Transcript MICE The International Muon Ionization Cooling Experiment MICE beam line review 16-11-2007 Alain Blondel.

MICE
The International Muon Ionization Cooling Experiment
MICE beam line review 16-11-2007 Alain Blondel
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MICE Overview
1. Why, what and how?
2. requirements on the beam line
3. other desirable features of the beam line
3. Conclusions
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Major challenges tackled
by R&D expts
High-power target
. 4MW
. good transmission
MERIT experiment
(CERN)
Fast muon cooling
MICE experiment
(RAL) , MUCOOL
Fast, large aperture
accelerator (FFAG)
EMMA (Daresbury)
ISS baseline
MICE beam line review 16-11-2007 Alain Blondel
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IONIZATION COOLING
principle:
this will surely work..!
reality (simplified)
….maybe…
Cooling is necessary for Neutrino Factory and crucial for Muon Collider.
Delicate technology and integration problem
Need to build a realistic prototype and verify that it works (i.e. cools a beam)
Can it be built? Operate reliably? What performance can one get?
Difficulty: affordable prototype of cooling section only cools beam by 10%,
while standard emittance measurements barely achieve this precision.
Solution: measure the beam particle-by-particle
state-of-the-art particle physics instrumentation
will test state-of-the-art accelerator technology.
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10% cooling of 200 MeV/c muons requires ~ 20 MV of RF
single particle measurements =>
measurement precision can be as good as D ( e out/e in ) = 10-3
never done before
Coupling Coils 1&2
Spectrometer
solenoid 1
Matching
coils 1&2
Focus coils 1
Focus coils 2
Focus coils 3
Matching
coils 1&2
Spectrometer
solenoid 2
m
Beam PID
TOF 0
Cherenkov
TOF 1
RF cavities 1
Variable
Diffuser
Incoming muon beam
RF cavities 2
Liquid Hydrogen absorbers 1,2,3
Downstream
TOF 2
particle ID:
KL and SW
Calorimeter
Trackers 1 & 2
measurement of emittance in and out
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THE MICE COLLABORATION
-128 collaborators-
Universite Catholique de Louvain, Belgium
University of Sofia, Bulgaria
The Harbin Institute for Super Conducting Technologies PR China
INFN Milano, INFN Napoli, INFN Pavia, INFN Roma III, INFN Trieste, Italy
KEK, Kyoto University, Osaka University, Japan
NIKHEF, The Netherlands
CERN
Geneva University, Paul Scherrer Institut Switzerland
Brunel, Cockcroft/Lancaster, Glasgow, Liverpool, ICL London, Oxford, Darsbury, RAL, Sheffield
Argonne National Laboratory, Brookhaven National Laboratory, Fairfield University,
University of Chicago, Enrico Fermi Institute, Fermilab, Illinois Institute of Technology,
Jefferson Lab, Lawrence Berkeley National Laboratory, UCLA, Northern Illinois University,
University of Iowa, University of Mississippi, UC Riverside,
University of Illinois at Urbana-Champaign USA
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UK
MICE
FIRST BEAM IN FEBRUARY 2008
Final PID:
TOF
Calorimeter
