Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session M4: Space-Based Cosmic Ray Observations |
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Sponsoring Units: DAP Chair: John Mitchell, NASA Goddard Space Flight Center Room: Virginia A |
Sunday, January 29, 2017 3:30PM - 3:42PM |
M4.00001: Latest AMS Results on Cosmic Ray fluxes Bruna Bertucci AMS-02 is a wide acceptance high-energy physics experiment installed on the International Space Station in May 2011 and it has been operating continuously since then. Accurate studies of CR composition and energy spectra can be performed in AMS thanks to the unprecedented collected statistics -- more than 90 billion events as of today -- and the redundant measurements of particle charge, velocity, rigidity and energy. In this contribution we will present an overview of the latest results on anti-particles, electrons and light nuclei fluxes. [Preview Abstract] |
Sunday, January 29, 2017 3:42PM - 3:54PM |
M4.00002: Preliminary CALET Ultra Heavy Cosmic Ray Abundance Measurements Brian Rauch The CALorimetric Electron Telescope (CALET) on the International Space Station (ISS) was launched August 19, 2015 and has been returning excellent data for over a year. The main calorimeter (CAL) on CALET measures the fluxes of high-energy electrons, nuclei and gamma rays. In addition to measuring the energy spectra of the more abundant cosmic-ray nuclei through $_{26}$Fe, CAL has the dynamic range to measure the abundances of the ultra-heavy (UH) cosmic-ray nuclei through $_{40}$Zr. In an anticipated 5 year mission on the ISS CALET will collect a UH data set with statistics comparable to that achieved with the first flight of the SuperTIGER balloon-borne instrument. The CALET space-based measurement has the advantage of not requiring corrections for atmospheric losses, and unlike other UH measurements the abundances of all nuclei from $_{1}$H through $_{40}$Zr are observed with the same instrument. We present preliminary CALET UH analysis results from the first year of operation. [Preview Abstract] |
Sunday, January 29, 2017 3:54PM - 4:06PM |
M4.00003: BESS-Polar II Hydrogen and Helium Isotope Measurements to Constrain Cosmic-Ray Propagation Models Nicolas Picot-Clemente The Balloon-borne Experiment with Superconducting Spectrometer BESS-Polar II flew over Antarctica for 24.5 days from December 2007 through January 2008, during the 23rd solar cycle minimum. The instrument is made of complementary particle detectors which allow to precisely measure the charge, velocity and rigidity of incoming cosmic rays. It can accurately separate cosmic-ray hydrogen and helium isotopes from 0.2 to 1.5 GeV/nucleon. Flux and secondary-to-primary ratios of these particles can bring important information to better understand the cosmic-ray propagation history in the Galaxy. BESS-Polar II provides the most precise isotope measurements to date between 0.2 and 1.5 GeV/nucleon. These data will be reported and constraints on cosmic-ray propagation models, using the GALPROP program, will be discussed. [Preview Abstract] |
Sunday, January 29, 2017 4:06PM - 4:18PM |
M4.00004: AMS results on the fluxes of light nuclei in cosmic rays Bruna Bertucci AMS-02 is a wide acceptance high-energy physics experiment installed on the International Space Station in May 2011 and it has been operating continuously since then. AMS-02 is able to separate cosmic rays light nuclei species (1$\le \quad Z \le $8) with contaminations less than 10$^{\mathrm{-3}}$ thanks to the redundant measurement of the particle charge in eight silicon tracker layers, four scintillator planes and the Ring Imaging Cherenkov detector. The accurate measure of their spectrum in the GeV-TeV range is performed by the magnetic spectrometer with a maximum detectable rigidity of $\approx $2-3 TV. Precise measurements from AMS will be presented, including proton, helium, boron to carbon flux ratio, and highlights of ongoing analyses discussed. [Preview Abstract] |
Sunday, January 29, 2017 4:18PM - 4:30PM |
M4.00005: Latest AMS Results on elementary particles in cosmic rays Andrei Kounine AMS-02 is a particle physics detector collecting data on the International Space Station since May 2011. Precision measurements of all elementary charged cosmic ray particles have been performed by AMS using a data sample of 85 billion cosmic ray events collected during the first five years of operations on the Station. The latest AMS results on the fluxes and flux ratios of the elementary cosmic ray particles are presented. They show unique features that require accurate theoretical interpretation as to their origin, be it from dark matter collisions or new astrophysical sources. [Preview Abstract] |
Sunday, January 29, 2017 4:30PM - 4:42PM |
