High-Sensitivity Measurement of 3He-4He Isotopic Ratios for Ultracold Neutron Experiments

Abstract

Research efforts ranging from studies of solid helium to searches for a neutron electric dipole moment require isotopically purified helium with a ratio of 3He to 4He at levels below that which can be measured using traditional mass spectroscopy techniques. We demonstrate an approach to such a measurement using accelerator mass spectroscopy, reaching the 10e-14 level of sensitivity, several orders of magnitude more sensitive than other techniques. Measurements of 3He/4He in samples relevant to the measurement of the neutron lifetime indicate the need for substantial corrections. We also argue that there is a clear path forward to sensitivity increases of at least another order of magnitude.

arXiv comment11 pages, 10 figures

References in corpus (2)

• Measuring the Neutron Lifetime Using Magnetically Trapped Neutrons
• Effects of ${}^3$He Impurity on Solid ${}^4$He Studied by Compound Torsional Oscillator

Cited by in corpus (3)

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• Optimizing neutron moderators for a spallation-driven ultracold-neutron source at TRIUMF
• Effect of an electric field on liquid helium scintillation produced by fast electrons