Measurement of 15 MeV γ-rays with the Ge cluster detectors of EUROBALL

A measurement of the response to 15.1 MeV γ-rays has been made for the Ge cluster detectors in the EUROBALL array. Each cluster detector consists of seven germanium capsules surrounded by a single anticompton shield of BGO. The reaction D(11B,γ)12C+n at Ebeam=19.1 MeV has been employed. The “adding-back” of signals simultaneously present in the capsules composing each cluster detector has been made on an event by event basis. The intensity in full-energy peak increases by a factor of three as compared to that of the spectrum obtained by summing the individual spectra of the 7 capsules. The pulse height to energy conversion is found to be very linear from few hundreds keV to 15 MeV. The efficiency is discussed relative to that of large volume BaF2 scintillators.