Eun-Suk Seo Inst. for Phys. Sci. & Tech. and Department of Physics University of Maryland

Transcription

1 Multiple Messengers and Challenges in Astroparticle Physics, October 6-17, 2014 Eun-Suk Seo Inst. for Phys. Sci. & Tech. and Department of Physics University of Maryland

2 Hess Centennial: Discovery of Cosmic Rays In 1912 Victor Hess discovered cosmic rays with an electroscope onboard a balloon Reached only ~ 17,000 ft but measured an increase in the ionization rate at high altitude (1936 Nobel Prize in Physics for this work) Discoveries of new particles in cosmic rays - Positrons by Anderson in 1932 (Nobel 36) - Muons by Neddermeyer & Anderson in Pions by Powell et al. in 1947 (Nobel 50) -... "Direct Measurements of Cosmic Rays Using Balloon Borne Experiments," E. S. Seo, Invited Review Paper for Topical Issue on Cosmic Rays, Astropart. Phys., 39/40, 76-87, Cosmic Rays Eun-Suk Seo 2

3 Cosmic Rays Eun-Suk Seo 3

4 How do cosmic accelerators work? BESS Super TiGER ATIC & CREAM Elemental Charge Relative abundances range over 11 orders of magnitude Detailed composition limited to less than ~ 10 GeV/nucleon AMS ground based Indirect measurements Cosmic Rays Eun-Suk Seo 4

5 SOURCES SNRs, shocks Superbubbles photon emission acceleration Halo Exotic Sources: Disk: sources, gas Antimatter Dark matter etc.. escape X, γ e - P He C, N, O etc. Z = 1-92 e - Energy losses Reacceleration Diffusion Convection P He C, N, O etc. Interstellar medium π e + e - + gas p π B γ gas o π Synchrotron Inverse Compton Bremstrahlung γ B Be 10 Be Chandra Fermi CGRO Voyager ACE ATIC BESS AMS CREAM Cosmic Rays Eun-Suk Seo 5

6 Search for the existence of Antimatter in the Universe The Big Bang was preceded by vacuum. Nothing exists in a vacuum. After the Big Bang there must have been equal amounts of matter and antimatter. What happened to the antimatter? Cosmic Rays Eun-Suk Seo 6

7 We do not know what 95% of the universe is made of! Weakly Interacting Massive Particles (WIMPS) could comprise dark matter. This can be tested by direct search for various annihilating products of WIMP s in the Galactic halo. Indirect Detection χ q χ q Particle Colliders GMm r 2 = mv r r 2 2 v = v GM r Direct Detection Cosmic Rays Eun-Suk Seo 7

8 BESS-Polar II Balloon borne Experiment with a Superconducting Spectrometer Abe et al. PRL, 108, , Antiproton Flux (m -2 sr -1 s -1 GeV -1) β 1 Rigidity Kinetic Energy (GeV) Original BESS instrument was flown nine times between 1993 and New BESS-Polar instrument flew from Antarctica in 2004 and 2007 Polar I: 8.5 days observation Polar II 24.5 day observation, 4700 M events 7886 antiprotons detected: no evidence of primary antiprotons from evaporation of primordial black holes. Cosmic Rays Eun-Suk Seo 8

9 BESS-Polar II Balloon borne Experiment with a Superconducting Spectrometer Phys. Rev. Lett., 108, , 2012 x 1/10 X 1/ x 10-8 Cosmic Rays Eun-Suk Seo 9

10 BESS Balloon borne Experiment with a Superconducting Spectrometer Fuke et al. PRL 95, , 2005 Secondary D probability is negligible at low energies due to kinematics Any observed D almost certainly has a primary origin! D 95% upper limit (first reported) 1.92 x 10-4 (m 2 s sr GeV/n) -1 Cosmic Rays Eun-Suk Seo 10

11 Charge-sign Dependent Solar Modulation Asaoka et al., PRL 88, , 2001 Antiproton /proton Ratio Cosmic Rays Eun-Suk Seo 11

