Presentation on theme: "1 Washington U. Bob Binns Jay Cummings Louis Geer Georgia deNolfo Paul Hink Martin Israel Joseph Klarmann Kelly Lave David Lawrence Caltech/JPL A.C. Cummings."— Presentation transcript:
1 Washington U. Bob Binns Jay Cummings Louis Geer Georgia deNolfo Paul Hink Martin Israel Joseph Klarmann Kelly Lave David Lawrence Caltech/JPL A.C. Cummings R.A. Leske R.A. Mewaldt E.C. Stone M.E. Wiedenbeck NASA/Goddard L. M Barbier T. Bradt E.R. Christian G.A. deNolfo T. Hams J.T. Link J. W. Mitchell K. Sakai M. Sasaki T.T. Von Rosenvinge U of Minnesota C.J. Waddington Constraints on the GCR Source Derived from Isotopic Abundance Measurements Mike Lijowski Jason Link Katharina Lodders Ryan Murphy Susan Niebur Brian Rauch Lauren Scott Stephanie Sposato John E. Ward ACE-CRIS (1997-Present) TIGER (2001-2003) Super-TIGER (2012) Erice 2014-Bob Binns
Outline Talk I--Isotopes Cosmic Ray Basics Sources of GCRs? Measurement Techniques and Instruments UH Isotope Measurements on ACE UH Element Measurements on TIGER, ACE, & SuperTIGER (Ryan Murphy’s talk) First Ionization Potential or Refractory/Volatility nature of elements Constraints placed on the cosmic-ray sources by low-E cosmic rays 59 N What is the time between nucleosynthesis and acceleration? Other important Isotopes (esp. 22 Ne) Normal ISM (SS composition) or a mix of material? Talk 2—Elements Element abundances--gas/dust components? Recent -ray measurements of distributed emission The OB association model of origin of GCRs Properties of massive stars & OB associations Conclusions 2 Erice 2014-Bob Binns
Origin in our Galaxy. 30 GeV proton in B~6 G has gyro radius ~0.5x10 -5 pc (~1 au). Learn about cosmic-ray sources from elemental and isotopic composition. Extragalactic origin. 3x10 21 eV proton in B~3 G has gyro radius ~1 Mpc. Andromeda galaxy is ~0.65 Mpc from Earth Erice 2014-Bob Binns 3
Elemental Abundances in the Galactic Cosmic Radiation Elements in the upper 2/3rds of the periodic table, are extremely rare compared to lighter elements. They contain unique information not obtainable from light cosmic rays. Measurement requires large instruments at the top of the atmosphere or in space for long exposure times.
Objectives of Galactic Cosmic Ray Research Determine the source(s) of cosmic rays What material is accelerated? What are the nucleosynthesis sites of the accelerated nuclei? What are the accelerators? Measure the elemental, isotopic, and energy spectra so that the source abundances can be determined Determine what changes occur as the CRs propagate from their source to us at 1AU. Nuclear interactions, Leakage from galaxy, Solar Modulation, Earth’s magnetic field (for Earth orbiting missions)
Cosmic Ray Source? Stellar atmosphere injection Low First-Ionization-Potential (FIP) elements enhanced (as in the solar corona, Solar Wind and SEPs). Casse & Goret 1978; Meyer 1985 Fractionation of particles from Sun “probably results from a separation of ions and neutrals, which takes place between the photosphere and corona at temperatures of 6,000-10,000 K.” Schmeltz et al 2012 Interstellar gas/grains with enhanced grain source Many low-FIP elements are refractory and most high-FIP elements are volatile Refractory elements enhanced Mass dependence for volatile elements Epstein 1980; Bibring & Cesarsky 1981; Ellison et al. 1997; Meyer et al. 1997 Acceleration of material in OB associations and their superbubbles by SN shocks and stellar winds Wind material from massive stars Montmerle 1979; Cezarsky & Montmerle 1981; Streitmatter et al. 1985; Bykov 1999; Parizot, et al. 2004; Higdon & Lingenfelter 2003, 2005, 2007; Meli & Biermann 2006; Prantzos 2012 Supernova material Credit: Gemini Observatory/AURA N44 Superbubble
