PAMELA Space Mission Antimatter and Dark Matter Research Piergiorgio Picozza INFN & University of Rome “ Tor Vergata”, Italy TeV Particle Astrophysics September, 2008 Beijing, China

Robert L. Golden

AMS PAMELA AMS in Space Accelerators The Big Bang origin of the Universe requires matter and antimatter to be equally abundant at the very hot beginning Search for the existence of anti Universe Search for the origin of the Universe Search for the existence of Antimatter in the Universe

Antimatter Direct research Antimatter which has escaped as a cosmic ray from a distant antigalaxy Antimatter which has escaped as a cosmic ray from a distant antigalaxy Sreitmatter, R. E., Nuovo Cimento, 19, 835 (1996) Antimatter from globular clusters of antistars in our Galaxy as antistellar wind or anti-supernovae explosion Antimatter from globular clusters of antistars in our Galaxy as antistellar wind or anti-supernovae explosion K. M. Belotsky et al., Phys. Atom. Nucl. 63, 233 (2000), astro-ph/

4% 23% 73%

(GLAST AMS-02)‏ Signal (supersymmetry)… … and background

Antimatter and Dark Matter Research - BESS (93, 95, 97, 98, 2000) - Heat (94, 95, 2000) -IMAX (96) -BESS LDF (2004, 2007) -AMS-01 (1998) Wizard Collaboration - MASS – 1,2 (89,91) - TrampSI (93) -CAPRICE (94, 97, 98)

Antimatter “We must regard it rather an accident that the Earth and presumably the whole Solar System contains a preponderance of negative electrons and positive protons. It is quite possible that for some of the stars it is the other way about” P. Dirac, Nobel lecture (1933)‏

Secondary production Bergström et al. ApJ 526 (1999) 215 Secondary production (upper and lower limits)‏ Simon et al. ApJ 499 (1998) 250. from χχ annihilation (Primary production m(c) = 964 GeV) Ullio : astro- ph/ P

CR antimatter Antiprotons Positrons CR + ISM  ± + x   ± + x  e ± + x CR + ISM   0 + x    e ± ___ Moskalenko & Strong 1998 Positron excess? Charge-dependent solar modulation Solar polarity reversal 1999/2000 Asaoka Y. Et al ¯ + CR + ISM  p-bar + … kinematic treshold: 5.6 GeV for the reaction Present status

What do we need? Measurements at higher energies Measurements at higher energies Better knowledge of background Better knowledge of background High statistic High statistic Continuous monitoring of solar modulation Continuous monitoring of solar modulation Long Duration Flights Long Duration Flights

PAMELA Payload for Antimatter Matter Exploration and Light Nuclei Astrophysics

Pamela as a Space Observatory at 1AU Study of solar physics and solar modulation Study of terrestrial magnetosphere Study of high energy electron spectrum (local sources?) Search for dark matter annihilation Search for antihelium (primordial antimatter)‏ Search for new Matter in the Universe (Strangelets?) Study of cosmic-ray propagation

PAMELA Collaboration Moscow St. Petersburg Russia: Sweden: KTH, Stockholm Germany: Siegen Italy: BariFlorenceFrascatiTriesteNaplesRome CNR, Florence

PAMELA Instrument GF ~21.5 cmsr GF ~21.5 cm 2 sr Mass: 470 kg Mass: 470 kg Size: 130x70x70 cm Size: 130x70x70 cm 3

Energy range Antiproton flux 80 MeV GeV Positron flux 50 MeV – 270 GeV Electron/positron fluxup to 2 TeV (from calorimeter) Electron flux up to 400 GeV Proton flux up to 700 GeV Light nuclei (up to Z=6) up to 200 GeV/n He/Be/C: Antinuclei search Sensitivity of O(10 -8 ) in He-bar/He Design performance Unprecedented statistics and new energy range for cosmic ray physics Simultaneous measurements of many species

