LCcal: a Calorimeter prototype for future Linear Colliders

1
LCcal a Calorimeter prototype for future
Linear Colliders
TALK SUMMARY

• Design principles
• Prototype description
• Construction details
• Test Beam results
• Conclusions and Future plans

Contributors (Como, ITE-Warsaw, LNF, Padova,
Trieste) M. Alemi, A.Anashkin, M. Anelli,
M.Bettini, S.Bertolucci, E. Borsato, M. Caccia,
P.C, C. Fanin, J.Marczewski, S. Miscetti,
B.Nadalut, M. Nicoletto, M. Prest, R. Peghin, L.
Ramina, F. Simonetto, E. Vallazza .
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Design principles
From the LC Physics requirements
Tesla TDR solutions

• Si W
• Shashlik (thanks to CALEIDO)

• Cristals
• Fully compensating EcalHcal

Alternatives
Proposed solution
Keep SiW advantages (flat geometry, high
granularity) Erec. not from Si but from
Scintillator-WLS fibers Reduce (factor gt10) the
number of channels
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Prototype description
Pb/Sc Si

• 45 layers
• 25 25 0.3 cm3 Pb
• 25 25 0.3 cm3 Scint. 25 cells 5 5 cm2
• 3 planes
• 252 .9 .9 cm2 Si Pads
• at 2, 6, 12 X0

Scintillation light transported with WLS s tail
fibers Cell separation with grooves in Sc.
plates with Tyvec strips inside
Coupled with clear fibers (to PM)
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Prototype (cntd)
3 Si planes

• Goal shower-shower separation, position
  measurement, e/h identification
• Pad dimensionlt shower dimension .9x.9 cm2
• Longitudinal sampling 3 planes
• Analogic RO VA hdr9c from IDEas
• See A. Bulgheronis talk for details

Pad diode ac(old)-dc(new) coupled

• Actual design
• - Detector 6x7 pads
• - Plane 3x2 detectors

pcb contact with conductive glue
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Construction detailsScintillator

• 3 mm Kuraray SCSN-61 (25x25 cm2)
• 3 mm Bicron BC-408 (25x25 cm2)

Machined with vacuum plate as holder
Whole Production (gt50 tiles) done in september
2002
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Fibers Kuraray 1mm d. Y11 300 ppm multicladding
Face polished and aluminized by sputtering
To make the 2.4 cm radius curvature middle
temperature(500-700) oven

• Splicing with optical glue
• and a supporting tube
• stable in gt30 day time

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Detector Assembling
45 Layers calorimeter prototype completely built
in 2002
Fibres grouped
into 25x4 bundles making a 4-fold longitudinal
segmentation. Slots for the insertion of
the 3 Si pad planes (Motherboard).
Mechanical support for Photomultipliers
in the 3x3 central cells
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Test beam activity

• after a 2002 pre test with the 1st layer only
  (2.1 X0) at CERN
• two runs at Frascati Beam Test Facility (n 50
  750 MeV)

it is possible to tune the multeplicity.....

• run at CERN SPS H6 beam line (e/? 5 150 GeV)
  All tests two beam position
  monitors (telescope) put in front of the
  calorimeter.
• - Each detector consisting of 400?400 xy Si
  strips with a pitch of 240 ?m
• - They cover the central area of the prototype
  (9.5 ? 9.5 cm2)

LCcal
trigger
beam
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Test beam activity detector calibration

• define cell as the calibrated sum of the 4
  longitudinal layers on the same lateral
  position Cibi?j1,4ajLij (4-19-116
  parameters)
• process in two steps
• equalise the layer response at the same
  incoming energy Lijbk/bi Lkj
• minimise the Energy spread on the sum of 9
  cells (iterative process) aj min. width
  Ecal?n1,9Cn

L4
L3
L2
L1
Ci
Si L3
Si L2
Si L1
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Test beam results Linearity and Energy Resolution
BTF test
?E?E
11.5??E
Ebeam (MeV)

• Photoelectron statistics negligble
• Stocastic Term 11.5 as in MC
• Light disuniformity ltlt10 Effects on resolution
  to be measured at SPS (August 2003)?

Cern TB 2002
Nphegt5.1 /layer ?Cal(45 layers) 250 MeV/Mip
800Npe/GeV OK also _at_ BTF (E 500 MeV)
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Test beam results Linearity and Energy Resolution
Cern TB 2003
?E?E
pm saturates
confirmed at high energy !!!
Ecal (GeV)
e-
11.1??E
Ebeam (GeV)
Ebeam (GeV)
75 GeV?
15 GeV e-
Ecal (GeV)
Ecal (GeV)
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Test beam results Si pad detector (Position
Meas.)
Cern TB 2003
y pad Si L2 (cm)
30 GeV electrons
y telescope (cm)
Si L1L2
?3.27 mm
?1.76 mm
Si L3
Si L2
Si L1
y pad y telescope (cm)
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Test beam results Si pad detector (Position
Meas.)
PRELIMINARY analysis pad noise subtraction not
optimised
Position resolution ? 2.5mm not
far from Monte
Carlo
10 GeV electrons
10 GeV simulated electrons
?2.5 mm
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Test beam results uniformity in (light) Energy
response
Cern TB 2003
30 GeV e-
disuniformity lt 2 correction from pad
reconstruction can be applied!
Ecal (GeV)
x telescope
2
PRELIMINARY cell border effects dominated by
residual miscalibration
x pad
x (cm)
2
Cj
y(cm)
x telescope
Cj-1
x pad
x (cm)
Ecal (GeV)
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Test beam results ( e/? rejection)
the redundancy of the information on the
linear/lateral shower development makes the
rejection very easy (difficult to quantify below
10-3 due to beam contamination)
Cern TB 2003
30 GeV e-
30 GeV e-
30 GeV?
30 GeV?
E Si pad Layer 1
E cal Layer 1
50 GeV e-
Si pad Layer 2
30 GeV e-
30 GeV?
75 GeV?
shower variance
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Test beam results Si Pad two particle separation
exhaustive analysis not fully accomplished
Two electrons with energy 750 MeV
Y silicon chambers
X silicon chambers
First layer
BTF test
Second layer
NB not fully equipped problematic channels
Third layer
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Conclusions and Future plans

• A calorimeter prototype with the proposed
  technique has been built and fully tested. All
  the results are preliminary.
• Energy and position resolution as expected
  ?E/E 11.-11.5 /?E, ?pos 2 mm (_at_ 30 GeV)
• Light uniformity acceptable.
• e/? rejection very good ( lt10-3).
• Two particle separation results coming soon.
• Next steps include a calorimeter made following
  this technique into the general LC simulation and
  Pattern recognition.
• Combined test with Hcal (?)

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backup
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Detector Assembling
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PMs
Fibres with PM support structure
Fibres faced to PMs
Scintill.
Piani Si
LCCAL in test _at_ BTF (Frascati)
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Test beam results CALORIMETER (2.1 X0)
4 layers m.i.p.?check light output and uniformity
in Light collection Ratio signal/sigma ?lower
limit for photoelectrons
Nphegt5.1 /layer ? cal(45layers)gt220 phe/m.i.p.
good uniformity
Simulated Light collection disunifority(20)