The Clock System in Readout Electronics System for the External Target Experiment in CSR of HIRFL

Abstract

A high precision clock system is required in the external target experiment of the Cooling Storage Ring (CSR) project in the Heavy Ion Research Facility in Lanzhou (HIRFL). Considering that the detectorsare located in different places of the experimental hall, a high quality clock signal is required to be generated and distributed to multiple measurement modules over long distances. The clock system is based on a master-slave structure: the slave clock module (SCM) receives the clock signal from the master clock module (MCM) through fiber, and then distributes it to the measurement modules within the same PXI crate. Laboratory test results indicate that the period jitter and cycle-to-cycle jitter of this clock system is better than 5 ps and 8.5 ps respectively. We also conducted tests on the TOF (time of flight) readout modules (with the highest time measurement resolution in the readout electronics) combined with this clock system, and a time resolution better than 25 ps is achieved, beyond the requirement. Keywords-cycle to cycle jitter; period jitter; clock skew; LVDS; clock system