Solid-state silicon detectors are nowadays widely used in particle physics experiments, e.g. at CERN Large Hadron Collider, as well as in astro-particle experiments. Fabrication technology advances have enabled the construction of very thin silicon detectors with associated fast read-out electronics. In the future, the requirements for particle tracking systems will be even more stringent, in particular in terms of low material budget and read-out speed. The reduction of the detector thickness decreases the signal rise time, increases the radiation resistance and reduces the material budget and the associated multiple scattering effects. Therefore it is important to investigate the energy loss distribution f (Δ) due to the passage of ionizing particles through thin layers of matter. To accomplish the f (Δ) measurement, the charge generated by ionizing particles crossing a silicon layer of known thickness is collected and measured. To perform a comprehensive study, a large number of detectors, each one with different thickness, is needed. This procedure is intrinsically cost and time consuming and very difficult to accomplish, especially for small thicknesses.
Fig .1 Energy loss distribution for 12 GeV protons passing through 5.6 mm of silicon with convolved function fit and Landau contribution of this fit.
In this paper a new method to precisely measure the f (Δ) at various silicon thicknesses (ranging from 5.6 to 120 um) is proposed, using only one CMOS Active Pixel Sensor in a grazing angle configuration.
S. Meroli et al., Energy loss measurement for charged particles in very thin silicon layers , JINST, 6 P06013 doi: 10.1088/1748-0221/6/06/P06013