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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.

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slide1

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

slide2

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
slide3

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
slide4

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
slide5

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
slide6

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

slide7

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

slide8

RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER

Data and calibration

2nd degree polynomial fit

Novosibirsk function

slide9

RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER

Results

PWO 5x5

Threshold 0.5 MeV

Beam: central crystal

Tagger plane not in focus

slide10

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
slide11

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

slide12

Contribution from focal plane summed quadratically to contribution from CATS

Contribution from CATS

RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER

NaI - CATS

slide13

RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER

Results after deconvolution

PWO 5x5

Threshold: 0.5 MeV

slide14

RESPONSE OF THE PANDA ELECTROMAGNETIC CALORIMETER

PWO 5x5

Threshold: 0.5 MeV

Beam off centre

Beam position

slide15

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

slide16

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 :

slide17

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!