First tests of LCCAL prototype at BTF

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First tests of LCCAL prototype at BTF
Talk Summary

• Construction of prototype
• Description of BTF
• Silicon Pads status
• First results from test run

LCCAL Official INFN RD project, official DESY
RD project PRC RD 00/02 Contributors (Como,
LNF, Padova, Trieste) M. Alemi, M.Bettini,
S.Bertolucci, E. Borsato, A.Bulgheroni, M.
Caccia, P.Checchia, C. Fanin, G. Fedel,
J.Marczewski, S. Miscetti , M. Nicoletto, M.
Prest, R. Peghin, L. Ramina, E. Vallazza.
ECFA-DESY LC Workshop 2 April 2003 Amsterdam
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Description of the proposed hybrid em calorimeter
Pb/Sc Si
(Slightly reduced to cope with budget45)
(Reduced to cope with budget252)
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)
Old slide from P.Checchia at last ECFA meeting in
Praha
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Status of Tile PB calorimeter early November 2002
The tile-Pb calorimeter is fully mounted!
Steps and status
Detector assembling

• Scintillator tiles

Si pad detectors
Fibres
Old slide from P.Checchia at last ECFA meeting in
Praha
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Status of Tile PB calorimeter end of November
2002
Final assembly done _at_ LNF where

• The tiles were surrounded by an Al support
  structure for PMs
• 44 bundles of fibers were connected to PMs, the
  optical coupling between fibers and PMs was left
  in air
• (i.e. no optical grease)
• The calorimeter was covered by PVC and made
  light tight.

As soon as the calorimeter was ready we went for
testing at BTF
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Areal view and BTF layout
BTF test facility
Da?ne Linac
Located _at_ Frascati close to Da?ne machine
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Da?ne Linac
focusing
Positron converter
focusing
gun
Length 60 m Maximum energy 850 (550) MeV
e- (e) Transverse emittance lt 1 (5) mm mrad e-
(e) mm mrad Energy spread lt 1 (2) e-
(e) Pulse duration 10 ns (RF 2.865 GHz) Max
repetition rate 50 Hz
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Single particle production at BTF
In the transfer line from Linac to BTF it is
possible to tune the multeplicity.....
W slits
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Example of single particle production at BTF

• Measured energy in BTF monitor calorimeters
  reflects the Poisson distribution of the number
  of produced particles

Events
Energy in calorimeter
ltNgt ? 1 means P(0) ? P(1) ? 37
Events in peak
N. of electrons
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Summary of BTF characteristics ...

• e- and e
• Energy 50 850 (550) MeV e- (e)
• Repetition rate 24 Hz (will be 49 Hz)
• Pulse Duration 10 ns (will be ?1.5 ns)
• Single particle production (1 energy selection)
• Maximum current/pulse is 500 mA
• but up to 103 allowed electrons/sec
• Upgrade asked for 1010 allowed electrons/sec
• 100 m2 Experimental Hall

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Test Beam Dic 2002 layout of prototype

• 254 cells 55 cm2
• Fibers grouped in four longitudinal
• sectors (L1-L4)
• L1/L2/L3/L4 4/7/11/23
• PB/Sc layers
• (2.3 4 6.3 13.2) X0.

1 2 3
4 5 6
7 8 9
Y
Z
MultiAnode PMs under test to readout all cells
......
X
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Test Beam Dic 2002 LCCAL in position ...
VME (diagnostics)
HV
VMECamac (users)
Calo2
LCCAL
Calo 1
Motorized table
BTF just started .. LCCAL proto was one of the
first user!
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Test Beam Dic 2002 more pictures ...
P.Checchia and G.Mazzitelli (BTF responsible)
Strange yellow beam
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Test Beam Dic 2002 equalization procedure ...

• Electron beams of 490 MeV
• used to test the energy
• response of each cell.
• A first cross-calibration of
• the PM gains was done by

• Minimizing energy res.
• Lowering gains to reduce
• saturation

• No exact knowledge of beam
• size and position.
• Just 3 days of running ..