Erice 2014-Bob Binns 7 UHCR Experiment Ball/SatDateDurationAreaRef.Detectors used First detection of Z>30 nuclei was in meteorite crystals; Fleischer, Price, Walker, and Maurette (1967) JGR 72, 331 Texas Flights VHCRN Balloon Texas 19660.6 days4.5 m 2 Fowler et al. 1967 Four layers of nuclear emulsions with absorber interleaved Barndoor I,II, & III Balloon Texas 1967- 1970 2.8 days 15 m 2 Wefel 1971 Plastic track detectors and nuclear emulsions Heavy Nuclei Experiment HEAO-3 Satellite 19791.7 years~2 m 2 Binns et al. 1989 Ionization chambers, Cherenkov counters, wire ionization hodo. HCREAreal-6 Satellite 19791 year equiv. 0.5 m 2 Fowler et al. 1987 Spherical gas scintillator and acrylic Cherenkov detector UHCRELDEF Satellite 19845.75 years20 m 2 Donnelly et al.2012 Plastic track detectors (Lexan) TrekMir Satellite 19911/3 rd 2.5 y 2/3 rd 4.2 y 1.2 m 2 Westphal et al.1998 Glass track detectors-Barium Phosphate Glass (BP-1) CRISACE Satellite 199717 years0.03 m 2 Stone et al. 1998 Silicon detector stack & scintillating optical fiber hodo. TIGERBalloon- Antarctica 2001, 2003 50 days1.3 m 2 Rauch et al. 2009 Plastic scint, acrylic & aerogel Cherenkov, scint fiber hodo. SuperTIGERBalloon- Antarctica 201244 days equiv. 5.6 m 2 Binns et al. 2014 Plastic scint, acrylic & aerogel Cherenkov, scint fiber hodo. Experiments aimed at measuring abundances of UHCRs
Low energy isotopic abundances dE/dx-E Total ACE-CRIS-Stone et al. 1998 IMP-7-Garcia-Munoz et al. 1979 ISEE-3-Wiedenbeck & Greiner 1981; Mewaldt et al. 1980 Voyager-Lukasiak et al. 1994; Webber et al. 1997 Ulysees-Connell & Simpson 1997 CRESS-DuVernois et al. 1996 Multiple dE/dx measurement crucial for good resolution Reject interactions in detector Consistency requirement for “funny” events Techniques used for Low Energy, high-resolution GCR Composition Measurements (0.1-10GeV/nuc) (continued) dE/dx = kZ 2 /β 2 E KE = 0.5 mβ 2
The Cosmic Ray Isotope Spectrometer (CRIS) on ACE Erice 2014-Bob Binns 12 CRIS 10 cm Advanced Composition Explorer (ACE) satellite launched in August, 1997. Still in orbit about the L1 Lagrange point between Earth and the Sun Still sending back good element and isotope data on GCRs No significant degradation in instrument performance
Instrument Cross-section Large geometrical factor of CRIS (~50 x previous instruments) Excellent mass resolution enables precise identification of abundances. Long time in orbit— nearly 17 years
14 How do we derive source abundances from data? CRIS concept is simple, but the DEVIL is in the details!! Mass resolution Angle Measurement Theta correction to signals (achieved <0.1º angle resolution) Require “good hodoscope” three consistent x,y coordinate pairs For best resolution, use events that are near vertical (e.g. 28, need all the particles we can get, so accept <60 º Reject interactions Reject penetrating events--signal in the bottom anticoincidence detector Require charge estimate consistency using different combinations of detectors for estimate Require penetration to E3 or deeper so can apply consistency rqmt Reject “dead layer” events (particles stopping within ~500 µm from surface on one side of wafer) & correct for nonlinearities in signal from silicon detectors Reject particles exiting through the side of the stack using anticoincidence rings Map actual thickness of all silicon detectors Abundances at top-of-detector Interaction corrections Energy interval corrections Source abundances Propagate from instrument through heliosphere Propagate back to the source 6 mm Dead layers ~500 m thick
What questions can we address with composition measurements of heavy nuclei (Z>26)? What is the time between nucleosynthesis and acceleration? How do GCR isotope and element ratios compare with those from possible sources? Does the volatile (gas) or refractory (dust grains) nature of an element affect the composition of CRs? Do cosmic ray abundances depend on mass? Erice 2014-Bob Binns 17
What is the time between nucleosynthesis and acceleration of GCRs? Does a SN shock accelerate nuclei synthesized in that same SN? Soutoul et al., 1978 radioactive isotopes that decay only by electron- capture can be used to measure the time between nucleosynthesis and acceleration. 59 Ni decays only by electron-capture with half- life 76,000yr in lab. 59 Ni + e - → 59 Co + BUT, at cosmic-ray energies it is stripped of electrons, so is essentially stable. Erice 2014-Bob Binns 18 If GCR are accelerated by the same SN in which the nuclei are synthesized, expect to see 59 Ni in the GCR. So what do we observe????
