The pumps were left on overnight, in the morning at 8:25 the pressure reads:

Up = 1.5e-5 mBar and Down = 4.0e-5 mBar.

We made a first attempt at collecting an alpha spectrum for the far S2 detector using ADC 2 and ADC 3. However ADC 3 appeared to be acting as a TDC for no obvious reason.

During this attempt we noticed ADC 2 channels 0, 1, and 5 had a high rate, and ADC 2 channel 8 had a low rate.

We moved the ribbon inputs on ADC 3 to ADC 4, the spectra on ADC 4 looked better. ADC 4 Channel 30 had a low rate.

We noticed ADC 3 was still active -> removing the ribbon inputs had no effect on the module writing to the DAQ. We raised the lower threshold of ADC 3 to 2046 (total 2047 channels), effectively stopping it from writing.

The thresholds for ADC 2 and ADC 4 were set to channel 40 for both. The thresholds on the RAL shaping amplifiers are set to 15mV.

At 9:09 we started collecting an alpha spectrum for a preset time of 900 seconds, finishing at 9:24. The dead time was 24% and the event multiplicity 3.2 (event mult. was 40 before removing ADC 3). The trigger rate was ~9kHz. The data were saved in /RemoteObjs/RData_1/180220091352/

To try and lower the trigger rate I removed the 6th breaker in the top IDC convertor box, which corresponds to the 5th channel of RAL I, which in turn corresponds to the 5th channel of ADC 2.

The trigger rate had risen (strangely) to ~12kHz, we saw ADC2 CH 0 had a high rate.So I removed the 1st breaker in the top convertor box, which corresponds to the 0th channel of RAL I, which in turn corresponds to the 0th channel of ADC 2.

Now the trigger rate was ~9kHz, with a good event rate ~ 40 Hz. We agreed that since the preamp box does not have its cover on there will be noise, particularly from the turbo located immediately downstream from the preamp box.

At 11:30 we started trying to tune the beam. Before sending beam I moved the target ladder to position 95.010mm, achieved by first moving the actuator to position 96mm and then back in position to account for backlash.

Note: All the target ladder calibration points were obtained by moving the ladder towards the actuator.

By 12:44 we were still tuning. We obtained a beam current of 200pA in FC-0, the faraday cup located ~1m upstream from the chamber, however we were unable to find the beam downstream from the chamber.

We were using the 3mm diameter blank frame for beam tuning, and decided to now attempt tuning with the 10mm blank frame.

We were using the only blank 10mm target frame available to support the alpha source, so we decided to vent the chamber and move this to an accesible part of the target ladder for beam. This would also allow us to inspect the beamline and check it is clear of obstruction with the telescope.

We switched off the detector and vented the chamber. I then removed the target ladder and switched the 10mm blank frame holding the alpha source with a 3mm blank frame. The 10mmblank frame was attached at position 2 of the ladder.

See attached (IMG_2709.jpg) for the first target ladder setup. See attached (IMG_2712.jpg) for the new target ladder setup.

We set the target ladder to 80.024mm for the 10mm blank frame, and then using the telescope confirmed it was in the beam axis. This involved removing the upstream lid and putting a piece of white paper in.

We then sealed the chamber and at 14:40 started the roughing pumps. The gate valve was cracked open -> we want a pumping speed <10mBar/s to avoid damaging the detectors and/or mylar foils.

At 15:04 the gate valve was fully opened and the turbos started. By 15:12 the pressures read: Up = 9.2e-5mBar, and Down = 1.0e-4mBar. The detector was biased at -130.3V with a leakage current 1.19uA.

With no beam the DAQ trigger rate ~ 6kHz.

At 15:29 we started the beam tuning with the 10mm blank frame in the beam axis.

During tuning the power supply on the 1st analysing magnet, located between the cathode source and accelerator, showed problems and was replaced.

At 17:50 I checked the S2 leakage current = 1.28 uA. The slight rise from 1.19 uA could be due to temperature fluctuations (8 degrees temp increase causes factor 2 difference)

At 18:20 we decided to vent the chamber and shine a light upstrean from the faraday cup FC-0. After switching off the detector and venting the chamber we discovered the piece of paper used to check the 10mm aperture alignment was left inside the upstream section of the chamber since the last time we vented. No beamspot was seen on the paper.

At 19:00 we restarted the roughing pump and cracked open the gate valve. At 19:03 the turbos were started. At 19:06 the pressures read Up = 7.0e-5, Down = 1.3e-4 mBar. The S2 was biased back to -130.3V, leak current = 1.20 uA.

We went back to tuning (third time today). With no beam we had a DAQ trigger rate ~ 2.6kHz, event multiplicity = 10.

We were able to see beam on FC-0, but unable to see beam on either of two faraday cups located downstream of the chamber. We decided to check the beamline again.

At 20:40 the detector was switched off. The turbos were then switched off. At 21:00 a tiny amount of air was allowed into the chamber to help slow the turbos, by 21:05 they were <12Hz. We vented the chamber.

After inspection of the beamline we discovered a new cause of the tuning problem. A small piece of mylar was in the bellow located downstream from FC-0. See attached IMG_2724.jpg.

We inspected the 12um mylar in front of the S2, it was not damaged, suggesting the rogue piece of mylar from the bellow is from a previous experiment.

We removed the rogue mylar and remounted the bellow to the beamline, we confirmed it was aligned using the telescope. We had a clear line of sight through the beamline, suggesting the problem is solved.

We declared victory.

At 22:30 we started the roughing pump for the section of beamline upstream from FC-0.