Antiparticle detection in space for dark matter search: the PAMELA experiment. Piergiorgio Picozza INFN and University of Rome Tor Vergata XCVI Congresso Nazionale della Società Italiana di Fisica Bologna 20 24 Settembre 2010
PAMELA Payload for Antimatter Matter Exploration and Light Nuclei Astrophysics
PAMELA Collaboration Italy: Bari Florence Frascati Naples Rome Trieste CNR, Florence Russia: Moscow St. Petersburg Germany: Siegen Sweden: KTH, Stockholm
The Physics of PAMELA Search for dark matter annihilation Search for antihelium (primordial antimatter) Search for new Matter in the Universe (Strangelets?) Study of cosmic-ray propagation Study of solar physics and solar modulation Study of terrestrial magnetosphere
PAMELA Instrument GF ~21.5 cm 2 sr Mass: 470 kg Size: 130x70x70 cm 3
PAMELA Instrument
Design Performance Energy range Antiprotons 80 MeV - 190 GeV Positrons 50 MeV 300 GeV Electrons up to 500 GeV Protons up to 1 TeV Helium up to 400 GeV/n Electrons+positrons up to 2 TeV (from calorimeter) Light Nuclei (Li/Be/B/C) up to 200 GeV/n AntiNuclei search sensitivity of 3x10-8 in He/He
PAMELA Launch 15/06/06 16 Gigabytes trasmitted daily to Ground NTsOMZ Moscow
Orbit Characteristics SAA 350 km 70 ο Low-earth elliptical orbit 350 610 km Quasi-polar (70 o inclination) SAA crossed 610 km
Download @orbit 3754 15/02/2007 07:35:00 MWT Outer radiation belt NP SP S1 Inner radiation belt (SSA) EQ 95 min EQ S2 S3 orbit 3751 orbit 3752 orbit 3753 Mirko Boezio, COSPAR, Bremen, 2010/07/18
Particle ID with PAMELA
Flight data: 0.171 GV positron Flight data: 0.169 GV electron
Flight data: 0.632 GeV/c antiproton annihilation
Flight data: 92 GeV/c positron
Antiproton / Positron Identification Time-of-flight: trigger, albedo rejection, mass determination (up to 1 GeV) Bending in spectrometer: sign of charge Ionisation energy loss (de/dx): magnitude of charge Antiproton (NB: e - /p ~ 10 2 ) Interaction pattern in calorimeter: electron-like or proton-like, electron energy Positron (NB: p/e + ~10 3-4 )
PAMELA Status Till now: 1562 days in flight ~20 TBytes of raw data downlinked >2.10 9 triggers recorded and under analysis
Antiparticles with PAMELA
Astrophysics and Cosmology compelling Issues Apparent absence of cosmological Antimatter Nature of the Dark Matter that pervades the Universe
Search for the existence of Antimatter in the Universe PAMELA AMS in Space AMS Accelerators The Big Bang origin of the Universe requires matter and antimatter to be equally abundant at the very hot beginning
Antimatter Direct research Observation of cosmic radiation hold out the possibility of directly observing a particle of antimatter which has escaped as a cosmic ray from a distant antigalaxy, traversed intergalactic space filled by turbulent magnetic field, entered the Milky Way against the galactic wind and found its way to the Earth. Streitmatter, R. E., 24 th ICRC, Rome, Italy, 1995 Nuovo Cimento, 19, 835 (1996) High energy particle or antinuclei
THE UNIVERSE ENERGY BUDGET
Another possible scenario: KK Dark Matter Lightest Kaluza-Klein Particle (LKP): B (1) As in the neutralino case there are 1-loop processes that produces monoenergetic γ γ in the final state. Bosonic Dark Matter: fermionic final states no longer helicity suppressed. e+e - final states directly produced.
DM annihilations DM particles are stable. They can annihilate in pairs. Primary annihilation channels Decay Final states σ a = <σv>
e-
Antiparticle detection Where do positrons come from? Mostly locally within 1 Kpc, due to the energy losses by Synchrotron Radiation and Inverse Compton scattering Typical lifetime Antiprotons within 10 Kpc
Antiproton Flux (0.06 GeV - 180 GeV) Donato et al. (ApJ 563 (2001) 172) Systematics errors included Ptuskin et al. (ApJ 642 (2006) 902) Adriani et al., Phys. Rev. Lett. 105, 121101 (2010)
Antiproton to proton ratio (0.06 GeV - 180 GeV) Simon et al. (ApJ 499 (1998) 250) Ptuskin et al. (ApJ 642 (2006) 902) Donato et al. (PRL 102 (2009) 071301) Systematics errors included Adriani et al., Phys. Rev. Lett. 105, 121101 (2010)
Wino Dark Matter in a non-thermal Universe G. Kane, R. Lu, and S. Watson arxiv:0906.4765v3 [astro-ph.he)
Trapped antiprotons in SAA PAMELA Trapped GCR
Trapped antiprotons in SAA Trapped PAMELA GCR
Positron to Electron Fraction Secondary production Moskalenko & Strong 98 Adriani et al, Astropart. Phys. 34 (2010) 1 arxiv:1001.3522 [astro-ph.he]
A Challenging Puzzle for CR Physics P.Blasi, PRL 103 (2009) 051104; arxiv:0903.2794 Y. Fujita arxiv.0904.5298 Positrons (and electrons) produced as secondaries in the sources (e.g. SNR) where CRs are accelerated. But also other secondaries are produced: significant increase expected in the p/p and B/C ratios. I. Cholis et al., Phys. Rev. D 80 (2009) 123518; arxiv:0811.3641v1 Contribution from DM annihilation. D. Hooper, P. Blasi, and P. Serpico, JCAP 0901:025,2009; arxiv:0810.1527 Contribution from diffuse mature &nearby young pulsars.
