C1 contribution from chloride. The potassium spallation production rate was deduced from 18 Scottish K- feldspar mineral separates to be 161 (9) atom (gK)'1 y r1 at sea level and high latitude.
Recommended publications
  • Arxiv:2010.09509V2 [Hep-Ph] 2 Apr 2021 in Searches for CLFV Or LNV, Incoming Muons Are the Source of Both the Μ → E Signal and the RMC Back- Ground

    Arxiv:2010.09509V2 [Hep-Ph] 2 Apr 2021 in Searches for CLFV Or LNV, Incoming Muons Are the Source of Both the Μ → E Signal and the RMC Back- Ground

    FERMILAB-PUB-20-525-T The high energy spectrum of internal positrons from radiative muon capture on nuclei Ryan Plestid1, 2, ∗ and Richard J. Hill1, 2, y 1Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506, USA 2Theoretical Physics Department, Fermilab, Batavia, IL 60510,USA (Dated: April 5, 2021) The Mu2e and COMET collaborations will search for nucleus-catalyzed muon conversion to positrons (µ− ! e+) as a signal of lepton number violation. A key background for this search is radiative muon capture where either: 1) a real photon converts to an e+e− pair “externally" in surrounding material; or 2) a virtual photon mediates the production of an e+e− pair “internally”. If the e+ has an energy approaching the signal region then it can serve as an irreducible background. In this work we describe how the near end-point internal positron spectrum can be related to the real photon spectrum from the same nucleus, which encodes all non-trivial nuclear physics. I. INTRODUCTION Specifically, on a nucleus (e.g. aluminum), the reaction µ− + [A; Z] ! e+ + [A; Z − 2] ; (1) Charged lepton flavor violation (CLFV) is a smok- ing gun signature of physics beyond the Standard Model becomes a viable target for observation (see also [7]). (SM) and is one of the most sought-after signals at the While neutrinoless double beta (0νββ) decay is often intensity frontier [1–4]. Important search channels in- touted as the most promising direction for the discovery volving the lightest two lepton generations are µ ! 3e, of LNV, there do exist extensions of the SM that predict µ ! eγ, and nucleus-catalyzed µ ! e [1–6].
  • EXTRACTION of BERYLLIUM-10 from SOIL by FUSION Summary

    EXTRACTION of BERYLLIUM-10 from SOIL by FUSION Summary

    EXTRACTION OF BERYLLIUM-10 FROM SOIL BY FUSION Summary This method is used to separate Be from soil and sediment samples, for AMS analysis. After adding Be carrier, the sample is fused with KHF2. Be is extracted from the fusion cake with hot water. K is removed by precipitation, the sample is dried to expel fluoride, and Be is recovered as Be(OH)2. Yields are typically 70-80 %, but can be increased by additional leaching of the fusion cake. Version Written by John Stone, 1996-2002. This version revised May 2004 by Greg Balco. Available at: http://depts.washington.edu/cosmolab/chem.html References If you use this method, please cite: Stone, J.O.H. (1998). A rapid fusion method for the extraction of Be-10 from soils and silicates. Geochimica et Cosmochimica Acta (Scientific comment) 62, 555-561. Sampling and grinding Mix and grind an unbiased ∼ 50-100 g sample of the material. If possible, mix the original sample bag before opening and take representative proportions of coarse and fine material. Fine soil, carbonate nodules, clay lumps, rock fragments, etc., all have different 10Be concentrations. Grinding homogenises the sample and ensures that these components are evenly represented in the small subsample used for the analysis. If the sample is wet, you will need to dry it before grinding. Initial sample drying Samples are best run in batches of four. This is because we currently have four Pt crucibles. Given more crucibles and sufficient hotplate space, batches of 8 or even 12 are equally feasible. ————————————————— UW Cosmogenic Nuclide Lab – 10Be fusion process 1 – Label and tare four disposable aluminum foil drying dishes and transfer a few grams of ground sediment to each with a steel spatula.
  • Isotopegeochemistry Chapter4