Demonstrate feasibility and performance
of a section of cooling channel by 2010
4T spectrometer II
Cooling cell (~10%)
b=5-45cm, liquid H2, RF
Status:
Approved at RAL(UK)
First beam: 10-2007
Funded in: UK,CH,It,JP,NL,US
Further requests: JP,UK,US,It...
4T spectrometer I
Single-m beam
~200 MeV/c
TOF
Liquid-hydrogen
absorbers
Prototyping:
Scintillating-fiber tracker
MICE beam line review 16-11-2007 Alain Blondel
200MHz RF cavity
with beryllium windows
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MICE STEPS and PHASES
m
STEP I
PHASE I
Febuary 2008
STEP II
April 2008
PHASE II
STEP III
STEP IV
July 2008
Delivery of 1st FC
~May 2009
STEP V
>summer 2009
STEP VI
2010
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MICE Status
Funding
Funding for Phase I is secured
some pending issues with INFN, support for visitors at RAL, beamline electricity
Funding for Phase II is essentially secure (excellent news from US, China summer07)
BUT: UK Phase II still awaiting decision, Japan for absorbers, SW calorimeter
Construction
DAQ, CKOV1 arrived at RAL in July 2007
Tracker I arrived at RAL Nov14 2007
Combined Cosmic Test in November-December
Beam line construction in full swing; will be closed and safe by Jan20 2008
TOF0/1, KL: detectors built, mechanics finishing, ETA at RAL 15 Dec 2007
Spectrometer solenoid I to arrive FNAL jan 2008 and RAL March 2008
Tracker II to arrive RAL in Feb 2008
Spectrometer solenoid II to arrive RAL in May 2008
TOFII June 2008
SW later in 2008
step IV to be defined by AFC module I.
Tender issued. OK from UK-STFC pending global review result end of 2007.
Crucial issue for PhaseII is RF tests in magnetic field:
RF cavity I arrived in 2006, tested to 19MV/m
coupling coil I will arrive FNAL end 2008.
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Challenges of MICE:
(these things have never been done before)
1.
Operate RF cavities of relatively low frequency (201 MHz) at high gradient
(nominal 8MV/m in MICE, 16 MV/m with 8 MW and LN2 cooled RF cavities)
in highly inhomogeneous magnetic fields (1-3 T)
dark currents (can heat up LH2), breakdowns
2. Hydrogen safety (substantial amounts of LH2 in vicinity of RF cavities)
3. Emittance measurement to relative precision of 10-3 in environment of RF bkg
requires
low mass (low multiple scattering) and precise tracker
fast and redundant to fight dark-current-induced background
precision Time-of-Flight for particle phase determination
(±3.60 = 50 ps)
complete set of PID detectors to eliminate beam pions and decay electrons
and…
4. Obtaining (substantial) funding for R&D towards a facility that is not (yet) in
the plans of a major lab
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Emittance measurement
Each spectrometer measures 6 parameters per particle
x y t
x’ = dx/dz = px/pz
y’ = dy/dz = py/pz t’ = dt/dz =E/pz
Determines, for an ensemble (sample) of N particles, the moments:
Averages <x> <y> etc…
Second moments: variance(x) sx2 = < x2 - <x>2 > etc…
covariance(x) sxy = < x.y - <x><y> >
Covariance matrix
 s 2x

