Forward end-cap for CALIFA

CALIFA is the γ-rays and high energy particles detector for the R3B setup at FAIR. Due to the different reactions considered at R3B, CALIFA has to be able to detect and identify a broad range of γ-rays (from a few 100 keV to about 20 MeV) as well as recoil and knocked-out protons, deuterons, alphas and neutrons. CALIFA is composed of two pieces: a barrel that surrounds the beam axis and the reaction target; and an End-Cap that closes the barrel in the forward direction. The barrel composed of about 2000 long CsI crystals read-out by Large-Area APDs read out by a fully digital system. The End-Cap covers from small polar angles up to the barrel limit. The exact design of the End-Cap is not yet settled as it should solve the difficult task of a good spectrometric response for protons even above 300 MeV without deteriorating the calorimetric resolution of a few MeV γ-rays. During this presentation the current investigation is explained. In particular, results of experiments with so-called ''phoswitch'', which is a combination of two different scintillators, are presented.