Surface Events and their Risetimes in PPC Germanium Detectors

Abstract: 

The LEGEND experiment is using germanium detectors to search for neutrinoless double beta decay in 76Ge at Q_ββ = 2039 keV. Surface alpha events that are degraded in energy make up a significant fraction of our background at Q_ββ, but low energy surface events also populate interesting regions of the LEGEND energy spectrum. With the help of the Krypton String Test Cryostat (KrSTC), we can study these low-energy surface effects on a p+ point contact (PPC) Ge detector, similar to detectors used in LEGEND. Data shows clear energy degradation of krypton decay products with a proposed dependence on surface charge accumulation, which is backed up qualitatively by simulation. Pulse shape discrimination is useful in tagging these energy degraded events and improvements in pulse risetime estimation will also be discussed.

Speaker : 

CJ Nave

Location: 

CENPA Conference Room NPL-178

Material: