  To efficiently detect energetic light charged particles, it is common to use
arrays of energy-loss telescopes involving two or more layers of detection
media. As the energy of the particles increases, thicker layers are usually
needed. However, carrying out measurements with thick-telescopes may require
corrections for the losses due to nuclear reactions induced by the incident
particles on nuclei within the detector and for the scattering of incident
particles out of the detector, without depositing their full energy in the
active material. In this paper, we develop a method for measuring such
corrections and determine the reaction and out-scattering losses for data
measured with the silicon-CsI(Tl) telescopes of the newly developed HiRA10
array. The extracted efficiencies are in good agreement with model predictions
using the GEANT4 reaction loss algorithm for Z=1 and Z=2 isotopes. After
correcting for the HiRA10 geometry, a general function that describes the
efficiencies from the reaction loss in CsI(Tl) crystals as a function of range
is obtained.
