Spectrometer Magnetic Field for Neutron Beta Decay at the SNS - - PowerPoint PPT Presentation

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Spectrometer Magnetic Field for Neutron Beta Decay at the SNS - - PowerPoint PPT Presentation

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Spectrometer Magnetic Field for Neutron Beta Decay at the SNS Introduction Design Requirements Spectrometer Magnetic Field Design Outlook January 8, 2006 Introduction The abBA Experiment : Precise Measurement of

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SLIDE 1

January 8, 2006

Spectrometer Magnetic Field for Neutron Beta Decay at the SNS

  • Introduction
  • Design Requirements
  • Spectrometer Magnetic Field
  • Design Outlook
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SLIDE 2

January 8, 2006

Introduction

  • The abBA Experiment: “Precise Measurement of Neutron Decay

Parameters”, J.D. Bowman (LANL) and W.S. Wilburn (LANL), spokespersons.

  • The Nab Experiment: “Precise Measurement of the Neutron Beta Decay

Parameters a and b”, J.D. Bowman (LANL) and D. Pocanic (Virginia), spokespersons.

  • The PANDA Experiment: “The Proton Asymmetry in Neutron Decay

Experiment”, T. Chupp (Michigan), spokesperson.

  • A Proposal Review and Advisory Committee (PRAC) reviewed these

proposals on September 8-9, 2005. The PRAC key recommendation reads, “ …We strongly encourage the three efforts to investigate the option of a common magnet which could be tuned to provide the different field profiles needed for the three experiments…”

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SLIDE 3

January 8, 2006

Design Considerations

  • 1. Magnetic Field Strength:

B (T) Decay Drift Detector abBA ~ 4.0 ~ 1.0 ~ 1.0 Nab 2.0 – 4.0 0.1– 0.4 0.5 –1.0 PANDA ~ 2.0 ~ 2.0 ~ 2.0

  • 2. A magnetic field homogeneity dB/B < 10-2 is required in the decay region.
  • 3. The length of the magnet should be at least 2 m on each side of the decay region.
  • 4. The magnet diameter should be at least 25 cm in the drift and detector regions.
  • 5. The spectrometer must permit an approximate 10 cm gap for transmission of the neutron

beam.

  • 6. The magnetic field must allow the transmission of a polarized neutron beam in and out
  • f the decay region without a significant loss of polarization. This requirement is that the

loss of polarization should be < 0.15%.

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SLIDE 4

January 8, 2006

The Baseline Design

NI [MA-turns] Split Pair Transport Solenoid abBA (4 T) 1.04 3.26 Nab (2 T) 0.56 1.36 PANDA (1.6 T) 0.22 5.80

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SLIDE 5

January 8, 2006

The abBA Configuration

Current Density along Solenoid

500 1000 1500 2000 2500 3000 3500 4000 50 100 150 200 250 z (cm ) J (A/cm 2

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SLIDE 6

January 8, 2006

The Decay Region

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SLIDE 7

January 8, 2006

Particle Trajectories

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SLIDE 8

January 8, 2006

The Nab Configuration

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SLIDE 9

January 8, 2006

The Decay Region

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SLIDE 10

January 8, 2006

Particle Trajectories

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SLIDE 11

January 8, 2006

The PANDA Configuration

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SLIDE 12

January 8, 2006

Polarized Neutrons Transmission

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SLIDE 13

January 8, 2006

Polarized Neutrons Transmission

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SLIDE 14

January 8, 2006

Design Outlook

  • Electric Field
  • Magnetic Shielding (w/wo Iron)
  • Simulations – Field Profiles
  • First cost estimate
  • First pass at mechanical design (forces, ….)
  • Design Report