    Isotopegeochemistry Chapter4

    Isotope Geochemistry W. M. White Chapter 4 GEOCHRONOLOGY III: OTHER DATING METHODS 4.1 COSMOGENIC NUCLIDES 4.1.1 Cosmic Rays in the Atmosphere As the name implies, cosmogenic nuclides are produced by cosmic rays colliding with atoms in the atmosphere and the surface of the solid Earth. Nuclides so created may be stable or radioactive. Radio- active cosmogenic nuclides, like the U decay series nuclides, have half-lives sufficiently short that they would not exist in the Earth if they were not continually produced. Assuming that the production rate is constant through time, then the abundance of a cosmogenic nuclide in a reservoir isolated from cos- mic ray production is simply given by: −λt N = N0e 4.1 Hence if we know N0 and measure N, we can calculate t. Table 4.1 lists the radioactive cosmogenic nu- clides of principal interest. As we shall, cosmic ray interactions can also produce rare stable nuclides, and their abundance can also be used to measure geologic time. A number of different nuclear reactions create cosmogenic nuclides. “Cosmic rays” are high-energy (several GeV up to 1019 eV!) atomic nuclei, mainly of H and He (because these constitute most of the matter in the universe), but nuclei of all the elements have been recognized. To put these kinds of ener- gies in perspective, the previous gen- eration of accelerators for physics ex- Table 4.1. Data on Cosmogenic Nuclides periments, such as the Cornell Elec- -1 tron Storage Ring produce energies in Nuclide Half-life, years Decay constant, yr the 10’s of GeV (1010 eV); while 14C 5730 1.209x 10-4 CERN’s Large Hadron Collider, 3H 12.33 5.62 x 10-2 mankind’s most powerful accelerator, 10Be 1.500 × 106 4.62 x 10-7 located on the Franco-Swiss border 26Al 7.16 × 105 9.68x 10-5 near Geneva produces energies of 36Cl 3.08 × 105 2.25x 10-6 ~10 TeV range (1013 eV).
  • 4 Muon Capture on the Deuteron 7 4.1 Theoretical Framework

    4 Muon Capture on the Deuteron 7 4.1 Theoretical Framework

    February 8, 2008 Muon Capture on the Deuteron The MuSun Experiment MuSun Collaboration model-independent connection via EFT http://www.npl.uiuc.edu/exp/musun V.A. Andreeva, R.M. Careye, V.A. Ganzhaa, A. Gardestigh, T. Gorringed, F.E. Grayg, D.W. Hertzogb, M. Hildebrandtc, P. Kammelb, B. Kiburgb, S. Knaackb, P.A. Kravtsova, A.G. Krivshicha, K. Kuboderah, B. Laussc, M. Levchenkoa, K.R. Lynche, E.M. Maeva, O.E. Maeva, F. Mulhauserb, F. Myhrerh, C. Petitjeanc, G.E. Petrova, R. Prieelsf , G.N. Schapkina, G.G. Semenchuka, M.A. Sorokaa, V. Tishchenkod, A.A. Vasilyeva, A.A. Vorobyova, M.E. Vznuzdaeva, P. Winterb aPetersburg Nuclear Physics Institute, Gatchina 188350, Russia bUniversity of Illinois at Urbana-Champaign, Urbana, IL 61801, USA cPaul Scherrer Institute, CH-5232 Villigen PSI, Switzerland dUniversity of Kentucky, Lexington, KY 40506, USA eBoston University, Boston, MA 02215, USA f Universit´eCatholique de Louvain, B-1348 Louvain-la-Neuve, Belgium gRegis University, Denver, CO 80221, USA hUniversity of South Carolina, Columbia, SC 29208, USA Co-spokespersons underlined. 1 Abstract: We propose to measure the rate Λd for muon capture on the deuteron to better than 1.5% precision. This process is the simplest weak interaction process on a nucleus that can both be calculated and measured to a high degree of precision. The measurement will provide a benchmark result, far more precise than any current experimental information on weak interaction processes in the two-nucleon system. Moreover, it can impact our understanding of fundamental reactions of astrophysical interest, like solar pp fusion and the ν + d reactions observed by the Sudbury Neutrino Observatory.
  • Status of the Alcap Experiment

