A. Dobbs 1

ISIS Related Issues for MICE

Adam DobbsProton Accelerator Development Meeting, RAL

24th March 2011

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Contents

• Introduction to MICE– Purpose– Ionisation Cooling– The Cooling Channel– MICE in ISIS and the Beamline

• ISIS beam loss measurement• ISIS beam loss and MICE particle rate

– Beam loss and target depth– Beam loss and particle rate– Beam loss and muon rate

• Conclusion24/03/2011

A. Dobbs 3

Muon Ionisation Cooling Experiment

• Purpose: investigate the feasibility of ionisation cooling, for application to a future Neutrino Factory or Muon Collider.

• Neutrino Factory → Precision measurements of neutrino oscillations

• Muon Collider → Multi-TeV lepton – anti-lepton collisions

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Ionisation Cooling - Why

• An NF muon beam requires cooling (emittance reduction) in order to fit efficiently within the acceptance of downstream acceleration components

• An MC also requires small interaction points to increase luminosity

• Muon lifetime of 2.2μs to fast to permit traditional cooling techniques → ionisation cooling

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Ionisation Cooling - How

• Pass the beam through an absorber e.g. liquid hydrogen, lithium hydride

• The particle beam ionises the medium, the beam particles losing energy and momentum in all directions

• Re-accelerate the beam in the beamline direction (z) only, using a radio frequency electric field

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LiH2

v

v RF v

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MICE Step VI

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MICE in ISIS and the Beamline

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The MICE target

• A 24 coil stator is used to drive a shuttle, consisting of a titanium shaft upon which are mounted permanent magnets to couple to the field produced by the stator

• The lower end of the shaft takes the form of a hollow cylinder, which is pulsed into the ISIS beam by the stator

• Upper and lower bearings are used to maintain the transverse position of the shaft.

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ISIS Beam loss

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• 39 argon gas ionisation chambers around the ring

• Use the summed signal of the four sector 7 BLMs, integrate over the whole 10ms ISIS cycle (V.ms)

• Slightly different gauge used than ISIS (smaller by ∼ 1/3 )Increased beam loss levels raise the concerns over machine

activation levels inhibiting hands-on maintenance

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Beam Loss and Target Depth

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Beam Loss and MICE Particle Rate

• Linear correlation

• Constant offset

• Averaged data – few hundred pulses per point

• Pion optics

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Beam Loss and MICE Particle Rate

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-ve π → μ optics +ve π → μ opticsStill linear

Spill-by-spill data (no averaging)

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Beam Loss and MICE Particle Rate

Not linear at low beam loss... not to worry,believed to be caused by a mis-configured gate24/03/2011

+ve π → μ optics, “10V study”

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...but what about Muons?

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• Use Time-of-Flight to perform Particle Identification

• -ve π → μ optics

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Beam Loss and Muon Rate

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-ve π → μ optics +ve π → μ optics

Still linear

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Muon Rate Numbers

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So, depending on MICE optics get a few 10’s of muons per 1ms spill

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Conclusion

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• The MICE Muon Beamline is functioning well in ISIS, and has been for sometime

• Depending on MICE optics, the beamline delivers a few 10’s of muons per 1ms spill that can be used

• Desired rate is several hundred “good” muons per 1ms spill• Would probably require beam loss levels that are intolerable

to ISIS• Various solutions put forward:

– Increased MICE target dip rate– Longer MICE data running to account for lower rates– ISIS beam bump at MICE target– Improved ISIS collimator system

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Appendix I: Run conditions

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