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Down-conversion phononnoise in optical TESs

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Resolving power of Ta/Al STJ detector

APL (2006)

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Down-conversion phonon noise in TES

DC: scenario, phonon generation Phonon distribution evolution over the

spectrum Phonon spatial distribution Phonon transport properties Energy transfer across the escape interface Energy loss Fluctuations

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Electron-phonon down-conversion.Scenario

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Electron-phonon down-conversion inTES

( ) psfs Dephs 101 ,10010 ÷!"÷! #$$

Characteristic time scales:

Characteristic energies:

111

~30/120/110/1* EEEE

DD!<<÷"#<<#$#!

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Electron-phonon down-conversion stageE1→ΩD: phonon bubble

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Electron-phonon down-conversion stageE1→ΩD: phonon bubble

phonon distribution in the bubble

is the duration

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E1→ΩD :Energy loss

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E1→ΩD: Energy loss fluctuations

angular interaction transmission

? ?

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ΩD→Ω1: Energy loss fluctuations

ψ

Ω1/ΩD

Graph of ψ as a function of Ω1/ΩD:η=0.76, p=0.07.For Al/Al2O3 interface Ω1/ΩD=0.09 ψ=0.43

0.23

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Down-conversion noise in TESs. W

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Down-conversion noise in TESs. W

Whilst noise contribution is small (<15%) the energy loss during this stage is significant (~50%)

This is expected, becausephonons of lower energy generationspossess longer mean free paths and all reach escape interface.At the same time their numbers increase leading doa decrease of fluctuations

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Down-conversion noise in TESs. W

ΔE

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Down-conversion noise in Al STJ and WTES in optical range. Comparison

R=E/ΔE

W TES Al STJ

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Down-conversion noise in Ta/Al STJ andW TES in optical range. Comparison

Ref.4 – D.Martin et alAPL, 88 123510 (2006)Ref.2 – B.Cabrera et alAPL, 73, 735 (1998)

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Summary