12 Voyager 1 in Interstellar Space E. C. Stone, ICRC 2013 Cosmic Rays Eun-Suk Seo 12

13 From MASS to PAMELA e - - p e + p He,... Matter Antimatter Superconducting Spectrometer (MASS) 1989 balloon flight in Canada GF ~21.5 cm 2 sr Mass: 470 kg Size: 130x70x70 cm3 Payload for Anti-Matter Exploration and Lightnuclei Astrophysics (PAMELA) satellite Launch 6/15/06 Cosmic Rays Eun-Suk Seo 13

14 Payload for Anti-Matter Exploration and Light-nuclei Astrophysics (PAMELA) High energy data deviate significantly from predictions of secondary production models (curves), and may constitute the evidence of dark matter particle annihilations, or the first observation of positron production from near-by pulsars. Cited > 300 times in ~ 1 yr Adriani et al., Nature, 458, (2009) Adriani et al., PRL, 106, (2011) Cosmic Rays Eun-Suk Seo 14

15 AMS Alpha Magnet Spectrometer Launch for ISS on May 16, 2011 Search for dark matter by measuring positrons, antiprotons, antideuterons and γ-rays with a single instrument Search for antimatter on the level of < 10-9 Precision Measurements Magnet 0.9Tm 2 TOF resolution 120 ps Tracker resolution 10µ TRD h/e rejection O(10 2 ) EM calorimeter h/e rejection O(10 4 ) RICH h/e rejection O (10 3 ) First Result: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of GeV Aguilar et al., PRL 110, , 2013 Cosmic Rays Eun-Suk Seo 15

16 "With AMS and with the LHC to restart in the near future at energies never reached before, we are living in very exciting times for particle physics as both instruments are pushing boundaries of physics, said CERN Director-General Rolf Heuer. Cosmic Rays Eun-Suk Seo 16

17 Latest AMS Results: Comparison with Models Accardo et al., Phys. Rev. Lett., 113, , 2014 Aguilar et al., Phys. Rev. Lett., 113, , 2014 Cosmic Rays Eun-Suk Seo 17

18 AMS Alpha Magnet Spectrometer ~16 billion events per year Flight data Tracker Monte Carlo Simulations Cosmic Rays Eun-Suk Seo 18

19 ATIC Advanced Thin Ionization Calorimeter Seo et al. Adv. in Space Res., 19 (5), 711, 1997; Ganel et al. NIM A, 552(3), 409, 2005 Beam test: electrons Beam measurements for 150 GeV electrons show 91% containment of incident energy, with a resolution of 2% at 150 GeV Proton containment ~38% Flight Data Cosmic Rays Eun-Suk Seo 19

20 ATIC discovers mysterious excess of high energy electrons Chang et al., Nature, 456, (2008) Cited > 200 times in ~ 9 mo 620 GeV Kaluza-Klein particle boosting factor 230 ATIC 1+2, AMS, HEAT BETS, PPB- BETS, Emulsion chambers Cosmic Rays Eun-Suk Seo 20

21 Ahn et al. (CREAM Collaboration) ApJ 714, L89, γ Tracker LAT Highly granular multi-layer Si striptracker (1.5 X 0 ) Finely segmented fully active CsI Calorimeter (8.6 X 0 ) Highly efficient hermetic Anti- Coincidence Detector (ACD) ACD e + e Calorimeter Latronico, Fermi Symposium, 2009 Abdo, A. A. et al., PRL 102, , 2009 Cited > 150 times in ~ 1 yr Cosmic Rays Eun-Suk Seo 21

22 CALET Calorimetric Electron Telescope Launch target JY mm Shower particles Charge Detector (Charge Z=1-40) 1 Layer of 14 Plastic Scintillators ( 32 x 10 x 450 mm 3 ) Imaging Calorimeter (Particle ID, Direction) Total Thickness of Tungsten (W) : 3 X 0 Layer Number of Scifi Belts: 8 Layers 2(X,Y) Total Absorption Calorimeter (Energy Measurement, Particle ID) PWO 20 mm x 20 mm x 320 mm Total Depth of PWO: 27 X 0 (24 cm) Cosmic Rays Eun-Suk Seo 22

