Transcript Slide 1

PANDA electromagnetic calorimeters
Pavel Semenov IHEP, Protvino
on behalf of the IHEP PANDA group
INSTR08
28 Feb - 05 Mar 2008
Outline
• PANDA detector setup
• Target Spectrometer EMC
– PANDA gamma irradiation facility at IHEP
– Light output at -20°C
– Radiation hardness measurements at -20°C
• Forward Spectrometer EMC
– EMC prototype module parameters
– Prototype testbeam results for energy and position resolution
– MC studies to find optimal parameters
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
2
PANDA EM Calorimeters placement
TS EMC
FS EMC
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
3
Target spectrometer EMC
• Requirements
–
–
–
–
–
Geometrical coverage close to 4π
Compact size
Fast signal, good time resolution
Low energy threshold (10 MeV) of photon detection
Excellent position and energy resolutions
• PbWO4 (PWO) crystal as a good candidate for the TS EMC
– 21 mm x 21 mm x 20 cm barrel cell size (front), 25 mm x 25 mm x 20 cm
endcap cell cize
– ~17000 crystals (96 % of 4 π)
• Improved light output is needed to reach excellent resolution and low
threshold
– Calorimeter operates at low temperature (about -200C, factor of 3 increase
of light output)
– PWO-II: enhanced light output PWO (~20 phe/MeV)
• PWO radiation hardness at room temperature is not a problem for
PANDA (dose rates not more then a few rad/hour). But there were no
data for PWO radiation hardness properties at -20 0C
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
4
PANDA-IF at IHEP features
• Crystal holder (Cu plate with heat-exchanging system) for
5 crystals
• Cryothermostat (LAUDA RC6CP) capable of temperature
stabilization in the region of -35 °C --- +200 °C
• LED system to monitor PMT gain and crystals
transparency in blue and red part of the visible spectrum
• Cs137 gamma source gives irradiation dose rate 100 rad/h
and below
• Monitoring of temperature sensors ( Pt100 and Pt1000
class A ) at 6 points (2 on crystals)
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
5
PANDA-IF picture
Cryothermostat
Crystal box
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
6
PWO properties studies at low temperatures
Light output change before the irradiation with
temperature change from +18.5 0C to -19.4 0C
Crystal #
S(-19.4) / S(+18.5)
b4
2.83
b16
2.80
b17
2.75
b24
2.78
b30
2.84
Radiation hardness studies of PWO-II at PANDA dose rates
(max 2 rad/hour) and -20 0C showed 20%-35% drop of DC
output signal after 300-400 hours of irradiation
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
7
PWO light transmittance recovery at -200C
Paper:
First study of radiation
hardness of lead tungstate
crystals at low temperatures
Published at NIM A
Vol 582/2 pp 575-580
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
8
Radiation hardness studies of PWO-II (high dose rate)
Still factor 1.4
enhancement of
light output
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
9
Forward Spectrometer EMC
• 7 meters from the interaction point
• Covers 3 m2
• Fine segmented sampling calorimeter with light collection
by optical WLS fibers passing through holes in the
scintillator and lead layers (shashlyk type)
• Not in magnetic field (PMT as photodetector)
• Working energy range 10 MeV – 10 GeV
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
10
Testbeam setup
ECAL
prototype
DC3
M14
DC2
DC4
DC1
Beam
• Spectrometer consisted of 4 drift chamber stations and
a magnet to measure beam particle momentum
precisely
• Calorimeter prototype installed on a movable platform
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
11
Shashlyk prototype module parameters
•
•
•
•
•
•
9 modules assembled in matrix 3x3
380 layers of 0.3-mm lead and 1.5-mm scintillator,
total length 680 mm
Transverse size 110x110 mm2
Effective Moliere radius: RM=59 mm
Effective radiation length: X0=34 mm
Total radiation length: 20X0
Light collection: 144 (1212) fibers BCF-91A (1.2
mm)
• PMT Hamamtsu R5800 as photodetectors
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
12
Shashlyk modules production
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
13
Shashlyk prototype pictures
3x3 matrix of shashlyk modules and PMT attached to the modules
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
14
Minimum ionizing particle peak
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
15
Energy Resolution dependence on energy
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
16
Energy Resolution parameterization
σE /E = a/E  b/√E  c [%], E in GeV
Experiment data fit:
a = 3.5 ± 0.3
b = 2.8 ± 0.2
c = 1.3 ± 0.04
MC data fit:
a = 0.0
b = 3.0 ± 0.3
c = 1.1 ± 0.7
Good agreement with MC without noise term.
Good agreement with previous studies of similar sampling modules at
lower energies (2.9%/ √E at 220-370 MeV: Test beam study of the
KOPIO shashlyk calorimeter prototype, G.Atoian,
S.Dhawan,V.Issakov et al. CALOR-2004 Proceedings )
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
17
Measured S-curve at 19 GeV
Xcog,au
Real Position, cm
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
18
Position resolution (center) dependence on energy
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
19
Position resolution parameterization
σx = a/√E  b [mm], E in GeV
Experiment data fit:
a = 17.6 ± 0.9
b = 4.6 ± 0.9
MC data fit:
a = 14.2 ± 0.6
b = 5.5 ± 0.9
Worst case – resolution at the module center.
Resolution near the module edge is 3 times better
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
20
Shashlyk 8x8 cells prototype
• We plan to have another shashlyk testbeam run in 2008
with prototype of 8x8 cells
• Now prototype with 55mm x 55mm module sizes is
under construction
• Testbeam studies includes prototype energy and position
resolution as well as test of π0 reconstruction capabilities in
the energy range up to 15 GeV
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
21
Conclusions
• PWO-II radiation hardness at -200C studies showed
deep light transmission drop (20%-35% at 2rad/hour)
and low light transmission recovery rate
• Testbeam studies of energy and position resolution of
shashlyk prototype (110x110mm cell) results:
– Energy σE /E = 3.5/E  2.8/√E  1.3 [%]
– Position (at the cell center) σx = 17.6/√E  4.6 [mm]
– Good agreement with MC results
• Further improvement of shashlyk parameters includes
prototype with 55x55 mm cell size testbeam study
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
22
Backup
3 March 2008
slides
Pavel Semenov, INSTR08@BINP, Novosibirsk
23
Radiation hardness temperature dependence
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
24
MC shashlyk parameters
•
•
•
•
•
•
•
•
Shashlyk module geometry including holes
Tile att. length 70 cm
Fiber att length 400 cm
Reflection from tile edges diffusive
Tot. internal reflection 0.97
Tile light output 100 eV/photon
Reemission probability in fiber 0.1
Refraction in tiles and fibers 1.59
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
25
S-curve MC (0.5 – 10 GeV)
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
26
PANDA-IF electronics
• Based on i7k (ICP DAS) modules with RS485 interface
• Short connections (0.5 m) from PMT and temperature
sensors to read-out electronics
• Temperature measurements with an accuracy better than
0.03 °C
• DC current measurements accuracy up to nA
• LED signals in DC mode – measurement of the mean
current thru 10 kΩ generated by a bunch of pulses
• HV for PMTs: LeCroy1440 system
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
27
PANDA-IF electronics diagram
RS485 bus
RS485/RS232
converter
VME
RS232
7013
PT1000
7017
ADC
7042
DO
7 signal lines
DAQ computer
Linux
PT1000
LED
generator
Opt. fibers
CAMAC
LAUDA
RS232CL
Shutter
Crystal Box
LRS1440
HV system
Cs137
HV
Control
room
Irradiation facility
Shutter digital control lines
3 March 2008
Pavel Semenov, INSTR08@BINP, Novosibirsk
28