Title: PETRA Laserwire Experiment Review December 2003 Run
1PETRA Laserwire ExperimentReview December 2003
Run
2From the Logbook
- 02 Dec
- Re-alignment of laser beam and installation of
cameras (2h) - Beam in PETRA at 7 GeV for the whole afternoon
- Started by driving orbit bumps in order to find
overlap (1h) - Stopped because of ADC trigger problems
- 03 Dec
- Replaced ADC card (morning)
- Laser security interlock event (4h)
- Stopped because of trigger problems with new ADC
- 04 Dec
- Everything is working but no beam in PETRA
(morning) - Start with orbit bump and then piezo scanner
(30min) - Low current scan with 7.1 mA (1h 30min)
- High current scan with 40.1 mA (1h 30min)
- 05 Dec
- Detector tests with asymmetric orbit bumps
- Xmas party of MIN group
3Boundary Conditions
- PETRA setup
- Positron beam at 7 GeV
- Bunch pattern 14 x 1 bunch evenly filled
- Low current setup 7.1 mA, first bunch 0.458 mA
(3.9 nC) - High current 40.5 mA, first bunch 2.686 mA (22.3
nC) - Vertical and horizontal orbit bumps to steer
positron beam into laser beam - Four steerers (max/min current 10A)
- 50 m bump length with 10 mm max offset
- Laser setup
- Optimization of laser trigger point
- Delay box with 0.5ns resolution
- Laser energy measured in hut with attenuators
- Energy/pulse 40 mJ (specs 90 mJ), PL 4 MW
- Piezo Scanner setup
- Move beam to offset position with orbit bump
- Scan in 0.5V steps from 0V to 10V ( 2.5 mrad)
and record 5000 trigger events at each step
4Raw Data ADC Signal vs Event Number
5Number of Events vs ADC Channel
6Background - Number of Events vs ADC Channel
7Peak Signal and Background
8Positron Beam Orbit Stability
x -1.99 0.04 mm
y 3.16 0.04 mm
x -2.18 0.04 mm
y 3.15 0.04 mm
9Results from Scanner Operation
- Slopy Background Gaussian approximation of beam
shape - sm (68 3 14) µm at low current
- sm (80 6 16) µm at high current
10Conclusions and Outlook
- Understand low Compton rate
- Laser characterisation (profile and power)
- Study Compton path from IP to detector
- Detector calibration
- Geant4 simulations
- Improve Compton rate
- Background suppression with shielding
- Improve trans. and long. laser profile
11This Run
K Balewski, G Blair, S Boogert, G Boorman, T
Kamps, H C Lewin, F Poirier, S Schreiber, M
Wendt, K Wittenburg
- Thanks to PETRA and BKR shift crews !