Antimatter in Antimatter in SpaceSpace

Mirko BoezioINFN Trieste, Italy

PPC 2010 - TorinoJuly 14th 2010

Astrophysics and Cosmology Astrophysics and Cosmology compelling Issuescompelling Issues

• Apparent absence of cosmological Antimatter

• Nature of the Dark Matter that pervades the Universe

CR + ISM p-bar + …kinematic treshold: 5.6 GeV for the reaction

Background:CR interaction with ISMCR + ISM p-bar + …

leaky box

dinamic halo

m=20GeVTilka 89

Balloon data : Positron fraction before Balloon data : Positron fraction before 19901990

What about heavy What about heavy antinuclei?antinuclei?

• The discovery of one nucleus of antimatter (Z≥2) in the cosmic rays would have profound implications for both particle physics and astrophysics.

o For a Baryon Symmetric Universe Gamma rays

limits put any domain of antimatter more than 100

Mpc away

(Steigman (1976) Ann Rev. Astr. Astrophys., 14, 339; Dudarerwicz and Wolfendale

(1994) M.N.R.A. 268, 609, A.G. Cohen, A. De Rujula and S.L. Glashow, Astrophys.

J. 495, 539, 1998)

Antimatter Search: current Antimatter Search: current limitslimits

P. Gondolo, IDM 2008

DM annihilationsDM particles are stable. They can annihilate in pairs.

Primary annihilation channels Decay Final states

σσa= <= <σσv>v>

Antimatter and Dark Matter Research

BESS (93, 95, 97, 98, BESS (93, 95, 97, 98,

2000)2000)

Heat (94, 95, 2000)Heat (94, 95, 2000)

IMAX (96) IMAX (96)

BESS LDF (2004, 2007)BESS LDF (2004, 2007)

AMS-01 (1998)AMS-01 (1998)

Wizard Collaboration

MASS – 1,2 (89,91)MASS – 1,2 (89,91)

TrampSI (93)TrampSI (93)

CAPRICE (94, 97, 98)CAPRICE (94, 97, 98)

PAMELA (2006-)PAMELA (2006-)

CR antimatterAntiprotons 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. 2002

¯

+

CR + ISM p-bar + …kinematic treshold: 5.6 GeV for the reaction

pppppp

Status in 2006

What do we need?

• Measurements at higher energies

• Better knowledge of background

• High statistic

• Continuous monitoring of solar modulation

Long Duration Flights

Antimatter Missions in Space

PAMELA15-06-2006

AMS-022010/2011

GAPS2013

AMS-011998

AALPHA MMAGNETIC SSPECTROMETER

Search for primordial anti-matter Indirect search of dark matter High precision measurement of the energetic spectra and composition of CR from GeV to TeV

AMS-01: 1998 (10 days)PRECURSOR FLIGHT ON THE SHUTTLE

AMS-02: 2010/2011 COMPLETE CONFIGURATION FOR SEVERAL YEARS LIFETIME ON THE ISS

» 500 physicists, 16 countries, 56 Institutes

AMS-01 : the detector AMS-01 : the detector

• Acceptance: » 0.15 m2sr • Bending power » 0.14 Tm2

• TOF : trigger + e dE/dx meas.• Tracker: sign Z + Rigidità + dE/dx meas.• Cherenkov: separatione e/p up to ~ 3 GeV.

The Completed AMS Detector on ISSTransition Radiation

Detector (TRD)

Silicon Tracker

Electromagnetic Calorimeter (ECAL)

Magnet

Ring Image Cerenkov Counter (RICH)

Time of Flight Detector (TOF)

Size: 3m x 3m x 3mWeight: 7 tons

AMS-02 new configuration

PAMELAPPayload for ayload for AAntimatter ntimatter MMatter atter EExploration xploration

and and LLight Nucleiight Nuclei AAstrophysicsstrophysics

PAMELA Collaboration

Scientific goalsScientific goals• Search for dark matter annihilation

• Search for antihelium (primordial antimatter)• Search for new Matter in the Universe

(Strangelets?)

• Study of cosmic-ray propagation (light nuclei and isotopes)

• Study of electron spectrum (local sources?)

