The R&D effort towards a neutrino factory
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Transcript of The R&D effort towards a neutrino factory
The R&D effort towards a neutrino factory
M. BonesiniSezione INFN Milano Bicocca
Dipartimento di Fisica G. Occhialini
Ro
adm
ap
2030
2010
2005
2015-20
K2K-II
JHF
? Off-Axis
HARP
MICE/MERIT
? Factory
CNGSNuMI
disappearance
down to 1o
appearanceNC/CC
CP violation
F R
&D
MiniBooNE
LSND?
KamLand
m212,12 at 2%
Yellow ReportCERN-2004-002, ECFA/04/230Further informations:http://muonstoragerings.cern.ch
ISS
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beams: conventional and nufact beams
Problem in conventional beams: a lot of minority components (beam understanding)
Following muon collider studies, accelerated muons are ALSO an intense source of “high energy”
Crucial features high intensity (x 100 conventional
beams) known beam composition
(50% 50% e )
Possibility to have an intense e beam
Essential detector capabilities:
detect and determine their sign
WANF
(conventional)
Nufact
ee ee
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+ e++ +e
+
Oscillate
Wrong Sign muons
1016p/s
3 1020 eyr
3 1020 yr
0.9 1021 yr
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Sensitivity of Nufact
present limit from the CHOOZ experiment0.75 MW JHF to super Kamiokande with an off-axis narrow-band beam, Superbeam: 4 MW CERN-SPL to a 400 kt water Cerenkov@ Fréjus (J-PARC phase II similar)Neutrino Factory with 40 kton large magnetic detector.
0.10 10 2.50 50 130
M. Mezzetto
X 5
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Towards a Neutrino Factory: the challenges
• Target and collection (HARP/MERIT)
– Maximize + and - production
– Sustain high power (MW driver)
– Optimize pion captureINTENSE PROTON SOURCE (MW);
GOOD COLLECTION SCHEME
• Muon cooling (MICE)
– Reduce +/- phase space to capture as many muons as possible in an accelerator
• Muon acceleration
– Has to be fast, because muons are short-lived !
(RLA, FFAG, … not covered in this talk)
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Neutrino Factory studies and R&D
USA, Europe, Japan have each their scheme. Only one has been costed, US study II:
Neutrino Factory CAN be done…..but it is too expensive as is. Aim: ascertain challenges can be met + cut cost in half.
+ detector: MINOS * 10 = about 300 M€ or M$
US Study II
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Study to optimize target : HARP experiment at CERN
~420 Mtriggers collected on different targets 1.5-15 GeV/c4 detector (TPC+forward)First results for NUFACT target optimization (see G. Catanesi talk)
HARP at CERN PS
A Layout of the Harp experiment
Tpc
spectrometer
CerenkovTof
Target length ()
BeamMomentum (GeV)
#events(millions)
2 (2001)
5
100
±3± 5± 8
± 12± 15
Negative only 2% and 5%
233.16
C
Al
Cu
Sn
Ta
Pb
K2K Al5, 50, 100,
replica
+12.9 15.27
MiniBooNE Be +8.9 22.56
Cu “button”Cu +12.9, +15
1.71
Cu “skew”Cu 2 +12
1.69
Cryogenictargets
N7
6 cm
±3± 5± 8
± 12± 15
58.4308
D1
H1
DeuteriumH2 18 cm ±3, ±8,
±14.513.83
WaterH20 10, 100 +1.5,
+8(10%)9.6
First results for NUFACT targetry optimizatio
From S. Borghi talk at NUFACT06
• Proof of principle demonstration of Hg-jet target for a 4MW proton beam, contained in a 15-T solenoid for maximal collection of soft secondary pions
– 24 GeV proton beam from CERN PS• Start Spring 2007 (nTOF area)
15-T solenoid during tests at MIT
Hg delivery and containment system under construction at ORNL. Integration tests scheduled this Fall at MIT.
MERIT (MERcury Intense Target)
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The big problem: reduction of emittance
The muon beam emittance must be reduced for injection into the acceleration system• Energy spread ► phase rotation• Transverse emittance ► cooling
AcceleratoAccelerator acceptance
R 10 cm, x’ 0.05 rad rescaled @ 200 MeV
and after focalization
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Muon ionization cooling
principle reality (simplified)
reduce pt and pl
increase pl
heating
Stochastic cooling is too slow.
A novel method for + and - is needed: ionization cooling
A delicate technology and integration problem Need to build a realistic prototype and verify that it works (i.e. cools a beam)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
IEEE 2004 - Roma
Muon Ionization Cooling Experiment Build a section of cooling channel long
enough to provide measurable cooling (10% ) and short enough to be affordable and flexible
Wish to measure this change to 1% Requires measurement of emittance of
beams into and out of cooling channel to 0.1% !
