The AMSThe AMS--02 TRD 02 TRD for the for the

International Space StationInternational Space Station

Florian Hauler (IEKP)On behalf of the AMS-02 TRD collaboration

I. Phys. Inst. RWTH-Aachen, INFN Rome, IEKP Univ. of Karlsruhe, MIT, Kyungpook National University Taegu Korea

October 2003 IEEE NSS conference Florian Hauler, IEKP 2

Physics InterestPhysics Interest

• Search for antimatter• Search for dark matter annihilation• Search for stranglets• Investigate earths particle environment• Determine the age of cosmic rays by Be9 / Be10

measurement• Gamma-ray astronomy• Investigate characteristic particle radiation of

microquasars, primordial black holes

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AMS and the International Space StationAMS and the International Space Station

AMS

To perform this search, we have to get rid of the disturbing atmosphere. A good place is 400km over ground on the ISS.

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AMS AMS –– 0202

General Purpose detector with excellent particle identification

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Antimatter production by Antimatter production by Dark Matter AnnihilationDark Matter Annihilation

• SUSY offers Neutralinos as candidates for Dark Matter• A Neutralino as a supersymmetric particle hardly interacts with common

matter due to R-Parity conservation.• But it can annihilate with another Neutralino and create Matter/Antimatter

e.g. Electrons/Positrons, Gammas, Proton/Antiprotons.

Diffuse Gamma Rays Positron Fraction Antiprotons

AnnihilationBackground

(From: W. De Boer et al. Indirect Evidence for the Supersymmetric Nature of Dark Matter..., hep-ph/0309029.)

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Difficulties for positron identificationDifficulties for positron identification• Background: p+/e+ = O(104)• The measured contamination should be at 1% level.• => Cosmic ray spectroscopy with highest-precision in particle

identification to achieve proton-rejection (e± efficiency = 90%) :• < 10-6 up to 300 GeV• This rejection can be achieved combining ECAL rejection (10-4) and TRD

rejection (10-2 – 10-3)

Primary Sources:Positron production by Neutralino-Annihilation

Secondary Sources:Positron production by particle fragmentation.

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Principle of transition radiationPrinciple of transition radiation

• Highly relativistic particle traverses the boundary of two media with different ε.

• To fulfill the coninuity conditions at the boundary, TR is emitted

• Probability of emitting a photon: ∼α=1/137 • In AMS-02, fleece is used as radiator• Approxim. 100 transitions

22 m

m

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Test beam resultsTest beam results

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Requirements for Space OperationRequirements for Space Operation• TRD Weight is limited to 480 kg

(all included) AMS complete weight about 7000 kg

• During Start: Vibration up to 6.8g. =>Tests are done in lab up to 9g.

• Temperature variations of TRD outer casing –180°C...+50°C.=>Multi-Layer insulation assures inner TRD temperature between 0..20°C.Gradient inside volume below 1°C.

• Operation in vacuum

• Outgasing deposition limits on ISS < 10-14 g/s/cm2

• Strict EMI limits on ISS

AMS

• Maintenance free for at least 3 years.Enough gas onboard for safety factor 5.

• Limited power consumption of 2000W for AMS and175 W (DAQ & CTRL) for TRD

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The StrawtubesThe Strawtubes• Modules: 16 tubes with 6mm diameter and 30 µm W-Au wire tensioned by 100g.• 20 layers separated by 22 mm fleece-radiator• Tubewall 72 µm Kapton-Al sandwich• Xe/CO2 (80/20) Pressure 1250 mbar, Gas Flow 1 liter/h, Gain 3000• To assure gastightness, single straw tube tests are done.

Capton wall, 72 µm

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The Gas SystemThe Gas System

Electronic-control

Command & Monitor SignalsGas Lines

UGBS UGBC

Pump Manifolds(on TRD)

computer

USCM

UGFV

Xe & CO2 tanksTRD

320 l @ 1 bar in 41 loops

46 kg Xe (8100 l @ 1bar)4 kg CO2 (2000 l @ 1bar)

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TRD mechanicsTRD mechanics• Conical octagon to minimize weight and keep max. steradian• 20 layers of proportional tubes• Lengths of tubes between 86 and 201cm• Walls made of aluminum honeycomb with CFC surface

to assure stability during start acceleration• Mechanical accuracy<200µm to assure no pressure on straw modules

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TRD(U)TRD(U)--Electronics OverviewElectronics Overview

Ucrate = TRD electronic crateUBP = TRD backplaneUPD = TRD power distribution boxUSCM = TRD power controller

UPSFE = TRD power supply for front endUDR = TRD data reduction boardJINF = data concentrator and link to higher DAQ for TRDUHVG = TRD high voltage generatorUFE = TRD front endUTE = TRD tube endUHVD = TRD high voltage distributor

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DAQDAQ--FactsFacts• 82 UFE boards in whole TRD each with 64 straw tubes, giving 5248 channels.• Due to limited data transmission to earth, data has to be zero-subtracted.

=> Each UDR consists of ACTEL FPGA and AD DSP to take over this job.• 2 U-crates with 21 VME-sized card powered each by its own UPD-Box with

9 DC/DC converters.• DC/DC converters with conversion efficiency of up to 80%.• Power consumption: 19 Watts in Frontend electronics, 41 Watts in U-crate,

36 Watts Power dissipation in UPD-Box => P ≈ 100 W• Read-out time for whole TRD ≈ 70 µs. Expected max. Trigger rate around

2000 Hz.• VA Input range: 1500 fC ≈ 50 Mips (gasgain 3000), Noise ≈ 7000 e- ≈ Mip/30

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Space Qualification of electronicsSpace Qualification of electronics• Thermo-Vacuum Test (TVT)

• Vibration-Test

Requirements:

Operating Temp.:-25°C to +55°C

Non-operating Temp.:-45°C to +85°C

Requirement:Vibration up to 9g.Eigenfrequency > 50 Hz

Eigenfrequency spectrum is measured before and after vibration. Difference in spectrum indicates a problem.

• EMI-Tests to assure no EM-pollution of ISS environment is caused.

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Electronics Production StepsElectronics Production Steps• Engineering Module-Production (EM): Europe

Purpose:Develop Actel firmware and DSP software, Functional test of readout-electronics in Testbeam. No rad-hard components.

• Qualification Module 1 - Production (QM1): EuropePurpose:Build electronics modules which can withstand the harsh environment of space. Tests on „board-level“ in TVT-chamber and vibration table. Partly rad-hard components (Actel FPGA).

• Qualification Module 2 - Production (QM2): CSIST, TaiwanPurpose:Modules are identical to QM1. One complete crate will be built to test electronics for space qualification on „crate-level“. This production serves as a FM production test.

• Flight Module Production (FM): CSIST, TaiwanPurpose: Produce real flight hardware according to production experience gained by previous steps.

Current working step!

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SummarySummary• AMS – 02 TRD provides a p+ rejection of 10-2 up to 300 GeV to distinguish

e+ from p+. Together with ECAL-information this gives a p+ rejection of 10-6

• Space qualification tests show that hard requirements for detector are fulfilled.

• Electronics development almost finished A prototype of each board is available and has been successfully tested in a beam test.

• Space qualification (TVT and vibration) for electronics ongoing

• Start of FM-Production next year

• Schedule:Complete test of TRD October 2004.