The n3He Experiment: Target Ion Chamber for the n3He Collaboration - - PowerPoint PPT Presentation

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The n3He Experiment: Target Ion Chamber for the n3He Collaboration - - PowerPoint PPT Presentation

Feb 17, 2024 339 likes •566 views

Introduction Experiment Setup Ion Chamber Assembly Current Status The n3He Experiment: Target Ion Chamber for the n3He Collaboration Mark McCrea University of Manitoba June 3, 2014 ACNS 2014 Knoxville, TN. Introduction Experiment Setup

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Introduction Experiment Setup Ion Chamber Assembly Current Status

The n3He Experiment: Target Ion Chamber

for the n3He Collaboration Mark McCrea University of Manitoba June 3, 2014 ACNS 2014 Knoxville, TN.

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Introduction Experiment Setup Ion Chamber Assembly Current Status

n3He: Target Ion Chamber

1 Introduction 2 Experiment Setup 3 Ion Chamber Assembly 4 Current Status

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n3He Introduction

n3He probes the weak nucleon-nucleon interaction by measuring the parity violating directional asymmetry between the polarization direction of the incoming cold neutrons and the direction of the

  • utgoing protons in the reaction
  • n +3He →4He → p + T + 765keV

kp" kT" σn"

n" p"

3He" 3H"

H1.05 The Status of the n-3He Experiment at the SNS, Irakli Garishvili

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Introduction Experiment Setup Ion Chamber Assembly Current Status

n3He Schematic Diagram in FnPB

Biological Shielding Neutron Guide C1 C2 M1 SMP RFSF Collimator

3He Target/

Detector HF Solendoid H2.05: Resonant Frequency Spin Rotator for the n3He Experiment, Christopher B. Hayes

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Beamline CAD Model

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n3He Target/Detector Chamber

Beam

HV Signal 17 HV Frames with 8 wires each 16 signal Frames with 9 wires each 1 atm. He-3

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Proton Asymmetry in Chamber

  • n +3He → p + T + 765keV

neutron proton Triton Charge Collection

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Introduction Experiment Setup Ion Chamber Assembly Current Status

Target CAD Drawing

Frame Stack with signal and HV PCB on mount plate Chamber exterior with all flanges in place.

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Aluminum Chamber Vessel

  • 10” conflat end flanges
  • windows are 1mm thick Al
  • 4 signal feed thrus
  • 2 gas feed thrus
  • 2 HV feed thrus
  • Al body, SS knife edges
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Target Frames

1/4” thick macor ceramic Signal Frame

  • 9 wires

HV Frame

  • 8 wires
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Completed Frame - HV

  • 0.02” dia. wire
  • 0.8kg Tension
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Frame Stack Assembly

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Assembled Frame Stack

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Circuit Boards Attached

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Frame Stack Shielding

  • Teflon Shielding on signal

board to stop stray charge collection

  • Teflon on HV to stop

unwanted discharge

  • Kapton around ends to

stop unwanted discharge

  • Ceramic beads on bare

wires when possible

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Survey and Alignment

  • The position and angle of

the frame stack inside the housing needs to be known to align it to the neutron beam.

  • Faro Arms are 3D

measurement devices.

  • Position and angle of frame

stack measured to base flange

  • Compression plate was
  • approx. 1.5 milliradian

from parallel to the base

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Mounting Housing on Frame Stack

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Housing In Place

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Survey and Alignment Checking for Frame Stack

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Vacuum Testing

  • Fully Assembled Chamber currently pumped down to less than

10−6 Torr

  • Leak checked at 10 × 10−10mbar.l/s level to be helium tight
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Introduction Experiment Setup Ion Chamber Assembly Current Status

Current Status:

  • n3He Chamber Assembled.
  • Initial HV testing passed
  • 1.5 × 10−8 amps at 1400V from HV to ground
  • Initial leak check passed
  • Currently pumping chamber to remove degassing residuals

Upcoming Tasks:

  • fill with pure 4He for final HV testing and electronics testing
  • fill with pure 3He for short testing on beam before SNS

summer maintenance break

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n3He Collaboration

Duke University, Triangle Universities Nuclear Laboratory

  • Pil-Neo Seo

Istituto Nazionale di Fisica Nucleare, Sezione di Pisa

  • Michele Viviani

Oak Ridge National Laboratory

  • Seppo Penttil
  • David Bowman
  • Vince Cianciolo
  • Jack Thomison

University of Kentucky

  • Chris Crawford
  • Latiful Kabir
  • Aaron Sprow

Western Kentucky University

  • Ivan Novikov

University of Manitoba

  • Michael Gericke
  • Mark McCrea
  • Carlous Olguin

Universidad Nacional Autnoma de Mxico

  • Libertad Baron
  • Jose Favela

University of New Hampshire

  • John Calarco

University of South Carolina

  • Vladimir Gudkov
  • Young-Ho Song

University of Tennessee

  • Nadia Fomin
  • Geoff Greene
  • S. Kucuker
  • C. Hayes
  • Irakli Garishvili

University of Tennessee at Chattanooga

  • Josh Hamblen
  • Caleb Wickersham

University of Virginia

  • S. Baessler