We've made some steps forward and some back. We successfully installed the insert into the Moller chamber, after disassembly of Christoph's apparatus. We had decided to leave the mirror at the 0 degree position, to be able to align it to the beam (tolerance is 0.5 mm mirror displacement before you run off the multilayer reflectivity, and due to changes in beamline -- see below). We haven't yet installed samples, apertures, or filter.
Pumping takes a couple of hours to get to 5x10^-7 (setpoint to open to beam), which seems to be about the same rate as earlier pumping tests. We had some trouble with interlocks and finally solved that. The beamline setup has changed, with the addition of the wavefront sensor out the back of the chamber. This could in principle be used to align the mirror but not quite operational as yet. However, this prevents us from using the transit to align. Another change is that the valve upstream of the chamber is no longer a window valve, so we only get HeNe when pumped. Or we could have vented part of the beamline, but that would require someone to come on Monday to reapprove the beamline. So we decided to use the photodiode and CCD to see the HeNe, with the system in vacuum.
There are problems with this approach. The HeNe is so intense that even the scattered light in the chamber saturates the CCD. The photodiode signal didn't make sense, but we realized at about 3 am this morning that we in fact installed the insert on the wrong bolt pattern. When we installed it, it looked about right and we had aligned two black marker marks that were on the chamber flange and our flange. But by stringing up a wire along the beam path it is obvious we need to rotate by one hole.
Sebastien's cooling was tested -- we get down to about -35 degrees, but not enough N2 flow to go lower. He will add more coils to the coil.
In the morning Magnus and Calle will look for a 1 micron thick Al foil and attach it to the aperture plate, so that we have some apertures with 1% attenuation, if need be.
Currently venting the chamber.
We need someone to talk to Elke in the morning to convince her to let us use the wavefront sensor.
Vented, more later.
Opened -- looks like the right bolt pattern after all. Just that photodiode is off-center (I think we knew that actually). Taking the opportunity to install the fibers to the attocubes.
