Scintillation and charge extraction from the tracks of energetic electrons in superfluid helium-4

TL;DR

This study measures the mean electron-ion separation distance in superfluid helium-4 by analyzing scintillation light quenching under electric fields, aiding the development of helium-based particle detectors.

Contribution

It provides the first measurement of the mean electron-ion separation distance in superfluid helium-4 for beta particle tracks, informing detector design.

Findings

Mean electron-ion separation distance determined

Scintillation quenching depends on electric field strength

Results support improved helium-based detector development

Abstract

An energetic electron passing through liquid helium causes ionization along its track. The ionized electrons quickly recombine with the resulting positive ions, which leads to the production of prompt scintillation light. By applying appropriate electric fields, some of the ionized electrons can be separated from their parent ions. The fraction of the ionized electrons extracted in a given applied field depends on the separation distance between the electrons and the ions. We report the determination of the mean electron-ion separation distance for charge pairs produced along the tracks of beta particles in superfluid helium at 1.5 K by studying the quenching of the scintillation light under applied electric fields. Knowledge of this mean separation parameter will aid in the design of particle detectors that use superfluid helium as a target material.