General GANIL-compatible system and test-bed electronics

For situations in which a cube of Exogam gamma-ray detectors is to be deployed away from the Exogam home location (i.e. area G1/G2 at GANIL; for example the LISE beamline for high intensity fragmentation beams), or if alternative gamma-ray detectors are to be used (e.g. other segmented germanium detectors that might become available, or a scintillator array), it is important to have the ability to operate TIARA without relying totally on the Exogam electronics infrastructure. The choice of NIM amplifiers gives this flexibility. The standard GANIL data acquisition system is presently being refurbished and reorganized. As a part of our involvement with the Charissa collaboration over the past several years, we have been actively involved in the development of this new system through our collaborators at Laboratoire de Physique Corpusulaire, Caen. The system is similar in concept to the Exogam system but with one very important difference, namely it is not buffered but has direct event-by-event readout. The control software is maintained by GANIL and our collaborators at LPC, Caen.

 

Figure 11: Schematic of the GANIL-type data acquisition system developed in collaboration with LPC, Caen. A scaled down version of this will be assembled for software development and detector testing in the UK.

The interface with the GANIL system is through C-size VXI non-buffered 32-channel ADC cards. The input is identical to the ADC's used with Exogam, but as noted already the readout is different. A set of these cards has been assembled through the Charissa collaboration during the last year, and it is planned to employ these for readout of TIARA when it is used on the LISE line, etc. Approximately half of the TIARA team also has a close involvement with the Charissa research, so this should not present significant problems. The ADC's would be controlled and the data stored using either one of the GANIL control systems or, preferably, the version assembled by the collaboration between Charissa and LPC. In order to develop software for the readout in advance of the experiments and to have spares available during experiments, it is planned to build a small version of the GANIL-type system, which will also be used at Surrey for testing detectors which require multiparameter data readout. This small version will dispense with the VXI chassis and will use ADC's operating in the VME. If tests with the VXI cards are necessary then the necessary hardware will be borrowed from collaborators. The control software that runs outside of the crate will exist in versions that run on a PC operating under Solaris and on a small SUN sparc workstation. Thus, an identical copy of the main VME-based part of the data acquisition can be assembled and used for testing purposes quite economically. If an experiment were planned at a different laboratory then the test system would be fully functional and able to be adapted as a standalone acquisition system for an experiment. More details of this are provided in the ``Resources'' document.