Simulation and experimental qualification of the response of microstrip detectors to ion beams
In the framework of the construction of a novel Femtoscope Array for Correlation and Spectroscopy, named FARCOS, aiming at the identification in charge and mass even of particles stopping in the first detection layer, we are performing a thorough characterization of the silicon detector layers in terms of the collection properties as a function of the point of incidence. We have experimental evidence - as previously observed also in the literature for other strip detectors - that interstrip incidence alters the signal shape not only for the trivial effect of charge sharing but also because of induction effects on neighbor strips. In order to clarify this issue we developed a custom simulation suite of the electron-hole transport and signal formation able to properly describe 3-D Coulomb interaction and thermal diffusion in semiconductor detectors. We ran a batch of significant and representative simulations presenting the qualitative correct interpretation and the quantitative validation as proved by the comparison of the simulation results with the experimental data.
Upgrade of the DEFEL proton beam line for detector response mapping
We exploited the possibility of using a pulsed mono-energetic proton beam (DEFEL beam-line @ LABEC, Italy) able to provide bunches of protons with tunable energies for detector qualification, diagnostics and calibration. This allows qualification of the response of the detector-front end system over a wide range of calibrated charge levels, with high precision in space and time, reaching the highest ionization levels foreseen in the imaging detectors for the novel FEL X-ray facilities and in the monolithic detector arrays for the present and future nuclear physics experiments. In order to better fulfill the requests of detector characterization we upgraded the beam line performance in terms of spatial resolution of the proton beam with novel remotely controlled in-vacuum hi-resolution profiling slits and with a CMOS imager as 2D beam monitor. Up to now a beam spot down to about 40 μm has been achieved and potentially can be further improved. The time jitter of the proton bunches is better than 0.5 ns opening the way to probe also the transport dynamics of the charge carriers with accurate time resolution.
Population of particle unbound states for the reaction 16O+Au at E/A=94 MeV
Abstract Populations of particle unbound states of light nuclei were measured for the reaction 16 O+Au at E / A = 94 MeV and compared to previous results for the reactions 14 N+Au at E/A = 35 MeV and 40 Ar+Au at E/A = 60 MeV . Emission temperatures extracted from the relative populations of states are surprisingly similar for all three reactions.