Machine R

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Machine R

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Title: Machine R

1
Machine RD towards a Neutrino Factorywith
focus on aMuon Ionization Cooling Experiment

Alessandra Tonazzo
Università Roma Tre and INFN Sez. Roma III

2
Towards a Neutrino Factory the challenges

Target and collection
High p and p- yield
Sustain high power
Capture as many produced pions as possible
Muon cooling
Reduce m/m- phase space to capture as many muons
as possible in an accelerator
Muon acceleration
Has to be fast, because muons are short-lived !

3
Target and collection

Achieve intense muon beam by
maximizing production of p and p-
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

4
Pion collection
The CERN magnetic horn for pion collection
Prototype built at CERN
5
Hg 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 ?

6
Target Hg jet tests

CERN/Grenoble
4 mm
v12 m/s
No p beam
0,10,20T B field

E951
1 cm
v2.5 cm/s
24 GeV 4 TP p beam
No 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

7
Target collection
Proposal to test a 10m/s Hg Jet in a 15T Solenoid
with an Intense Proton Beam

Participating Institutions
RAL
CERN
KEK
BNL
ORNL
Princeton University

Installation and commissioning at CERN by April
2006
8
Reduction of m emittance
Accelerator acceptance R ? 10 cm, x ? 0.05
rad rescaled _at_ 200 MeV
p and m after focalization

The muon beam emittance must be reduced for
injection into the acceleration system
Energy spread ? phase rotation
Transverse emittance ? cooling

9
Muon ionization cooling
Stochastic cooling is too slow. Frictional
cooling is only for m. A novel method for m and
m- is needed ionization cooling
principle
reality (simplified)
reduce pt and pl
heating
Never realized in practice ! A realistic
prototype should be built and proven to be
adequate to the Neutrino Factory requirements.
increase pl
10
Muon Ionization Cooling Experiment

Aims
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)

11
MICE 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 precision
2) transmittance of the channel

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 ps,
electrons from ms)
The advantages
Separate measurement of transmittance and
emittance variation
A precision on (eTin-eTout) lt10-3 can be achieved
The challenge
The measurement should not affect the cooling

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

12
MICE setup cooling diagnostics
13
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

Minimize heating term
Absorber with large X0
SC solenoid focusing for small bT

3 Liquid Hydrogen absorbers
8 cavities 201MHz RFs, 8MV/m
5T SC solenoids

14
MICE cooling channel RD
RF module (Berkeley, Los Alamos, JLAB, CERN,
RAL)
LH2 window (IIT, NIU, ICAR)
First cavity has been assembled
The challenge Thin windows safety regulations
Be window to minimize thickness
15
MICE cooling channel
Beam properties
Quantities to be measured
Equilibrium emittance
cooling effect at nominal input emittance 10
Curves for 23 MV, 3 full absorbers, particles on
crest
16
MICE Emittance measurement
Simulation of a muon traversing MICE
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 ltxgt ltygt etc
Second moments variance(x) sx2 lt x2 -
ltxgt2 gt etc covariance(x)
sxy lt x.y - ltxgtltygt gt Covariance matrix M
Evaluate emittance with
Compare ein with eout
17
Spectrometer requirements and errors

Measurements
10 emittance reduction measured to 1 ? absolute
errors lt0.1
Resolution on all measured parameters better than
10
Statistical
105 muons ? d(eTin-eTout) lt 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 lt
1 level
Robustness against harsh environment
Noise from RF cavities
Background
Intense magnetic fields

18
MICE Tracker
Alternative option TPC with GEM readout (TPG)
Baseline option Scintillating fiber tracker
5 planes of Sci-Fi With double layer. 0.35 X0 per
layer
The prototype
19
MICE Tracker performance
Point resolution 440 mm
A typical cosmic ray event
Measured and expected efficiencies
Light yield
20
MICE Particle ID

Upstream
TOF hodoscopes with 10m path, 70 ps resolution
Cherenkov
p/m separation at better than 1 at 300 MeV/c
Downstream
0.5 of ms decay in flight need electron
rejection at 10-3 to avoid bias on emittance
reduction measurement
TOF hodoscope
Aerogel Cherenkov (n1.02, blind to ms)
Calorimeter for MIP vs E.M. Shower

Ckov
Cal
21
MICE at RAL
Hall has been emptied and preparation to host the
experiment begun
22
MICE installation phases
2006

2007

2008
Subject to availability of funds
23
Muon 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 gt10 times faster
than in ordinary synchrotrons

Japan Scheme
New US Scheme
24
Muon acceleration FFAG
Much progress in Japan with the development and
demonstration of large acceptance FFAG
accelerators

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)
RD in Europe is just starting
Perhaps the different concepts are merging to
produce something better ??

25
We are working towards a World Design Study
with an emphasis on cost reduction
(S.Geer - CERN MW ws April 2004)
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 m and m- !
Good hope for improvement in performance and
reduction of cost!
26
Summary and outlook