1. 17 March 2005Edda Gschwendtner1 MICE Cooling Channel: Can we predict cooling to 10 -3 ? Edda Gschwendtner Challenge Systematics Cooling Channel Beam Line Summary

2. 17 March 2005Edda Gschwendtner2 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 LH 2 )  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 LH 2 in vicinity of RF cavities and SC magnets

3. 17 March 2005Edda Gschwendtner3 Goal of MICE Science fiction example: MICE measures ( ε out / ε in ) exp = 0.904 ± err stat and compares with ( ε out / ε in ) sim = 0.895  Try to understand the difference.  10% cooling of 200MeV/c muons  With measurement precision: Δ (ε out / ε in ) = 10 -3 Theory uncertainties:  Model and simulation choices Experimental uncertainties:  Design of detectors/cooling elements

4. 17 March 2005Edda Gschwendtner4 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!

5. 17 March 2005Edda Gschwendtner5 Cooling Channel  three Absorber and Focus Coil modules (+ three LH 2 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)

6. 17 March 2005Edda Gschwendtner6 How to Handle Systematics Design considerations Define tolerances Monitoring Calibration measurements with the muon beam

7. 17 March 2005Edda Gschwendtner7 QuantityTolerancesMonitoring Calibration with muon beam RF CAVITIESRF field 3·10 -3 measure E to  E/E= 3.10 -3 Measure phase measure energy of muons vs RF phase before and after cooling channel. ABSORBER Amount of absorber (in g/cm 2 ) 3·10 -3 = 1mm/35cm Cryogenics… Density through T & P measure energy loss of muons for 0 absorber, 1 absorber, 2 absorbers with RF off. MAGNETS Positions of coils some mmalignment transfer matrix: e.g.: (p t, p L, phi, x 0, y 0 ) in (p t, p L, phi, x 0, y 0 ) out measure with no RF and empty absorbers each time one changes the magnetic set-up. Currents some 10 -4 amp-meter Magnetic field some 10 -4 magn. probes Cooling Channel NB thickness of H2 absorbers cannot be easily measured in situ (safety windows are in the way)

8. 17 March 2005Edda Gschwendtner8 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 RF Cavities I (Calibration & Design)

9. 17 March 2005Edda Gschwendtner9 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

10. 17 March 2005Edda Gschwendtner10 ΔE = (E out -E in )(GeV) of muons  measures E RF (t) RF Cavities III (Calibration with Beam) (Simulation by P. Janot in 2001 at 88 MHz) ΔE 1  -E loss + E RF ΔE 2  -E loss - E RF ΔE1ΔE1 ΔE2ΔE2

11. 17 March 2005Edda Gschwendtner11 Absorber Monitoring of:  H2 gas system and He gas system Pressure gauge  LH 2 reservoir at 1 st 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

12. 17 March 2005Edda Gschwendtner12  - STEP I: spring 2007 STEP II: summer 2007 STEP III: winter 2008 STEP IV: spring 2008 STEP V: fall 2008 STEP VI: 2009

13. 17 March 2005Edda Gschwendtner13 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

14. 17 March 2005Edda Gschwendtner14 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

15. 17 March 2005Edda Gschwendtner15 dipole quads solenoid quads Diffuser bar-code reader? v v v v v v VV Target ISIS: -BLM -Cycle information Solenoid Cryogenics & control system MICE Diagnostics DAQ  Control System Hybrid Beam Line I

16. 17 March 2005Edda Gschwendtner16 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

17. 17 March 2005Edda Gschwendtner17 Summary 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. 10% cooling of 200MeV/c muons with measurement precision: Δ (ε out / ε in ) = 10 -3