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MICE RF Workshop 16-4-2012 Alain Blondel
MICE = critical R&D for neutrino factory and muon collider
1
neutrino factory: accelerate muons andstore to produce neutrinos
e e
-- flux known to <±1%
-- high energy electron neutrinos
long baseline oscillation manifests itself by wrong sign muons:
e ; N X
LARGE (100kton) magnetized iron detector
Golden channel:Golden channel:
Or opposite charges (and anti-)
+ unique ability to test e
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)
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)
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
MICE RF Workshop 16-4-2012 Alain Blondel 5
Incoming muon beam
VariableDiffuser
Beam PIDTOF 0, TOF 1
Cherenkovs
Trackers 1 & 2
Liquid Hydrogen absorbers 1,2,3
Downstreamparticle ID: TOF 2, KL
EMR
RF cavities RF power
Spectrometer solenoid 1
Spectrometer solenoid 2
Coupling Coils 1&2
Focus coils
MICE Collaboration across the planet
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)
MICE RF Workshop 16-4-2012 Alain Blondel 7
RF requirements:
1.Baseline mode, step V / VI
2.Beyond the baseline
MICE RF Workshop 16-4-2012 Alain Blondel 8
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
MICE RF Workshop 16-4-2012 Alain Blondel 9
MICE should cool by 10%. For 200 MeV particles this requires 22 MV ofRF 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 E9
4. It was preferred to operate MICE with 8 cavities at 8MV/m
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
MICE RF Workshop 16-4-2012 Alain Blondel 11
2 ms
MICE particle spill
Presently 1 every 2.56 seconds
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
Eout-Ein
-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!
MICE RF Workshop 16-4-2012 Alain Blondel 13
MICE is an R&D experimentPhases 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)
MICE RF Workshop 16-4-2012 Alain Blondel 14
T1
T2RF acceleration 1RF acceleration 2
Rikard Sandström – PhD thesis
Px Py, Pz, x,y
Px Py, Pz, x,y
A muon in MICE
MICE RF Workshop 16-4-2012 Alain Blondel
RF specification summary from A. Moss, MICE CM32
Comment:
unchanged
unchanged
baseline
DF= 10-
32-1 msec
0.4-1 Hz
What is needed here is ability to provide phase and gradient for each muon
MICE RF Workshop 16-4-2012 Alain Blondel
RF specification summary from A. Moss, MICE CM32Beyond baseline
Liq N2 operation or re-connection of RF power into fewercavitieswould 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
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.
MICE RF Workshop 16-4-2012 Alain Blondel 18
Imagine this is the RF pulse:
Millisecond scale nanosecond scale
¦A¦(t)
2 ms
tMuon i , i= 1,200
2.5 ns
t0
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
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 105 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)
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 ???