On the morning of 23/02/18 we aimed to complete beam tuning of 7Li at 3.45MeV.

At 8:43 CHUP = 7.2e-6mBar, CHDW = 1.9e-5mBar.

The S2 bias was ramped to -130.3V, leak I = 1.67uA. The diode bias was ramped to -70.1V, leak I = 0.01uA. The preamp power was also switched back on.

With no beam the DAQ monitor read a trigger rate ~ 50Hz and event multiplicity = 5.3.

We started beam tuning. A mistake was made where the accelerator side of the wrong valve was opened at the bending magnet, causing the beamline to be vented from 10^-7mBar to 10^-3mBar. Fortunately the line valve was closed, so the pressure of the chamber holding the detectors was unaffected.

We struggled with beam tuning for a few minutes, until we discovered the venting of the beamline tripped an interlock, causing turbo entrance 1 and 2 to be switched off. Restarting these turbos both improved the accelerator beamline vacuum and the beam tuning.

After beam tuning with the 3mm blank frame, we achieved beam currents:

FC-E0 (pre-chamber) = 250 pA

FC-E1 (post chamber and GSSI magnet) = 185pA

Transmission ~ 74%.

We felt satisfied and decided to remove the 12um mylar from the S2 ready to perform the measurement.

At 10:39 both detectors and the preamp power were switched off. The turbos were switched off. The manual gate valve and T1600 gate valves were closed. Ecodry pumps 1 and 2 were switched off. (We should write a procedure for pumping down and venting the chamber)

During venting we removed the S2 preamp box from the top of the chamber.

At 11:05 the CSSM gate valve interlock was tripped. In future we should make sure the CSSM magnet is OFF when not in use. David checked the pressures in and around the chamber, he concluded everything was fine.

After venting the chamber I removed the 12um mylar from the front of the S2.

I also removed the target ladder and rotated the alpha source 180 degrees to face downstream - this is so we can obtain a second alpha calibration of the S2 at the end of the beamtime.

Whilst handling the target ladder I noticed target VII is loose at one side, either from beam or my epoxy skills. I decided to leave all the targets mounted and we run beam on target 2, located at target ladder position 4, 50.015mm.

The target ladder configuration is now:

At 12:18 the chamber was sealed up and we began roughing it down. At 12:29 we started the turbos and went to lunch.

At 13:02 after lunch: CHUP = 9.7e-6mBar and CHDW = 2.5e-5mBar.

We remounted the S2 preamp box back onto the downstream chamber lid, the preamp box lid was also remounted. The following pin diode preamp box cables were replugged in: input, -15V, +15V, +ve test, and HV.

At 13:25 the pressures read: CHUP = 9.6e-6mBar and CHDW = 2.5e-5mBar.

The S2 was biased to -130.3V, leak I = 1.56uA. The diode was biased to -70.1V, leak I = 0.01uA. Preamp power was applied -> correct currents drawn.

The target ladder was set to position 4, 50.015mm, target: CH2 930 ug/cm2 target III.

With no beam the DAQ trigger rate ~ 50Hz, the beam current at FC-E0 = 240pA.

We were confident to begun a beam measurement.