    Status of the Alcap Experiment

    Status of the AlCap experiment R. Phillip Litchfield∗† UCL E-mail: [email protected] The AlCap experiment is a joint project between the COMET and Mu2e collaborations. Both experiments intend to look for the lepton-flavour violating conversion m + A ! e + A, using ter- tiary muons from high-power pulsed proton beams. In these experiments the products of ordinary muon capture in the muon stopping target are an important concern, both in terms of hit rates in tracking detectors and radiation damage to equipment. The goal of the AlCap experiment is to provide precision measurements of the products of nuclear capture on Aluminium, which is the favoured target material for both COMET and Mu2e. The results will be used for optimising the design of both conversion experiments, and as input to their simulations. Data was taken in December 2013 and is currently being analysed. 16th International Workshop on Neutrino Factories and Future Neutrino Beam Facilities - NUFACT2014, arXiv:1501.04880v1 [physics.ins-det] 20 Jan 2015 25 -30 August, 2014 University of Glasgow, United Kingdom ∗Speaker. †On behalf of the AlCap Collaboration © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/ Status of the AlCap experiment R. Phillip Litchfield 1. Muon to electron conversion and the motivation for AlCap The term ‘muon to electron conversion’ refers to processes that cause the neutrinoless decay of a muon into an electron, specifically those in which the muon is the ground-state orbit of an atomic nucleus.1 In this case the conservation of momentum and energy can be achieved by coherent interaction on the nucleus, i.e.
  • Meteoric Be and Be As Process Tracers in the Environment

    Meteoric Be and Be As Process Tracers in the Environment

    Chapter 5 Meteoric 7Be and 10Be as Process Tracers in the Environment James M. Kaste and Mark Baskaran 7 10 Abstract Be (T1/2 ¼ 53 days) and Be (T1/2 ¼ occurring Be isotopes of use to Earth scientists are the 7 1.4 Ma) form via natural cosmogenic reactions in the short-lived Be (T1/2 ¼ 53.1 days) and the longer- 10 atmosphere and are delivered to Earth’s surface by wet lived Be (T1/2 ¼ 1.4 Ma; Nishiizumi et al. 2007). and dry deposition. The distinct source term and near- Because cosmic rays that cause the initial cascade of constant fallout of these radionuclides onto soils, vege- neutrons and protons in the upper atmosphere respon- tation, waters, ice, and sediments makes them valuable sible for the spallation reactions are attenuated by tracers of a wide range of environmental processes the mass of the atmosphere itself, production rates of operating over timescales from weeks to millions of comsogenic Be are three orders of magnitude higher in years. Beryllium tends to form strong bonds with oxygen the stratosphere than they are at sea-level (Masarik and atoms, so 7Be and 10Be adsorb rapidly to organic and Beer 1999, 2009). Most of the production of cosmo- inorganic solid phases in the terrestrial and marine envi- genic Be therefore occurs in the upper atmosphere ronment. Thus, cosmogenic isotopes of beryllium can be (5–30 km), although there is trace, but measurable used to quantify surface age, sediment source, mixing production as oxygen atoms in minerals at the Earth’s rates, and particle residence and transit times in soils, surface are spallated (in situ produced; see Lal 2011, streams, lakes, and the oceans.
  • Beryllium-10 Terrestrial Cosmogenic Nuclide Surface Exposure Dating of Quaternary Landforms in Death Valley

    Beryllium-10 Terrestrial Cosmogenic Nuclide Surface Exposure Dating of Quaternary Landforms in Death Valley

    Geomorphology 125 (2011) 541–557 Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph Beryllium-10 terrestrial cosmogenic nuclide surface exposure dating of Quaternary landforms in Death Valley Lewis A. Owen a,⁎, Kurt L. Frankel b, Jeffrey R. Knott c, Scott Reynhout a, Robert C. Finkel d,e, James F. Dolan f, Jeffrey Lee g a Department of Geology, University of Cincinnati, Cincinnati, Ohio, USA b School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA c Department of Geological Sciences, California State University, Fullerton, California, USA d Department of Earth and Planetary Science Department, University of California, Berkeley, Berkeley, CA 94720-4767, USA e CEREGE, BP 80 Europole Méditerranéen de l'Arbois, 13545 Aix en Provence Cedex 4, France f Department of Earth Sciences, University of Southern California, Los Angeles, California, USA g Department of Geological Sciences, Central Washington University, Ellensburg, Washington, USA article info abstract Article history: Quaternary alluvial fans, and shorelines, spits and beach bars were dated using 10Be terrestrial cosmogenic Received 10 March 2010 nuclide (TCN) surface exposure methods in Death Valley. The 10Be TCN ages show considerable variance on Received in revised form 3 October 2010 individual surfaces. Samples collected in the active channels date from ~6 ka to ~93 ka, showing that there is Accepted 18 October 2010 significant 10Be TCN inheritance within cobbles and boulders. This
  • Subject Categories and Scope Descriptions Co Q

