Counting photons at low temperature with a streaming time-to-digital converter

TL;DR

This paper demonstrates photon counting at low temperatures using a streaming time-to-digital converter, enabling detailed analysis of scintillator light yield, timing, and optical transmission with flexible data processing.

Contribution

It introduces the use of a streaming TDC for photon counting in low-temperature scintillator studies, offering comparable results to fast digitizers and enhanced analysis flexibility.

Findings

Light yield and timing data comparable to fast digitizers

Confirmed low-energy spectral features such as the 60 keV line

Studied optical transmission variations with temperature

Abstract

We present some aspects of photon counting to study scintillators at low temperatures. A time-to-digital converter (TDC) had been configured to acquire several-minute-long streams of data, simplifying the multiple photon counting coincidence technique. Results in terms of light yield and time structure of a ZnWO4 scintillator are comparable to those obtained with a fast digitizer. Streaming data also provides flexibility in analyzing the data, in terms of coincidence window between the channels, and acquisition window of individual channels. We discuss the effect of changing these parameters, and use them to confirm low-energy features in the spectra of the number of detected photons, such as the 60 keV line from 241Am in the ZnWO4 sample. We lastly use the TDC to study the transmission of the optical cryostat employed in these studies at various temperatures.