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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
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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! Galactic Rotation Curves v1 v2 R1 v1 R2 v2 R1 R2
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 HEAT Balloon Experiment X 0 e+ ve _ ve X 0 e-
AMS-02 experiment • Constraints: • 9 g at takeoff/landing. • Weight < 14809 lbs • Power = 3 kW • Temperature: -40˚- +65˚ C • Date rate = 2 Mb/sec • 3 year remote operation without servicing ISS Operational Experience AMS-01 engineering test flight 10 days: ~ 100 Million events
The Experiment TRD: p+ rejection 102-103 ECAL: p+ rejection 103-104
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
Detector Volume Distribution System Supply/Mixing System Circulation System 50 liter/hr DAQ Electronics Slow Control and Monitoring
Extensive Testing Vibration Tests Thermal Vacuum Tests Leak Tests
328 Modules (5248 straw tubes) Lengths: 0.8 – 2.0 m and 100 μm tolerance Straw tube walls
Carbon Fiber Structure Aachen
Gas System: Box S Engineering model: CERN Flight system: ARDE Corp. • Mix Gas: Xe:CO2 80:20 (to 1% accuracy) • Refresh Supply Daily: max 7 liter/day Xe 49.5 kg CO2 4.5 kg
Gas System:Box C • Circulate Gas: 50 liter/hr through Octagon • Monitor gas gain: Calibration tubes coated with Fe55 Spirometer: Measures CO2 fraction
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 5-250 GeV
Physics Reach HEAT experiment(experimental data + DM model) AMS-02 experiment(simulated data + DM model) TRD + ECAL Paolo Maestro: SIENA
Summary AMS on the ISS: 2008 AMS TRD currently under construction Beam tests: achieve 102-103 p+ rejection to 300 GeV Combined with ECAL will obtain precise e+ spectrum