The Mu2e Experiment

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MANX Meeting
The Mu2e Experiment and Stopping Muon Beams
Chuck Ankenbrandt Fermilab July 14, 2008
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Introduction

• Whats Mu2e?
• Charged-lepton flavor violation experiment
• Why talk about Mu2e at a MANX meeting?
• Another possible application of an HCC channel
• An application that doesnt need re-acceleration
  (no rf)
• Status of Mu2e
• LOI submitted a year ago
• Intensely discussed in Fermilab Steering Group
• Strong support from P5 and PAC
• Baseline like MECO (a BNL proposal)
• Activity so far has focused on adapting to
  Fermilab beam
• Proposal being prepared for Autumn PAC meeting

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mu2e Apparatus
1 T
1 T
Muon Beam
2 T
Superconducting Solenoids
Calorimeter
Straw Tracker
Stopping Target Foils
Proton Beam
Detector Solenoid 10 m long x 0.95 m rad
2.5 T
5 T
Pion Production Target
Transport Solenoid 13 m long x 0.25 m rad
Production Solenoid 4m long x 0.75 m rad
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Paper at EPAC08
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Initial design, gaseous absorber
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Range-momentum in LiH
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Use of LiH wedge absorbers
Cross sectional view of LiH wedge absorber.
Final momentum spectra in various channels. The
red curve is for a helical magnet with wedge-
shaped absorbers, the blue one is for a helical
magnet with flat plate absorbers, and the dotted
curve is for a pure solenoid.
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DipoleWedge Concept
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DipoleWedge simulations
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DW Advantages

• We take advantage of the pion production peak,
  which is at zero degrees.
• We can also choose to work near the peak of the
  pion momentum spectrum for forward produced pions
  to maximize the pi/p yield.
• The proton beam points away from the detector,
  reducing neutral backgrounds.
• Wrong-sign background particles never get into
  the muon transport, so an S-bend solenoid (as
  used in mu2e) is not needed.
• After the wedge, the quasi-monochromatic beam can
  be at a momentum for which the HCC works well.
• With the right amount of absorber material in the
  HCC, we can select those muons that result from
  forward decays of the pions in order to produce a
  polarized stopping beam.
• With that same amount of material, pions that
  dont decay and heavier particles will range out
  in the absorber in the HCC and not reach the
  stopping target, thereby greatly reducing
  hadronic flash background