EFDA-JET-CP(03)02/04
A PCI Time Digitizer for the New JET Time-of-Flight Neutron Spectrometer
A PCI time digitizer module with eight independent Time-to-Digital Converter (TDC) channels is being developed for the new Time-of-Flight spectrometer designed for Optimized Rate (TOFOR) which diagnoses deuterium plasmas of the EFDA-JET tokamak. The module shall measure with high accuracy and resolution flight-times of 2.5MeV neutrons in the 100ns range as given by two groups of scintillation detectors operating at event rates up to several hundred kHz. To attain the requirements of the TOFOR, the time digitizer module was designed to handle a peak event rate of 1.25Gevents/s/channel and a sustained event rate of 5Mevents/s/channel. The digitizer time resolution and the dead-time between events are as low as 400ps. A maximum of 8 Mevents/channel can be stored in the 512Mbytes onboard memory and the time marks cover a period of up to 300 days. The module incorporates a Digital Signal Processor and a System-On-Chip device which performs the data transfer, the device control/monitoring and may perform statistical, data reduction or control algorithms in real-time. The high channel count, the implementation of the TDCs around a 2.5Gbit/s digital communications device and the use of common industry components, contribute to reduce the overall cost per channel.