White Rabbit Newsletter - December 2015
JINR
The Data Acquisition Group in the Laboratory of High Energy Physics (LHEP) of the Joint Institute for Nuclear Research (Dubna, Russia) develops and produces readout electronics and software for data taking. This year WR-enabled devices took part in a real data taking run. The BMN [1] technical run was carried out at the extracted beam of the Nuclotron in February - March 2015.
Readout electronics included waveform digitizers [2] for Zero-Degree and Electromagnetic Calorimeters readout and time-stamping TDC for Time-of-Flight and Drift Chamber detectors. Multiple TDC boards [3] [4], Trigger Master [5] and Readout Controller were built in the VME standard. Trigger and clock are distributed within the crate over a private bus driven by the Trigger Master. Both the waveform digitizer and the trigger master run the White Rabbit Node Core for time synchronization. They have a hardware IP stack for communication.
In the waveform digitizers we had to synchronize a 62.5 MHz clock across devices. It is derived directly from the 125 MHz WR clock and its phase is aligned with timestamp. The TDC system uses a 41.667 MHz clock that is exactly 1/3 of the WR clock. A hardware divider-by-3 is reset every time WR acquires sync and timestamp is a multiple of 3. This method is not ideal and requires a complete system reset after each divider reset.
White Rabbit technology provided a stable and precise time base. The Gigabit data path has been used for readout and board control. The use of an 18-port WR switch for bulk data transfer is limited by the 1 Gb/s port bandwidth. This may be improved by either link aggregation (etherchannel) or implementing 10G interfaces.
WR technology is planned to be used for the control and monitoring systems of NICA, Nuclotron-based Ion Collider Facility in JINR. WR is considered as a timing system in the Multi-Purpose Detector (MPD) of NICA.
[1] http://nica.jinr.ru/
[2] http://afi.jinr.ru/ADC64s2
[3] http://afi.jinr.ru/TDC72VHL
[4] http://afi.jinr.ru/TDC64V
[5] http://afi.jinr.ru/FVME2TM