results from step i of mice d adey 2013 international workshop on neutrino factories, super-beams...
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Results from Step I of MICE
D Adey
2013 International Workshop on Neutrino Factories, Super-beams and Beta-beams
Working Group 3 – Accelerator Topics
Institute of High Energy Physics Beijing 21st August 2013
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Outline
MICE The detectors The method The results What you should think about it
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755 m
12.6–25 GeV FFAG
3.6–12.6 GeV RLA
0.9–3.6 GeV RLALinac to 0.9 GeV
Muon DecayRing
Muon Decay Ring
Linac optionRing option
Proton Driver:
Neutrino Beam
Neutrino Beam
Targ
et
Buncher
Phase
Rota
tion
Cooling
IDS-NF Baseline 2010
Muon ColliderMuon Collider
Muon beams are big (20 mm.rad at a Neutrino Factory)
Reducing the transverse emittance of the beam to 2-5 mm.rad can mean a 10^3 difference in flux between a Neutrino Factory and less involved muon storage rings
Longitudinal emittance reduction will be essential for a muon collider
Existing methods of emittance reduction are too slow for the short lifetime of the muon
Need something new
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Isotropic energy loss achieved in an absorber
Multiple scattering unavoidable, so material must be chosen with care, optimising dE/dx (cooling) against scattering (heating)
Longitudinal momentum replaced with RF cavities
Net loss in transverse momentum spread and total 4D emittance
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The Muon Ionisation Cooling Experiment
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Single particle measurement using precision spectrometers
Calculate emittance from particle ensemble
Pass through absorber and RF modules
Solenoidal lattice for focussing into absorber and coupling in Rf cavities
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Based at the Rutherford Appleton Laboratory near Oxford, UK
Utilises the proton synchrotron of the ISIS neutron spallation source
Staged planning with addition of liquid hydrogen absorbers and RF cavities
Step I – Beamline comissioning (complete)
Step IV –Tracking detectors and single absorber focus coil module
Step V –2 AFC and RF modules (sustainable cooling)
Step VI –3 AFC and 2 RF modules (one cooling cell)
ISIS
MICE HallR5.2
ISIS
MICE HallR5.2
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Based at the Rutherford Appleton Laboratory near Oxford, UK
Utilises the proton synchrotron of the ISIS neutron spallation source
Staged planning with addition of liquid hydrogen absorbers and RF cavities
Step I
Step IV
Step V
Step VI
Steps II and III removed due to changes in completion time of components
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140 – 240 MeV/c momentum range
3-10 mm.rad transverse emittance inflated by diffuser mechanism
Measure 10% reduction in emittance to within 1% - 0.1% measurement of emittance
Achieved with single particle measurements in precision spectrometer
Irises
Actuators
Optical sensors
Step I aim – prepare and characterise muon beam up to the diffuser
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TOF0
0.40 m
10 x 4cm scintillator barsx = 1.15 cm
TOF1
0.42 m
7 x 6cm barsx = 1.73 cm
Scintillating Time of Flight counters
4-6cm segmentation with X-Y views covering the beam profile
Low timing resolution Position resolution improved by
timing difference between PMTs
TOF0: 55psTOF1: 53ps
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e
μ
π
Selected forward decays Selected backward decaysSelected forward decays
TOF counters placed either side of Quadrupole triplet
Time of Flight coupled with momentum selection from dipoles allows for PID between electrons, muons on pions
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Results from Step I of MICE
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Measurement planes
Position measurements at two planes and knowledge of the transfer matrices between points provides the angle x'
Elements are momentum dependant MICE has a longitudinal momentum spread of
10% A modified technique is required
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1) Estimate Pz from time of flight between TOF planes
2) Calculate transfer matrix element based on this Pz estimate and OPERA model of quadrupole fields
3) Estimate path direction and use residual to update path length ds and Pz
4) Repeat until convergence
5) Correction of 1.5MeV/c included to account for material interactions
TOF0 – First measurement plane
TOF1 – Second measurement plane
Q798 – Quadrupole triplet
x0, y0
x1, y1
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Position measurements obtained by functions of Pz
x1 = A(pz )x0 + B(pz )
Strong Pz dependance below 200MeV/c leads to large scale deviations between single particle transfer matrices – no single matrix for a MICE beam
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Monte Carlo simulation shows Pz resolution is dominated by TOF resolution
Using the reconstruction method, true x' and x' reconstructed (from MC) are compared
σx and σy MC approximately 9.8 and 11.4 mm respectively
Simulation allows for characterisation of reconstruction performance and correction to real data emittance calculations due to reconstruction resolution
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Simulation Simulation Rec Data
Data MC comparison for positions measurements
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Comparison of Pz between data (black) MC (red) and reconstructed MC (blue)
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Reconstruction method generates trace space values from which ellipses can be defined (chi squared = 6 shown)
Covariance matrix of trace space values provides optical functions
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Correction was applied to account for reconstruction resolution
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140MeV/c
200MeV/c
240MeV/c
Beam momenta take loss in diffuser into account
Step I results Data taken for MICE beamline
operating modes (inflation to 3-10 mmrad is post-beamline)
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140MeV/c200MeV/c 240MeV/c
Beam momenta take loss in diffuser into account
Step I results Data taken for MICE beamline
operating modes (inflation to 3-10 mmrad is post-beamline)
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Summary
MICE Step I beamline commissioned and characterised
Reconstruction technique using Time of Flight counters enabled measurement of trace space parameters and Twiss functions of MICE muon beam
Analysis paper accepted by European Physics Journal C
Preparations and planning for Step IV ongoing – see next talk by D. Kaplan
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Backup
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Trackers Scintillating fibre trackers
(~0.5mm resolution) placed within 4T solenoids
Direct precision measurements of phase space values
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