Neutrino2004 - Paris, June 14-19 2004A.Tonazzo – Machine R&D towards a Neutrino Factory /1 Machine R&D towards a Neutrino Factory with focus on a Muon

Neutrino2004 - Paris, June 14-19 2004 A.Tonazzo – Machine R&D towards a Neutrino Factory / 1

Machine R&D towards a Machine R&D towards a Neutrino FactoryNeutrino Factory

with focus on awith focus on a

Muon Ionization Cooling ExperimentMuon Ionization Cooling Experiment

Alessandra TonazzoUniversità Roma Tre and INFN Sez. Roma III


Towards a Neutrino Factory: the challengesTowards a Neutrino Factory: the challenges

• Target and collection– High + and - yield– Sustain high power– Capture as many produced

pions as possible

• Muon cooling– Reduce +/- phase space

to capture as many muons as possible in an accelerator

• Muon acceleration– Has to be fast, because

muons are short-lived !


Target and collectionTarget and collection

Achieve intense muon beam by maximizing production of + and -• Soft pion production

– E910 measurements available– HARP cross-section results awaited!

(talk by J.J.Gomez-Cadenaz tomorrow)

• High Z material• Sustain high power (4 MW)

– Solid target is not adequate• Optimize pion capture

Neutrino Factory Targetry concept:• Hg jet continuous flow target• Pion focusing magnetic system

– EU: horn– US: 20T SC solenoid


Pion collectionPion collection

2.2 GeV4 MW

Protons

Current of 300 kA

B1/RB = 0

The CERN magnetic horn for pion collection

Prototype built at CERN


Hg jet targetHg jet target• Continuous flow

free Hg jet– Tilted w.r.t. incoming proton

beam direction– Intense solenoidal B field to

capture low pt pions

• Key issues:– To what extent will the jet

disperse due to rapid energy deposition by intense proton pulse ?

– To what extent will magnetic forces perturb the flow of the jet into the magnet and affect the possible dispersal of the jet by the beam ?


Target: Hg jet testsTarget: Hg jet testsE951

•1 cm•v=2.5 cm/s•24 GeV 4 TP p beam•No B field

CERN/Grenoble•4 mm•v=12 m/s•No p beam•0,10,20T B field

Hg jet dispersal properties :• proportional to beam intensity• velocities ~½ times that of “confined

thimble” target• largely transverse to the jet axis • delayed 40 ms

• The Hg jet is stabilized by the 20 T B field• Minimal jet deflection for 100 mrad angle

of entry • Jet velocity reduced upon entry to B field


Participating Institutions1) RAL2) CERN3) KEK4) BNL5) ORNL6) Princeton University

Proposal to test a 10m/s Hg Jet in a 15T Solenoid with an Intense Proton Beam

Target & collectionTarget & collection

Installation and commissioningat CERN by April 2006


Reduction of Reduction of emittance 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


Muon ionization coolingMuon ionization cooling

principle reality (simplified)

Never realized in practice !A realistic prototype should be built and proven to be adequate to the Neutrino Factory requirements.

reduce pt and pl

increase pl

heating

Stochastic cooling is too slow. Frictional cooling is only for +.A novel method for + and - is needed: ionization cooling


Muon Ionization Cooling ExperimentMuon Ionization Cooling ExperimentAims:• Show that it is possible to

design, build and operate a section of cooling channel capable of giving the desired performances for a Neutrino Factory

• Place it in a muon beam and measure its performances in a variety of operating modes, thereby investigating the limits and practicality of cooling

• Proposal submitted to RAL on Jan.10 2003

• Approval “strongly recommended” by Review Panel (May 20, 2003)

• Scientific approval from CCLRC chief executive (Oct 24, 2003)


MICE goalsMICE goals Build a section of cooling channel long enough to provide measurable

cooling (10% reduction of transverse emittance) and short enough to be affordable and flexible

Measure: 1) transverse emittance reduction with 0.1% precision2) transmittance of the channel

►Delicate integration of accelerator and particle detector physics !►Never done before !

