Experimental evidence of an incomplete thermalization of the energy in an x-ray microcalorimeter with a TaAu absorber.
We have conducted an experimental test at our XACT facility using an x-ray microcalorimeter with TaAu absorber and neutron transmutation doped germanium thermal sensor. The test was aimed at measuring the percentage of energy effectively thermalized after absorption of x-ray photons in superconducting tantalum. Moreover, in general, possible formation of long living quasiparticles implies that by using a superconducting absorber, a fraction of the deposited energy could not be thermalized on the useful time scale of the thermal sensor. To investigate this scenario, we exploited an absorber made of gold, where no energy trapping is expected, with a small piece of superconducting tantalum attached on top. We obtained evidence that the thermalization of photons absorbed in tantalum is delayed by energy trapping from quasiparticles. We compare the experimental results with numerical simulations and derive a value for the intrinsic lifetime of quasiparticles.
INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, 90146 Palermo, Italy.
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Perinati
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M
Barbera
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Varisco
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Silver
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J
Beeman
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C
Pigot