CRD-2010

Students: Stephanie and Randy

Notre Dame QuarkNet Center

Teachers: Jeffery Chorny Dale Wiand

Professor Randy Ruchti

Abstract: Comparison of Liquid Scintillators and Solid Scintillators

This project was designed to study the differences between types of liquid and solid scintillators. In order to study these things, a variety of different detectors, various analysis programs, and voltage supplies were used in order to look at different aspects of the project. So far, the liquid scintillator seems to be less efficient, but faster than the solid scintillator. Speed can be more important than efficiency since it would be able to keep up with the faster reactions at CERN. The data has not yet been fully analyzed since the project is still in its beginning stages. In the future, the data will be fully analyzed and new liquids will be tested as scintillators in order to find the fastest, most efficient liquid scintillator that would be able to replace the plastics in the LHC at CERN.

Abstract: Study of Cosmic Rays

Two set ups exist to count the cosmic rays, shower (showers of particles) and flux (single particles). DAQ boards were set at triple coincidence and used to count the cosmic rays. The shower study has been working properly and the data collected has all been sent into the cosmic ray e-lab. The flux study has had its ups and downs: problems with plateauing, performance, and voltage settings. The data from the flux study has also been uploaded into the e-lab. In the future, tests will continue to run with the data being uploaded into the e-lab.

Group: CRD Students: Stephanie and Randy Log Sheet 1

__Monday: June 21, 2010__ We were introduced to the equipment used in the CRD area of the lab. We learned how to set up the logic in order to count double and triple coincidences to test the efficiency of the middle counter in a set of three stacked. We first plateaued the middle counter (2.4B) by changing the voltage in increments of 50 mV starting at 750 mV and ending with 1050 mV. All tests were run for 5 minutes. We found that the ideal voltage to run counter 2.4B at is 950 mV. We then tested the effects of various thresholds. We also raised these in increments of 50 mV starting with 300 mV and ending at 1250. All tests were run for 5 minutes. The efficiency of counter 2.4B decreased with the increase of the threshold.

__Tuesday: June 22, 2010__ We began testing the set up that would be used for the liquid scintillater tests with a plastic scintillater of a similar size. We plateaued the middle counter (the plastic scintillater) at various gains. Due to the fact that the signal had to amplified, the gain controlled how much the signal was amplified. We tested the efficiency at three gains: 25, 10, and 5. The voltage used to power the scintillater was increased in increments of 50 V starting at 900 V and ending at 1250 V. We found that the best results were found at 1200 V at gain 10. We received strange results at 1250 V. We were getting over 100% efficiency at gains 25 and 10.The change in gain lowered the efficiency at the lower voltages, but came to the same efficiency for gains 25 and 10 by 1100 V while gain 5 made it to the same efficiency at 1200 V. All tests were run for 5 minutes.

__Wednesday: June 23, 2010__ We began how to use another counting system, the DAQ board. This one is linked to the computer so in order to the data we had to use a program called HyperTerminal. The data in HyperTerminal is mostly in hex rather than decimal or binary. We learned how to read hex, convert binary, and interpret what the binary means. The 4 detectors were stacked for a flux test. We ran one 10 minute test counting quadruple coincidence with all four channels on. We then learned how to upload data to the e-lab and interpret the rest of the numbers in HyperTerminal.

__Thursday: June 24, 2010__ We started the day by going through the information on the e-lab. We learned about cosmic rays and more information on how to interpret the data on HyperTerminal. We then started a shower study triple coincidence on the DAQ board. While it was running, we helped to fill the liquid chamber with the liquid scintillator. We ran into problems when scintillator seemed to deteriorate the rubber in syringe. They started the count while we wrapped the shower study at 45 minutes. The DAQ board counted 125 hits with the triple coincidence. We uploaded it into the e-lab and began learning how to set the geometry. It all went well except for the fact that we ran into issues setting latitude and longitude. It would not accept the coordinates given by the GPS. We had to leave be since it was then time for lunch.

