The n3He Experiment:

The n3He experiment is a measurement of hadronic parity violation in the reaction:

\vec{n}~ + ~^{3}He~ \rightarrow ~^{3}H~ + ~p~ + 765~\rm{keV}

The experiment is approved and in preparation at the Spallation Neutron Source, at Oak Ridge National Laboratory, in Tennessee, USA. It is the last one in a series of four experiments needed to provide a self-consistent description of the hadronic weak interaction (HWI) using few-body systems alone. Beam time has been allocated, tentatively starting in the early Fall of 2014.

The measurement observable is the parity violating forward-backward asymmetry in the number of protons emitted in the breakup of the intermediate ^{4}He state, for a beam of longitudinally polarized, cold neutrons.

Recent theoretical calculations ( PRC) show that the asymmetry is related to a linear combination of weak hadronic couplings involving pion, \rho, and \omega meson exchange:

A^{L}_{p} = -0.1892(86)f_{\pi} -0.0326(40)h^{0}_{\rho} -0.0334(29)h^{0}_{\omega} \simeq 1.14\times 10^{-7}

The aim is to measure the asymmetry to 10% of its predicted size, with an approximate running time of 1 beam year.

Our group, at the University of Manitoba, is responsible for the construction of the target-detector chamber, consisting of a 15 liter ^{3}He ion wire chamber.

More detailed information about this experiment is available in the original proposal from 2007 (Proposal Δ) and an update is provided in the official DOE proposal from 2013 (DOE Proposal Δ).