Electron thermalization length in solid para-hydrogen at low-temperature

TL;DR

This study measures the thermalization length of low-energy electrons in solid para-hydrogen at low temperature, revealing it to be significantly longer than in liquid helium, using a novel pulsed Townsend photoinjection technique.

Contribution

First measurement of electron thermalization length in solid para-hydrogen at low temperature employing a new photoinjection method.

Findings

Thermalization length is approximately 260 Å.

Thermalization length is 3 to 5 times longer than in liquid helium.

Demonstrates the effectiveness of pulsed Townsend photoinjection technique.

Abstract

We report the first ever measurements of the thermalization length of low-energy electrons injected into solid para-hydrogen at a temperature \(T\approx 2.8\,\)K. The use of the pulsed Townsend photoinjection technique has allowed us to investigate the behavior of quasi-free electrons rather than of massive, slow negative charges as reported in all previous literature. We have found an average thermalization length \(\langle z_0\rangle\approx 260\,\)\AA\ which is 3 to 5 times longer than that in liquid helium at the same temperature.