A spallation target at TRIUMF for fundamental neutron physics

¹ TRIUMF, Vancouver, BC, Canada
² University of British Columbia, Vancouver, BC, Canada
³ University of Manitoba, Winnipeg, MB, Canada
⁴ Center for European Nuclear Research, CH-1211 Geneva 23, Switzerland
⁵ McGill University, Montreal, QC, Canada
⁶ Carleton University, Ottawa, ON, Canada
⁷ Coburg University of Applied Science, Coburg, Germany
⁸ Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka, Japan
⁹ High Energy Accelerator Research Organization, KEK, Tsukuba, Ibaraki, Japan
¹⁰ University of Northern British Columbia, Prince George, BC, Canada
¹¹ University of Winnipeg, Winnipeg, MB, Canada
¹² J-PARC, Tokai, Ibaraki, Japan
¹³ Simon Fraser University, Burnaby, BC, Canada

^* Corresponding author: svanbergen@triumf.ca

Published online: 22 June 2023

Abstract

Ultracold neutrons (UCNs) are a powerful tool for probing the Standard Model at high precision. The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration is building a new UCN source to provide unprecedented densities of UCNs for experiments. This source will use a tantalum-clad tungsten spallation target, receiving up to 40 µA of 480-MeV protons from TRIUMF’s main cyclotron. The beamline and target were constructed from 2014 to 2016 and operated at beam currents up to 10 µA from 2017 to 2019 as part of a prototype UCN source. We describe the design choices for the target and target-handling system, as well as our benchmarking of the target performance using UCN production measurements.