Resurs-DK1 satellite Mass: 6.7 tonnes Height: 7.4 m Solar array area: 36 m 2  Main task: multi-spectral remote sensing of earth’s surface  Built by TsSKB Progress in Samara, Russia  Lifetime >3 years (assisted)  Data transmitted to ground via high-speed radio downlink  PAMELA mounted inside a pressurized container

PAMELA Launch 15/06/06 16 Gigabytes trasmitted daily to Ground NTsOMZ Moscow

Orbit Characteristics    km  km SAA Low-earth elliptical orbit 350 – 610 km Quasi-polar (70 o inclination) SAA crossed

– 15/02/ :35:00 MWT S1 S2 S3 Inner radiation belt (SSA)‏ orbit 3752 orbit 3753 orbit 3751 NP SP EQ EQ Outer radiation belt 95 min PAMELA Orbit

Flight data: GeV/c antiproton annihilation

Flight data: GeV/c antiproton annihilation

PAMELA Status ~630 days of data taking (~73% live- time) ~630 days of data taking (~73% live- time) ~10 TByte of raw data downlinked ~10 TByte of raw data downlinked >10 9 triggers recorded and under analysis >10 9 triggers recorded and under analysis

Antiprotons

Flight data: 84 GeV/c interacting antiproton

PAMELA Protons Spillover

Antiproton-Proton Ratio PAMELA Preliminary

Antiproton to proton ratio Preliminary

Antiproton to proton ratio

Preliminary

Positrons

Flight data: 92 GeV/c positron

Mirko Boezio, INFN Trieste - San Diego IEEE2006 Flight data: 36 GeV/c interacting proton

Positron selection with calorimeter Preliminary p (non-int) e-e-e-e- e+e+e+e+ Fraction of charge released along the calorimeter track (left, hit, right) p (int) Rigidity: GV

Positron selection with calorimeter e-e-e-e- Fraction of charge released along the calorimeter track (left, hit, right) p e+e+e+e+ + Energy-momentum match Starting point of shower Rigidity: GV Preliminary

Positron selection with calorimeter e-e-e-e- Fraction of charge released along the calorimeter track (left, hit, right) p e+e+e+e+ + Energy-momentum match Starting point of shower Longitudinal profile Rigidity: GV Preliminary

Positron selection with calorimeter p e-e-e-e- e+e+e+e+ p Flight data: rigidity: GV Fraction of charge released along the calorimeter track (left, hit, right) Test beam data Momentum: 50GeV/c e-e-e-e- e-e-e-e- e+e+e+e+ Energy-momentum match Starting point of shower

Positron selection e-e-e-e- p e-e-e-e- e+e+e+e+ p Neutrons detected by ND Rigidity: GV Fraction of charge released along the calorimeter track (left, hit, right) e+e+e+e+ Energy-momentum match Starting point of shower

Positron to Electron Fraction Mirko Boezio, IDM2008, 2008/08/20 Secondary production Moskalenko & Strong ApJ 493 (1998) 694

Positron to Electron Fraction Preliminary!!! End 2007: ~ positrons total Charge sign dependent solar modulation

Positrons with HEAT

Kinetic Energy (GeV) Flux (p/cm^2 sr s) Proton flux July 2006

Galactic H and He spectra Preliminary !!!

Challenges Solar Modulation at low energies Solar Modulation at low energies Charge-sign dependence of solar modulation Charge-sign dependence of solar modulation Background calculation Background calculation

Solar Modulation of galactic cosmic rays BESS Caprice / Mass /TS93 AMS-01 Pamela Continuous monitoring Continuous monitoring of solar activity Study of charge sign dependent effects Study of charge sign dependent effects Asaoka Y. et al. 2002, Phys. Rev. Lett. 88, ), Asaoka Y. et al. 2002, Phys. Rev. Lett. 88, ), Bieber, J.W., et al. Physi- cal Review Letters, 84, 674, Bieber, J.W., et al. Physi- cal Review Letters, 84, 674, J. Clem et al. 30th ICRC 2007

Solar modulation Interstellar spectrum July 2006 August 2007 February 2008 Decreasing solar activity Increasing GCR flux sun-spot number Ground neutron monitor PAMELA (statistical errors only)

