I. Count Rate linearity and Absolute Quantum Efficiency measurements.
Run ID, CMDB ID, Fpc, Filter, Comments
PTB ran into a control problem when trying to use the "scraper" to reduce ring current. The "scraper" wouldn't stop scraping. It was again under control after the ring current fell below the desired 163 electrons and reached 104 electrons.
Beryllium filter removed, no filter put into place.
The BESSY control network died completely, a fellow had to be called in from BESSYII .....so we went to lunch (my second) at the Schnell Imbiss (currywurst but no beer). We got back and the beam was still not up, we lost a few hours while BESSY was getting the beam back. When we got the injection, we started setting up for aperture relative size measurements using the PTB photodiode. As expected for setups of this sort, this turned out to take quite some time for PTB to center the photodiode on the beam, center apertures, etc .... a few more hours later and we are almost ready to run.
Meanwhile, backgrounds were taken (started before we went to lunch and continued thru the afternoon). The first background seemed to show much more noise than we got the night before. We checked for potential noise sources but found nothing. Paul Okun sent us a list of things to check. Ian checked electronics settings to see if there were changes but found nothing. He also checked pulser amplitude effects but found no contributor here.
Beryllium filter installed.
The network link to Cambridge has been very unreliable all afternoon.
II. PTB Photodiode Aperture Relative Area measurements. The PTB primary vertical stage had to be moved down 2 mm. This stage moves the photodiode, apertures, and filters as a whole. The following files were generated by PTB for these measurements (note that PTB uses two slide aperture assemblies mounted at right angles to one another and both perperendicular to the beam):
a) Apertures of PTB aperture slide #1. Each data set contains 20 data points until file number SCAN024.HDF.
PTB File, Aperture, Current
Inserted the Beryllium filter.
Jutta increased number of data points to 30 per set.
Note: setups for 100 um and 150 um apertures with Beryllium filter appear to have part of their beams obscurred by the filter as suspected during initial setup. First look analysis suggests that the rate should be approximately 106 nA for the 100 um aperture when we were only able to achieve 98.6 nA. The setup for the 150 um aperture with Be filter got us only 225 nA when we expected around 250 nA.
Filter removed for a rerun of the 200 um without a filter.
a) Apertures of PTB aperture slide #2.
Achtung, achtung, beam injektion ..........
Installed Fe filter
Installed Be filter.
Filters removed and reduced ring current
High background, probably from scattering, makes measuring the 5um useless. We skip this and move to the 7.5 um aperture.
Done with photodiode relative aperture size measurements. Ian and Tim signing off for the evening. Bill and Ed are here to releive us.