Difficulty: standard emittance measurement barely reach the required precision Solution: Single particle measurement

–Measure track parameters before/after cooling channels–Reject non-muon background (undecayed s, electrons from s)

•The advantages:–Separate measurement of transmittance and emittance variation–A precision on (T

in-Tout) <10-3 can be achieved

•The challenge:–The measurement should not affect the cooling


MICE setup: cooling + diagnosticsMICE setup: cooling + diagnostics


MICE cooling channelMICE 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(11XmEEds

dEdsd nn

Minimize heating term:•Absorber with large X0

•SC solenoid focusing for small T


RF module(Berkeley, Los Alamos, JLAB, CERN, RAL)

MICE cooling channel R&DMICE cooling channel R&D

LH2 window(IIT, NIU, ICAR)

First cavity has been assembled

Be window to minimize thickness

The challenge:Thin windows + safety regulations


MICE cooling channelMICE cooling channelBeam properties Quantities to be measured

Curves for 23 MV, 3 full absorbers, particles on crest

cooling effect at nominal input emittance ~10%

Equilibrium emittance


MICE: Emittance measurementMICE: 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

2'

''2'

''2'

'2

'2

'''2

...........................

............

............

............

t

tyy

txx

ttt

yty

xtxyxxxtxyx

M

2''

4

'''6

)det(

)det(

yxyxD

tyxytxD

M

MEvaluate emittance with: Compare Compare in in with with outout

Simulation of a muon traversing MICE

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


Spectrometer: requirements and errorsSpectrometer: requirements and errorsMeasurements• 10% emittance reduction measured to 1% absolute errors <0.1%• Resolution on all measured parameters better than 10%

Statistical• 105 muons (T

in-Tout) < 10-3 (in ~ 1 hr)

Systematic• Description of apparatus• Systematic differences between in/out spectrometers• Transport: wrong particles with different kinematics will spoil the

measurements– Muon in … muon out / and /e rejection at < 1% level

Robustness against harsh environment– Noise from RF cavities– Background– Intense magnetic fields


MICE TrackerMICE TrackerAlternative option:

TPC with GEM readout (TPG)Baseline option:

Scintillating fiber tracker

5 planes of Sci-FiWith double layer.0.35 X0 per layer

The prototype


MICE Tracker performanceMICE Tracker performanceA typical cosmic ray event

Measured and expected efficiencies

Point resolution ~440 m

Light yield


MICE: Particle IDMICE: Particle ID• Upstream:

– TOF hodoscopes with 10m path, 70 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– TOF hodoscope– Aerogel Cherenkov

(n=1.02, blind to s)– Calorimeter for MIP vs

E.M. Shower

Ckov Cal


MICE at RALMICE 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


- STEP I: spring 2006

STEP II: summer 2006

STEP III: winter 2007

STEP IV: spring 2007

STEP V: fall 2007

STEP VI: 2008

MICE installation phasesMICE installation phases

2006

2007

2008

Subject to availability of funds…

……

……

……

……

……


Muon accelerationMuon acceleration• Previous accelerator

scheme: LINAC + Recirculating Linear Accelerator (RLA)– Very costly: need high RF

gradient to limit losses from muon decay

• Proposed solution: use Fixed Field Alternating Gradient (FFAG) accelerator – Repetition rate can be

raised >10 times faster than in ordinary synchrotrons

New US Scheme

Japan Scheme


Muon acceleration: FFAGMuon acceleration: FFAG

• Latest ideas in US have lead to the invention of a new type of FFAG (“non-scaling FFAG”) – interesting for more than just Neutrino Factories– may require a demonstration experiment (plans are developing)

• R&D in Europe is just starting

Perhaps the different concepts are merging to produce something better ??

Much progress in Japan with the development and demonstration of large acceptance FFAG accelerators


Why we are optimistic/enthusiastic – US perspective:

Note: In the Study 2 design roughly ¾ of the cost came from these 3 roughly equally expensive sub-systems.

New design has similar performance to Study 2 performance but keeps both + and - !

(S.Geer - CERN MW ws April 2004)

Good hope for improvement in performance and reduction of cost!

We are working towards a “World Design Study” We are working towards a “World Design Study” with an emphasis on cost reductionwith an emphasis on cost reduction


Summary and outlookSummary and outlookThe construction of a Neutrino Factory poses several

stimulating challenges

• Target and collection– Magnetic horn prototype built at CERN

– Complete target test experiment proposed and approved

• Muon cooling– International Muon Ionization Cooling Experiment at RAL

• Acceleration– The FFAG solution is progressing both in Japan and in the US

• Enthusiastic R&D is ongoing, and a lot has already been accomplished

Documents

Neutrino2004 - Paris, June 14-19 2004A.Tonazzo – Machine R&D towards a Neutrino Factory /1 Machine R&D towards a Neutrino Factory with focus on a Muon