response of the panda electromagnetic calorimeter response of the panda electromagnetic calorimeter...
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RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER TO PHOTONS IN THE ENERGY RANGE 10 – 120 MeV
Stockholm University, Uppsala University, Lund University(Klas Marcks von Würtemberg)
Status report, PAC Nuclear Physics, Lund, November 9, 2010
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
PANDA (@FAIR) Aim of project Review Experimental set-up, analysis Results and current situation Future
Outline
Tord JohanssonErik ThoméKjell FranssonPawel MarciniewskiMagnus Wolke
Bent SchröderKurt HansenMagnus LundinJason BrudvikLennart Isaksson
Klas Marcks von WürtembergLinda Gerén
Per-Erik TegnérChristoph BargholtzPia Thörngren Engblom
Olle Lundberg
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
PANDA (@FAIR)
Study of gluonic excitations and the physics of strange and charm quarks
Demands on calorimeter: High resolution and low energy threshold
Calorimeter material: Scintillating PWO-crystals cooled to -25 ° C
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Aim Determine the energy resolution and spatial resolution of a realistic set-up
of a 5x5 matrix of PWO-crystals.
VPT (vacuum photo triods) as light converters Flash-ADC read-out system
Support structure: Carbon fibre alveoli Pre-shaped wrapping
Crystal shape (slightly tapered)
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Review2007
3x3 matrix, straight crystals
PM-tubes, Peak sensing ADCs
Today 2010
5x5 matrix, tapered crystals Carbon fibre
alveoli Provisional support structure
PM-tubes, Peak sensing ADCs / Flash-ADC
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Tomorrow (2011)
VPTs will be used. A complete setup can be tested.
Adjustable support structure planned
Current setup representative of central part of forward end-cap
Peripheral part of forward end-cap
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
5x5 PWO crystals
Climate chamber -25 °C
PM-tubes (anode signal) Preamplifiers
Cave
2x16 chn shapers 0.8 μs Peak-sensing ADC
DAQ
Radiator
Cave Daq
e-
e-
γ
B
Foca
l plan
e
Focal plane 62 detectors δE ~ 1 MeV (std 0.29 MeV) Covers 13 – 64 MeV
Schematic view of experiment
164.7 MeV
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Data and calibration
Novosibirsk function 35.2*FWHM35.2*FWHM
2nd degree polynomial fit
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Results
Threshold 0.5 MeV
35.2/FWHM
Beam: central crystal
Tagger plane not in focus
PWO 5x5
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Independent measurement of focal plane resolution with CATS
500 kg NaI in 7 segments
Calibrated by 15.11 MeV line of Carbon
Revealed features
Decreased resolution of focal plane below 35 MeV
Nominal energies of focal plane detectors scaled by a factor 1.075
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Independent measurement of tagged photon energies with CATS
Fitting region
Tagger detector 61
Tagger detector 8
E_CATS=0.18+0.94*E_Nominal
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Contribution from focal plane summed quadratically to contribution from CATS
Contribution from CATS
NaI - CATS
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Threshold: 0.5 MeV
Results after deconvolution
PWO 5x5
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Threshold: 0.5 MeV
Beam off centre
Beam position
PWO 5x5
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Position of a photon striking the detector estimated by weighted average of energy depositions (non-linear weights)
Fine structures of estimated position when deposited energy is spread over few crystals.
Spatial resolution13 - 30 MeV
40 - 63 MeV
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Spatial profile of beam measured with ccd-camera
Total width: 14 mm
Standard deviation: 2.9 mm
Contribution from beam width to measured spatial resolution small if quadratical summing assumed :
][0.7][9.26.7 22 mmmmx mmmmx 0.79.26.7 22
RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER
Future
Next experiment: March 2011 New light converters: Vacuum triods
Thank you for your attention!
Increased energy resolution of focal plane below 35 MeV would be valuable.
From the projects point of view: