====== DAQ:Mode 2 data loss (Chris) ====== ====== Severity ====== We cannot afford losing any triggered data //**in an uncounted manner**//. For absolute x-section measurements with GRETINA efficiency is crucial. ====== Problem ====== For S800-GRETINA data with GRETINA self-trigger only we find S800 events in Global.dat without corresponding GRETINA event. == Size of problem (from Scott's email)== In a low rate file, the following event counts were found: 11,886 coincident events (s800 and gretina present with correlated timestamp) 719 s800 only events 15 gretina only events (now fixed in S800 daq) So, ~6% of the decomposed data is missing. Also, missing gretina data is spread throughout the file, not concentrated at the beginning or end. ====== Progress ====== * 5/17/2012: Discussed losses with Mario. Code review and version check to follow. * 5/24/2012: (kathrin) checked runs 694 (old decomp) and 697 (new decomp) taken on 05/22 coincidences = s800 and gretina GGEB header with time stamps within 1000 ticks s800 singles = missing gretina GGEB header and event gretina singles = no s800 in this event decomp fails = error in decomposition, "pad" of gretina struct is != 0 (I get errors 3 and 5 see below) Run 694: 172171 coincidences (94.4 %) 10207 S800 singles (5.6 %) 18 Gret singles (0.0 %) 0 Decomp fails (0.0 %) Run 697: 97888 coincidences (91.2 %) 9477 S800 singles (8.8 %) 0 Gret singles (0.0 %) 81 Decomp fails (0.1 %) decomp fails are included in the coincidences (since they have a valid time stamp), as error I get 3 and 5. in both cases the event is completely empty (everything is zero) except for the crystal_id. out of the 81 failures I have 54 error 3 (no net charge segments) and 27 times error 5 (bad chi^2) this test has to be repeated, to me it is completely unclear, why run 694 has again S800 problems (these were thought to be solved before)