1. MICE RF Workshop 16-4-2012 Alain Blondel MICE = critical R&D for neutrino factory and muon collider 1 neutrino factory: accelerate muons and store to produce neutrinos -- flux known to <±1% -- high energy electron neutrinos long baseline oscillation manifests itself by wrong sign muons: LARGE (100kton) magnetized iron detector Golden channel: Or opposite charges (and anti-) + unique ability to test e  

2. MICE RF Workshop 16-4-2012 Alain Blondel 2 Practical realizations of ionization cooling are delicate… IDS Neutrino Factory Cooling Figure of Merit MICE (from Study II 2001)

3. MICE RF Workshop 16-4-2012 Alain Blondel 3 Practical realizations vary… But all contain solenoid magnets (for transport and focus) RF cavities (for re-acceleration) and absorbers (for cooling itself. Best is Liq H2)

4. MICE RF Workshop 16-4-2012 Alain Blondel 4 MICE the Muon Ionization Cooling Experiment -- Design, engineer and build a section of cooling channel capable of giving the desired performance for a Neutrino Factory; -- Place it in a muon beam and measure its performance in various modes of operation and beam conditions, thereby investigating the limits and practicality of cooling. Particle by particle measurement   [ (  in -  out )/  in ] = 10 -3

5. MICE RF Workshop 16-4-2012 Alain Blondel 5 Incoming muon beam Variable Diffuser Beam PID TOF 0, TOF 1 Cherenkovs Trackers 1 & 2 Liquid Hydrogen absorbers 1,2,3 Downstream particle ID: TOF 2, KL EMR RF cavitiesRF power Spectrometer solenoid 1 Spectrometer solenoid 2 Coupling Coils 1&2 Focus coils MICE Collaboration across the planet

6. MICE RF Workshop 16-4-2012 Alain Blondel MICE SCHEDULE update February 2012 V1 Q1-4 2013 Run date: Completed, submitted to publication (Tracker station and EMR run in 2012) Under construction: NB: target date 2016 STEP VI (may skip)

7. MICE RF Workshop 16-4-2012 Alain Blondel 7 RF requirements: 1.Baseline mode, step V / VI 2.Beyond the baseline

8. MICE RF Workshop 16-4-2012 Alain Blondel 8

9. 9 MICE should cool by 10%. For 200 MeV particles this requires 22 MV of RF voltage. This could be reached with 4 RF cavities operating at 16MV/m, 201MHz However: 1.It is not clear that RF cavities could operate stably at this voltage in magnetic field (separate R&D, MUCOOL) 2.This would require 16 MW of peak RF power at room temperature  which we do not have 3.This would likely cause so much dark current that operation of detectors would be impossible. Dark current (electrons) grow as E 9 4. It was preferred to operate MICE with 8 cavities at 8MV/m

10. MICE RF Workshop 16-4-2012 Alain Blondel 10 Nominal MICE step VI  will operate with 8 RF cavities at 8MV/m. This requires 1MW of peak RF power per cavity, shared among two RF couplers  Frequency 201 MHz. Value is not critical within ~1MHz as long as we have coherent system RF cavities themselves are equipped with tuners Should be tuned to maximize RF cavities performance and then fixed and stable  Duty factor about 10 -3 -- this is not a hard fact – is this a problem? e.g. 1ms RF pulse every second -- or 2ms every 2s if this is preferred are compatible with MICE beam operations (target dips in ISIS beam for 2ms) pulse longer than 2ms is not useful for MICE beam pulse shorter than ~0.5 ms becomes inefficient

11. MICE RF Workshop 16-4-2012 Alain Blondel 11 2 ms MICE particle spill Presently 1 every 2.56 seconds

12. MICE RF Workshop 16-4-2012 Alain Blondel 12 Step V STEP V “sustainable” cooling: cooling happens in the absorbers but production of cool beam requires acceleration with RF cavities old simulation (at 88MHz) RF phase E out -E in -1- running with shutters to commission RF cavities (no beam needed) -1’- running with LH2 and RF first with no beam to check RF noise -2- running with beam with no RF and no LH2 to check optics -3- running with beam with LH2 no RF -4- running with beam with LH2 and RF -5- or running 2-3-4- with solid absorbers? limited in optics and performance  step VI!

13. MICE RF Workshop 16-4-2012 Alain Blondel 13 MICE is an R&D experiment Phases of each pair of cavities should be tunable to match changes in muon momentum from 140 to 240 MeV/c this should be routine operation and not require a specialist (presently done several times a day) Phase and Volts should be recorded in real time to match with muon measured arrival time Possibility to run higher gradients should be preserved -- by feeding more RF power to fewer cavities -- by cooling cavities at LN2 rather than water This is *not* routine operation (change over a shut down)

14. MICE RF Workshop 16-4-2012 Alain Blondel 14 T1 T2 RF acceleration 1 RF acceleration 2 Rikard Sandström – PhD thesis Px Py, Pz, x,y Px Py, Pz, x,y A muon in MICE

15. MICE RF Workshop 16-4-2012 Alain Blondel RF specification summary from A. Moss, MICE CM32 Comment: unchanged baseline DF= 10 -3 2-1 msec 0.4-1 Hz What is needed here is ability to provide phase and gradient for each muon

16. MICE RF Workshop 16-4-2012 Alain Blondel RF specification summary from A. Moss, MICE CM32 Beyond baseline Liq N2 operation or re-connection of RF power into fewer cavities would allow exploration of higher gradients shouldthese appear to be feasible from e.g. MUCOOL Should not preclude this, although will be done at the end of experiment

17. MICE RF Workshop 16-4-2012 Alain Blondel 17 Concerning regulation of phase and amplitude: 1.phase regulation by pair of cavities is enough and simplifies the system 2.what is really needed is ability to know phase and gradient for each muon there is no unique way of doing this and this should be an outcome of this workshop With which precision? -- Absolute scale of amplitude -- Global phase shift (time delay) between RF system and TOF system will both come from analysis of large samples of muons in operation.

18. MICE RF Workshop 16-4-2012 Alain Blondel 18 Imagine this is the RF pulse: Millisecond scale  nanosecond scale ¦A¦(t) 2 ms t Muon i, i= 1,200 2.5 ns t0t0 Muon i, i= 1,200 A(t) t1_i Must be able to tell ¦A¦(t_i) and  t_i for each muon  t_i Desired reproducibility : few 10 -3 for amplitude and few ps for phase over a day individual measurement fluctuations can be larger (up to a few % and 15ps) +-5% OK

19. MICE RF Workshop 16-4-2012 Alain Blondel 19 Explanation Individual measurement precision can be ~1/3 of the measurement resolution on time and energy gain of individual particles But if one measures 10 5 particles in identical conditions several times a day the measurement device should not drift or vary by more than a few 10 -3 for the amplitude or a few ps for the timing. If we observe a larger variation it should be because the RF system itself has varied (which is OK), not the measurement device itself. Desired reproducibility : few 10 -3 for amplitude and few ps for phase over a day individual measurement fluctuations can be larger (up to a few % and 15ps)

20. MICE RF Workshop 16-4-2012 Alain Blondel 20 Comments as discussed immediately after the RF review 1. we need a MICE-wide RF group – and organization (we have recast the WBS in this direction) 2. we should consider an RF system test before launching ourselves into MICE step VI. there is a good window for this in 2014 when step IV meaasurements are complete these should also be outcomes of this workshop 2.7-RF Systems Derun Li 2.7.1-RF Power source Moss 2.7.2-RF Cavities DeMello 2.7.3-RF Power distribution Grant 2.7.4-Low level RF ??? 2.7.5 RF instrumentation ???