2023-01-20
11:000 Start phase displacement measurement
Set scraper postion with new scintillator which we just installed
Beam current is low this moring, likely caused by ion source, it could be difficult to see signal on the scintiallator
Fully inserted the scintillator and saw no signal
Increased the bias voltage on the scintillator from 500 to 900 V
After the change we can see some signal on the scintillator, now we will try to set the postion of the scraper such that it is positioned at a slightly larger radius than the outter edge of the bunched beam.
Ishi-san noted that the transverse beam size might not be the same run to run, its depends on the injection error (which should be the same shot by shot but it cannot be garanteed)
The ion source is causing low beam itensity so pause measurments to try and increase the beam intensity
The low intensity is making it difficult to get a signal on the scraper
13:30 Spent some time trying to improbe the beam intensity but only a small improvement
We will try again to set the scraper position
14:18 We have had some problems with the foil and we are not seeeing any beam. However, the foil is intact. We are still investigating the issue.
14:34 The foil seems to be okay the problem was with the timing between the ion source and the linac
14:43: Beam signal on the FAB monitor again
14:56 The camera on the scraper positon rule has died so we are fixing that now.
15:05 Trying to set the scraper position again
Scraper positions:
DISTANCE ON SCRAPER CAMERA (mm) | STEPPER MEASUREMENT (toaster units) Notes
835.5mm () | -135026 START POSITION
475.5mm Picture 1 -0048463 Scintallator signal position
476.5mm Picture 2 -0048763 Scintallator signal position almost no sig time 15:23 ish
477.5mm Picture 3 -0048863 time 15:28 less signal - bur still there, due to variation in transverse beam size??
Ion source problems 15:32
15:52 Beam back on but the intensity is very low
The transverse beam size could change run to run so the point where we see no signal on the scintallator is a little less well defined by this
In the pictures below the top trace is the FAB the bottom is the scintillator. This mode adds up all the traces over time, the redder the colour the more common a signal is a that location.
On the scintaillator there are two regions showing signal. We do not know the cause of the left most peak. The one on the right is due to beam loss on the scraper, ie thats the signal we are interested in.
Picture 1 Can see beam loss on the scraper on the FAB monitor
Picture 2
No beam loss on the FAB but still some signal on the scintillator
Picture 3
16:38 Foil has broken no more beam for today
The foil itself might be okay but the rod that inserts the foil into the pipe moves through a gate valve. The contol for the gate valve has run out of air pressure (maybe) and closed onto the foil rod. The gate has damaged the rod, not sure how badly. The rod cannot be moved at the moment
If we cannot open the gate valve thenwe will have to break the vacuum, if we do open the beam pipe we will isntall Emi's BPM at the same time.
17:28 Don't need to break the vacuum, the rod is undamaged. Should be fine for monday.
Max will take some beam off data of the kicker waveform
