The electromagnetic calorimeter of the HERA-B experiment

Abstract

The electromagnetic calorimeter of the HERA B experiment built at the HERA proton accelarator at DESY (Hamburg) is described. The construction characteristics of the detector, of the related front-end, readout, trigger and service electronics are discussed together with the constraints and the motivations which inspired the design philosophy. The detector performance are presented as obtained from the analysis of the data acquired during the HERA B running period, including calibration procedures and achievements and the electron identification capability exploiting a method, proposed here for the first time, based on the observation of the associated bremsstrahlung γ. Finally some observed physical signals and a short overview of the main obtained physics results are presented.

Measurement of D0, D+, Ds + and D*+ production in fixed target 920 GeV proton–nucleus collisions

“…The wires were positioned in the beam halo, and their distance to the beam core was automatically adjusted to maintain a constant interaction rate. Details of the various subdetectors have been published [16,17,18,19,20,21], so only a brief overview of the apparatus is given here.…”

“…The ECAL [20] was a sampling calorimeter of the "shashlik" type, with scintillator plates sandwiched between tungsten (inner region) or lead (outer region) absorbers. The calorimeter was read out by optical fibers and photomultiplier tubes with the readout granularity of inner and outer regions adapted to different particle rates in order to maintain acceptable occupancies.…”

Measurement of the J/ψ production cross section in 920 GeV/c fixed-target proton–nucleus interactions

“…Particle identification was performed by a Ring Imaging Cherenkov detector (RICH) [14], an electromagnetic calorimeter (ECAL) [15] and a muon detector (MUON) [16]. The RICH used C 4 F 10 as radiator gas and two large spherical mirrors to project Cherenkov photons on the photon detector employing multi-anode photomultipliers.…”

An improved Shashlyk calorimeter

“…and an inefficiency in photon detection due to the nature of the modules of ǫ ≈ 5 × 10 −5 (Θ beam > 5 mrad) (6) have been constructed and experimentally tested. The characteristics experimentally determined for the Calorimeter prototype well meet the design goals of the KOPIO experiment.…”

“…experiment E865 at Brookhaven [1,4], and has been adopted by others, e.g. the PHENIX RHIC detector [5], the HERA-B detector at DESY [6], and the LHCb detector at CERN [7].…”