On 21/02/2018 we reattempted the beam tuning. We expected this to be easier now the rogue mylar is removed from the beamline.

At 8:30 we started the roughing pumps. At 8:37 the turbos were switched on. By 8:55 the preassures read: Up = 1.6e-5, and Down = 4.3e-5 mBar.

The preamp box was mounted on top of the chamber ready, the box lid was still left off.

The S2 was biased to -130.3V, leak current = 1.03 uA.

On FAIR DAQ with no beam: Trigger Rate ~ 8000/s, Event Mult = 5.0

The 10mm blank frame was in the beam axis. We began beam tuning. By 11:30 we had beam on the downstream faraday cup FC-E1 = 40pA, so now we can pass beam through the chamber - good!

We moved the target ladder to 95.010mm, swapping from the blank 10mm frame to the blank 3mm frame to assist in beam tuning. Now FC-E1 ~ 8pA.

We decided to move back to the 10mm frame to optimise tuning. The target ladder was moved back to position 80.024mm for this purpose.

We moved the slits located upstream from the bending magnet (close to FC-4) to 1.5X1.5mm.

We moved the GSI slits located before the quadrupole to optimise current on FC-0, the upstream faraday cup. We find the following slit positions:

Up = 0mm, Right = 1.5mm, Down = 5.5mm, Left = 5.5mm.

We also performed further tuning by adjusting the quadrupoles located at the immediate end of the tandem accelerator - note the beam tuning is very sensitive here.

After beam tuning we had the following currents:

For 10mm blank frame in beam axis: FC0 = 42pA, FCE1 = 30pA, transmission ~ 71%

For 3mm blank frame in beam axis: FC0 = 41pA, FCE1 = 13pA, transmission ~ 32%

We decided this was acceptable for testing

At 13:30 we switched off the S2 and vented the chamber.

After venting we did the following:

• Removed 12um mylar from the front of the S2
• Visually inspected the ribbon cable connections on the S2 connector and the vacuum feedthrough connector. I saw no loose connection and left the cable alone.
• Set the Si diode angle to 62 degrees relative to the beam axis (28 degrees relative to the normal of the beam axis) - in future we need a fixed angle mount to ensure this angle is reproducible
• Mounted targets on the ladder at the following positions:

The target ladder was set to position 3, looking from above I confirmed it was in the center of the beam axis.

The alpha source was removed as someone pointed out the ladder may be moved in such a way that beam hits the source. However later on (morning of 22/02/2018) I was informed this is being over cautious and we can leave the source at the far position 7 of the ladder during beam.

The ladder, downstream, and upstream lids were remounted on the chamber. The S2 (no mylar) was still on the downstream lid. The diode was still on the central lid.

The roughing pumps were switched on. However the following mistake was made: when both Ecodry 1 and Ecodry 2 were switched on, the automatic gate valve for Ecodry 1 was still open. This meant the chamber was evacuated at a fast rate, likely > 10mBar/s. When I noticed this after a few seconds of pumping the pressures read 10^-1mBar at the chamber upstream and downstream positions.

Speaking to David I learned Ecodry 1 may be switched on ready as long as the gate valve "T1600 Backing" is closed

Learning point: Ensure the automatic gate valve "T1600 Backing" is closed before pumping. This way we can control the roughing speed using the manual gate valve on Ecodry 2.

I wanted to inspect if anything was damaged in the chamber by this fast pump speed. The pumps were stopped and the chamber vented.

Upon visual inspection the S2 and 0.9um mylar in front of the diode were undamaged.

Target CH2 I on the ladder was loose at one side, the target ladder was removed and CH2 I at position 3 was replaced with CH2 VII.

Now the target ladder is in the following configuration: See attached IMG_2738.jpg

At 16:45 the roughing pumps were switched on, this time with the "T1600 Backing" gate valve closed. The manual valve was cracked open.

By 17:01 the pressures read Up = 4.2e-1 mBar, Down = 4.1e-1 mBar.

At 17:08 the turbos were switched on.

At 18:07 the pressures read Up = 1.2e-5mBar, Down = 3.2e-5mBar.

We are ready to connect the preamp box for the S2, and also connect the preamp for the pin diode.