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Phonon-Mediated Distributed Transition-Edge-Sensor X-ray Detectors

Detailed study on phonon-mediated detectors with goals, performance goals, energy systems, and comparisons between Si and Ge detectors. Investigates X-ray energy absorption and losses affecting energy resolution. Analyzes electron-hole pairs variation and phonon energy dynamics.

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Phonon-Mediated Distributed Transition-Edge-Sensor X-ray Detectors

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  1. Phonon-Mediated Distributed Transition-Edge-Sensor X-ray Detectors Steven W. Leman Department of Nuclear Engineering and Management, The University of Tokyo LTD-12 August 2007

  2. Important People • Paul Brink • Blas Cabrera • Astrid Tomada • Betty Young

  3. Overview • Goals, applications and detector basics • Energy systems, charge traps and neutralization • 2-d Si • 2-d Ge • 2-d Si with deep trenches • Energy Resolution

  4. Scientific Motivation Warm-hot intergalactic medium Galaxy cluster surveys

  5. Performance Goals • 2 dimension resolving • 1-10 keV band • Position resolution x/dx and y/dy ~ 100 • Energy resolution E/dE ~ 1000 • Large area ~1-10 cm2 • Via 30 x 30 multiplexed arrays • Equivalent to a 10 megapixel device

  6. Phonon Mediated Detector L.E.D.

  7. 3 Detector Comparisons Ge… ½ Si Debye freq fTES reduced by ½ 550 275 500 350 220 500 350 320 500

  8. Detector with Source 2cm 1cm refrigerator cold stage that little spot is the 4 transition edge sensors x-ray source

  9. Position Determination Resolution ~20mm.

  10. Spectra Silicon Silicon deep trench Germanium

  11. Energy Absorption

  12. Energy Losses • Energy resolution is degraded due to energy going into nondetectable channels. • Electron—hole pairs lost in charge traps. • Electron—hole pairs diffuse through bridge and lost to the environment. • Phonons escape through bridge and lost to the environment.

  13. Electron-holenumber variation • X-rays absorbed  electron—hole pairs produced. • F = 0.116, Fano factor. • Eg = 5.9 keV, X-ray energy. • e0 = 3.8 eV, electron-hole production energy.

  14. Phononenergy variation • The electron—hole pairs shed energy until they reach the velocity of sound. • Egap = 1.2 eV, electron-hole gap energy.

  15. Full-Width at Half-Maximum • edet ~ 0.5, detection efficiency. • 2.355 to convert to FWHM.

  16. Combined with baseline noise • Baseline noise = 37 eV. • 68% of energy initially goes into phonons. 76% could be absorbed in completely trenched TESs. • Could this suggest the electron—hole pairs are not releasing their energy in the detector?

  17. Trap Concentrations • Penn / Dougherty • 8,000 W cm • 1013 traps / cm3 • Us • 10 W cm • 1016 traps / cm3

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