Cannot be done with conventional beam monitoring device
Instead perform a single particle experiment: High precision measurement of
each track (x,y,z,px,py,pz,t,E) Build up a virtual bunch offline Analyse effect of cooling channel
on many different bunches Study cooling channels parameters
over a range of initial beam momenta and emittances
• Experiment approved in 2003 y CLRC and scheduled for first run in October 2007
MICE setup: cooling + diagnostics
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RF cavitiesRestore lost pL
•8 MV/m accelerator gradient•4 T axial magnetic field
MICE cooling channel R&D
LH2 absorbersreduce muons momenta•Large ionization energy loss rate•Low scattering
First cavity has been assembled
Be window to minimize thickness
The challenge:Thin windows + safety regulations
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MICE cooling channel
•
• High gradient reacceleration– 10% reduction of muon emittance for 200 MeV muons requires ~20MV RF
• Challenge: integration of these elements in the most compact and economic way
• 3 Liquid Hydrogen absorbers
• 8 cavities 201MHz RFs, 8MV/m
• 5T SC solenoids
0
2
32 2
)014.0(11
XmEEds
dE
ds
d nn
Minimize heating term:•Absorber with large X0
•SC solenoid focusing for small T
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equilibrium emittance = 2.5 mm.radian
cooling effect at nominal inputemittance ~10%
curves for 23 MV, 3 full absorbers, particles on crest
Acceptance: beam of 5cm and 120 mrad rms
Quantities to be measured in a cooling exp
Difficulty: standard emittance measurement barely reach the required 0.1 % precision
Solution: Single particle measurement
•The advantages:–Separate measurement of transmittance and emittance variation
–A precision on (Tin-T
out) <10-3 can be achieved
•The challenge: The measurement should not affect the cooling
Muon Emittance measurement
Determines, for an ensemble (sample) of N particles, the moments:Averages <x> <y> etc… Second moments: variance(x) x
2 = < x2 - <x>2 > etc… covariance(x) xy = < x.y - <x><y> >
Covariance matrix M = M =
2't
't'y2
'y
't'x2
'x
'tt2t
'yt2y
'xt'xy'xxxtxy2x
...............
............
............
............
............
2'y'xyx
D4
't'y'xytxD6
)Mdet(
)Mdet(
Evaluate emittance with:
Compare Compare in in with with outout
Getting at e.g. Getting at e.g. x’t’x’t’ is essentially impossibleis essentially impossible with multiparticle bunch with multiparticle bunch measurements measurements
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
G4MICE simulation of Muon traversing MICE
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1. must be sure particles considered are muons throughout
a) reject incoming e, p, => TOF 2 stations 10 m flight with 70 ps
resolution b) reject outgoing e => Cerenkov + Calorimeter 2. measure 6 particle parameters i.e. x,y,t, px/pz , py/pz , E/pz
3. measure widths and correlations … resolution in all parameters must be better than 10%
of width at equilibrium emittance (correction less than 1%)
meas = true+
res = true [ 1+ (res/ true
)2 ] (n.b. these are r.m.s.!)
4. robust against noise from RF cavities
=>
Statistical precision 105 muons out/ in ) = 10-3 in ~ 1 hour Systematics!!!!
Spectrometer system requirements
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B
Baseline tracker5 planes of scintillating fiber tracker with 3 double layers. passive detector + fastgood for RF noise
Very small fibers needed to reduce MSLittle light VLPC readout (D0 experience)
Mice: tracker
Must measure muon momenta & positions
KEK TB Data: Residual Distribution
DATADATA MCMC
KEK TBTracker
1T BESS Magnet
TOF0 TOF1
Ckov1
IronShield
TOF2EMCal
ISISBeam
DiffuserProtonAbsorber
IronShield
Apparatus: PID overview
In the cooling channel muons can be contaminated by •Pions in the incoming beam (muons parents)
•Electrons in the outgoing beam (muon decay products) PID
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MICE: Particle ID
• Upstream:– TOF0/1 hodoscopes
with 10m path, ~60 ps resolution
– Cherenkov / separation at
better than 1% at 300 MeV/c
• Downstream: 0.5% of s decay in
flight: need electron rejection at 10-3 to avoid bias on emittance reduction measurement– TOF2 hodoscope– Calorimeter for MIP vs
E.M. Shower
TOF2Cal
Frascati TB – TOF & CAL
TOF stationEMCAL
Emittance measurement
from Geant-4 simulations
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-
STEP I
STEP II
STEP III
STEP IV
STEP V
STEP VI
PHASE 1 (funded): start October 2007
•Characterize beam
•Calibrate spectr I
PID + Tracker
+Solenoid
2008 ->
~ 2008
2009?
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MICE at RAL
Site Proposed for MICE Plant
Proposed route for services
Alternative route for services
Proposed site for controls & control room (presently the cable store and under the ISIS control room).
Proposed new linac cooling plant room
Hall has been emptied and preparation to host the experiment begun
MANX (Muon collider And Neutrino factory eXperiment)
• Proposed follow-up of MICE to obtain large cooling factors (~0.5) in few meters, using graded B fields to mach decreasing p
• Optimization under study, proposal submitted to FNAL (May 2006)
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Summary and outlook
“ Neutrino Oscillations provide us with exciting experimentally driven science. We might be in for big surprises. Neutrino Factories offer a new type of neutrino beam with impressivestatistical and systematic precision, and flexibility. If 13 is smaller than O(0.01) they will offer a way forward … but only if we invest in the R&D so that the option exists when the time comes. “
• As an example, R&D on muon cooling is
a critical point (MICE at RAL)
• Enthusiastic R&D is ongoing, and a lot has
already been accomplished