The AMS Transition Radiation Detector and the Search for Dark Matter Gianpaolo Carosi Lab for Nuclear Science, MIT The AMS Collaboration Lake Louise Winter Institute 2/23/05
Outline Signatures of dark matter in cosmic rays Overview of the AMS-02 detector Principles of Transition Radiation Construction of the AMS TRD system Physics reach of AMS-02 detector with the TRD
The Problem of Dark Matter What is it? - Matter which appears to not interact electromagnetically. -Observed from gravitational interactions only! v2v2 v1v1 Galactic Rotation Curves R1R1 R2R2 R2R2 R1R1 v1v1 v2v2
SUSY Dark Matter Neutralino – majorana particles Direct searches: Scattering off nuclei Indirect searches: Look for annihilation products. Positrons: low intrinsic background Energy correlated to WIMP mass X 0 e+e+ e-e- HEAT Balloon Experiment veve veve _
AMS-02 experiment Constraints: 9 g at takeoff/landing. Weight < lbs Power = 3 kW Temperature: -40˚ - +65˚ C Date rate = 2 Mb/sec 3 year remote operation without servicing Operational Experience AMS-01 engineering test flight 10 days: ~ 100 Million events ISS
The Experiment TRD: p + rejection ECAL: p + rejection
Principle of Transition Radiation High energy charged particles crossing boundary between materials of different dielectric constants gives off X-rays. Detection possible with Lorentz boosts > 300. Discriminate e + (TR) / p + (no TR) AMS TRD: Proportion tubes and fleece radiator
Construction of AMS TRD TRD Octagon/straw tubes RWTH Aachen TRD Gas Supply/Circulation System MIT – Design CERN & MIT - Construction TRD Slow Control System MIT & INFN Rome TRD DAQ TH Karlsruhe
DAQ ElectronicsSlow Control and Monitoring 50 liter/hr Detector Volume Distribution System Circulation System Supply/Mixing System
Vibration Tests Thermal Vacuum Tests Leak Tests Extensive Testing
328 Modules (5248 straw tubes) Lengths: 0.8 – 2.0 m and 100 μm tolerance Straw tube walls
Carbon Fiber Structure Aachen
328 straw modules have been produced:
Gas System: Box S Mix Gas: Xe:CO 2 80:20 (to 1% accuracy) Refresh Supply Daily: max 7 liter/day Engineering model: CERN Flight system: ARDE Corp. Xe 49.5 kg CO kg
Gas System:Box C Circulate Gas: 50 liter/hr through Octagon Monitor gas gain: Calibration tubes coated with Fe 55 Spirometer: Measures CO 2 fraction
TRD Gas Slow Control/Monitoring
TRD DAQ TRD FE-electronics: 20 Watt for 5248 channels => multiplexed pulse height only
20 layer TRD detector in the test beam at CERN in 2000 we have recorded 3 million events providing signals for protons, electrons, muons and pions at energies from GeV
HEAT experiment (experimental data + DM model) AMS-02 experiment (simulated data + DM model) Physics Reach TRD + ECAL Paolo Maestro: SIENA
AMS on the ISS: 2008 AMS TRD currently under construction Beam tests: achieve p + rejection to 300 GeV Combined with ECAL will obtain precise e + spectrum Summary