Euroball III Data Acquisition
Data Acquisition
The Euroball Data Acquisition system is required to be able to collect the data generated by event rates up to 50 - 100 kHz in order to be suitable for a wide range of experimental situations. The corresponding raw data rate will depend on the particular experiment but data rates up to 20 Mbyte/sec are required to be handled by the initial system. Additionally the system design has to be scalable so that higher data rates can be handled in the future simply by the addition of further hardware within the existing structure.
Euroball will often be used coupled with ancillary detectors of varying complexity. In some cases these will have their own VXI electronics and thus will couple into the core system without problem. However, others will use CAMAC ADCs with FERA readout and possibly VME ADCs. It is therefore important that the ReadOut system be able to handle these other type of data source in addition to DT32 bus for data from the VXI crates.
The Eurogam ROCO can output data onto the DT32 bus at 330 nsecs/word (12 Mbytes/sec) which is less than the required data rate from Euroball.
In its core configuration Euroball will consist of 9 VXI crates which could expand to 12 or more when PPADCs and ancillary detector electronics are added.
Thus Euroball will use multiple DT32 bus readout chains. It is expected that 3 buses each with 3 or 4 VXI crates will be adequate for all uses. Also the Eurogam ROCO will be replaced by the Struck STR8080 which was developed for the Heidelberg Crystal Ball. The STR8080 contains a DSP (Motorola 96002) which can be programmed to generate the control tokens needed for secure operation within a multi-bus readout system. It can output data onto the DT32 bus at 100 - 125 nsecs/word (dependent on DSP program) which is 32 - 40 Mbyte/sec and thus greater than our requirements for Euroball.