Front-end electronics of the ALICE photon spectrometer

The photon spectrometer (PHOS) in the ALICE experiment at LHC is dedicated to measuring photons, π 0 ʹs and η ʹs in a broad pT range from about 100 MeV/c to 100 GeV/c, providing the best possible energy and position resolution in order to narrow the π 0 and η mass peaks and thus to increase the signal to background ratio. The front-end electronics (FEE) of the PHOS is thus required to cover a large dynamic range, to have a timing resolution better than ∼ 2 ns in order to discriminate against 1–2 GeV/c (anti-)neutrons, and to provide high pT trigger to select rare high pT events. In addition, to equalize the gains of individual detector channels, it is desired that the PHOS FEE can regulate the bias voltage of APD. In this paper, we will present the performance and status of the 32-channel low noise front-end electronics for the PHOS with a dynamic range of 14 bits. Measurements with LED pulse at laboratory and results from beam test with the first PHOS module at T10 of the CERN PS show that its performance fulfills the PHOS requirements.