First Precision Measurement of the Parity Violating Asymmetry in Cold Neutron Capture on He 3

M. T. Gericke, S. Baeßler, L. Barrón-Palos, N. Birge, J. D. Bowman, J. Calarco, V. Cianciolo, C. E. Coppola, C. B. Crawford, N. Fomin, I. Garishvili, G. L. Greene, G. M. Hale, J. Hamblen, C. Hayes, E. Iverson, M. L. Kabir, M. McCrea, E. Plemons, A. Ramírez-MoralesP. E. Mueller, I. Novikov, S. Penttila, E. M. Scott, J. Watts, C. Wickersham

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


We report the first precision measurement of the parity-violating asymmetry in the direction of proton momentum with respect to the neutron spin, in the reaction He3(n,p)3H, using the capture of polarized cold neutrons in an unpolarized active He3 target. The asymmetry is a result of the weak interaction between nucleons, which remains one of the least well-understood aspects of electroweak theory. The measurement provides an important benchmark for modern effective field theory and potential model calculations. Measurements like this are necessary to determine the spin-isospin structure of the hadronic weak interaction. Our asymmetry result is APV=[1.55±0.97(stat)±0.24(sys)]×10-8, which has the smallest uncertainty of any hadronic parity-violating asymmetry measurement so far.

Original languageEnglish
Article number131803
JournalPhysical Review Letters
Issue number13
StatePublished - Sep 2020

Bibliographical note

Publisher Copyright:
© 2020 American Physical Society.

ASJC Scopus subject areas

  • General Physics and Astronomy


Dive into the research topics of 'First Precision Measurement of the Parity Violating Asymmetry in Cold Neutron Capture on He 3'. Together they form a unique fingerprint.

Cite this