2023-01-25

View out of the window at KURNS, 10:12

9:19 - Ishi-san and Uesugi-san cannot get to the lab because of ice on the roads, it is snowing quite a lot here at the moment. We cannot access the lab until they arrive. Until then, we are doing some analysis at the hotel. The cold weather may also cause some issues with the magnet cooling systems.

10:39 We are at the lab now, the weather is quite bad here. Legally, 3 KURNS staff members are required to operate the machine we are still waiting for everyone to arrive.

10:57 Begining machine startup soon (hopefully)

AWG script filename for max's tune measurements - tmp_19_6_2_0.096039_freq_3.8461.equ

12:00 measuring wire delays for bpms, FAB, ct, etc..

12:37 taking background data for schottky- RF off and FD and correctors on, measurement of noise on FAB we will take the same data with RF later today (note that we took this data before the first beam so there is no chance of any influence from previous beams.


12:54 Linac issues, the field in the DTL is unstable - We will have some lunch now as this could take some time to fix

13:47 Beam is still weak

14:28 Continuing to optimise the beam intensity

The field in DTL1 is oscillating a bit which causes a coreesponding oscillation in beam intensity

14:40 Max is taking data for tune measurements with all the BPMs connected

nominal KURNS RF offset 1.490ms

Using the AWG script mentioned above, the RF offset was set to 2.130ms

Flat top script:

BPM 6: Pink

BPM 7: Blue

BPM8: Green


As the beam accelerates, the inner BPM signal decreases; the middle BPM grows and then decreses, and the outer BPM signal grows as we approach the flat top region. The inner BPM signal has died much earlier than the flat top region



It appears that the kicker fails to fire every few cycles

  • kicker is misfiring.

  • Frequency of misfires proportional to kicker voltage

  • Must limit kicker voltage to below 15kV

    • Higher kicker voltage risks damaging the kicker power supply

15:30 Intensity looks low for 7.5kV run



Move onto schottky measurements. This time we will fully insert the scraper before taking beam off data. We will use the same AWG scripts as yesterday, ie the scripts where we recapture any beam left over and accelerate into the scraper positioned at 80MeV. The machine is running at 10Hz which will help to ensure all of the previous beam is cleared.

First we will fully insert the scraper to ensure that there is absolutely no beam left over from Max's measurements. We will then fully retract the scraper and take a full set of beam off data for each RF script. With this method we can guarantee that there is no beam in the machine. The combination of the full scraper insertion with the time elapsed since finishing max's experiments should be sufficient to ensure there is no surviving beam.

Set scraper postion 505mm / 0055663 (same as yesterday)


17:00 Start taking beam on data

Comparing beam on/beam off scintillator data: ( the scintiallator data shows that we are scraping beam when we recapture and accelerate into the scraper.) We also have the data to show this. The screen shots below use the scope's persistence mode where the signal is built up over time.

Beam on:

Beam off:

This plot shows the beam loss signal on the scintillator after recpaturing the beam and accelerating into the scraper. The scintillator signal appears at the same time as a dip in the FAB signal (20230125 data file number 00015)

Taking data for Schottky (+reaccelerate) programmes

While taking the schottky data we noticed that the kicker voltage has stabalised, we will return to taking tune measurements before installing the wire scanner monitor.

We will run Shinj's 3 new AWG scripts tomorrow morning instead.


Tune measurements:

Scope 1: vert bpm, 3x horizontal

Scope 2: fab, kicker CT

Massive ion source fluctuations. Proceeding with data collection anyway

18:26 Linac has gone down.