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HK: Hadronen und Kerne
HK 56: Postersitzung
HK 56.58: Poster
Mittwoch, 18. März 1998, 17:00–19:00, Foyer
Response Function to High Energy Photons of Large BaF2-Detectors 1) — •M. Pfeiffer, W. D"oring, V. Metag, and R. Novotny — II.Physikalisches Institut, Heinrich Buff Ring 16, 35392 Giessen
The photon spectrometers TAPS consists of more than 400 hexagonal BaF2 crystals of 25 cm length. The luminescent yield consists of two major scintillation components in the UV at wavelengths of λ = 220 nm and ∼ 320 nm, respectively. The latter component of much longer decay time provides the dominant part of scintillation light and determines the achievable energy resolution in particular at lower energies. Due to the scintillation mechanism (self-trapped excitons) the luminescence yield LY is strongly temperature dependent (dLY/dT ∼ 1.4%/0C). Therefore, the long range temperature stability or proper off-line correction limit the achievable energy resolution. A mechanical set-up has been designed and brought into operation, which allows to cool down and stabilize the crystal temperature of a calorimeter unit consisting of 64 TAPS modules. Tests with monochromatic photons up to 790 MeV energy provided by the tagged photon facility of MAMI at Mainz have been performed to measure the response function and to determine the influence of temperature fluctuations. In addition, the quality of BaF2-crystals up to 35 cm length provided by BGRI (China) will be compared to the performance of the TAPS scintillator modules.
1) supported by BMBF and GSI.