SEMINAR ANNOUNCEMENT
Speaker:
Kush AggarwalDate and Location:
Monday, September 9, 2024 2:30 PM
CENPA Conference Room NPL-178
Title:
Measurement of Fast Neutrons in CCD storage room at CENPA
Abstract:
The DAMIC-M experiment aims to directly detect sub-GeV dark matter particles using Charge-Coupled Devices (CCDs) with single-electron resolution. A key challenge for the experiment is the production of tritium in the silicon detectors due to interactions with cosmic-ray-induced neutrons, which leads to background noise that mimics dark matter signals. Neutrons with energies above 16 MeV are particularly problematic as they activate tritium production, with peak contributions occurring at around 75 MeV.
In this work, we present an analysis of the neutron flux and activation cross-sections that influence tritium production in our CCDs. We utilize a BC501A scintillator to measure the neutron flux and apply pulse shape discrimination (PSD) to differentiate neutron events from gamma and muon backgrounds. The data indicate that storing the CCDs in a gravity-shielded environment significantly reduces exposure to high-energy neutrons, achieving a 50-fold reduction compared to surface-level exposure. The detector's efficiency in identifying fast neutrons is estimated at 13%, and we demonstrate that the CCDs are well protected in this environment, with 50 days of storage equivalent to just one day of surface exposure. This ensures minimal tritium activation, thereby preserving the sensitivity of the DAMIC-M detectors to dark matter interactions.