JB Undergraduate Research Log, Fall 2013

Week 1 - I turned my focus to the testing of the active collimator. I read sections of “Quality Assurance and Acceptance Test Plan for the Tagger Microscope and Active Collimator.” There are numerous references to other documents that would help me (D0000-19-02-S003 - Specification of the active collimator and electronics), but I was unable to find them on the GlueX wiki page. I have asked Alex and Dr. Jones to acquire the file for me.

Alex looked over the write up for the piping project. I fixed various pieces according to his suggestions. I then continued reading about the active collimator. Ann Marie picked up the Tektronix TDS 2024 oscilloscope from downstairs for me. I spent some time familiarizing myself with it, as I have never worked with this particular oscilloscope before. I downloaded the pdf and spent time learning how to use it. I also started reading “A Tungsten Pin Cushion Photon Beam Monitor” to further understand the relationship between the knock-on electrons in the showering medium and the differences in the currents through the collimator that are used to pinpoint the location of the photon beam.

Week 2 - I attempted to test the tungsten pin cushions within the active collimator. I connected one of the pin cushions to a PMT-5R transimpedance amplifier, which was then connected to the oscilloscope. Dr. Jones told me to also use a F-100PS power supply. I attempted to connect the power supply to the amplifier via a F3B207-06 DB9 Belkin serial cable. However, this seemed to have made the power supply short out. I am awaiting Dr. Jones’ instructions for what to do about this matter; Neither Jim nor Ann Marie are able to help me with this problem.

I looked into buying a new F-100ps power supply. Dr. Jones and I removed the fuse from the power supply, and found that it needed replacement. I went to Mansfield Supply, and ordered a set of new fuses to place in the power supply.

Week 3 - The fuses came in. I had time to quickly test that the power supply was still functional. I replaced the fuse, and the power supply's "Power" light turned on. I was also given a set of cables used specifically for the active collimator.

Week 4 – I connected the collimator to the amplifiers to the oscilloscope for testing today. I believe that I had the correct setup, but the power supply did not turn on again. I tried unplugging the power supply from the setup and testing a fresh fuse. The “Power” light went on for a few seconds, and then dimmed out. I used an ohmmeter o verify that the other remaining fuses were working. Brendan helped me with examining the interior of the power supply for possible issues. Once we tried a third fuse, the power supply worked. I then connected the collimator to the oscilloscope and used my finger to test each pin cushion; I received a signal from each one.

After collecting the compact flash card from Brendan, I started taking pictures of waveforms from the oscilloscope. Professor Jones has instructed me to set a threshold, wait for the oscilloscope to request a trigger, and then tap the screw connected to the pin cushion in order to create a snapshot on the oscilloscope. I spent more time reading the oscilloscope manual to ensure that I understand the terminology and the full functionality of the oscilloscope.

Week 5 - Using the knowledge I gained from the oscilloscope's manual, I was able to record a few transient waveforms. Using a “good-looking” waveform, I exported the data from the oscilloscope to my computer in order to fit a decaying exponential to the wave. However, Dr. Jones notified me that I am instead looking for the time it takes for the waveform to return to its initial value, rather than its decay. I was also told to connect my computer to a unit which I can use to control the gain settings in the amplifiers.

I spent a some time collecting the BNC splitter, terminal board, and DAQ. A computer must be set up in order to begin using the data acquisition program; Alex will help me get one going.

Week 6 (11:30-1:00) I requested Igor Senderovich's notes on the active collimator from Professor Jones. I spent a while reading through his work, which included ActiveX programming and testing of the PMT-5R amplifiers.