23 Cosmic Ray Electron-Synchrotron Telescope (CREST) CREST Detector A 2 x 2 m array of diameter BF 2 crystals. CREST identifies UHE electrons by observing the characteristic linear trail of synchrotron gamma rays generated as the electron passes through the Earth s magnetic field - This results in effective detector area much larger than the physical instrument size CREST had its first LDB flight over Antarctica in the season Upgrade of CREST for ULDB operation in plan. Expected result: 100-day CREST exposure Cosmic Rays Eun-Suk Seo 23

24 Transition Radiation Array for Cosmic Energetic Radiation (TRACER) 1.2 m 2 m SIGNAL (arb. units) Cherenkov de/dx TRD LORENTZ FACTOR γ ENERGY RESPONSE: Acrylic Cherenkov Counter (γ < 10) Specific Ionization in Gas (4 < γ < 1000) Transition Radiation Detector (γ > 400) 2003 ANTARCTICA 14 days OXYGEN (Z=8) to IRON (Z=26) 2006 SWEDEN CANADA 4.5 days BORON (Z=5) to IRON (Z=26) Cosmic Rays Eun-Suk Seo 24 24

25 Cosmic Rays Eun-Suk Seo 25 CREAM Cosmic Ray Energetics And Mass Seo et al. Adv. in Space Res., 33 (10), 1777, 2004; Ahn et al., NIM A, 579, 1034, 2007 Transition Radiation Detector (TRD) and Tungsten Scintillating Fiber Calorimeter - In-flight cross-calibration of energy scales Complementary Charge Measurements - Timing-Based Charge Detector - Cherenkov Counter - Pixelated Silicon Charge Detector The CREAM instrument has had six successful Long Duration Balloon (LDB) flights and have accumulated 161 days of data. This longest known exposure for a single balloon project verifies the instrument design and reliability.

26 Balloon Flights in Antarctica Offer Hands-On Experience CREAM has produced >12 Ph.D. s Typical duration: ~1 month/flight Seo s lab at UMD The instruments are for the most part built inhouse by students and young scientists, many of them currently working in the on-campus laboratory. Instruments are fully recovered, refurbished & reflown. Seo s lab at UMD Cosmic Rays Eun-Suk Seo 26

27 Elemental Spectra over 4 decades in energy Yoon et al. ApJ 728, 122, 2011; Ahn et al., ApJ 715, 1400, 2010; Ahn et al. ApJ 707, 593, 2009 Excellent charge resolution from SCD PAMELA Results (Sparvoli, ISCRA 2012) Distribution of cosmic-ray charge measured with the SCD. The individual elements are clearly identified with excellent charge resolution. The relative abundance in this plot has no physical significance Cosmic Rays Eun-Suk Seo 27

28 CREAM spectra harder than prior lower energy measurements Yoon et al. ApJ 728, 122, 2011; Ahn et al. ApJ 714, L89, 2010 He γ CREAM = 2.58 ± 0.02 PAMELA (Adriani et al., Science 332, 69, 2011) AMS-02 (Choutko et al., #1262; Haino et al. #1265, ICRC, Rio de Janeiro, 2013) γ AMS-01 = 2.74 ± 0.01 CREAM-I γ P = 2.66 ± 0.02 γ He = 2.58 ± 0.02 (Ahn et al., ApJ 714, L89, 2010) CREAM C-Fe γ < 200 GeV/n = 2.77 ± 0.03 γ > 200 GeV/n = 2.56 ± 0.04 It provides important constraints on cosmic ray acceleration and propagation models, and it must be accounted for in explanations of the electron anomaly and cosmic ray knee. Cosmic Rays Eun-Suk Seo 28

29 Cosmic Rays Eun-Suk Seo 29 Taking into account the spectral hardening of elements for the (AMS/PAMELA/ATIC/FERMI) high energy e + e - enhancement Yuan & Bi, Phys. Lett. B, 727, 1, 2013 & Yuan et al. arxiv: , 2013

30 CREAM solves the puzzle with the knee and beyond T. K. Gaisser, T. Stanev and S. Tilav, Front. Phys. 8(6), 748, 2013 S. Tilav s presentation, TeV Particle Astrophysics, Irvine, CA, August 2013 Acceleration limit: E max_z = Ze x R = Z x E max_p, where rigidity R = Pc/Ze Cosmic Rays Eun-Suk Seo 30

