Investigation into Time-of-Flight Detectors for Use with LYCCA at FAIR

The LYCCA (Lund-York-Cologne-CAlorimeter) array is a core device in the upcoming HISPEC (High-resolution In-beam SPECtroscopy) campaign that will take place at the FAIR (Facility for Anti-Proton and Ion Research) facility. LYCCA consists of a number of position, energy and timing detectors that aim to track and uniquely identify the fragments generated after the secondary target. Two time-of-flight options are currently proposed for LYCCA, fast plastic scintillators and large-area diamond detectors, both of which have shown to possess excellent timing properties. This thesis presents an in-depth analysis into the performance of LYCCA-0, and uses data from the first LYCCA commissioning experiment to directly compare the two timing options in order to determine which option is best for future LYCCA experiments. This thesis also focuses upon the development of the large-area diamond timing option, and in particular, establishes whether it is feasible to create a large-area detector whilst still maintaining the good timing resolution observed for smaller area detectors.

The developmental work was undertaken in the form of two optimisation experiments. An initial timing resolution of 103 ps was achieved from the first of these experiments, whilst the second experiment demonstrated that increasing the diamond detector’s capacitance lengthens the rise time of the current signal from the detector, causing the timing resolution to deteriorate. Analysis of the commissioning experiment showed that LYCCA was able to uniquely identify the fragments after the secondary target using the fast plastic scintillator timing option, and a timing resolution of 51 ps was obtained for each scintillator. The diamond detector option performed less well, achieving a timing resolution of 193 ps. This poor resolution is attributed, amongst other reasons, to parasitic capacitances generated by long cables present between the detector and the preamplifiers. As it would be difficult to eliminate these long cables without a considerable re-design of the signal processing arrangements for LYCCA, it has been decided that the ToF measurements for the final LYCCA device should be undertaken using the fast plastic scintillators.