Dark Matter Searches with AMS-02 AMS: Alpha Magnetic Spectrometer 2007/2008 Wim de Boer on behalf of the AMS collaboration University of Karlsruhe July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 1
Outline Physics Motivations Detector requirements Prospects for Indirect Dark Matter searches Conclusions July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 2
AMS Physics motivations Search for cosmic anti matter Search for Dark Matter Precision measurement on cosmic rays AMS will collect ~10 10 Cosmic Rays (e ±, γ, p ±,3,4He,B,C, 9,10 Be, elements Z<25 in Near-Earth Orbit from few GV to few TV Gamma ray astrophysics Region of antimatter July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 3
WIMP Annihilation Final States χ χ ~ f f f χ χ f f χ χ f f χ χ χ W χ ± χ 0 W χ Z Z Dominant Diagram for WMAP cross section: χ + χ A b bbar quark pair B-fragmentation well studied at LEP! Yield and spectra of positrons, gammas and antiprotons well known! July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 4
Model of our galaxy July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 5
Diffusion equation Particle density: Source function: Diffusion coefficient: GALPROP program by Moskalenko and Strong provides numerical solution to this diffusion eq. for equilibrium taking into account particle densities of ALL nuclei. Convection velocity: Diffusive reacceleration: Momentum loss rate: Radioactive decay: Fragmentation: Source fct??? July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 6
Propagation in GALPROP compared with DarkSusy: LARGE DIFFERENCE Antiprotons Positrons Spectrum after propagation of injection of 1-3 GeV source with NFW profile in DarkSusy (analytical solution of diffusion equation l) and GalProp (numerical solution of diffusion equation including more physical effects, like reacceleration July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 7
Problems: Any unidentified background produces a WIMP signal For every antiproton at some energy there are 10,000-100,000 protons For every positron at some energy there are ~10,000 protons which have same charge sign Secondary particles (long and short lived) are locally produced Single scatters change apparent particle charge sign in simple trackers July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 8
AMS-02 Particle Identification July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 9
Superconducting Magnet Flux Return Coils B Dipole Coils B He Vessel 2500 Liters Superfluid He Analyzing power BL 2 = 0.8 Tm 2 July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 10
TRD detector to separate e + from protons : 3 300GeV e+/p rejection 10 2 10 3 in 1.5 300 GeV with ECAL e+/p rejection >10 6 July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 11
TRD detector 20 layers,328 chambers,5248 tubes Mechanical Accuracy <100µm Assembly in progress CERN beamtest with TRD prototype: proton rejection > 100 up to 250 GeV at electron efficiency 90% reached Single tube spectra for p+/e separation. July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 12
Silicon Tracker Rigidity ( R/R 2% for 1 GeV Protons) with Magnet Signed Charge (de/dx) 8 Planes, ~6m 2 Pitch (Bending): 110 µm (coord. res. 10 µm ) Pitch (Non-Bending): 208µm (coord. res. 30 µm ) Charge measurent up Z ~ 26 July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 13
Ring Imaging Cerenkov Counter Accurate Velocity Aerogel Radiator(n=1.03, 3cm) NaF radiator (n=1.33, 0.5cm) Cerenkov Cone β/β = (0.67±0.01)*10-3% (test beam) Isotopic Separation. Mirror Q measurements up Z~ 30 Photomultipliers 8.5 x 8.5 mm 2 spatial pixel granularity July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 14
Charge measurements ToF, Tracker, RICH performance verified at heavy ion test beam (CERN,GSI) Fe Ca P Ne B July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 15
Electromagnetic Calorimeter 3D sampling calorimeter 9 superlayers of 10 fiber/lead planes each alternate in x and y scintillating fibers viewed by PMT 16.4 X 0 radiation length Measure energy (few % resolution) and angle (1-0.5 angular resolution) of γ, e +,e - p ± e ± 10-3 p ± Rejection at 95% e ± Efficiency Via Shower Profile 1 GeV - 1 TeV July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 16
AMS-02 capabilities Beryllium Boron Helium 1 year 1 year 6 months 1 day 6 months 1 day 10 Be (t 1/2 =1.5Myr) / 9 Be will allow to estimate the propagation time and size of the ISM B is secondary produced in nuclear interaction, C is primary produced in stars. B/C is sensitive to the diffusion constant 3 He/ 4 He ratio is sensitive to the density of the ISM July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 17
AMS02 : detector performance Acceptances defined by selection cuts during reconstruction Preliminary Antiprotons: A(<16 GeV) 1200cm 2 sr >16GeV 330 cm 2 Rejection e- 10 4 p 10 6 Positrons: Acceptance 550 cm 2 sr Rejection e- 10 3 p 10 5 Gamma (ECAL mode): Acceptance ~ 600 cm 2 sr Rejection e+ - ~ 10 4 p ~ 10 5 Gamma (Conversion mode): Acceptance ~ 550 cm 2 sr July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 18
Expected statistics after one year of AMS-02 operations Antiprotons Gamma rays Positrons July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 19
Summary AMS is a High Energy Physics detector in space foreseen to operate on the ISS for 3 years Asked by NASA to be Ready For Flight in September 2007 The cosmic rays, including gamma rays, will be measured with a high accuracy from the GeV to the TeV range Unique opportunity to perform Dark Matter searches July, 20. 2004 COSPAR, Paris, W. de Boer, Univ. Karlsruhe 20