Carter, Faustin W. and Hertel, Scott A. and McClintock, Peter Vaughan Elsmere and McKinsey, Daniel N. and Prober, Daniel E. (2017) Calorimetric observation of single He2* excimers in a 100 mK He bath. Journal of Low Temperature Physics, 186 (3). pp. 183-196. ISSN 0022-2291
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Abstract
We report the first calorimetric detection of individual He2* excimers within a bath of superfluid 4He. The detector used in this work is a single superconducting titanium transition edge sensor (TES) with an energy resolution of 1 eV, immersed directly in the helium bath. He2* excimers are produced in the surrounding bath using an external gamma-ray source. These excimers exist either as short-lived singlet or long-lived triplet states. We demonstrate detection (and discrimination) of both states: in the singlet case the calorimeter records the absorption of a prompt 15 eV photon, and in the triplet case the calorimeter records a direct interaction of the molecule with the TES surface, which deposits a distinct fraction of the 15 eV, released upon decay, into the surface. We also briefly discuss the detector fabrication and characterization.