The MUST array

The MUST array comprises charged-particle telescopes (Si-SiLi-CsI(Tl)) that are designed to detect charged particles from radioactive beam experiments, over a large dynamic range of energies. It is owned by a consortium of French laboratories with whom we have collaborated on some of our transfer work with radioactive beams. These detectors complement the TIARA array, or vice versa, in many respects. Their large dynamic range means that they are quite bulky and could not possibly be utilised inside a close-packed array of gamma-ray detectors, being precluded both through the physical size of the telescopes and their gamma-ray absorption. The TIARA array, in contrast, has simplified detectors arranged in a complicated fashion to achieve compactness and angular coverage as the foremost concern. Certain functionality is sacrificed in order to achieve the design aims. Thus, whilst the MUST and TIARA arrays each include silicon strip detectors in their construction, the further specifications of the two arrays diverge in opposite directions and they are very much complementary devices. Thus, the experiments that would be designed use the different arrays are different. Detectors from MUST could reasonably be used in the forward angular range of TIARA. Since each detector has of order 150 signals, considerable extra complications are introduced compared to the single annular detector that should suffice for many of the types of experiment at which TIARA is specifically aimed. The annulus is also a more practical alternative when coupling TIARA to the VAMOS spectrometer, owing to the limited space available between the target and the spectrometer entrance. Subject to the compatibility of the electronics, a MUST detector could usefully be deployed at the zero degree position beyond the annulus, to provide particle identification in stand-alone mode. Note that the MUST array has its own dedicated electronics which has no immediate compatibility either with the Exogam system or with the standard GANIL system, but the MUST electronics personnel are presently involved in designing the electronics for VAMOS and making that compatible with Exogam. Hence, it is anticipated that MUST will be made fully compatible with Exogam in the first instance, and subsequently with the GANIL system. Thus it may well be appropriate to collaborate with the MUST collaboration on certain experiments.