Current Status of a Measurement of Hadronic Parity Violation in the - PowerPoint PPT Presentation

Current Status of a Measurement of Hadronic Parity Violation in the Capture of Cold Neutrons on Helium-3 for the n3He Collaboration Mark McCrea University of Manitoba 2015 CAP Congress June 18, 2015

Introduction Motivation Spallation Neutron Source Experiment Setup Ion Chamber Details Ion Chamber Simulation

n3He Introduction n3He probes the low energy strong interaction, using the weak interaction by measuring the parity violating directional asymmetry in the proton recoil from the reaction n + 3 He → p + T + 765 keV � θ s ,� k p n Beam 3 He T The goal of the experiment is to measure the asymmetry to the 2 × 10 − 8 level.

Theoretical Motivation q q q q Z 0 , W ± g q q q q Strong Interaction Weak Interaction u d d u d d N N π, ρ, ω ? PC PV Strong Weak u d d u d d N N Uncertain HWI DDH Parameterization DDH Meson Exchange Parameters: O pv = a 1 π h 1 π + a 0 ρ h 0 ρ + a 1 ρ h 1 ρ + a 2 ρ h 2 ρ + a 0 ω h 0 ω + a 1 ω h 1 ω

A Brief Look at Parity Under a parity transformation P polar vectors such as the momentum transform as P ( � k n ) → − � P ( � k p ) = − � k n and k p but axial vectors, such as the neutron spin, remain unchanged P ( � s n ) → � s n θ s ,� k Orignal State: p n 3 He Beam T Parity Transformed: p 3 He n T Beam θ s ,� k Spin Flipped: θ s ,� k n p Beam 3 He T

Spallation Neutron Source ◮ Located at the Oak Ridge National Laboratory (ORNL) in Tennessee ◮ 60 Hertz pulsed spallation source ◮ approximately 10 10 neutrons/second ◮ n3He is running at the FnPB ◮ Three 20K liquid hydrogen moderator for cold neutron beam lines

n3He Schematic Diagram Collimator C1 C2 Neutron 3 He Target/ M1 SMP RFSF Detector Guide HF Solendoid Biological Shielding

n3He Target Chamber Beam HV 17 HV Frames with 8 wires each Signal 16 signal Frames with 9 wires each

Assembled Frame Stack ◮ 17 HV frames ◮ 16 signal frames ◮ 9 signal wires per frame ◮ 144 signals to read out

Proton Asymmetry in Chamber n + 3 He → p + T + 765 keV � Neutron Proton Triton Electron Collection A proton and triton asymmetry occur in the chamber but the longer range of the proton causes its asymmetry to dominate

Target Chamber on Stand ◮ 4 point adjustable stand ◮ roll, pitch, height were not independent ◮ target electrically isolated from stand ◮ angle block used for initial alignment

Components on Beamline

First Data from Ion Chamber

Ion Chamber Simulation - Garfield++ Garfield++ is a toolkit for the detailed simulation of particle detectors that use gas and semi-conductors as sensitive medium. ◮ Gas properties calculated using Magboltz ◮ Ion Mobility from Data from Atomic Data and Nuclear Data Tables 17, 177-210 (1976) ◮ Signal calculated with Shockley-Ramo Theorem: i ( t ) = − q v · E w ( r ) ◮ E w ( r ) is a calculated weighting field as though the electrode had a potential of 1V and everything else is ignored ◮ Fields and Electrode locations from Gmsh and Elmer ◮ Looking at charge collection times and signals

Geometry - Gmsh

Geometry - Gmsh

Fields - Elmer FEM

Initial Simulation Details ◮ 200 events at 6 locations spaced evenly between HV and Signal wire ◮ ion and electron propagated from each point ◮ collection time to be compared with measured values

Collection Times Electron Collection Times 120 100 80 60 40 20 0 0 500 1000 1500 2000 2500 3000 3500 4000 t(ns) ◮ Six equally spaced starting positions gave 6 peaks. ◮ 200 electrons per positions

Integrated Signal - electron hist Integrated Signal e -0 hist Integrated Signal e -1 hist Integrated Signal e -2 hIntegratedSig-e-0 hIntegratedSig-e-0 hIntegratedSig-e-1 hIntegratedSig-e-1 hIntegratedSig-e-2 hIntegratedSig-e-2 25 16 Entries Entries 200 200 Entries Entries 200 200 Entries Entries 200 200 16 Mean -22.85 Mean -22.85 Mean -71.36 Mean -71.36 14 Mean -108.7 Mean -108.7 20 14 RMS 0.7114 RMS 0.7114 RMS 1.393 RMS 1.393 RMS 2.172 RMS 2.172 12 12 15 10 10 8 8 10 6 6 4 4 5 2 2 0 0 0 -25 -24 -23 -22 -21 -20 -74 -72 -70 -68 -66 -114 -112 -110 -108 -106 -104 -102 × -6 × -6 × -6 fC 10 fC 10 fC 10 hist Integrated Signal e -3 hist Integrated Signal e -4 hist Integrated Signal e -5 hIntegratedSig-e-3 hIntegratedSig-e-3 hIntegratedSig-e-4 hIntegratedSig-e-4 hIntegratedSig-e-5 hIntegratedSig-e-5 14 12 Entries Entries 200 200 Entries Entries 200 200 Entries Entries 200 200 100 Mean Mean -149.4 -149.4 Mean -126.5 Mean -126.5 Mean -140.2 Mean -140.2 12 10 RMS RMS 27.27 27.27 RMS 2.433 RMS 2.433 RMS 2.506 RMS 2.506 80 10 8 8 60 6 6 40 4 4 20 2 2 0 0 0 -132 -130 -128 -126 -124 -122 -120 -146 -144 -142 -140 -138 -136 -134 -150 -100 -50 0 × -6 × -6 × -6 fC 10 fC 10 fC 10 Ion/Electron pair signals measure from 6 positions

Summary ◮ Target chamber assembled and tested November 2014 ◮ Target chamber installed December 2014 ◮ First Data from Chamber January 2015 ◮ Data taking to continue until end of 2015 ◮ Charge collection simulations are progressing

n3He Collaboration Duke University, Triangle Western Kentucky University of Tennessee Universities Nuclear University ◮ Noah Birge Laboratory ◮ Ivan Novikov ◮ Chris Coppola ◮ Pil-Neo Seo University of Manitoba ◮ Nadia Fomin Istituto Nazionale di ◮ Michael Gericke ◮ Connor Gautham Fisica Nucleare, Sezione ◮ Mark McCrea di Pisa ◮ Geoff Greene ◮ Carlos Olguin ◮ Michele Viviani ◮ Irakli Garishvili Universidad Nacional Oak Ridge National ◮ Chris Hayes Aut´ onoma de M´ exico Laboratory ◮ Libertad Baron ◮ Serpil Kucuker ◮ Seppo Penttil¨ a ◮ Jose Favela ◮ Eric Plemons ◮ David Bowman University of New ◮ Mae Scott ◮ Vince Cianciolo Hampshire ◮ Jack Thomison University of Tennessee ◮ John Calarco at Chattanooga ◮ Paul Mueller University of South ◮ Josh Hamblen University of Kentucky Carolina ◮ Jeremy Watts ◮ Chris Crawford ◮ Vladimir Gudkov ◮ Latiful Kabir ◮ Matthias Schindler University of Virginia ◮ Aaron Sprow ◮ Young-Ho Song ◮ S. Baessler