GCR Nickel and Cobalt Histograms So GCR source is ambient interstellar matter accelerated >10 5 years after nucleosynthesis Corolary: Whatever the source of GCRs, there must be time between nucleosynthesis and acceleration for the 59 Ni to decay Constraint #1 Wiedenbeck, et al., ApJL, 523, L51 (1999)
Mass Ratio What fraction of mass-59 nuclei is expected to be synthesized as 59 Ni in core-collapse SNe? Note that Type-1a Sne are also copious producers of 59 Co and 59 Ni (Iwamoto et al. 1999) However, Type 1a SNe ~15% of total SN rate ejecta spreads throughout the galaxy over time Core-collapse SNe seed a high-metallicity superbubble environment, ready for acceleration by the relatively frequent, nearby SNe.
Erice 2014-Bob Binns 21 Other Isotopes measured by ACE-CRIS
22 Samples of the local interstellar medium (ISM) ~4.6 Gyr ago Galactic Cosmic-Ray Source Sample of local ISM today The cosmic-ray source composition differs from that of the Solar System. The CRIS experiment, finds a 22 Ne/ 20 Ne source ratio relative to SS of 5.3 0.3 Earlier experiments also found substantial enhancements (e.g. Ulysses, Voyager, CRRES, ISEE-3) Best accepted explanation is that this might result from an admixture of WR wind material, rich in 22 Ne, with normal ISM (with SS composition). (Montmerle, 1979; Cesarsky & Montmerle, 1981; Higdon & Lingenfelter 2003, 2005)
Evolution of surface abundances (mass fraction) with stellar mass for 60M ⊙ star (Meynet & Maeder, 2003) Time evolution of WR abundances Non- rotating star Rotating Star 300 km/s at equator Top curve—total mass; Bottom curve—convective core mass Time evolution of mass Non-rotating Star Rotating star 22 Ne greatly enhanced during helium burning through the -capture reaction 14 N( , ) 18 F(e +, ) 18 O( , ) 22 Ne
Higdon and Lingenfelter (2003) GCR 22 Ne/ 20 Ne ratio consistent with a source made of a mixture of ~82% SS composition and 18% wind outflow+ejecta from massive stars. Superbubble/OB association origin of GCRs. But, used Schaller et al. 1992 for massive star wind yield. More recent calculations (Hirshi, et al. 2005) show reduced 22 Ne production. Binns, et al (2005) GCR abundances of a range of isotope and element ratios for Z≤28 nuclei are consistent with ~20% massive star outflow (Meynet & Maeder, 2003, 2005) mixed with ~80% normal ISM (SS composition). 24 ACE-CRIS isotope ratios for Z ≤ 28 Ne Mg Si Fe Ni C/0
Z>28 Nuclei 26 ACE-CRIS has provided the first, and only existing measurements of isotopic abundances of 29 Cu, 30 Zn, 31 Ga, & 32 Ge. We see well resolved isotope peaks from 29 Cu through 32 Ge with sufficient statistics for a meaningful measurement. Note “possible” 3-event peak at mass 67-- Electron capture isotope—lifetime 3.3d If real, they have to be secondaries
27 Ultra-heavy isotopes in context of previous lower-Z data 27 New data are consistent with model, but also with solar system abundances. CR source must be able to produce isotope ratios that are “equivalent to” that obtained by mixing ~20% of MSO with ~80% of normal ISM. Note that the isotopic ratio error bars for new UH isotopes are statistical only. Constraint #2
Summary of constraints imposed by isotope measurements Isotopes measured by ACE-CRIS have provided two constraints for the source of GCRs Constraint 1—The acceleration of GCRs must occur more than ~10 5 years after nucleosynthesis Constraint 2—The abundances of the isotopic ratios measured must be “equivalent to” that obtained by mixing ~20% of massive star outflow material with ~80% of normal ISM (with SS abundances) Erice 2014-Bob Binns 28