Electron Tagger (ET6)
12 channels (6 x 2 cells) SpaCal type calorimeter, made of lead and scintilator-fiber planes Total transverse size = 75.6 x 25 mm^2 Depth = 20 cm (22 radiation lengths, X0) Position in the tunnel: z = -5.4 mPhoton Detector (PD)
24 channels electromagnetic calorimeter, made of quartz-fibre planes between tangsten absorber plates. Total transverse size = 12 x 12 cm^2 Depth = 25 radiation lenghts, X0 Position in the tunnel: z = -101.8 mVeto Counter (VC)
A Quartz Preshower, installed in front Photon calorimeter and after berillium syhchrotron radiation absorber. Position in the tunnel: z = -101.4 mElectron Tagger (ET40)
6 channels (2 x 3 crystals) total absorption Cherenkov calorimeter, made of 2 x 2 cm^2 KRS_15 crystals, with a hodoscopic structure. Position in the tunnel: z = -40.0 mLumi System Tasks
a) measure the luminosity without dead time b) tag photoproduction (Q^2 < 0.01GeV^2) c) measure hard photons from the initial state QED radiation in DIS