  The energy range above 60 keV is important for the study of many open
problems in high energy astrophysics such as the role of Inverse Compton with
respect to synchrotron or thermal processes in GRBs, non thermal mechanisms in
SNR, the study of the high energy cut-offs in AGN spectra, and the detection of
nuclear and annihilation lines. Recently the development of high energy Laue
lenses with broad energy bandpasses from 60 to 600 keV have been proposed for a
Hard X ray focusing Telescope (HAXTEL) in order to study the X-ray continuum of
celestial sources. The required focal plane detector should have high detection
efficiency over the entire operative range, a spatial resolution of about 1 mm,
an energy resolution of a few keV at 500 keV and a sensitivity to linear
polarization. We describe a possible configuration of the focal plane detector
based on several CdTe/CZT pixelated layers stacked together to achieve the
required detection efficiency at high energy. Each layer can operate both as a
separate position sensitive detector and polarimeter or work with other layers
to increase the overall photopeak efficiency. Each layer has a hexagonal shape
in order to minimize the detector surface required to cover the lens field of
view. The pixels would have the same geometry so as to provide the best
coupling with the lens point spread function and to increase the symmetry for
polarimetric studies.