M4.00006: Cosmic Rays below 1 GeV/nucleon: Results from 19 Years of Observations with the Cosmic Ray Isotope Spectrometer on ACE M. E. Wiedenbeck, W. R. Binns, E. R. Christian, C. M. S. Cohen, A. C. Cummings, G. A. de Nolfo, M. H. Israel, A. W. Labrador, R. A. Leske, R. A. Mewaldt, E. C. Stone, T. T. von Rosenvinge The Cosmic Ray Isotope Spectrometer (CRIS) instrument on NASA's Advanced Composition Explorer mission has been making high-precision measurements of cosmic-ray elemental and isotopic composition and energy spectra below 1 GeV/nucleon since August 1997. The long period of data collection, now in its 20th year, and the large geometrical acceptance ($\sim$250 cm$^{2}$sr) have made it possible to study very rare species, including including some primary radionuclides and a number of stable elements with Z$>$28. Using measurements of elemental spectra on time scales as short as a month, CRIS has been tracking the level of solar modulation over nearly two full solar cycles, including the lowest level encountered since the start of the space age. The energy range covered by these spectra is being extended using new techniques for measuring nuclides that penetrate beyond the sensitive volume of the CRIS instrument and by utilizing complementary data obtained from the Solar Isotope Spectrometer (SIS), also on ACE. A summary of the most significant cosmic-ray results from ACE will be presented and future prospects will be discussed. [Preview Abstract] |
Sunday, January 29, 2017 4:42PM - 4:54PM |
M4.00007: Preliminary SuperTIGER Abundances of Galactic Cosmic-Rays for the Charge Interval Z$=$41-60 and Prospects for SuperTIGER-2 Nathan Walsh Launched on December 8, 2012 from Williams Field, Antarctica, the SuperTIGER (Trans-Iron Galactic Element Recorder) instrument flew for 55 days on a long-duration balloon flight at a mean altitude of 125,000 feet. SuperTIGER measured the relative abundances of Galactic cosmic-ray nuclei with well resolved individual element peaks in the charge range Z$=$10-40. In addition to these measurements made with high statistical precision, SuperTIGER made exploratory measurements of the relative abundances up to Z$=$60. Although the statistics are low in this charge range, we will show how these relative abundances compare to those reported by HEAO3. A second fight, SuperTIGER-2, is planned for December 2017, during solar minimum which we estimate will result in SuperTIGER-2 collecting about 20 percent more particles per unit time. The combined data sets of SuperTIGER-1 and 2 will be used to improve statistics in the Z$=$30-40 range and to measure individual elemental abundances up to Z$=$60. [Preview Abstract] |
Sunday, January 29, 2017 4:54PM - 5:06PM |
M4.00008: Ultra-Heavy Galactic Cosmic Ray Abundances from the SuperTIGER Instrument: evidence for an OB association origin of GCR Ryan Murphy We report Galactic Cosmic Ray (GCR) abundances of elements from $_{26}$Fe to $_{40}$Zr measured by the SuperTIGER (Trans-Iron Galactic Element Recorder) instrument during 55 days of exposure on a long-duration balloon flight over Antarctica. SuperTIGER measures charge (Z) and energy (E) using a combination of three scintillator and two Cherenkov detectors, and employs a scintillating fiber hodoscope for event trajectory determination. These observations resolve elemental abundances in this charge range with single-element resolution and good statistics. We also derived GCR source abundances, which support a model of cosmic-ray origin in which the source material consists of a mixture of 19$^{+11}_{-6}$\% material from massive stars and $\sim$81\% normal interstellar medium (ISM) material with solar system abundances. The results also show a preferential acceleration, ordered by atomic mass (A), of refractory elements over volatile elements by a factor of $\sim$4. Both the refractory and volatile elements show a mass-dependent enhancement with similar mass dependence. [Preview Abstract] |
Sunday, January 29, 2017 5:06PM - 5:18PM |
M4.00009: Observation of the $^{\mathrm{60}}$Fe Nucleosynthesis-Clock Isotope in Galactic Cosmic Rays~ W.R. Binns, M.H. Israel, E.R. Christian, A.C. Cummings, G.A. de Nolfo, K.A. Lave, R.A. Leske, R.A. Mewaldt, E.C. Stone, T.T. von Rosenvinge, M.E. Wiedenbeck We have measured the abundance of $^{\mathrm{60}}$Fe, a radioactive isotope in cosmic rays that serves as a clock to infer an upper limit on the time between nucleosynthesis in supernovae and cosmic ray acceleration. The ACE-CRIS instrument has collected 3.55 \texttimes 10$^{\mathrm{5}}$ iron nuclei from which we have resolved 15 $^{\mathrm{60}}$Fe nuclei. From this a $^{\mathrm{60}}$Fe/$^{\mathrm{56}}$Fe source ratio of (7.5 \textpm 2.9) \texttimes 10$^{\mathrm{-5}}$ is obtained. The detection of supernova-produced $^{\mathrm{60}}$Fe in cosmic rays implies that the time required for acceleration and transport to Earth does not greatly exceed the $^{\mathrm{60}}$Fe half-life of 2.6 Myr and that the $^{\mathrm{60}}$Fe source distance does not greatly exceed the distance cosmic rays can diffuse over this time, \textless \textasciitilde 1 kpc. A natural place for $^{\mathrm{60}}$Fe origin is in nearby clusters of massive stars. [Preview Abstract] |
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