User:Misu
From MariachiWiki
My name is Alicia DiStefano and I am a senior at Rocky Point High School. I am in the Rocky Point Chapter of the National Honor Society. I love school and I take a great amount of pride in all of my hardwork. I want to attend college for either culinary arts or hotel/restaurant management. I enjoy life and everything that comes along with it.
My family is very large and I wouldn't have it any other way. I have four syblings. We have three boats and we are definitely those annoyingly loud people on the dock. We have a 30' sailboat, a 22' Parker, and an 11' Boston Whaler that is mine and my brother's to share. My summer weekends are spent on Fire Island with my family. I have grown up at the beach and I think that I will never grow out of my love for it.
I have been working as an intern at BNL for the past few weeks. I have been working with the cosmic ray detectors and working on a new procedure for calibrating the photo multiplier tubes that is more sufficient and simpler. My tries turned out successful after many setbacks. For more details visit this link : Calibration of Scintillator Panels You can comment me by sending me an email at adistefano9@yahoo.com
OVERVIEW
*All processes for methods can be found in paper titled "Calibration of Scintillator Panels" above*
July 11
This is my first day working at the lab. Dr. Takai has me calibrating the cosmic ray PMTs using a new method. Instead of using all of these complicated devices like a discriminator board, logic board, counter, and coincidence board, all I have to use is an oscilloscope to determine the threshold at each voltage that the PMT is operated at. I simply use two small scintillator panels with smaller PMTs attached to them as trigger panels and they are places over and under the scintillator panel in the gun case (cosmic ray detector). They are operating at about 5.0 V and are also put into the oscilloscope on channels A and C. The PMT is hooked up to another power supply and is also hooked in to the oscilloscope (channel B). When I take measurements, I set the power supply of the PMT to 5.0 V and wait about two minutes to let the PMT acclimate. Then I go to the oscilloscope and look at the pulses that are displayed for channel B. When a pulse that is lower than the previous ones is seen, I move the cursor up to indicate the amplitude of that pulse. I do this for approximately 20 pulses and then I record the lowest pulse amplitude (in mV) and this is the optimum threshold value for that operating voltage. I increase the voltage of the PMT by 0.5 V and then repeat the process. I repeat the process until the voltage of the PMT is 7.5 V. I was able to calibrate all three PMTs by lunch time.
After lunch, Joe Sundermier and I attempted to make efficiency measurements, but our the first nimh crate that we had was dysfunctional and then our coincidence board went, and then our logic board went, and then so did our discriminator board. We went through three coincidence boards and two discriminator boards before we found ones that functioned properly. By that time, we didn't have enough wires to hook everything up and it was getting close to time to leave. So we abandoned that project for the day and decided to pick it up first thing in the morning. I made some graphs based on the data that I took.
July 12
In the morning, Joe, Helio and I picked up where we left off the day before. We found some more wires to hook everything up properly and we figured out how the counter worked. I started collecting data on the efficiency of the PMTs and whether or not our new method will work. We set the threshold of the discriminator board to about 30.0 mV and set the power supply of the PMT to 5.0 V. We set the counter to 5.0 minutes and set two channels on it up. One channel had the two trigger panels hooked into it and the second had all three scintillator panels hooked in. We let the counter count the events for five minutes and then I recorded the data and calculated the efficiency. To calculate the efficiency, you take the amount of events counted on the channel with all of the scintillater panels and divide it by the amount of events seen by the trigger panels and then you multiply that number by 100% and that is your efficiency. Any number above 90% is a decent efficiency. I repeated the process after you increase the voltage of the PMT by 0.5 V five times (until the voltage reaches 7.5 V), recording the data and calculating the efficiency for each 0.5 V increment. After I did that for one gun case, I performed an attenuation on that gun case by calculating the efficiency for the PMT while it was operating at the voltage where it was most efficient (based on the data taken from the efficiency test) and placing the trigger panels in five different places over and under the large scintillator panel. All of the data revealed that the efficiency was over 95% each time. As you got closer to the PMT the efficiency increased and right in the middle there was 100% efficiency.
Unfortunately, after taking the efficiency measurement for the second detector, one of the small trigger panels broke. So, because we couldn't access the glue that we needed, I worked on writing a paper based on the data I had collected so far (see link above: Calibration of Scintillator Panels).
July 13
In the morning, we got the glue that we needed and glued together the scintillator panel and the PMT. I continued to work on my paper. Now all we can do is wait....
July 14
I checked on the glue this morning and it seemed to be drying nicely. After lunch Zina and I wrapped the panel and then Joe and I tested it to make sure that there were no light leaks. Unfortunately, that didn't go over very well. There was a lot of noise displayed on the oscilloscope screen. So I unwrapped the panel and found that the glue bond between the panel and the PMT had been broken again. I think that it's from the two metal supports that Zina and I constructed. It seemed that the way we taped it on to the panel put too much tension on the panel and caused the glue bond to break. It is also possible that the glue did not dry correctly. When I looked at the glue after I unwrapped the panel the first time, it was flaky and hard to get off. The second time I unwrapped the panel, the glue seemed tacky and almost sticky still. It is very possible that this also caused the break. I am led to believe that it was a mix of the two possibilities. Nevertheless, I still had to glue the panel again. This time, I am going to let it sit for the whole weekend. Hopefully our results will be better this time.
July 17-18
I spent Monday morning wrapping the panel again. This time we didn't use the metal supports. When we tested the panels the pulses displayed on the oscilloscope screen looked much better. That afternoon I conducted the last efficiency test on the last detector. That took up most of the rest of the day and when I finished I made a few charts and graphs to show trends in the data. On Tuesday morning, I began taking data to prove that our new method is as efficient as the older method. I began by taking calibration measurements through the old method. I made a mistake and only recorded the count number of all three panels instead of recording the count number of all three panels and the count number of only the two trigger panels. Only recording the count number of the three panels is not sufficient because you don't have anything to naturalize it against. So I set the threshold for the discriminator board to 30.0 mV and then calibrated the PMT again using the old method, but increasing the low voltage by 0.2 V instead of 0.5 V increments. After recording the data and determining the efficiency, I repeated the process with the threshold set at 50.0 mV. The data taken during the 30.0 mV threshold trial showed that the most efficient operating voltage was between 6.4 V and 6.8 V. The data taken during the 50.0 mV threshold trial showed that the most efficient operating voltage was between 7.0 V and 7.4 V. I then proceeded to perform the new method of calibrating the panels using the oscilloscope. After I conducted the test twice using the oscilloscope, I determined that the two sets of data were very different. After going over it with Joe and Helio, we determined that the reason that the data was very erratic and different was that we were basing our data upon errant pulses since we had the oscilloscope set to 10 second delay fade. We decided that the next day we would repeat the measurements except set the oscilloscope to infinite persistance. After thirty counts, we would ignore very small or irregularly small pulses, as they are probably errant pulses, and look at the pulse with the smallest amplitude. We would use this amplitude in our data.
July 19-21
After performing the calibration with the oscilloscope set to infinite persistance our data looked much more regular and much similar between the two sets. And, best of all, the data taken using our method was concurrent with the data taken using the old method. At 6.4 V, the threshold was 31.2 mV and at 7.0 V, the threshold was 50.4 V. In the afternoon and for the next two days, I made charts and graphs to show the consistencies and I made my own best fit lines using least squared fit equations. I also added the graphs and charts into my paper and I worked on the paper for those days.
