Transition Radiation Detectors to Study Elemental Composition near the Knee

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Transition Radiation Detectors to Study Elemental
Composition near the Knee

• Jojo Boyle
• Enrico Fermi Institute
• University of Chicago

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Precision TRDs
TRDs used widely in HEP as threshold
devices For Z 3, the TR yield increases as
Z2 Verified by the CRN experiment (1985) Swordy
et al., Phys. Rev. D 1990, 42, 9 Sensitivity can
extend up to Lorentz factors of g 105,
corresponding to an energy of 5x1015 eV for Iron
Nuclei, well into the knee of the cosmic ray
spectrum.

• For a more detailed discussion on Precision
  TRDs Wakely, APh 2002 (in Press)

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TR Detector Set up

• Our TRD consists of a combination of
• Radiator
• (Plastic Foam with Bubbles)
• 2. Detector
• (thin walled Proportional tubes)

Tube 2cm diameter Wall Thin Mylar Wire
3mil Gold Gas Xe / CH4 Mix
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TRACERTransition Radiation Array for Cosmic
Energetic Radiation
A long Duration Balloon Flight (14 days) TRD
1600 Proportional Tubes Area 2m x 2m Weight
6000 lbs (2800 kg) Optimized for Oxygen lt Z lt
Iron
Successful test flight at Fort Sumner 1999,
reproduced the CRN Energy Spectra for Oxygen,
Silicon and Iron. Two postponed flights (June
2001, 2002) from Fairbanks, Alaska. Pending to
fly from McMurdo, Antarctica, December 2003.
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CREAM Cosmic Radiation Energetics And Mass
CREAM is a Cosmic Ray Detector set to fly as a
ULDB Mission planned for a 100 day flight over
Antartica
CREAM will employ a combination of thin
Calorimetry (UMD), scintillation counters (PSU)
and a TRD (UC) to determine the energy spectrum
and composition of cosmic rays.
The objective of CREAM will be to accumulate at
least 500 particles each for protons, helium,
CNO, Ne-Si and Fe group Nuclei above 1014 eV,
with a statistical accuracy of 30 above 1015 eV.
Launch date is 2004
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CREAM Setup
TRD 512 Tubes Area 1.1 m x 1.1
m Payload 3000lbs (1400 kg) Tube 2cm
diameter Wall Thin Mylar Wire 3mil Gold
Gas Xe / Ch4 Mix Signal Dual Gain
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Radiator Setup Properties
Tested the setup and radiator configurations 1.
Quash 2. Ethafoam 3. Solid Plastic Block 4.
Background
Beam
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Radiator Response
Fe 5x1015 eV
Ethafoam (11 cm)
Quash (44 cm)
Signal (dc)
Quash (22 cm)
Quash (11 cm)
Bremsstrahlung
Background
1 day
14 days
100 days
5 years
Lorentz factor
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Summary

• TRACER ready to fly
• CREAM Flight 2004
• To fully exploit Transtion Radiation as a
  detection technique need ACCESS

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Accelerator Calibration
Thin walled Gas Chamber 64 wires separated by
1mm 64 strips etched perpendicular on G10
Charge induced on lower strips 2 Chambers
orientated orthoganally 128 Channels read out by
Amplex ASIC (8 Chips)