A > 0 Positive particles A < 0 ¯ + ¯ + Pamela 2006 (Preliminary!) Charge dependent solar modulation

Charge sign dependence of cosmic ray modulation. Two systematic deviations from reflection symmetry of the interplanetary magnetic field: Two systematic deviations from reflection symmetry of the interplanetary magnetic field: 1) The Parker field has opposite magnetic polarity above and below the equator, but the spiral field lines themselves are mirror images of each other. This antisymmetry produces drift velocity fields that for positive particles converge on the heliospheric equator in the A + state or diverge from it in A - state. 1) The Parker field has opposite magnetic polarity above and below the equator, but the spiral field lines themselves are mirror images of each other. This antisymmetry produces drift velocity fields that for positive particles converge on the heliospheric equator in the A + state or diverge from it in A - state. Negatively charged particles behave in the opposite manner and the drift patterns interchange when the solar polarity diverge. Negatively charged particles behave in the opposite manner and the drift patterns interchange when the solar polarity diverge. 2) Systematic ordering of turbulent helicity can cause diffusion coefficients to depend directly on charge sign and polarity state. Bieber, J.W., et al. Phys. Rev. Letters, 84, 674, ) Systematic ordering of turbulent helicity can cause diffusion coefficients to depend directly on charge sign and polarity state. Bieber, J.W., et al. Phys. Rev. Letters, 84, 674, 1999.

Radiation Belts South Atlantic Anomaly Secondary production from CR interaction with atmosphere

Pamela maps at various altitudes PRELIMINARY !!!! Altitude scanning

Primary and Albedo (sub-cutoff measurements) ‏

Size of SAA for altitudes between km Altitudes changes from 350 to 600km Longitude Latitude B<0.21Gs, L-shell <1.2

Proton spectrum in SAA, polar and equatorial regions

e + /e - ratio in the equatorial region (L 0.25)

Differential energy spectra of secondary electron and positron fluxes at the geomagnetic equator (L 0.25) Fluxx Flux (a.u.)

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 December 13th 2006 He differential spectrum

Diffusion Halo Model

Flight data: 14.7 GV Interacting nucleus (Z = 8)‏

Secondaries / primaries i.e. Boron/ Carbon to constrain propagation parameters D. Maurin, F. Donato R. Taillet and P.Salati ApJ, 555, 585, 2001 [astro-ph/ ] F. Donato et.al, ApJ, 563, 172, 2001 [astro-ph/ ] Astrophysic B/C constraints Nuclear cross sections!! B/C Ratio Antiproton flux

B/C selected experiments

Preliminary Results B/C Preliminary

Helium and Hydrogen Isotopes

Secondary to Primary ratios

High Energy electrons The study of primary electrons is especially important because they give information on the nearest sources of cosmic rays The study of primary electrons is especially important because they give information on the nearest sources of cosmic rays Electrons with energy above 100 MeV rapidly loss their energy due to synchrotron radiation and inverse Compton processes Electrons with energy above 100 MeV rapidly loss their energy due to synchrotron radiation and inverse Compton processes The discovery of primary electrons with energy above eV will evidence the existence of cosmic ray sources in the nearby interstellar space (r  300 pc) The discovery of primary electrons with energy above eV will evidence the existence of cosmic ray sources in the nearby interstellar space (r  300 pc)

A calorimeter self-triggering showering event. Note the high energy release in the core of the shower and the high number (26) neutrons detected. CALO SELF TRIGGER EVENT: 167*10 3 MIP RELEASED 279 MIP in S4 26 Neutrons in ND

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. i.A stable, single “super nucleon” with three types of quarks ii. “Neutron” stars may be one big strangelet Carbon Nucleus Strangelet u d s sdd s s u d u d uu d d s u s uu d dd d d d u u u u s u s s s d d u u u d u u d d d u u u d d d u d d u d d u d d u u u d u u d u u d p n AMS courtesy Search for New Matter in the Universe:

MANY THANKS! pamela.roma2.infn.it