Energy loss due to defect creation in solid state detectors

by Dr Matti Heikinheimo (Department of Physics, University of Helsinki and Helsinki Institute of Physics, Finland)

Wednesday 19 Oct 2022, 14:30 → 16:00 Asia/Shanghai

Meeting Room N631 (Tsung-Dao Lee Institute)

Abstract:

The threshold displacement energy in solid state detector materials varies from several eV to ~100 eV. If a stable or long lived defect is created as a result of a nuclear recoil event, part of the recoil energy is stored in the deformed lattice and is therefore not observable in a phonon detector. Thus, an accurate model of this effect is necessary for precise calibration of the recoil energy measurement in low threshold phonon detectors.
In a hard material such as diamond, the sharp defect creation threshold will cause a sudden onset of the energy loss effect, resulting in a prominent peak in the observed recoil spectrum just below the threshold displacement energy. We describe how this effect can be used to discriminate between nuclear and electron recoils using just the measured recoil spectrum. We demonstrate this identification criteria in the context of the low-energy excess observed in multiple DM detectors.

Biography:

 9/2018 to present: University researcher, University of Helsinki.
• 10/2015 to 8/2018: Postdoctoral researcher, Helsinki institute of physics.
• 1/2013 to 9/2015: Postdoctoral researcher, National Institute of Chemical Physics and Biophysics, Tallinn.
• 1/2011 to 12/2012: Postdoctoral fellow, Department of Physics and Astronomy, York University, Toronto and 4/2012 - 12/2012: also LAPTh, Annecy-le-Vieux.
• 5/2007 to 11/2010: Graduate student, Department of Physics, University of Jyväskylä.
 

 

C_impact_80eV.mp4

EnergyLoss.pdf