 ...

M =  ...
 ...

 ...
 ...

Evaluate emittance with:
s xy
s xt
s xx'
s xy '
s 2y
...
...
...
...
...
...
...
s t2
...
...
...
...
s 2x'
...
...
...
...
s 2y '
...
s xt' 

s yt ' 

s tt ' 
s x't ' 

s y 't ' 
s t2' 
Getting at e.g. sx’t’
is essentially impossible
with multiparticle bunch
measurements
Compare ein with eout
e 6 D  p / m det(M xytx' y 't ' )
e 4 D  p / m det(M xyx' y ' )  e 2
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The experiment MICE wants to do
Beam optics and diffuser to provide
this set of emittances
Changeover should be fast (30')
and should not require switching off
MICE magnets.
MICE diffuser system:
equilibrium emittance = 2.5 mm.radian
curves for 23 MV, 3 full absorbers, particles on crest
repeat this curve for various momenta, absorbers, etc..
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Requirements on detectors for MICE:
1.
Must be sure to work on muons
1.a use a pion/muon decay channel with 5T, 5m long decay solenoid
1.b reject incoming pions and electrons
TOF over 8m with 70 ps resolution+ threshold Cherenkov
1.c reject decays in flight of muons
downstream PID (TOF2 + calorimeters)
2. Measure all 6 parameters of the muons x,y,t, x’, y’, bz=E/Pz
tracker in magnetic field, TOF
3. Resolution on above quantities must be better than 10% of rms of beam
at equilibrium emittance to ensure correction is less than 1%.
+ resolution must be measured
4. Detectors must be robust against RF radiation and field emission
Design of MICE detectors and beam test results
satisfy the above requirements
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MICE is a precision experiment!
Cooling in MICE is only ~10% (eout / ein)exp = 0.9
establishing effect requires % precision, optimizing it requires permil precision
This is the goal of MICE.
requires:
statistics of 106 muons per measurement point (a few hours at 100 good muons/s)
systematics at permil level,
individual sources must be a small fraction of this!
Beam related systematics
In principle, individual muons can be reweigted to form an 'ideal beam'
This is not very easy – avoid reweighting factors of more than ~50% overall
Alignment in x,x', y,y', p
has been studied and leads to the constraint that
beam offsets should not exceed 3-5% of beam sizes at diffuser
Effect of mismatch, x-y asymmetries, coupling, dispersion have not been
completely studied
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Experimental Systematics
Mice-fiction in 2009 or so.
. MICE measures e.g.
and compares with
(eout / ein)exp
= 0.904 ± 0.001 (statistical)
(eout / ein)theory. = 0.895
and tries to understand the difference.
SIMULATION
theory systematics:
modeling of cooling cell
is not as reality
REALITY
MICE beam line review 16-11-2007 Alain Blondel
experimental systematics:
modeling of spectrometers
or beam is not as reality
MEASUREMENT
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Requirements on MICE beam
-- 'single' muons of either sign (low intensity, long spill, dt >~ 100 ns)
-- beam momentum: 140MeV/c – 240 MeV/c (MICE channel momentum range)
+ higher momentum desirable: 240 + 1sp = 265 MeV/c
to cover phase space incl. amplitude-momentum correlation.
-- emittance: optically matched, ~1-10 mm.rad, symmetric in x-y, sp /p ~ 10%
from: below equilibrium emittance (2.5 mm.rad) <== this is not easy
to:
exceed acceptance of MICE (10 mm rad)
-- time structure: pulse duration*rep rate = RF duty factor of 0.001
this is achieved with rep. rate 1Hz and pulse length of 1ms (ISIS)
-- statistics: ~ 100 good muons per second (i.e. within 15cm radius in tracker)
this requires 600 good muons per pulse (to allow RF timing cut of 1/6)
Fewer muons --> run the facility longer, cost more!
-- alignment: requires offset < 3% of beam size at MICE (small reweight)
i.e. ~1mm centering in x,y ~3mrad in x' y' at absorber
-- purity: electrons and protons are easy to discriminate (if not too numerous)
pion/muon contamination should be less than 1/10 (1/100 desirable)
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Beam Line Review
1 November 2007
Beam Line Design and Commissioning Review
1 November 2007
Beam Line Design and Commissioning Review
Charge to Committee
Agenda
16th November 2007, Room 539, Blackett Laboratory, Imperial College London
09:00 Executive session:
09:30 Presentations:
1.
2.
3.
4.
5.
6.
MICE Overview [Blondel, Long, or Zisman]
Beam Line Design: Guiding principles & expected capabilities [Tilley]
Simulation comparison /design tools/issues [Nebrensky]
Diffuser Issues [Apollonio]
Diffuser Mechanical Design [Yang or Lau]
Diffuser control system [Apollonio]
[25+5]
[30+10]
[20+5]
[20+5]
[15+5]
[15+5]
13:00 Lunch
14:00 Presentations:
7. Magnet refurbishment, measurement, installation [Flower]
8. Commissioning Plans [Tilley]
9. Beam Line Diagnostics [Kyberd]
[25+10]
[25+10]
[15+5]
15:30 Executive session:

