The Silicon telescope array ISIS

ISIS is an array of 40 silicon dE-E telescopes which are used to detect light charged particles (from protons to alphas) produced in the reactions.

The detector assembly is a soccer like ball of 16 cm in diameter using the 40 HpGe faces of the already mentioned polyhedron.
In this way each silicon telescope is placed at the same angle of the HpGe detector, thus reducing the gamma-ray absorption. The dE and E detectors have a thickness of 130 ~ µm and 1 mm respectively.
The dE(E) detectors of the Si-ball covers a solid angle of about 76%(65%) of 4p and has a telescope average detection efficiency of 50% and 40% for protons and alphas respectively (Ref.1).
The telescope event is defined by the presence in the detected event of both energy and time signals in the two detectors.
The efficiency reduction is mainly due to the particle energy total absorption in the dE detector or in the shielding foils used to stop the elastically scattered beam ions.
Clearly the selectivity of GASP when coupled to both ISIS and CAMEL is increased considerably and this is particularly important when studying weak channels.