The TAPS detector

At the present time, TAPS comprises 384 detection modules, the associated electronics and an data acquisition system.

Each module comprises a telescope of BaF₂ crystal and plastic scintillator. The BaF₂ crystal is a hexagonal prism (inner radius of 2,95 cm). Its length of 25 cm is 12 radiation lengths. The last 2.5 cm of the crystal are a 2.7 cm diameter cylinder (to ease the adaptation to the photomultiplier). The plastic scintillator (NE120A), has also a hexagonal shape and is mounted on the front face of the BaF₂ crystal. It is read out by an individual phototube via a light guide.
Usually, the modules are arranged in 8 x 8 blocks surrounding the target. Other geometries have been used, as the one where all the crystals are setup in an unique hexagonal frame ("supercluster").

The TAPS characteristics are :

Time resolution of about 100 ps; gammas and neutrons are discriminated by TOF technique.
(gamma,leptons,neutrons)-charged particules discrimination is performed by pulse-shape technique.
Energy resolution : a good gathering of EM shower can be obtained over a wide range (E_gamma=5 - 1000 MeV)
Position resolution : its high granularity allows meson identification by reconstruction of their decay photons invariant mass.

The broad dynamics range of TAPS (photons from 1 MeV to 10 GeV), has sustain a rich and diversified resarch program.