Andrei Kounine / MIT on behalf of AMS-02 collaboration ICHEP 2004, Beijing Astroparticle physics with AMS-02

Andrei Kounine / MITon behalf of AMS-02 collaboration

ICHEP 2004, BeijingICHEP 2004, Beijing

Astroparticle physics with AMS-02

Goals:

•Astroparticle Physics:

- Search for Cosmic Antimatter

- Searches for Dark Matter

• Cosmic Ray Astrophysics

• …

AMS-02 ExperimentAMS-02 Experiment

A.Kounine Dark Matter searches with AMS-02 ICHEP 2004

Collect ~1010 Cosmic Particles (p, D, He, C, …,e, ) from ~ GV to few TV.


Anticoincidence: veto plastic scintillators used in Trigger

Time of Flight: 2x2 planes of scintillator hodoscopeResolution T=90-150 ps .

Used in Trigger Velocity measurement L/ct1-ct2 /0.03 dE/dx measurements

Tracker : 8 layers of Si strip planes (6 m 2). 27.5 / 52pitchResolution: = 10 (bending) and 30 (non bending)

Rigidity measurements up to ~3TeVdE/dx ~ Z2 measurement.Conversion of gamma e+e-

Magnet: B

dipol =0.86 Tesla I~460A NbTi/copper conductor

Size: d=1.2m l=0.8 m; Mass 2.3 t E=5.2MJ storedcooled to 1.8K by superfluid He



Ring Image Cherenkov Detector: radiators (NaF n=1.336 and Aerogel n=1.035) +PMT's

measurement up to 20 GeV/n, / 0.01-0.04%

Charge measurements Nγ~Z 2 (=0.2) up to Z=26

Electromagnetic Calorimeter: 18 planes of Pb+ scintillator fibers Thickness ~16 X

o and ~ 0.5

nucl. .

Energy resolution: dE/E=0.023+0.10/E[GeV]Used in gamma triggere, / h separation ~10 3 E=1-1000 GeV

Transition Radiation Detector: 20 layers of 6mm straw tubes filled with Xe/Co2 interleaved with fleece radiator (22 mm).

dE/dx measurements .Separation e/h ~10 3 - 10 2 p=1-300 GeV


AMS-02 Detector PerformanceAMS-02 Detector Performance


Data MC Data

ECAL resolution:

Energy resolution Angular resolution

ΔE/E=0.023+0.10/E(GeV)

AMS-02 Detector PerformanceAMS-02 Detector Performance


MC

Data

Tracker resolution:

Spatial resolution Rigidity resolution

• The Primordial Antimatter content of the Universe is unknown.

• ~100 MeV flux excludes wide antimatter regions up to 20-100 Mpc

• Sakharov’s 3 Principles of Baryogenesis :

1. Baryon Number Violation (not confirmed….)

2. C and CP Violation (strong….)

3. Deviation from Thermal Equilibrium

… but alternative models predict distant Antimatter local domains !

• Single anti-He Cosmic Rays nucleus Strong Evidence for Large Anti-matter Domains in the Universe

Search for AntimatterSearch for Antimatter


Search for AntimatterSearch for Antimatter

Model-independent AMS-01 limit


AMS-02 will probe antimatter domains to the edge of Universe

““Standard Cosmology”Standard Cosmology”

• Dark Energy – 73 % of critical density

• Matter – 27 % of critical density

• Matter breakdown: – 0.5 % Stars

– 4.4 % Barions

– 22 % CDM

• We do not know what CDM is:

– Super Symmetry: LSP

– Low Scale Gravity: KK particles

– SuperWIMP: Graviton, Gravitino

– …


SUSY Dark MatterSUSY Dark Matter

• SYSY postulates spin partners for all known particles

• MSSM best CDM candidate – neutralino : 01 – LSP

010

1 e+ e- – suppressed by spin

010

1 WW, ZZ, – vanishing coupling for Bino

Plausible signature – low energy anti-protons and anti-deuterons:

010

1 bb , W+W-, ZZ, Z, H+H-, ...

p– ,anti-D, e+, , +X

High energy electrons and photons is also a possibility.


• Low Scale Quantum Gravity (Extra Dimensions) generically predict Kaluza-Klein bosons with mass n/R.

BB e+ e- - dominant channel (~20%)


Kaluza-Klein Dark MatterKaluza-Klein Dark Matter

Cheng, Feng, Matchev (2002)

Graviton/Gravitino Dark MatterGraviton/Gravitino Dark Matter


• Heavy WIMPs exist in early universe only.

• They decay slowly to non-interacting sWIMPs

• Signature:

photons from decays: WIMP sWIMP

• Decay time is sensitive to

m = mWIMP – msWIMP

Feng, Rajaraman, Takayama (2003)

gravitino graviton

msWIMP = 0.1, 0.3, 1 TeV (from below)

Dark Matter SearchesDark Matter Searches

AMS-02 is a general purpose particle detector:

– p- : Excess at Low Energy and spectrum distortion

at High Energy

– D- : Excess at Low Energy

– e + : Structure in Spectra above few GeV

– : Energy Spectra differ from “power laws”


7 models

Dark Matter Searches: AntiprotonsDark Matter Searches: Antiprotons

Background Primary antiprotons from Background Primary antiprotons from

SUSY SUSY χχ annihilation annihilation


Dark Matter Searches: AntiprotonsDark Matter Searches: Antiprotons

After 3 years of runningAfter 3 years of running

Background rejection:

p/p- > 106 and e-/p- 103-104


Dark Matter Searches: Anti-deuteronDark Matter Searches: Anti-deuteron

More promising than antiprotons


Dark Matter Searches: PositronsDark Matter Searches: Positronsee++ AMS02-spectrum after 3 years of data taking: AMS02-spectrum after 3 years of data taking: • p/e+ and e-/e+ background rejection: 104-106

• Excellent energy resolution.Excellent energy resolution.• ~30% stat error at 300 GeV, ~1% stat error at 50 GeV. ~30% stat error at 300 GeV, ~1% stat error at 50 GeV.


Precise data extended to higher energies will be provided by AMS

m 130.3 GeV

Dark Matter Searches: PositronsDark Matter Searches: Positrons

m 336 GeV

Based on the work of E.A. Balts et al. 99


Dark Matter Searches: Dark Matter Searches: PhotonsPhotons


Diffusion flux

Extra-galactic flux

MC

MC

mSUGRA results: Integrated flux from GC as a function of m in the Focus Point scenario(large m0 values), for two NFW halo profile parameterizations.

R0 = 8.0 kpc, r0 = 0.3 GeV/cm3, a = 20 kpc R0 = 8.5 kpc, r0 = 0.4 GeV/cm3, a = 4 kpc

Dark Matter Searches: PhotonsDark Matter Searches: Photons


AMS prospectsAMS prospects

• Launch ready – September 2007

as of now AMS launch is foreseen for end of 2007 - beginning 2008

• AMS-02 will collect data for 3-5 years on ISS:– Antimatter search with a sensitivity 10-9

– Dark Matter content in various channels (p-, D-, e+, )

– High statistics cosmic ray measurements

– -Astrophysics

– Exotics, …


Documents

Andrei Kounine / MIT on behalf of AMS-02 collaboration ICHEP 2004, Beijing Astroparticle physics with AMS-02