A Challenging Puzzle for Dark Matter Interpretation
All three ATIC flights are consistent Preliminary Preliminary ATIC 1+2+4 ATIC 1 ATIC 2 ATIC 4 Source on/source off significance of bump for ATIC1+2 is about 3.8 sigma J Chang et al. Nature 456, 362 (2008) ATIC-4 with 10 BGO layers has improved e, p separation. (~4x lower background) Bump is seen in all three flights. Significance for ATIC1+2+4 is 5.1 sigma
Example: DM I. Cholis et al. arxiv:0811.3641v1 I. Cholis et al. arxiv:0811.3641v1 See Neal Weiner s talk
Fermi (e + + e - ) M. Ackermann et al. astro-ph 1008.3999
Fermi (e + + e - ) Di Bernardo et al. astro-ph 0912.3887
Fermi (e + + e - ) and PAMELA ratio Bergstrom et al. astro-ph 0905.0333v1
PAMELA Cosmic Ray Spectra
Cosmic Rays Propagation in the Galaxy
Standard Positron Fraction Theoretical Uncertainties γ = 3.54 γ = 3.34 T. Delahaye et al., arxiv: 0809.5268v3
Electron (e - ) Spectrum
All electrons PAMELA very preliminary
Proton and Helium spectra p He
Proton flux
Boron Spectrum
Carbon Spectrum
Preliminary Preliminary C/O ratio
Solar Modulation of galactic cosmic rays Study of charge sign dependent effects Asaoka Y. et al. 2002, Phys. Rev. Lett. 88, 051101), Bieber, J.W., et al. Physi-cal Review Letters, 84, 674, 1999. J. Clem et al. 30th ICRC 2007 U.W. Langner, M.S. Potgieter, Advances in Space Research 34 (2004) Pamela AMS-01 Caprice / Mass /TS93 BESS
Time Dependence of PAMELA Proton Flux
Time Dependence of PAMELA Electron (e - ) Flux
Charge dependent solar modulation + + Pamela 2006 (Preliminary!) A > 0 A < 0 Positive particles
Gradients in the Heliosphere, PAMELA & ULYSSES Mirko Boezio, COSPAR, Bremen, 2010/07/18
Gradients in the Heliosphere, PAMELA & ULYSSES Comparison of the proton flux measured between 1.5 and 1.57GV by PAMELA and ULYSSES as a function of time Mirko Boezio, COSPAR, Bremen, 2010/07/18
Gradients in the Heliosphere, PAMELA & ULYSSES Comparison of the proton flux measured between 1.5 and 1.57GV by PAMELA and ULYSSES as a function of time Mirko Boezio, COSPAR, Bremen, 2010/07/18
December 2006 Solar particle events Dec 13 th largest CME since 2003, anomalous at sol min
December 13th 2006 event Preliminary!
December 13th 2006 He differential spectrum Preliminary!
Preliminary! December 14th 2006 event X-ray P,e- Low energy tail of Dec 13th event Arrival of event of Dec 14th Magnetic Field Solar Quiet spectrum Neutron Monitor Below galactic spectrum: Start of Forbush decrease End of event of Dec 14th Decrease of primary spectrum Arrival of magnetic cloud from CME of Dec 13th Shock 1774km/s (gopalswamy, 2007) Decrease of Neutron Monitor Flux
Radiation Belts South Atlantic Anomaly Secondary production from CR interaction with atmosphere
Study terrestrial magnetosphere Pamela World Maps: 350 650 km alt 36 MeV p, 3.5 MeV e-
Subcutoff particles
Proton spectrum in SAA, polar and equatorial regions
Other Objectives
Search for New Matter in the Universe: An example is the search for strangelets. There are six types of Quarks found in accelerators. All matter on Earth is made out of only two types of quarks. Strangelets are new types of matter composed of three types of quarks which should exist in the cosmos. Carbon Nucleus p u u d u u d u u d d d u d d u d d u u d u d d u u u d n d d u u d u d d u Strangelet d s u d s s d u s u u u s s d d u s uu s d d d d d u u s s d ud u d i. A stable, single super nucleon with three types of quarks ii. Neutron stars may be one big strangelet AMS courtesy
Thanks! http:// pamela.roma2.infn.it