# High-precision characterization of the neutron light output of stilbene along the directions of maximum and minimum response

## TL;DR

This study precisely measures the light output of stilbene crystals for proton recoils along different axes, revealing the maximum response along the a-axis, contrary to previous findings, through multiple experimental methods.

## Contribution

It provides the first high-precision characterization of stilbene's light output response along different crystalline axes, challenging prior assumptions.

## Key findings

- Maximum light output occurs along the a-axis.
- Results contradict previous measurements favoring the b-axis.
- Multiple experimental approaches confirm the a-axis as the maximum response direction.

## Abstract

The scintillation light output response of stilbene crystals has been measured for protons recoiling along the \textit{a}, \textit{b}, and \textit{c'} crystalline axes with energies between 1.3 and 10 MeV using neutrons produced with the tandem Van de Graaff accelerator at Triangle Universities Nuclear Laboratory. The proton recoil energy and direction were measured using the coincident detection of neutrons between a stilbene scintillator and an array of EJ-309 liquid scintillators spanning arranged neutron recoil angles. The maximum light output was found to coincide with proton recoils along the \textit{a}-axis, in disagreement with other published measurements, which reported the \textit{b}-axis as the direction of the maximum light output. Additional measurements were conducted using two different stilbene crystals to confirm these results: a second measurement using the coincident detection of neutrons; measurements of neutron full energy deposition events along the \textit{a} and \textit{b} axes; and measurements of the count rate for $^{252}$Cf neutrons traveling along the \textit{a} and \textit{b} axes directions. All measurements found that recoils along the \textit{a}-axis produce the maximum light output.