31 Cosmic Rays Eun-Suk Seo Cosmic Ray Propagation Consider propagation of CR in the interstellar medium with random hydromagnetic waves. Steady State Transport Eq.: The momentum distribution function f is normalized as where N is CR number density, D: spatial diffusion coefficient, σ: cross section Cosmic ray intensity Escape length Xe Reacceleration parameter α E. S. Seo and V. S. Ptuskin, Astrophys. J., 431, , { } k j k jk j j ion j j j e j I m Q I dx de de d I m X I < + = σ ρ α σ 0,... < + = j k jk j j ion j j j j j j S q f dt dp p p p p f K p p p f v m z f D z, σ ρ f N dp p = 2 ) ( ) ( 0 2 p f p A E I j j j = 31

32 What is the history of cosmic rays in the Galaxy? Ahn et al. (CREAM collaboration) Astropart. Phys., 30/3, , 2008 Measurements of the relative abundances of secondary cosmic rays (e.g., B/C) in addition to the energy spectra of primary nuclei will allow determination of cosmic-ray source spectra at energies where measurements are not currently available This first B/C ratio at such high energies will distinguish among propagation models X e δ R Cosmic Rays Eun-Suk Seo 32

33 ISS-CREAM: CREAM for the ISS E. S. Seo et al, Advances in Space Research, 53/10, 1451, 2014 JEM-EF #2 To be installed on the ISS in 2015 by Space X Mass: ~1400 kg Power: ~ 550 W Nominal data rate: ~350 kbps Building on the success of the balloon flights, the payload is being transformed for accommodation on the ISS (NASA s share of JEM-EF). Increase the exposure by an order of magnitude ISS-CREAM will measure cosmic ray energy spectra from to >10 15 ev with individual element precision over the range from protons to iron to: - Probe cosmic ray origin, acceleration and propagation. - Search for spectral features from nearby/young sources, acceleration effects, or propagation history. Cosmic Rays Eun-Suk Seo 33

34 Cosmic Rays Eun-Suk Seo 34 CREAM Instrument Ahn et al., NIM A, 579, 1034, 2007; Anderson et al., Hyun et al., & Seo et al. 33 rd ICRC, 2013 Silicon Charge Detector (SCD) Precise charge measurements with charge resolution of ~ 0.2e 4 layers of 79 cm x 79 cm active area (2.12 cm 2 pixels) Carbon Targets Induces hadronic interactions Top/Bottom Counting Detector (T/BCD) Plastic scintillator instrumented with an array of 20 x 20 photodiodes for e/p separation Independent trigger Calorimeter 20 layers of alternating tungsten plates and scintillating fibers Determines energy Provides tracking and trigger Boronated Scintillator Detector (BSD) Additional e/p separation by detection of thermal neutrons

35 Data Flow & Science Operations TDRSS Ethernet & MIL-STD-1553 CREAM S band Low rate (up/down) 30 kbps monitoring 1 kbps cmd Ku band High rate 10 Mbps (down) White Sands, NM Huntsville Operations Support Center (MSFC) Payload Operations and Integration Center (POIC) Maintains databases for commands and telemetry Holds recorded data for 2 yrs Data Commands Research Data Center (UMD) Data Server Data Backup, Archive & Processing Level-0 data Level-1 data Level-2 data Web Server Data Distribution Science Operation Center (UMD) Data Plots Software Toolkit for Ethernet Lab-Like Architecture (STELLA) Raw Data Real-time data Playback data Data relay Data Monitoring Command & Playback Request Data Verification Event Display Cosmic Rays Eun-Suk Seo 35

36 ISS-CREAM takes the next major step The ISS-CREAM space mission can take the next major step to ev, and beyond, limited only by statistics. The 3-year goal, 1-year minimum exposure would greatly reduce the statistical uncertainties and extend CREAM measurements to energies beyond any reach possible with balloon flights. ISS-CREAM Cosmic Rays Eun-Suk Seo 36

37 Cosmic Ray Observatory on the ISS AMS Launch May 16, 2011 ISS-CREAM Sp-X Launch 2015 JEM-EUSO CALET on JEM HTV Launch 2015 Launch Tentatively planned for >2018 Cosmic Rays Eun-Suk Seo 37

38 Thank you! Cosmic Rays Eun-Suk Seo 38