• Study solar physics and solar modulation• Study terrestrial magnetosphere

Design Performance energy range

• Antiprotons 80 MeV - 190 GeV

• Positrons 50 MeV – 300 GeV

• Electrons up to 500 GeV

• Protons up to 700 GeV

• Electrons+positrons up to 2 TeV (from calorimeter)

• Light Nuclei (He/Be/C) up to 200 GeV/n • AntiNuclei search sensitivity of 3x10-8 in He/He

Simultaneous measurement of many cosmic-ray species New energy range Unprecedented statistics

• Resurs-DK1: multi-spectral imaging of earth’s surface• PAMELA mounted inside a pressurized container• Lifetime >3 years (assisted, first time February 2009) • Data transmitted to NTsOMZ, Moscow via high-speed radio downlink. ~16 GB per day

• Quasi-polar and elliptical orbit (70.0°, 350 km - 600 km)

• Traverses the South Atlantic Anomaly • Crosses the outer (electron) Van Allen belt at south pole

Resurs-DK1Mass: 6.7 tonnesHeight: 7.4 mSolar array area: 36 m2

350 km

610 km

70o

PAMELA

SAA

~90 mins

Resurs-DK1 satellite + orbit

Main antenna in NTsOMZ

Launch from Baikonur June 15th 2006, 0800 UTC.

‘First light’ June 21st 2006, 0300 UTC.

• Detectors operated as expected after launch• Different trigger and hardware configurations evaluated

PAMELA in continuous data-taking mode sincecommissioning phase ended on July 11th 2006

Trigger rate* ~25HzFraction of live time* ~ 75%Event size (compressed mode) ~5kB 25 Hz x 5 kB/ev ~ 10 GB/day(*outside radiation belts)

Till ~now:~1400 days of data taking~20 TByte of raw data downlinked>2x109 triggers recorded and analyzed(Data till January 2010 under analysis)

PAMELA milestones

PAMELA detectors

GF: 21.5 cm2 sr Mass: 470 kgSize: 130x70x70 cm3

Power Budget: 360W

Spectrometer microstrip silicon tracking system + permanent magnetIt provides:

- Magnetic rigidity R = pc/Ze- Charge sign- Charge value from dE/dx

Time-Of-Flightplastic scintillators + PMT:- Trigger- Albedo rejection;- Mass identification up to 1 GeV;- Charge identification from dE/dX.

Electromagnetic calorimeterW/Si sampling (16.3 X0, 0.6 λI)

- Discrimination e+ / p, anti-p / e- (shower topology)- Direct E measurement for e-

Neutron detector3He tubes + polyethylene moderator:- High-energy e/h discrimination

Main requirements high-sensitivity antiparticle identification and precise momentum measure+ -

Antiparticles with PAMELA

Antiproton to Proton Flux Antiproton to Proton Flux RatioRatio

Donato et al. (PRL 102 (2009) 071301)

Simon et al. (ApJ 499 (1998) 250) Ptuskin et al. (ApJ 642 (2006) 902)

Adriani et al., accepted for publication in PRL; arXiv:1007.0821 

Antiproton FluxAntiproton FluxDonato et al. (ApJ 563 (2001) 172)

Ptuskin et al. (ApJ 642 (2006) 902)

Adriani et al., accepted for publication in PRL; arXiv:1007.0821 

Trapped pbar, SAA

GCR

• PAMELA

• PAMELA

Preliminary

Positron to Electron Positron to Electron FractionFraction

Secondary production Moskalenko & Strong 98

Adriani et al, Astropart. Phys. 34 (2010) 1 arXiv:1001.3522 [astro-ph.HE]

Solar modulation

July 2006

August 2007

February 2008

PAMELA

¯

+¯

+

A-A+A+ A-

Decreasing solar activity

Increasing flux

~11 y

Low fluxes!

PAMELA

But antiprotons in CRs are in agreement with secondary production

Uncertainties on:• Secondary production (primary fluxes, cross section)• Propagation models• Electron spectrum

A Challenging Puzzle for CR PhysicsA Challenging Puzzle for CR Physics

A Challenging Puzzle for CR PhysicsA Challenging Puzzle for CR Physics

P.Blasi, PRL 103 (2009) 051104; arXiv:0903.2794Positrons (and electrons) produced as secondaries in the sources (e.g. SNR) where CRs are accelerated.

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.

Conclusions• Astroparticle physics from space is a fascinating

field, fertile and rich of scientific potentials.• Several very important esperiments are, or

going to, directly measuring cosmic rays and their antimatter component: PAMELA, AMS-2010...

• Important results have already been published and soon more will come.

• Stay tuned, interesting times ahead!