A 103kHz fast clock is sent to both LHRS and bigbtie scalars. The difference between clock counts of two scalars are no more than 10^-5 level. However there is some interesting structure below 10^-5. The count difference between the two scalars are checked to be ** count difference <1ms for a 1M/50min run for scalar sets of ungated, (++),(+-) and (-+) . ** For scalar sets of (--), The count difference of bigbite - LHRS is climbing @ ~10 count/s = ~2 count / scalar read = ~2 count /100 event. This climbing is also correlated to data taking rate. Besides, there is a ~200us = ~20 counts vibration in counts diff of gated scalars. It's correlated to helicity state. For, ex: for scalars (spin=-1,hel=+1), the bigbite scalar will read extra ~20 more count when the scalar event is read in helicity=+1 state. It appears as if gate for left HRS scalar is applied 200us later than the one on Bigbite (although the cable delay is 3 order of magnitude smaller). See plots below & in Last entry. run # 3308 is taken as an example.
Scalar count difference for (spin=-1, helicity=-1) sets. It's climbing when scalar is actived
20 count vibration when scalar is actived. Same for 4 gated scalar. Disappear on ungated scalar