Detection of particle unbound states using a single Gas–Si–CsI hybrid telescope

A Gas–Si–CsI hybrid detector telescope is described and its performance assessed in measuring breakup reactions leading to particle unbound states. The telescope consists of an ionisation chamber, a silicon strip detector and a CsI(Tl) scintillator-photodiode detector. The segmentation of the strip detector allows the simultaneous detection, identification and reconstruction of heavy and light ions within a single hybrid telescope. For double hits in the strip detector, crosstalk between the two active strips modifies the measured energies requiring a correction to the energy calibrations. The technique has been extended to the detection of energetic α-particles from the decay of 8Begs fragments. Using two telescopes, a measurement of the 12C(24Mg, 16O 12C α)α reaction at 170 MeV has identified final states where the 12C ion and α-particle originate from unbound states in 16O. The sensitivity to small relative energies between the fragments makes the telescope particularly suitable for the study of near-threshold states of astrophysical interest.