Still .. compare cell 4,6
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Test Beam Dic 2002 first look at response
resolution
Energy in tower after gain equalization
Energy in tower before gain equalization
Cell 4
Cell 4
No bad for the first try .... still some hints
of saturation with 2 particles
2nd electron
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Upgrade of prototyping during last 4 months

• SI Pads detector
• 20 detectors produced by IET (Warsaw)
• - 1 used on the old Test beam
• - 16 OK and assembled on 3 PCB
• - 1 noisy , 2 bad

6 cm
7 cm

• PCBs also fully developed
• (see next talk by A.Bulgheroni)
• Each motherboard mounts 3x2 Si
• wafers, for a total of 18x14 pads.

Problems, adopted solutions, running conditions
and future plans still refer to Bulgheronis
talk
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Silicon Pads insertion in prototype

• PCB with SiPad inserted inside prototype the
  28-03-03

Picture 1 HERE
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Running _at_ BTF in 2003
Last Friday a 1 week data taking started.
Improvements

• Si Pads inserted
• Two beam position monitors 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)

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Running _at_ BTF in 2003
Moreover

• easier life during data taking ...
• HV monitor setting remotely controlled
• movement of table remotely controlled
• a faster DAQ
• Large test program underway..
• energy scan at low energy 140 750 MeV
• energy response resolution for 1-2-3 impinging
  particles
• a more stable equalization procedure
• scanning along cell and pads in progress

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Test Beam Mar 03 Beam monitor
490 MeV
The beam position monitor allow us to control the
particle multeplicity

• Typical beam size
• ?x of few mm
• ?y of ? 0.5cm

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Test Beam Mar 03 first look at response vs cell
profiles
In red (green) the x-y position of the events
with 1 hit and Energy ? (?)150 counts.
Given the small beam size we tried to position
the beam as well as possible inside the cell.
Example of cell boundaries for central cell.
Ecell (a.u.)
Ecell (a.u.)
?10
Scan along cell is in progress
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Test Beam Mar 03 Energy spectra for 1-2-3
electrons
No calibration applied
1 e-
2 e-
3 e-

• Test of calibration procedure on central cell.
• multeplicity from ext. strips
• no gaussian tails disappear
• linearity and resolution improve

Calibration done after a first round of HV
setting to reduce saturation
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Test Beam Mar 03 Energy linearity
A larger energy region can be approximately
scanned merging dat with single and multiple
electrons ? Linearity preserved
2 electrons
Ecal (MeV)
3 electrons
Ebeam (MeV)
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Test Beam Mar 03 Energy resolution I

• Resolution for single electrons on the expected
  ball park!
• Slightly worse resolution for multiple
  electrons ...
• probably due to overlapping multiple
  hits on ext. strips

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Test Beam Mar 03 Energy resolution linearity

• Nphegt5.1 /layer ? cal(45 layers)gt220 phe/m.i.p.
• 250 MeV/Mip ? 800-900 Phe/GeV
• Light uniformity better than 20 OK also _at_ BTF

From Cern TB with first longitudinal sector only

• PRELIMINARY CONCLUSIONS ..
• Photoelectron stat. negligible
• Sampling term 11.5 as in MC
• Uniformity of light collection still at a level
  lt 10-20 using all layers. Effect on resolution
  to be evaluated as eventual constant term at next
  Cern TB.
• Expectations by MC

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Test Beam Mar 03 distribution of fired Si
Pads
First layer
Second layer
Nev
Yes ! They are FIRING
Xpad
Qpad (a.u.)
Xpad
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Test Beam Mar 03 position resolution at low
energy
Ebeam 490 MeV

• Just for fun online correlation plot between
  position given by pads and external strips.
• show only Y direction
• (since Xb is small!!)
• No clustering tried ?
• fast weighted average
• (Y-centroid) of firing Si
• pads with Q ? 5 ?Q

Ypad (cm)
Yb (cm)
Still a clear correlation and a space
resolution of 6-7 mm are found
to be compared with ?x,y of 2 mm found _at_ 25 GeV
Ypad-Yb (cm)
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Conclusions and perspectives

• The LCCAL prototype is ? fully working!
• - more Si Pads are under constructions
• - the third Si layer will be fully equipped.
• - multianode PMs to be installed in late
  autumn.

• After a first learning phase in Nov 02 a
  succesfull test run with
• the whole prototype is under way at the BTF in
  Frascati.

• Energy response and resolution as expected!
• Work is in progress to understand discriminating
  power of
• multiple hits by merging Silicon and Energy
  information.
• Two test beams at Higher Energy in preparation
• PS (June 2003 ??) SPS (August 2003)

Needs to start the simulation of this hybrid
technique in LC software