Results from Step I of MICE D Adey

1. 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

2. Outline • MICE • The detectors • The method • The results • What you should think about it

3. 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

4. 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

5. The Muon Ionisation Cooling Experiment

6. 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

7. 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)

8. 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 Steps II and III removed due to changes in completion time of components Step V Step VI

9. Actuators Irises Optical sensors • 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 • Step I aim – prepare and characterise muon beam up to the diffuser

10. 0.40 m 0.42 m TOF0 TOF1 10 x 4cm scintillator bars x = 1.15 cm 7 x 6cm bars x = 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: 55ps TOF1: 53ps

11. μ π e Selected forward decays Selected forward decays Selected backward 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

12. Results from Step I of MICE

13. 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

14. Estimate Pz from time of flight between TOF planes Calculate transfer matrix element based on this Pz estimate and OPERA model of quadrupole fields Estimate path direction and use residual to update path length ds and Pz Repeat until convergence Correction of 1.5MeV/c included to account for material interactions x1, y1 x0, y0 Q798 – Quadrupole triplet TOF0 – First measurement plane TOF1 – Second measurement plane

15. 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

16. 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

17. Data MC comparison for positions measurements Simulation Rec Data Simulation

18. Comparison of Pz between data (black) MC (red) and reconstructed MC (blue)

19. 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

20. Correction was applied to account for reconstruction resolution

21. 240MeV/c 140MeV/c 200MeV/c Step I results • Data taken for MICE beamline operating modes (inflation to 3-10 mmrad is post-beamline) Beam momenta take loss in diffuser into account

22. Step I results • Data taken for MICE beamline operating modes (inflation to 3-10 mmrad is post-beamline) 140MeV/c 200MeV/c 240MeV/c Beam momenta take loss in diffuser into account

23. 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

24. Backup

27. Trackers • Scintillating fibre trackers (~0.5mm resolution) placed within 4T solenoids • Direct precision measurements of phase space values