Preparation of additional questions and close-out
16:00 Close-out:
10. Closeout
11. Adjourn
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[45]
Background
The general purpose of the review is to evaluate the final design of the MICE muon beam
line, its implementation plan, and the initial plans for its commissioning. The current
MICE schedule calls for the installation to be complete, and for commissioning to
commence, in January 2008.
The line comprises two sections:
1. an upstream portion to transport the pion beam from the production target through
the decay solenoid;
2. a downstream portion to transport the muon beam from the decay solenoid to the
entrance to the MICE experiment, and to optically match the beam into the
upstream spectrometer solenoid.
Design Goals
It is required that:
 muon beam purity be as high as possible;
 muon beam momenta in the range of roughly 140 MeV/c to 240 MeV/c, with a
momentum spread of up to ±10%, be transportable by suitably tuning the beam
line; and
 matched emittance values in the range 1 mm-rad  eN  10 mm-rad be deliverable
to MICE.
Charge
1. Review and comment on the optical design of the line, and its ability to fully or
partially meet its design goals.
2. Review and comment on plans and schedule for magnet refurbishment, magnetic
field measurements, fiducialization, installation, alignment, and testing.
3. Review and comment on plans for initial commissioning of the beam line,
including the adequacy of proposed diagnostic devices.
Prepare a written summary of findings for the MICE experiment management
(Spokesperson and Project Manager) within one week from the review.
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Target and time structure
Target mechanism has been developed to dip
Ti target into ISIS beam in the last ms
of ISIS cycle
80 g acceleration achieved !
1 Hz rate
Tested with >3M actuations
Wear solved with Diamond bearings
Will be installed in Xmas 07 shut down
micro structure:
330ns
100ns
detectors and DAQ well adapted to this structure
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The MICE BEAM LINE
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Upstream beam line: Xmas work
VERY TIGHT
working hard
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Beam line
-- Construction at RAL is in full swing
main issues:
-- target just in time.. now authorized! to be installed over X-mas
-- repairing the PSI solenoid and cold check
-- original misalignment of assumed point of target impact on beam by 2cm...
being fixed
-- Q4-6 refurbishment finished; Q7-9 still ongoing tight schedule
-- schedule of Xmas shut down is very tight!
-- beam monitors and TOF0 are all somewhat late
risk: delays in startup
At this point the beam line does not include:
-- collimators (maybe needed for small emittance beam)
-- alignment correctors
there is a couple schemes possible, but not completely worked out
correcting dipoles or trim coils on quadrupoles
risk: loss of performance and practicality
-- ratio of particle production to beam loss monitors not completely understood
risk: considerable loss of performance.
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Aspirational MICE Schedule as of October 2007
m
Febuary 2008
STEP I
STEP II
April 2008
STEP III
STEP IV
July 2008
Delivery of 1st FC
~May 2009
STEP V
>summer 2009
STEP VI
MICE beam line review 16-11-2007 Alain Blondel
end 2009
(or 2010)
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Run plan -- steps I and II
m
STEP I
Jan-Feb 2008
Goals:
I – Commission target
Establish beam rates
commission beam line, optics,
alignment
II – Match beam with diffuser
STEP II
fill {p,e} matrix necessary to draw
march –April 2008 emittance vs. transmission curve.
Measure emittance
Runnng time:
Take 200-400 muons per 1ms spill once per second
In steps I-IV 1% (0.1%) emittance meast will take ~1 (100) minute
6 times longer in steps V and VI where phase matters.
preliminary estimate
total for steps I & II: 70 days
STEP I requires 60 shifts (20 days of running)
beam line commissionning, target tuning (rates), DAQ and detector shake down
STEP II requires 150 shifts (50 days, will extend in summer 2008)
Alignment of beam x,x’,y,y’, (Lack of) dispersion,
check range of transverse emittance, and range of momenta
measure emittance and…
publish first paper
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Conclusions
0. MICE will be taking data in 66 days
1.
demonstration of cooling is an important R&D milestone for neutrino factory
and muon collider
MICE is on track to demonstrate/study cooling precisely 2010.
2. MICE will start phase I data taking in february 2008... hard work!
Steps I, II, III will allow target and beam commissioning, tuning, first
measurement of emittance and verification of systematics
3. The MICE beam line has been designed to provide adequate statistics and the
range of momentum and emittances needed to measure transmission, cooling
and equilibrium emittance with high precision.
4. To the reviewers:
statement on collimators and correctors will be useful
you will do MICE a great help by finding the bug...
.... before we find it the hard way in 2008. THANKS!
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