Shift Log 20120411
AA, LC, LN, PK, SB.
Shift Plan
- Find OTR.
- Measure beam size at LWIP.
- Alter optics to minimise beam size.
- Minimise background - aim < 0.5V.
- Alignment.
- Collisions search.
Shift Log 20120411
17:30
Access to repair polariser cable for OTR.
17:50
Beam on. OTR data taking.
23:20
OTR data taking finishes. Fitted min beam size at LWIP σy = 1.49 +/- 0.06 um.
LW detector on - nearly saturated (1.5V) gives 12000 ADC detector counts with 16dB of attenuation. Background tuning.
ZH3X seems to have a good effect on the background.
Change back the magnets used to reduce the beam size on the OTR screen - (nominal optics gives 100um x 30um)
QM14 -43.32A is nominal setting σy 30um
QM14 -88.73A gives σy 1.5um
Nominal setting of QM14 gives 100mV background but too large beam size - change QM14 gradually to optimise beam size/background.
QM14 -63.32A σy = 24um
Attenuation reduced to 10dB after detector, 700mV, 9000 counts with this QM14 -73A, QM12 -21A.
QM14 -73.73A, QM12 -21A reduces background to 5000.
Move QM14 to -88.73A, background 7000, σ 1.5um.
Do a final OTR beam size check and detector voltage, then move to timing and collision search.
Detector voltage at this setting 600mV, beam size 1.2um.
02:35
Timing check - laser not locked to e beam. Locked again. Laser/e beam adjusted to be on top of each other for ~ 4.5V.
Wire scanner detector HV turned on.
Searching for e beam
chamber vertical position ~ 460
chamber horizontal position ~ -300
CH: -300 CV: 300 - 600 5um steps - nothing |
CH: -300 CV: 450 - 500 70 steps - nothing |
Steering through the LWIP region with ZH1FF to flatten horizontal orbit in case photons missing detector (new setting 0.231A).
CH: -300 CV: 400 - 600 100 steps - nothing |
Set ZH1FF back to -0.269A (original setting) - horizontal angle good but position shifts by ~ 1mm - need to rescan for e beam. ZV1FF also changed from -0.449 to -0.049A.
New position horizontal: 490.
CH: 490 CV: 500 - 700 100 steps - nothing |
CH: 490 CV: 700 - 900 100 steps - nothing |
CH: 490 CV: 900 - 1100 100 steps - nothing |
CH: 490 CV: 300 - 500 100 steps - nothing |
Move to new horizontal position: -500.
CH: -500 CV: 100 - 1100 250 steps - nothing |
05:30
Try vertical alignment again using sharp edge of screen rather than notch. Turn down wire scanner detector HV to 800V and move screen away from notch to find flat edge, scan screen into beam and look for sharp change in wire scanner detector.
06:30
Checking the timing - laser and e pulses seem overlapped for too large a change of the phase shifter. Try phase scan over region of best spatial alignment.
- Vertical scan (CH: 490 CV: 450 - 650, 50 steps), starting at phase 4V and repeating in steps of 1V.
- Vertical scan (CH: 490 CV: 350 - 550, 50 steps), starting at phase 4V and repeating in steps of 1V.
07:25
Collisions!
CH: 490, CV: 540, phase 6V. Most sensitive to phase timing.
Phase scan to optimise timing. New phase: 5.7
- Vertical scan - signal centred at 535um. Initial fit estimate σy 5.1 +/-0.3um, offset 8848 +/- 18 ADC counts, centre 535.0 +/- 0.3, amplitude 2332 +/- 139.
- Horizontal scan - signal centred at 305um.
- Vertical scan - σy 4.1 +/- 0.2, offset 8465 +/- 47, centre 535.9 +/- 0.1, amplitude 3622 +/- 189.
Phase scan again: peak at 5.5V, ~12000 counts.
Vertical steering ZV1FF from -0.049A to -0.069A. Set file set12apr12_0806
Laser telescope actuator 5mm.
08:05
Quad QM14FF scan:
- -88.73A (CH:305, CV:500 - 580, 80 steps) /dat/raw/20120412_0805_lws.dat σy 4.9 +/- 0.4, offset 7077 +/- 33, centre 534 +/- 0.3, amplitude 2748 +/- 211.
- Using longer vertical scan (CH: 305, CV: 490 - 580, 90 steps).
- -90.73A, /dat/raw/20120412_0818_lws.dat
- -92.73A, /dat/raw/20120412_0834_lws.dat
- -86.73A, /dat/raw/20120412_0849_lws.dat
- -84.73A, /dat/raw/20120412_0903_lws.dat
- -82.73A, /dat/raw/20120412_0916_lws.dat
Figure 6 : Quadrupole Scan.
- CV:540, CH:305, 250 pulse log for uncertainties /dat/raw/20120412_0934_lws.dat
10:00
Telescope scan. Lab movers crashed. LN restored control of telescope mover (QM14FF -88.73A).
- Vertical scan CH:305, CV: 490 - 580, 90 steps, 10 pulses for telescope actuator = 2mm /dat/raw/20120412_1016_lws.dat
- Vertical scan CH:305, CV: 490 - 580, 90 steps, 5 pulses for telescope actuator = 0mm /dat/raw/20120412_1030_lws.dat
- Vertical scan CH:305, CV: 490 - 580, 90 steps, 5 pulses for telescope actuator = 7mm /dat/raw/20120412_1040_lws.dat
Figure 8 : Laser input beam size scan (as function of 2nd lens position.