    Subject Categories and Scope Descriptions Co Q

    International Nuclear Information System (INIS) • LU Q CD XA0202260 D) c CO IAEA-ETDE/TNIS-2 o X LU CO -I—• SUBJECT CATEGORIES AND SCOPE DESCRIPTIONS CO Q ETDE/INIS Joint Reference Series No. 2 CT O c > LU O O E "- =3 CO I? O cB CD C , LU • CD 3 CO -Q T3 CD >- c •a « C c CD o o CD «2 i- CO .3-3/33 CO ,_ CD a) O % 3 O •z. a. Renewable energy technologies • Radiation protection • Energy storage, conversion, and consumption Radioactive waste management • Energy policy • Radiation effects on living organisms • Fossil fuels INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, JULY 2002 ETDE/INIS Joint Reference Series No. 2 SUBJECT CATEGORIES AND SCOPE DESCRIPTIONS INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA, JULY 2002 SUBJECT CATEGORIES AND SCOPE DESCRIPTIONS IAEA, VIENNA, 2002 IAEA-ETDE/INIS-2 ISBN 92-0-112902-5 ISSN 1684-095X © IAEA, 2002 Printed by the IAEA in Austria July 2002 PREFACE This document is one in a series of publications known as the ETDE/INIS Joint Reference Series. It defines the subject categories and provides the scope descriptions to be used for categorization of the nuclear literature for the preparation of INIS input by national and regional centers. Together with volumes of the INIS Reference Series and ETDE/INIS Joint Reference Series it defines the rules, standards and practices and provides the authorities to be used in the International Nuclear Information System. A list of the volumes published in the IMS Reference Series and ETDE/ENIS Joint Reference Series can be found at the end of this publication.
  • Polar Desert Chronologies Through Quantitative Measurements of Salt Accumulation

    Polar Desert Chronologies Through Quantitative Measurements of Salt Accumulation

    Polar desert chronologies through quantitative measurements of salt accumulation Joseph A. Graly1, Kathy J. Licht1, Gregory K. Druschel1, and Michael R. Kaplan2 1Department of Earth Sciences, Indiana University–Purdue University Indianapolis, Indianapolis, Indiana 46202, USA 2Lamont–Doherty Earth Observatory, Palisades, New York 10964, USA ABSTRACT isotopes suggest a primarily atmospheric ori- We measured salt concentration and speciation in the top horizons of moraine sediments gin, with some trace mineral boron (Leslie et from the Transantarctic Mountains (Antarctica) and compared the salt data to cosmogenic- al., 2014). However, the Dry Valleys boron iso- nuclide exposure ages on the same moraine. Because the salts are primarily of atmospheric tope values that suggest a trace mineral compo- origin, and their delivery to the sediment is constant over relevant time scales, a linear rate of nent could also form from Rayleigh distillation accumulation is expected. When salts are measured in a consistent grain-size fraction and at during the precipitation of atmospheric boron a consistent position within the soil column, a linear correlation between salt concentration (Rose-Koga et al., 2006). and exposure age is evident. This correlation is strongest for boron-containing salts (R2 > 0.99), Atmospheric aerosols exist either as acid 2 but is also strong (R ≈ 0.9) for most other water-extracted salt species. The relative mobility vapors and gases (e.g., HNO3, N2O5, etc.) or of salts in the soil column does not correspond to species solubility (borate is highly soluble). as anion-cation pairs, commonly adhering to Instead, the highly consistent behavior of boron within the soil column is best explained by particulate matter.
  • Radiative Muon Capture on Carbon, Oxygen and Calcium