__Friday: June 25, 2010__ We began the day by finally figuring out how to fix the geometry by simply modifying an old one. We then began more shower studies in order to test how area affected the count. We redid the same one from Thursday. The counter paddles were arranged in a 0.51 m x 0.77 m set up. We ran it for a half an hour so that is would be uniform with the other two tests that would be run. The DAQ board counted 88 counts. We then ran a second test for a half an hour with the dimensions set at 0.51 m x 1.54 m thus doubling the area. The DAQ board counted 41 counts. We then ran a third test for a half an hour with the dimensions set at 1.02 m x 1.54 m thus quadrupling the original area. The DAQ board counted 32 counts. We then ran a fourth test for a half an hour with the dimensions set at 1.02 m x 3.08 m thus making the area 8 times greater than the area of the original. The DAQ board counted 21 counts. We then ran a fifth test for a half an hour with the dimensions set at 1.02 m x 2.31 m thus making the area 6 times greater than the area of the original. We decreased the size due to the fact that there was not any room on the lab table to expand. The DAQ board counted 29 counts. We uploaded all of the data onto the e-lab in order to be able to study the data through the graphs that the website is able to create and compare the effects the area has on detecting showers.

Group: CRD Students: Stephanie and Randy Log Sheet 2 __Monday: June 28, 2010__ We continued with the shower studies that we had begun on June 25. We did three half an hour runs changing the dimensions each time. The first run of the day was 1.79m x 2.31m; we got 30 counts. The second run was 0.51m x 2.31m; we got 36 counts. The third and final run was 0.51m x 3.08m; we got 31 counts. We then uploaded all of the data into the e-lab. We also tested the efficiency of a large piece of scintillating plastic that had been acquired. We did five minute runs and found that it was most efficient at 2200V. We then spent time unwrapping it and taping it up so that it could be cut into smaller pieces.

__Tuesday: June 29, 2010__ We ran 3 shower studies as well as two flux studies throughout the morning. The first shower study was set at the dimensions of 0.51m x 3.08m. It was run for half an hour and got 30 counts. The second shower study was run for two hours at the dimensions of 0.51m x 3.08m. We got 120 counts. The third shower study was run at the same dimensions for 45 minutes, getting a count of 49. While the shower studies were running we also did flux studies. The two flux studies were done with the paddles stacked three high and at triple coincidence. The first run ran for 1 hr and 40 min. we got 65663 counts. The second run ran for 45 min and we got 29158 counts. While the studies were running, we were in the machine shop cutting the two giant scintillating paddles into 16 9in x 9in squares (eight squares from each paddle). We returned to the QuarkNet building and began the tedious process of sanding each of the squares.

__Wednesday: June 30, 2010__ We spent the day sanding and learning how to buff the scintillating squares. We had to start by sanding each of the saw cut edges on the sanding belt. We then had to go over each of those edges by hand with 220 grit, 320 grit, 400 grit, and 600 grit. After that, they had to be buffed with two different compounds and then hand polished. We got the majority of the squares to the 320 grit. We also helped to empty the liquid scintillater and opened it to make sure that the fibers survived. We then looked at a program that Mr. Baumbaugh had created to help with analyzing the data. Throughout the morning we were also running flux studies. The first flux study ran for 1 hr 40 min and got 63873 counts. We ran the second study for an hour and a half and got 57883 counts.

__Thursday: July 1, 2010__ We spent the day sanding and buffing. We finished of the sanding and buffed all of them with the first compound. Randy had accidentally melted a small part of one of the squares. We used it as a test to finish polishing. We did completely finish two of the squares including the melted one. We also ran two flux studies, each for two hours. The first got 76318 counts and the second got 76288 counts. Throughout the day, our two mentors tested some squares at various stages of sanding and buffing.

