SEM Calibration in H6 Beam Line, 20cm Cupper Target May 2009, 105 detectors tested

Standard Signal with Negative Offset Current 105 SEM detectors have been tested in H6 beam line In blue: raw measured data In green: corrected data (offset current is subtracted) In red: Beam charge from PIC scaled by factor 1.32 (from Geant4) 28 out of 105 had no shrinking tube and were repaired by Bernd due to missing isolation of high voltage cable

Different (Problematic?) Behaviour of Several SEM‘s Should be installed where fast losses are important (dump line, injection line); not in collimation area Should be not installed in collimation area In total: 32 SEM‘s that should be not installed in collimation area This will be excluded

Offset Current and Position Dependency Offset current vs SEM number: 22 out of 105 detectors have a (small) positive offset current but show good performance -->these detectors are not excluded Signal increase expected for positions 13...16 due to showering from the table, but the effect is small --> due to lower beam intensity compared to 2008?

Chambers with Positive Offset Current 22 Chambers with positive offset current measured Mainly offset current < 0.3pA Good detector performance

28 SEM‘s without Shrinking Tube 28 out of 105 detectors are without shrinking tube 14 out of these 28 show higher signal (factor ~10)-->need to be repaired Can be explained with different detector architecture Offset current is negative for the 28 detectors without shrinking tube

Secondary Electrons per Protons on Target Including the 14 SEM‘s without shrinking tube but higher signal Data: mean ratio=2.44, StdDev=2.61 Geant4: mean ratio=1.36,StdDev=0.06 Excluding these 14 SEM‘s Data: mean ratio=1.48, StdDev=0.61 Geant4: mean ratio=1.36,StdDev=0.06

Iist of SEMs with higher signal (signal <=> HV electrode) there were 14 SEM's without shrinking tube that should be repaired (signal electrode exchanged with HV electrode) 192 229 292 333 338 371 372 373 374 375 376 377 379 380 Cheers Annika

3 Problematic SEM‘s Nr.84 was filled with air Nr. 146 shows constant signal increase Nr. 63 shows bad performance

SEM Nr. 81 as Spare