    Radiative Muon Capture on Carbon, Oxygen and Calcium

    TRI-PP -90-21 May 1990 Radiative muon capture on carbon, oxygen and calcium D.S. Armstrong/") S. Ahmad/6) R.A. Burnham/C) T.P. Gorringe.W M.D. Hasinoff, A.J. Larabee<e>, and C.E. Waltham University of British Columbia, Vancouver, B.C., Canada V6T 2A6 G. AzuelosO, J.A. Macdonald, T. Numao and J-M. Poutissou TRIUMF, Vancouver, B.C., Canada VST 2A3 M. Blecher and D.H. Wright'^ Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 E.T.H. Clifford^) and J. Summhammer*1' TRIUMF and University of Victoria, Victoria, B.C., Canada V8W 2Y2 P. Depommier and R. Poutissou Universile de Montreal, Montreal, P.Q., Canada II3C 3J7 H. Mes National Research Council of Canada, Ottawa, Canada KlA OR6 B.C. Robertson Queen's University, Kingston, Ontario, Canada K7L 3N6 The photon energy spectra from radiative muon capture on 12C,16 O and 40Ca have been measured using a time projection chamber as a pair spec- trometer. The branching ratio for radiative muon capture is sensitive to <7P, the induced pseudoscalar coupling constant of the weak interaction. Ex- pressed in terms of the axial-vector weak coupling constant ga, values of 40 16 ffp/So = 5.7 ± 0.8 and gp/ga = 7.3 ± 0.9 are obtained for Ca and O respectively, from comparison with phenomenological calculations of the nu- clear response. From comparison with microscopic calculations, values of {oT 4 Ca 16 and 12 gp/ga = 4.6± 1.8, 13.6 +}|, and 16.2 ±J$ ° . °. C, respec- •:« tively are obtained.
  • Electroweak Structure of Light Nuclei Within Chiral Effective Field Theory

    Electroweak Structure of Light Nuclei Within Chiral Effective Field Theory

    Few-Body Systems (EFB22) manuscript No. (will be inserted by the editor) Laura E. Marcucci Electroweak structure of light nuclei within chiral effective field theory Received: date / Accepted: date Abstract We review the results of the most recent calculations for the electromagnetic structure of light nuclei, the weak muon capture on deuteron and 3He and the weak proton-proton capture reaction at energies of astrophysical interest, performed within the chiral effective field theory framework. Keywords Chiral effective field theory · Electromagnetic Form Factors · Light nuclei · Muon capture · Proton-proton weak capture 1 Introduction Among the great advantages of the chiral effective field theory (χEFT) framework, the two following ones are here of interest: (i) the possibility of deriving nuclear electroweak (EW) currents consistently with the nuclear interaction, and (ii) the possibility of setting a hierarchy among the different contri- butions, both for the interactions and the currents. In fact, it is well known that χEFT can justify a priori the empirical observation that the contribution of three-nucleon interactions to nuclear structure is far less significant than that of the two-nucleon force. Furthermore, the χEFT power counting allows to recognize which are the most significant contributions also among the different currents. The idea of using χEFT to derive the nuclear EW transition operators was first implemented by Park et al. [1] in the nineties. They derived the nuclear electromagnetic (EM) current and charge operators, within the so-called heavy-baryon chiral perturbation theory (HBχPT) approach, where the baryons are treated as heavy static sources, and the perturbative expansion is performed in terms of the involved momenta over the baryon mass.
  • Charged-Particle Spectra from $\Mu ^{-}$ Capture on Al

    Charged-Particle Spectra from $\Mu ^{-}$ Capture on Al

    PHYSICAL REVIEW C 101, 035502 (2020) Charged-particle spectra from μ− capture on Al A. Gaponenko ,1,* A. Grossheim,2 A. Hillairet,3 G. M. Marshall ,2 R. E. Mischke,2 and A. Olin 2,† 1Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA 2TRIUMF, Vancouver, British Columbia, Canada V6T 2A3 3Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada V8P 5C2 (Received 20 August 2019; revised manuscript received 13 December 2019; accepted 10 February 2020; published 13 March 2020) Published data on the emission of charged particles following nuclear muon capture are extremely limited. In addition to its interest as a probe of the nuclear response, these data are important for the design of some current searches for lepton flavor violation. This work presents momentum spectra of protons and deuterons following μ− capture in aluminum. It is the first measurement of a muon capture process performed with a tracking spectrometer. A precision of better than 10% over the momentum range of 100–190 MeV/c for protons is obtained; for deuterons of 145–250 MeV/c the precision is better than 20%. The observed partial yield of protons with emission momenta above 80 MeV/c (kinetic energy 3.4 MeV) is 0.0322 ± 0.0007(stat) ± 0.0022(syst) per capture, and for deuterons above 130 MeV/c (4.5 MeV) it is 0.0122 ± 0.0009(stat) ± 0.0006(syst). Extrapolating to total yields gives 0.045 ± 0.001(stat) ± 0.003(syst) ± 0.001(extrapolation) per capture for protons and 0.018 ± 0.001(stat) ± 0.001(syst) ± 0.002(extrapolation) for deuterons, which are the most precise measurements of these quantities to date.