1. SOS Cerenkov Purpose: provide PID for NA Cerenkov efficiency studies
Installed 24 April during 687MeV run (Dave, Hamlet, Walter et al.) – OCTANT 7 ONLY
Roughly facing geometric center of octant, but rotated 12 deg towards target
12º
FPD 1 2
SOS Cerenkov
Octant 7
SCER1
SCER2
SCER3
SCER4

2. NA Cerenkov Efficiency at 687 MeV (LH2, 31 MHz data)
To define a good event sample use SOS Cerenkov: 2pe
Cut on NA Cer: TDC Cut
Extracted Cerenkov efficiency for octant 7 comparable to 31MHz analysis

3. Status SOS Cerenkov
LH2 Results consistent with using FPD/32ns (L. Lee’s results)
LD2 analysis more complicated in general
Difficult to determine single photoelectron peak for calibration - pedestal and detector response large
Use of SOS Cerenkov limited to 1 octant, but useful cross check

4. NA Cerenkov TOF at 362 MeV LD2, 32ns time structure
All FPDs for Octant 7 in hclog#117319
SOS HV off during test run
FPD MT
electron
pion
NA CER ADC SUM
Octant 7, FPD7
Clear separation of particles at sufficiently low energy
FPD MT
pions

5. NA Cerenkov Efficiency at 362 MeV (LD2)
Define good events using cut on FPD TDC
Require hit in Cerenkov TDC (analog sum and multiplicity 2) for electron/pion cuts
Cerenkov trigger
electron
Cer ADC Sum

6. Status LD2 at 362 MeV
Electron efficiencies for LD2 range between 30% and 86% - lowest for octant 3
Pion efficiencies between 4% and 6%
Peak location in FPD TDC varies up to 15ns between octants
Run FPD 10 missing
32ns beam structure is not the standard running condition

7. Tighter gated Charge ADC - Simple ARS analysis
For timing require CED/FPD coincidence
Average ARS reading over relevant time range – depends on octant
Pedestal separation appears cleaner than in usual Fastbus ADC pedestal

8. NA Cerenkov Efficiency at 362 MeV (LD2)
Veto events outside defined time interval
ARS threshold cuts

9. Background Calculations

10. Background Calculations

11. Background Calculations