Compact ultracold neutron source concept for low energy accelerator-driven neutron sources

TL;DR

This paper proposes a small-scale, pulsed-proton accelerator-based ultracold neutron source using superfluid helium and supercold moderators to achieve high UCN production with low thermal load, suitable for compact facilities.

Contribution

It introduces a novel compact UCN source design utilizing supercold moderators and superfluid helium, enabling efficient UCN production at low-energy proton facilities.

Findings

UCN production rate of 80 UCN/cc/sec achieved

Thermal load maintained at 22 mW in the UCN converter

Potential for small-scale, low-energy neutron source applications

Abstract

The concept of a small-scale, pulsed-proton accelerator based compact ultracold neutron (UCN) source is presented. The essential idea of the compact UCN source is to enclose a volume of superfluid $^{4}\mathrm{He}$ converter with a supercold moderator in the vicinity of a low-radiation neutron production target from (p, n) reactions. The supercold moderator should possess an ability to produce cold neutron flux with a peak brightness near the single-phonon excitation band of the superfluid $^{4}\mathrm{He}$ converter, thereby augmenting the UCN production in the compact UCN source even with very low intensity of neutron brightness. The performance of the compact UCN source is studied in terms of the UCN production and thermal load in the UCN converter. With the proposed concept of the compact UCN source, a UCN production rate of $P_{\mathrm{UCN}}=80\mathrm{UCN}/\mathrm{cc}/\mathrm{sec}$ in the UCN converter could be obtained while maintaining thermal load of on the superfluid $^{4}\mathrm{He}$ and its container at a level of $22\mathrm{mW}$. This study shows that the compact UCN source can produce a high enough density of UCN at a small-scale, low-energy, pulsed-proton beam facility with reduced efforts on the cooling and radiation protection.