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

2. 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

3. 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

4. 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 due to showering from the table, but the effect is small
--> due to lower beam intensity compared to 2008?

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

6. 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

7. 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

8. 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

9. 3 Problematic SEM‘s Nr.84 was filled with air
Nr. 146 shows constant signal
increase
Nr. 63 shows bad performance

10. SEM Nr. 81 as Spare