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

Bunc

her

Phas

eRo

tatio

n

Cool

ing

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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SummaryMICE Step I beamline commissioned and

characterisedReconstruction 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