For now, we have two types of efficiency measurements with : 1) Mixed thresholds of 30mv(veto, N1, half of N2) and 50mv(half of N2, N3-6) 2) All thresholds are at 30mv.
The different measurements gave the following resultst: 1) Total number on neutrons: 5000 Efficiency for bars with 50mv: 10%
2) Total number on neutrons: 10000 Efficiency for bars with 50mv: 15%
The ratio of BG/(e,e'p)[30mv] / BG/(e,e'p)[50mv] = 1.6
The main conclusion is that we have a ~40% difference in the efficiency and 60% difference in the BG when going from 30mv to 50mv.
NOTE: These numbers are cut dependent. All runs are using a 6uA, pass 2, beam except for 1422 with had 12uA.
For those who are interestead in the details of the analysis here is a short summery.
A) The runs for setting 1 are 1398-1427 (Note 1422 is with 12uA) The runs for setting 2 are 1431-1460 (for now - we are still taking data!)
B) The cuts we used to identefy neutrons are: abs(SK.emiss - 0.0055)<0.0035 abs(SK.Mrecoil-0.942)<0.008 abs(atan(SK.Prec_y/SK.Prec_x)*180/3.14)<15 abs(atan2(SK.Prec_x,SK.Prec_z)*180/3.14+97)<5
For the efficiency determination we changed the angular cuts to +/-10 and +/-3 degrees instead of the normal 15 and 5.