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RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER

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.

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RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER

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  1. 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

  2. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Per-Erik Tegnér Christoph Bargholtz Pia Thörngren Engblom Klas Marcks von Würtemberg Linda Gerén Olle Lundberg Bent Schröder Kurt Hansen Magnus Lundin Jason Brudvik Lennart Isaksson Tord Johansson Erik Thomé Kjell Fransson Pawel Marciniewski Magnus Wolke Outline • PANDA (@FAIR) • Aim of project • Review • Experimental set-up, analysis • Results and current situation • Future

  3. 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

  4. 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. • Crystal shape (slightly tapered) • Support structure: Carbon fibre alveoli • Pre-shaped wrapping • VPT (vacuum photo triods) as light converters • Flash-ADC read-out system

  5. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Review 2007 Today 2010 • 3x3 matrix, straight crystals • 5x5 matrix, tapered crystals • Provisional support structure • Carbon fibre alveoli • PM-tubes, Peak sensing ADCs • PM-tubes, Peak sensing ADCs / Flash-ADC

  6. 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

  7. DAQ Cave • 2x16 chn shapers 0.8 μs • Climate chamber -25 °C • Peak-sensing ADC • 5x5 PWO crystals • PM-tubes (anode signal) • Preamplifiers Cave Daq γ e- Focal plane Focal plane B • 62 detectors Radiator • δE ~ 1 MeV (std 0.29 MeV) • Covers 13 – 64 MeV e- RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Schematic view of experiment 164.7 MeV

  8. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Data and calibration 2nd degree polynomial fit Novosibirsk function

  9. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Results PWO 5x5 Threshold 0.5 MeV Beam: central crystal Tagger plane not in focus

  10. 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

  11. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Independent measurement of tagged photon energies with CATS E_CATS=0.18+0.94*E_Nominal Tagger detector 8 Fitting region Tagger detector 61

  12. Contribution from focal plane summed quadratically to contribution from CATS Contribution from CATS RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER NaI - CATS

  13. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Results after deconvolution PWO 5x5 Threshold: 0.5 MeV

  14. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER PWO 5x5 Threshold: 0.5 MeV Beam off centre Beam position

  15. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Spatial resolution 13 - 30 MeV 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. 40 - 63 MeV

  16. 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 :

  17. RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER Future • Next experiment: March 2011 • New light converters: Vacuum triods From the projects point of view: • Increased energy resolution of focal plane below 35 MeV would be valuable. Thank you for your attention!

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