Production and chemical separation of $^{229}$Pa toward observation of ${\gamma}$ rays of $^{229\rm{m}}$Th

TL;DR

This study produced and chemically separated $^{229}$Pa with high yield to facilitate the observation of gamma rays from the isomeric state of $^{229}$Th, advancing nuclear physics research.

Contribution

The paper reports a new method for producing and separating $^{229}$Pa with significantly higher yields than previous methods, enabling future gamma-ray observations.

Findings

Chemical yield of Pa was 93(4)%

Production yield of $^{229}$Pa was 9.4(8) MBq/μAh

Yield exceeds that of other Pa isotopes by over ten times

Abstract

To observe the ${\gamma}$ rays emitted from the low-lying isomeric state of $^{229}$Th ($^{229\rm{m}}$Th), we aim to dope fluoride crystals with its precursor $^{229}$Pa. In this study, we produced $^{229}$Pa by a 30-MeV proton bombardment on $^{232}$Th and developed a chemical separation method. The chemical yield of Pa was 93(4)%, and the physical production yield of $^{229}$Pa for the proton energy range of 29.0${-}$30.1 MeV was measured to be 9.4(8) MBq/${\rm{\mu}}$Ah, which was more than 10 times higher than those of $^{232,230,228,233}$Pa. These high chemical and production yields will allow us to prepare fluoride crystals having a sufficient amount of $^{229}$Pa for the observation of the ${\gamma}$ rays of $^{229\rm{m}}$Th.