ALEPH in 1999 Alain Blondel, Ecole Polytechnique

Report
MICE: Constraints on the solenoids
1. Dimensions: we decided in Chicago in February that
the useful spectrometer field region should be 100 cm long and 30 cm diameter.
the inner bore should be 40 cm
2.
Field Homogeneity: 10-2 or 10-3 ?
this will be dictated by the detector requirements.
TPG will be more demanding (uses the field actively as guide for drift)
=> STUDY to be made!
3. Matching:
MICE should be magnetically transparent.
This requires a matched magnetic system for a certain number of configurations
 availability of the corresponding KNOBS
 Movable elements
4. WHICH CONFIGURATIONS?
Personal thoughts……..for discussion:
Alain Blondel
10% cooling of 200 MeV muons requires ~ 20 MV of RF
single particle measurements =>
measurement precision can be as good as D ( e out/e in ) = 10-3
SC Solenoids;
Spectrometer, focus pair, compensation coil
T.O.F. I & II
Pion /muon ID
precise timing
Liquid H2 absorbers
or LiH ?
201 MHz RF cavities
Tracking devices:
He filled TPC-GEM (similar to TSLA R&D)
and/or sci-fi
Measurement of momentum, angles and position
T.O.F. III
Precise timing
Electron ID
Eliminate muons that deca
Alain Blondel
STEP I: we get the muon beam
In this first phase we define the beam tunings, composition,
settings for both mu+ and mu- as a function of momentum.
10 m
needed:
beam (!)
TOF,
trigger
some DAQ
two SCI FI arrays or beam chambers
PID
Alain Blondel
Step II: the first solenoid arrives, the tracker arrives a few weeks later.
In this step we
1. turn on and map the first solenoid
2. study the acceptance
and the required thickness of the diffusers
3. debug the Tracker
4. verify the matching of TPG with Sci-fi or beam chamber
5. debug track identification devices
6. (MEASURE BEAM EMITTANCE IN SOLENOID!)
+
and
needed:
solenoid and all services
magnetic measurement system
tracking devices
Alain Blondel
Step III: TWO spectrometers
At this step we:
-- Turn on and map the second solenoid
-- Debug Spectrometer # 2
-- Measure ein, eout and the ratio
-- Field reversal is important for E ^ B effects
+
+
do we need
and
-
-
+
-
THIS IS A VERY IMPORTANT STEP :
THESE RESULTS WILL BE PART OF THE FINAL ONES
(Systematics on ein/ eout )
-- can insert a number of materials
to measure e.g.
dE/dx vs scattering angle correlation
Alain Blondel
?
Step III- B: TWO spectrometers
-- can insert a number of materials
to measure e.g.
dE/dx vs scattering angle correlation
At this point we might want to bring in an absorber
and measure its properties in this simpler configuration
+
+
Alain Blondel
Step IV: TWO spectrometers and the LH2 absorber
At this step we:
-- Turn on and map the flip pair
-- Match the system
-- Measure ein, eout and the ratio
-- for full AND empty absorber.
-- for ++ AND +- configuration
+
-
+
+
or
Alain Blondel
Step V: first cooling cell
At this step we:
-- Turn on and map the flip pair
-- Match the system
-- Measure ein, eout and the ratio
-- for full AND empty absorber.
-- for ++ AND +- configuration
+
+
or
+
+
with flips
without flips
Alain Blondel
Step VI: low beta study
See; Palmer – Fernow Note – or talk at the October 2001 Workshop at CERN.
Limit is: current X 2 in flip coils and zero in coupling coil.
Alain Blondel
Step VI: low beta study
+
+
with flips
this has to be completely re-matched…. and re-mapped! Quite an operation…
Alain Blondel
Other momenta?
MICE could certainly map the acceptance as a function of beam momentum
for a given magnetic setting.
Off-nominal-momentum performance may be sub-optimal (?).
Should we try MICE matched for lower/higher momentum as well? more/less cooling!
Alain Blondel
Step VII The full two-cell MICE
ibid. sensitivity will be better since volts will be higher.
can try various settings of polarities and absorbers (full / empty)
and of absorber thicknesses (to match available RF or beam momentum)
Alain Blondel
Preliminary conclusions
for discussion
1.
It will be necessary to have enough knobs
to vary the magnetic configuration to adapt to the various avatars of MICE
2.
The various components of the magnetic channel will have to move
along the experiment
3.
There will be a lot of magnetic
measurements to do!
(I must have been a mice (sorry, mouse) in one of my previous lives) Alain Blondel

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