detection & measurement of gamma rays in the ams-02 detector

Lake Louise - February 20-26 2005Lake Louise - February 20-26 2005 11

Detection & Measurement of gamma Detection & Measurement of gamma rays in the AMS-02 Detectorrays in the AMS-02 Detector

Detection & Measurement of gamma Detection & Measurement of gamma rays in the AMS-02 Detectorrays in the AMS-02 Detector

J. Bolmont - LPTA - IN2P3/CNRS

Montpellier - France

On behalf of AMS collaboration

J. Bolmont - LPTA - IN2P3/CNRS

Montpellier - France

On behalf of AMS collaboration

Lake Louise - February 20-26 2005Lake Louise - February 20-26 2005

22J. Bolmont - LPTAJ. Bolmont - LPTA

OutlineOutline

• Detecting with AMS-02- Conversion Mode- Single Photons

• Cosmic Ray Fluxes• Various sources

- Pulsars, GRBs- Cold Dark Matter



AMS-02AMS-02

Launch scheduled in 2008Launch scheduled in 2008



Detecting Detecting with AMS with AMS

• Two complementary modes- Tracker mode : e+e-

conversion in TRD- ECAL mode : single

no hit in TOF & Tracker

• Completeness of AMS-02 : overall proton to gamma supression factor 104 - 105

e+ e-



Detecting Detecting with AMS : with AMS : e e++ee--

• The Si Tracker : charged track reconstruction & identification- 8 layers- Double sided silicon strips- Total area : 7 m2

- 200000 channels

A layer completely equipped



Tracker ResolutionsTracker ResolutionsBeam test results• Angular resolution ~0.02° when E > 100 GeV.• Energy resolution at high energy affected by the leptons trajectory reconstruction errors.

Energy ResolutionAngular Resolution



Detecting Detecting with AMS : with AMS : single single showers showers• The Electromagnetic Calorimeter

- SPACAL calorimeter (Pb + Scintillating fibers)

- 9 superlayers (~16 X0), X-Y sampling

- 324 PMTs with 4 pixels 1296 channelshigh granularity

3 Superlayers



EM Calorimeter ResolutionsEM Calorimeter Resolutions

Energy Resolution Angular Resolution

Beam test results



Acceptance / Effective AreaAcceptance / Effective Area

• Monte Carlo simulations + Preliminary analysis

Cos(incident angle)



Cosmic Ray FluxesCosmic Ray Fluxes

• Cosmic Rays Composition :- p : 88 %

- He nuclei : 9 %

- e- : 2 % : < 1%

• Standard CR spectra follows a "power law" E- with = 2-3

• DM signal : exponential cut-off in the spectra



Various Various sources sources

• Energy range : 1-300 GeV• Sources in scope of AMS:

- Galactic : pulsars, nebulas (VELA, CRAB,…)- Extra-Galactic : GRBs

• Diffuse emission : interaction of Charged Rays with galactic medium produce (0)



Some Results Of SimulationsSome Results Of Simulations• Using a fast simulation tool with parametrizations of

ECAL & Tracker acceptances and resolutions

3EG Catalog Other Name N (Tracker) N (ECAL) N (total)

J0210-5055 0208-512 47.0 13.4 60.4

J0530+1323 0528+134 18.7 4.0 22.7

J0534+2200 Crab 102.2 26.6 128.8

J0834-4511* Vela 491.4 203.8 695.2

J1255-0549 3C279 138.6 35.8 138.6

J1409-0745 1406-076 31.7 5.9 37.6

J1635+3813 1633+382 65.5 18.3 83.8

One year of operation



Some Results Of Simulations : Some Results Of Simulations : CRAB nebula+pulsar CRAB nebula+pulsar

Results in 5 energy bands for 1 year of operation :• 1-2 GeV• 2-5 GeV• 5-20 GeV• 20-50 GeV• > 50 GeV



Predictions for GRBsPredictions for GRBs

• GRBs : the most explosive cosmological events after Big Bang : ~5x1051 erg released in

• Taking into acount the most luminous GRBs observed by EGRET & BATSE, we expect a few GRBs per year in AMS detector.

• Big uncertainties : processes of production at high energies not known !



Cold Dark MatterCold Dark MatterThe matter content of the Universe is 90% dark and non-baryonic. Astrophysical measurements of the star rotation velocities in the galaxies, of the large structures, gravitational arc phenomena confirm the CDM paradigm.

Hypotheses :•Dark Matter is Cold (CDM) and weakly interacting (WIMPs)•Exotic – Supersymmetry (Particle Physics) offers an excellent WIMP candidate – the LSP as neutralino : 0

1 •The WIMPs interact in the underground detectors with nucleons and annihilate in the halo of the Dark Matter and produce stable particles : , neutrinos, e+, anti-p, …



Predictions for benchmark fluxesPredictions for benchmark fluxesGalactic CentreGalactic Centre• mSUGRA models MC simulation• Accelerators & WMAP constraints• Various DM halo profiles

Model B G I K L

m 98.3 153.6 143.0 571.5 187.2

m0 59.0 116.0 178.0 999.0 299.0

tan 10. 20. 35. 38.2 47

relic 0.122 0.124 0.122 0.116 0.101

n (NFW) 0.11 0.07 0.47 0.14 1.17

n (NFW cuspy) 4.8 2.8 20.3 6.0 50.5

n (Moore) 14.1 8.2 59.0 17.5 146.7

One year of operation

J. Ellis et al. Eur. Phys. J. C24 (2002) 311



Predictions for Predictions for fluxes from the fluxes from the Galactic Centre : Galactic Centre : DarkSUSY + Suspect MCDarkSUSY + Suspect MC

• Different Models :- SUSY conventional

(MSSM, mSUGRA)- Non thermal (AMSB)- Kaluza-Klein scenario

MSSM = Minimal SuperSymetric Model

mSUGRA = Minimal SUGRA model

SUGRA = SuperGravity grand unified models

AMSB = Anomaly Mediated SUSY Breaking



SummarySummary

• Using Si-Tracker and EM Calorimeter, AMS-02 will provide new measurements in the range1-300 GeV during 3 to 5 year mission.

• AMS-02 will study several galactic and extragalactic sources as Pulsars, GRBs…

• (At least) constraints in various Cold Dark Models will be provided.

detection & measurement of gamma rays in the ams-02 detector

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