N. Anfimov (JINR) on behalf of
the ECAL0 team
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Introduction
Installation and commissioning
Calibration
Data taking
Preliminary result
Plans for 2013
Summary
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Requirements for ECAL0
1. The geometrical size is ~ 2.0 - 2.5 m2 with a central hole ~ 0.4 - 0.8 m2 and
the total length (thickness) of the calorimeter should be of about 50 cm.
2. Located downstream of RPD.
ECAL0 should cover the polar angular range 0.15-0.6 Rad.
3. A modular structure.
4. Energy resolution ≤ 10.0%/√E (GeV) or better.
5. The photodetector should be insensitive to the magnetic field.
R&D of ECAL0 prototype was being performed in 2008-2011
Final prototype had been tested in 2011.
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ECAL0 in the COMPASS setup
The upgrade for GPD measurements includes production of the new electromagnetic
calorimeter ECAL0 to be installed after RPD (ToF barrel CAMERA) shown in Fig. 1.
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“Shashlyk”-type calorimeter module for ECAL0
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Micropixel Avalanche PhotoDiodes – MAPD
Surface-pixellated structure
- Pixels are on the surface
- Gain is up to 106
- Has pixel density ~ 102 - 103 mm-2
- PDE is up to 40% (100 mm-2)
- PDE depends on pixel density (decrease with
increasing density)
- Small dynamic range (depends on total number of
pixels)
-Typical pixel size is (25-100)x(25-100) µm
Deep micro-well structure
- Pixels are deep inside epitaxial layer
- Gain is up to 105
- Has pixel density ~ 104 mm-2 (up to 40 000 mm-2)
- PDE is up to 30% (15 000 mm-2)
- PDE slightly depends on pixel density (decrease
with increasing density)
- Large dynamic range (depends on total number of
pixels)
-Typical pixel size is (2-5)x(2-5) µm
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Results of beam tests for 3x3 modules prototype
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Modules mass-production
Institute for Scintillation Materials, Kharkov, Ukraine is playing major role in calorimeter
production by JINR design (lead and sci plates, assembling, fiber insertion, pretests, etc)
injection-molding of
scintillation plates
Painting scintillation
plates
Joint Institute for Nuclear Research is responsible for:
- Has organized and is managing production in Kharkov
- MAPD production (from Zecotek’s wafers) and tests
- Photodetector unit production and tests
- Tests of final modules, cosmic tests
- Beam tests and investigation of modules
Prober setup for wafer
tests
Intermediate tests and studies of
electronics, MAPD, photodetector
units, etc
Assembling calorimeters
Cosmic tests of
modules
Wafer of MAPD-3N chips
General view of assembled
calorimeter module
Production of photodetector
units
MAPD casing
procedure
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Installation and commissioning
 Aluminium frame filled with 56 modules
ECAL0 tests with cosmics performed in assembly zone
(COMPASS DAQ used)
 ECAL0 craned into final position in spectrometer
 Air cooling installation
 Power supplies(Bias voltage)&Thermostabization
&monitoring(LED) elements were developed by HVSYS
company (Dubna)
The first fragment of the ECAL0 consisting of 56 modules
was made for 2012 Run.
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Conditions
The first part of ECAL0 installed in COMPASS was successfully prepared for 2012 GPD pilot run
data taking and operated well during October-December. Figures show beam load over
ECAL0, MAPD amplitude variation and temperature inside the ECAL0 box.
The temperature stabilization system operating in a range 15-25 °C .
MAPD temperature is maintained with an accuracy < 0.1 °C
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ECAL0 Intercalibration
October 12, 2013 ECAL0 calibration with muon beam
For ECAL0 module deposited fraction energy e/γ Eactive ~16%, 1 GeV e/γ -> 160 MeV
Energy deposition from muon at 160 GeV -> 34.3 MeV in cell -> muon peak corresponds to 214 MeV
All channels were roughly settled in according to this procedure.
Calibration energy coefficient correction based on LED_in_spill / LED_out_of_spill.
This correction is different muon/pion beams due to different backgrounds.
Muon beam -> average ~1.65%
Pion beam-> 4.75%
Muon peak in different towers
Nonlinearity of MAPD response at
5GeV was measured to be about 5%
and it also can be taken into account
on the cluster reconstruction level.
Correction coefficients distribution for 504 towers.
Muon beam (top), Pion beam (bottom)
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Long-term stability of FEM-system
FEM LED stability studies.
FEM#1÷4 stability over 1 month:
November1 – Novenmber30, 2013
4 PIN-photodiodes for LED light monitoring were used
Monitoring system consist of 4 Light sources. Each
source supplied quarter of ECAL0-prototype
channels via light distributor 1 -> 16
LEDs amplitudes variations < 1%
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Long-term stability of ECAL0
MAPD response stability over 1 month:
November1 – Novenmber30, 2013
MAPDs amplitudes variations ≈ 1%
over all cells
cell# X=15 Y=1
cell# X=15 Y=22
cell# X=15 Y=25
cell# X=1 Y=13
cell# X=28 Y=13
cell# X=15 Y=4
cell# X=4 Y=13
cell# X=31 Y=13
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Results
Cluster reconstruction
• Cluster position -position of a
All cells
central cell
Peak width is 12%
• Cluster energy -sum of energy
~8% -resolution of 1 cell
deposition in 9 (3x3) cells
~8% -cell-to-cell misalignment
• Cluster position -position of a
Intercalibration of each of the ECAL0 cells with central cell
• Cluster energy -sum of energy
muon halo provides precision about 8%
deposition in 9 (3x3) cells
MIP signal obtained in inter-calibration
with muon halo (all cells together).
Physical calibration:
• π-beam of 190 GeV/c with intensity 0.5 106 s-1
• LH target
• Special ECAL0-based trigger was developed.
• ECAL0 based trigger: total energy deposition in ECAL0 >6GeV (3 GeV)
• Working tracking for primary vertex reconstruction
• Final calibration constants were obtained by moving π0 mass peak to
it’s nominal position
π0 peak in γγ mass spectrum obtained in
calibration with pion beam. (π0 mass is
subtracted in X-axis)
Physical data sample collected with muon beam demonstrates wellvisible π0 peak in γγ mass spectrum. Its position is shifted from the
nominal because precise π0 calibration was not used yet for production
of the data.
The time resolution of cluster depends
on cluster energy and for energy
above 1GeV is less 1 ns
γγ mass spectrum for semi- inclusive muon events
(π0 calibration is not applied yet).
π0 peak =127.2 MeV
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Summary
1.
Part (56 modules) of ECAL0 for 2012 DVCS PILOT RUN built up and put
into operation. It demonstrated good performance: E and T resolutions,
linearity and stability fully correspond to expectations.
2.
The signal from π0 decays was seen in ECAL0
3.
Data for calibration with π- was taken and are being used.
4.
The full scale ECAL0 is under production. 200 modules will be produced at
ISMA (Kharkov, Ukraine) till the end of this year. We are going to produce
Registration Units as soon as we get new batch of photodiodes.
5.
Beam tests in Bonn at ELSA: studying angular dependences
6.
The design of the ECAL0 modules is could be used for the NICA/SPD ECAL.
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