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

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

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

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

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

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 29304 FPD 10 missing 32ns beam structure is not the standard running condition

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

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

Background Calculations

Background Calculations

Background Calculations