This morning I unpacked the chamber parts.

I mounted the downstream and central lids with the iris arm hooks to double check we could still successfully mount them, see previous eLog entry (#25) for photos from this procedure performed in Edinburgh.

When attempting to move the aperture arm, I noticed the hook was catching on the Al tube used to support the aperture onto the side of the chamber collar. I cut the hooks used for both the downstream and central apertures, they still hooked onto the iris arm.

The actuator positions were found as follows:

Downstream:

Mounting (iris "closed" to ~18mm diameter) aperture setting = 82.5mm

During measurement (iris open) aperture setting = 1.0mm

Central:

Mounting (iris "closed" to ~18mm diameter) aperture setting = 87.0mm (Old = 85.5mm)

During measurement (iris open) aperture setting = 14.0mm

Note: these were measured by moving the actuator arm away from the chamber collar (105 -> 0 on actuator scale). This is to avoid backlash in the position, particularly because the iris arm hole allows moderate (~4mm) movement of the aperture arm hook.

I then cleaned the upstream, central, and downstream lids, the chamber collars o-rings and top and bottom surfaces, and the metal part of the diode mount all with alcohol.

Me and Raffaele mounted the chamber collar onto the chamber target section (already mounted on beamline from February 2018 shifts)

We then attempted to mount the downstream lid, with S2 detector mask, onto the collar, however we had difficulty connected the iris arm to the actuator hook. This was also the case for the central lid.

We decided to implement a new approach, this requires 2 people to ensure the aperture can be adequately supported during mounting:

1. Leaving the aperture off of the chamber collar, mount the chamber lid (downstream/central) with iris arm mounted

2. Using tweezers or another small tool, gently pull the iris arm out through the chamber collar side hole

3. Using the iris arms hole, hook the aperture arm onto the iris arm

4. Carefully insert the aperture into the chamber collar side hole, whilst simultaneously shortening the aperture arm to ensure the arm will fit

5. Bolt the aperture onto the side of the chamber collar

We performed this operation for both the downstream and central lids, we were successful in both cases on our first try. The irises were visually seen to open and close by looking through the beamline from the position of FC-E0.

When mounted the iris "closed" (18mm diameter) positions were:

Downstream = 82.5mm,

Central = 85.5mm (suggesting my 87.0mm quoted above is due to the iris arm hole size)

On the central lid I mounted the diode at 39 degrees and 22.0mm from the upstream side of the lid. This was very efficient due to the new mounting block. See pictures IMG_2823 and IMG_2839

I also mounted the S2 2623-26 in the central position with 12um mylar. See attached IMG_2841

In the meantime Raffaele mounted the target ladder with the following targets:

I need to check the CH2 target number at position 3. Target VII was removed from position 3 because it looked like it was peeling off -> needs additional epoxy

At 18:45 we left the lab.

Tomorrow morning we intend to mount the downstream S2 detector with 12um mylar and both aperture hooks. We then plan to pump down the chamber, setup the electronics, and perform an alpha source calibration.

If all goes well we will perform a beam measurement of 7Li at 5.0 MeV