Resolving multiple particles in a highly segmented silicon array

The design, construction, and performance of a new highly segmented charged particle detector array, FIRST, are described. This forward angle annular array ( 2 ∘ ⩽ θ lab ⩽ 28 ∘ ) has been developed to study peripheral and mid-central heavy-ion collisions at intermediate energies ( E / A ≈ 50 MeV ). FIRST consists of three individual telescopes that each utilize ion-passivated silicon detectors in either a Si(IP)–Si(IP)–CsI(Tl) stack or a Si(IP)–CsI(Tl) stack. This array provides elemental identification for 1 ⩽ Z ⩽ 50 with isotopic identification of lighter elements, Z ⩽ 13 , over a wide dynamic range in energy. The high segmentation of each silicon detector provides good angular resolution in a compact geometry and allows deconvolution of multiple particles incident on a single telescope. The performance of the array in a commissioning experiment Zn 64 + Zn 64 , Bi 209 at E / A = 45 MeV is shown.