Jun 13 – 19, 2015
University of Alberta
America/Edmonton timezone
Welcome to the 2015 CAP Congress! / Bienvenue au congrès de l'ACP 2015!

Current Status of a Measurement of Hadronic Parity Violation in the Capture of Cold Neutrons on Helium-3

Jun 18, 2015, 10:00 AM
CCIS 1-140 (University of Alberta)

CCIS 1-140

University of Alberta

Oral (Student, Not in Competition) / Orale (Étudiant(e), pas dans la compétition) Instrumentation and Measurement Physics / Physique des instruments et mesures (DIMP-DPIM) R1-6 Testing Fundamental Symmetries II (DTP-PPD-DNP) / Tests de symétries fondamentales II (DPT-PPD-DPN)


Mr Mark McCrea (University of Manitoba)


The n3He experiment aims to measure the parity violating asymmetry in the direction of proton emission from the capture polarized cold neutrons in an unpolarized gaseous $^3$He target from the reaction $\vec{n}+^3He\rightarrow T+p$. The size of the asymmetry is estimated to be $(-9.5 \rightarrow 2.5)\times 10^{-8}$, and our goal measurement accuracy is $2\times10^{-8}$. The asymmetry is a result of the low energy weak interaction between quarks and its measurement will provide a benchmark for modern effective field theory calculations. The experiment uses a $^3$He multiwire ionization chamber as the combined target and detector operated in current mode. Simulation is required study the ideal behavior of the chamber and verify it works as expected. To simulate the charge collection in the chamber Garfield++ is used to simulate the electron avalanches and ion mobility in the wire chamber fields. 3D field maps are generated using Gmsh and Elmer. Garfield++ does not simulate low energy particles ionizing gas so it is paired with a Geant4 simulation for charge deposition in the chamber. The experiment is currently running at the Oak Ridge National Lab (Tennessee, USA) and I will report on the simulation of, and initial data taken with the chamber.

Primary author

Mr Mark McCrea (University of Manitoba)

Presentation materials