PANDA electromagnetic calorimeters Pavel Semenov IHEP, Protvino on behalf of the IHEP PANDA group INSTR08 28 Feb - 05 Mar 2008
Jan 12, 2016
PANDA electromagnetic calorimeters
Pavel Semenov IHEP, Protvinoon behalf of the IHEP PANDA group
INSTR08 28 Feb - 05 Mar 2008
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 2
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 3
PANDA EM Calorimeters placement
FS EMCTS EMC
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 4
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 5
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 6
PANDA-IF picture
Cryothermostat
Crystal box
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 7
PWO properties studies at low temperatures
Crystal # S(-19.4) / S(+18.5)
b4 2.83
b16 2.80
b17 2.75
b24 2.78
b30 2.84
Light output change before the irradiation with temperature change from +18.5 0C to -19.4 0C
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 8
PWO light transmittance recovery at -200C
Published at NIM A Vol 582/2 pp 575-580
Paper:First study of radiation hardness of lead tungstate crystals at low
temperatures
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 9
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 10
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 11
Testbeam setup
DC1M14 DC2DC3
DC4ECAL prototype 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 12
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 (1212) fibers BCF-91A (1.2 mm)
• PMT Hamamtsu R5800 as photodetectors
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 13
Shashlyk modules production
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 14
Shashlyk prototype pictures
3x3 matrix of shashlyk modules and PMT attached to the modules
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 15
Minimum ionizing particle peak
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 16
Energy Resolution dependence on energy
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 17
Energy Resolution parameterization
σE /E = a/E b/√E c [%], E in GeV
Experiment data fit: MC data fit:
a = 3.5 ± 0.3 a = 0.0
b = 2.8 ± 0.2 b = 3.0 ± 0.3
c = 1.3 ± 0.04 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 18
Measured S-curve at 19 GeV
Real Position, cm
Xcog,au
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 19
Position resolution (center) dependence on energy
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 20
Position resolution parameterization
σx = a/√E b [mm], E in GeV
Experiment data fit: MC data fit:
a = 17.6 ± 0.9 a = 14.2 ± 0.6
b = 4.6 ± 0.9 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 21
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 22
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 23
Backup slides
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 24
Radiation hardness temperature dependence
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 25
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 26
S-curve MC (0.5 – 10 GeV)
3 March 2008 Pavel Semenov, INSTR08@BINP, Novosibirsk 27
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 28
PANDA-IF electronics diagram
7013PT1000
CAMAC
RS485 bus
Irradiation facilityControlroom
7017ADC
7042DO
LED generator
HV
Crystal Box
Shutter
LRS1440HV system
VME
Shutter digital control lines
RS232
DAQ computerLinux
RS485/RS232converter
LAUDA
PT1000
7 signal lines
Opt. fibers
RS232-CL
Cs137