Author/Authors :
K. and Marcks von Würtemberg، نويسنده , , K. and Gerén، نويسنده , , L. and LUNDBERG، نويسنده , , O. and Tegnér، نويسنده , , P.-E. and Fransson، نويسنده , , K. and Grape، نويسنده , , S. and Johansson، نويسنده , , T. and Thomé، نويسنده , , E. and Wolke، نويسنده , , M. and Brudvik، نويسنده , , J. and Fissum، نويسنده , , K. and Hansen، نويسنده , , K. and Isaksson، نويسنده , , L. and Lundin، نويسنده , , M. and Schrِder، نويسنده , , B.، نويسنده ,
Abstract :
The response of a matrix of 25 lead tungstate (PWO) scintillator detectors, operated at −25 °C, to photons in the range 13 MeV–64 MeV has been measured at the tagged-photon facility at MAX-lab, Lund. The tapered PWO crystals, each with a length of 200 mm and a cross-section of 24.4×24.4 mm2 in the front end, read out by 19 mm photomultiplier tubes, were arranged in a 5×5 matrix. The response was measured for photons directed towards the centre of the central crystal as well as for photons directed towards the corner of the central crystal, where four crystals meet. The obtained energy resolution surpasses what has been published so far and is close to the limit given by Poisson statistics and escaped energy. For photons directed towards the centre(corner) of the central crystal the relative energy resolution, defined as (FWHM/2.35) / E γ , decreases from 7.3%(11.0%) at E γ = 13 MeV to 3.3%(3.6%) at E γ = 64 MeV . The reconstructed point of impact of a photon in this energy range is determined with an uncertainty (one standard deviation) of 7.3±0.1 mm.
Keywords :
Lead tungstate , PWO scintillators , Electromagnetic calorimeter , PANDA , Tagged photons
