R&D proposal for LHC crystal calorimeter readout by gaseous (and liquid) detectors with photocathodes

We propose to develop fast and radiation hard electromagnetic calorimetry at the LHC using BaF2 crystals (or similar scintillators) preceded by layers of low density VUV scintillators (such as KCaF3) to separate e/gamma, and by BaF2 preshower counters for a good e/pi rejection and precise position measurements. The readout of the preshower counter and of the low density VUV scintillators is done with parallel plate avalanche chambers combined with photocathodes. For the BaF2 calorimeter, gaseous ionization chambers with photocathodes are good readout candidates due to their high stability, energy resolution and radiation hardness. Another approach for the calorimeter readout could be photosensitive liquid ionization chambers, having good optical coupling with the BaF2. A systematic study of new photocathodes and new scintillators is also proposed.