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MICE Cooling Channel: Can we predict cooling to 10 -3 ? Edda Gschwendtner

MICE Cooling Channel: Can we predict cooling to 10 -3 ? Edda Gschwendtner. Challenge Systematics Cooling Channel Beam Line Summary. Challenges of MICE. Operate RF cavities of relatively low frequency (200MHz) at high gradient (up to16MV/m) in highly inhomogeneous magnetic fields (1-3T)

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MICE Cooling Channel: Can we predict cooling to 10 -3 ? Edda Gschwendtner

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  1. MICE Cooling Channel:Can we predict cooling to 10-3 ?Edda Gschwendtner • Challenge • Systematics • Cooling Channel • Beam Line • Summary Edda Gschwendtner

  2. Challenges of MICE • Operate RF cavities of relatively low frequency (200MHz) at high gradient (up to16MV/m) in highly inhomogeneous magnetic fields (1-3T) • Dark currents (can heat up LH2)  breakdowns • Emittance measurement to relative precision of 10-3 in environment of RF background requires • low mass and precise tracker • Low multiple scattering • Redundancy to fight dark current induced background • Excellent immunity to RF noise • Hydrogen safety • substantial amounts of LH2 in vicinity of RF cavities and SC magnets Edda Gschwendtner

  3. Goal of MICE 10% cooling of 200MeV/c muons  With measurement precision: Δ (εout/ εin) = 10-3 Science fiction example: MICE measures (εout/εin)exp = 0.904 ± errstat and compares with (εout/εin)sim = 0.895 Try to understand the difference. • Theory uncertainties: • Model and simulation choices • Experimental uncertainties: • Design of detectors/cooling elements Edda Gschwendtner

  4. Sources of Experimental Systematic Uncertainties • Particle tracker • Assume: tracker can give precision of particle position and momentum that won’t contribute significantly to the error. • Particle ID • Assume: Particle ID < 1% error • Cooling channel / detector solenoid • Main source of systematic errors! • Should be under control to a level such that up to 10 independent sources of systematics will be < 10-3 ( each of them < 3 ·10-4) • (Beam line) This talk! Edda Gschwendtner

  5. Cooling Channel • three Absorber and Focus Coil modules (+ three LH2 handling systems) • two RF Cavity and Coupling Coil modules (+ RF power systems) • power supplies, field monitoring, and quench protection for magnets • infrastructure items • vacuum systems (pumps, valves, monitoring equipment) Edda Gschwendtner

  6. How to Handle Systematics • Design considerations • Define tolerances • Monitoring • Calibration measurements with the muon beam Edda Gschwendtner

  7. Cooling Channel NB thickness of H2 absorbers cannot be easily measured in situ (safety windows are in the way) Edda Gschwendtner

  8. RF Cavities I (Calibration & Design) • RF dark currents were measured at Fermilab on 805MHz cavities in magnetic field • Extrapolation to 201 MHz • Simulation of RF backgrounds • Will resume tests on 201 MHz prototype in spring 2005 Edda Gschwendtner

  9. RF Cavities II (Monitoring) Monitoring of: • Voltage, phase and temperature in each cavity • temperature of Be windows • Cavity position and alignment w.r.t. solenoid • cavity and cryostat vacuum, incl. couplers • cryopump performance (P, compressor control, valve status) • roughing system (pump status, pump vacuum, pump valves) • tuner hydraulic reservoir pressure and dynamic control Edda Gschwendtner

  10. RF Cavities III (Calibration with Beam) • ΔE = (Eout -Ein )(GeV) of muons • measures ERF(t) ΔE1 ΔE1 -Eloss + ERF ΔE2 -Eloss - ERF ΔE2 (Simulation by P. Janot in 2001 at 88 MHz) Edda Gschwendtner

  11. Absorber Monitoring of: • H2 gas system and He gas system • Pressure gauge • LH2 reservoir at 1st stage of Cryocooler • Thermometers • Level sensor • 2 Heater • Hydrogen absorber • Thermometer • Level sensor • Absorber windows • Thermometer • Heater • Safety windows • Thermometer • Absorber vacuum and Safety vacuum • Pressure gauge • Pirani & cold cathode gauge • Mass spectrometer → Windows will be measured before and after a run (by photogrammetry or laser) to verify that they did not suffer inelastic deformations Edda Gschwendtner

  12. m - STEP I: spring 2007 STEP II: summer 2007 STEP III: winter 2008 STEP IV: spring 2008 STEP V: fall 2008 STEP VI: 2009 Edda Gschwendtner

  13. Magnets I • Variety of currents and even polarities • Field maps: not simply the linear superposition of those measured on each single magnet • Forces are likely to squeeze the supports and move the coils in the cryostat • Measure magnetic field with field probes Edda Gschwendtner

  14. Magnets II • Monitoring of : • current in each individual supply (incl. trim supplies, if any) • magnetic field at external probes (Bx, By, Bz); • proposal is 4 probes per coil • quench protection system • cryocooler, coil temperatures • He level sensors • correlations between current, field, and temperature need to be obtainable as a diagnostic tool • cryostat vacuum Edda Gschwendtner

  15. Target quads solenoid dipole v v v v v v Solenoid Cryogenics & control system • ISIS: • BLM • Cycle information V V MICE dipole Diffuser bar-code reader? quads quads Diagnostics DAQ  Control System Hybrid Beam Line I Edda Gschwendtner

  16. Beam Line II • Beam Line: • All magnets Qs (9), Ds(2), decay solenoid • Currents • Alarms on temperature, cryogenics, vacuum etc • Target: • Synchronisation inputs • ISIS Machine Start (once per injection) • ISIS clock (200 kHz) • Control Settings • insertion depth • insertion time • Operational monitors • Up to 8 temperature measurements per cycle (inner coil, outer coil, cooling water inlet, water outlet, ...) • Target position Edda Gschwendtner

  17. Summary 10% cooling of 200MeV/c muons with measurement precision: Δ (εout/ εin) = 10-3 • Systematics must be understood to 10-3 level. • Main sources are Cooling Channel • Detailed monitoring is in most cases possible and being designed. • Muons will provide very powerful cross-checks for themselves (energy loss, energy gain, transfer matrix…) • Dedicated ’monitoring runs’ will be possible and necessary. Strategy being discussed. Edda Gschwendtner

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