__Friday: July 2, 2010__ We plateaued the middle paddle of a three stack of the new scintillating squares. The top paddle was sanded to the 600 grit while the bottom had had no sanding or buffing whatsoever. The middle paddle had been completely polished and buffed. We ran the top and bottom at 950 V and increased the voltage of the middle paddle by 50 V. The numbers for the double coincidence were much higher than predicted so we turned out all of the lights and checked for a light leak. There was no light leak so we are still not sure what happened. We also ran a flux study for 1 hour 15 min and got 47405 counts. We uploaded the data onto the e-lab. We then went back to plateauing the middle paddle. We changed the gate width (the amount of time given to find a coincidence) from 100 ns to 50 ns. We ran the middle paddle at 1000 V, a voltage we had already tested. There was no difference in the rate at which the paddles detected a particle. We changed the set up so that we used two of the old paddles and kept the same middle paddle. The top and bottom were running off a different voltage source at 950 mV and the middle was run at 100 V. The numbers seemed much more reasonable with 2378 counts at triple and 2701 counts at double coincidence. We then returned the gate width to 100 ns and got 2499 counts at triple coincidence and 2793 counts at double coincidence. We then discovered we would have to redo the plateau on Tuesday due to the fact that we had to set up the tables for the cook out.

Group: CRD Students: Stephanie and Randy Log Sheet 3 __Monday: July 12, 2010__ We ran tests to verify the efficiency of the scalar for the three paddles. We did five minute runs with only one paddle running in order to compare the count and the scalar. At default settings, the scalar ranged from 1.4% off to 3.9% off. We changed the gate width and time delay and increased the efficiency of the scalars, but they never reached 100% efficiency.

__Tuesday: June 13, 2010__ We started the day by sending in a help request to the e-lab since the results of the performance studies of the week before had strange results. We then tested the boards with a pulser and ran performance studies as well. Each twenty minute run, we increased the length of time it took for channel 0 to send a signal to the DAQ board. There was no change in the performance study until channel 0 was increased by 40 ns. The corners were cut off of some of the newly polished paddles to see how it affected the efficiency. Randy ended up melting a small part of the plastic again.

__Wednesday: June 14, 2010__ We ran two different studies. We continued the tests from Tuesday, using a different board. We got different results and so we started to change the voltage of the pulser, decreasing it by 20 each run. The second study we ran was to test the effect of time on the scalar. For the most part, the scalar never changed by a significant amount. The only time it continually rose was when it was covered with the black cloth.

__Thursday: June 15, 2010__ We went to Fermilab and found the tour relatively interesting. After lunch, we struggled to follow the complexity of the lecture that had followed. We particularly enjoyed the surplus store and looking at the bunch of inexpensive geeky stuff.

__Friday: June 16, 2010__ We continued the two tests we had been running on Wednesday. We completed the pulser study with the voltage at 40 mV. Any lower would not have registered due to the fact the threshold was set at 300 mV. The scalar study over time continued to have similar results with paddles 2.1A and 2.1B. Randy also helped check for light leaks in new paddles 1-4 and found one in both 3 and 4. All of the PMTs also had light leaks.

Group: CRD Students: Stephanie and Randy Log Sheet 3 __Monday: July 19, 2010__ We spent most of the morning planning what to do next. We decided to continue the pulsar tests using only two channels rather than four. We only ran two tests since most of the morning was spent in discussion with Professor Ruchti.

__Tuesday: July 20, 2010__ We continued the pulsar studies that we had started on Monday. Rather than using four pulsar channels, we only used two to better compare the differences between a delayed signal and a standard signal. We began by increasing the delay in increments of 8 ns. Each test ran for 20 minutes. In the ten tests we ran, there was a large change between the 40ns and 48 ns. Professor Ruchti suggested that we use smaller increments in order to locate where the change happens.

__Wednesday: July 21, 2010__ We continued the same tests following Professor Ruchti’s advice and increasing the delay by 2 ns each time. We discovered that the change occurs at the 46 ns mark. At this point we also discovered an unexplainable jump in counts and found it could only be explained by the Higgs Boson…jk. Each of the 10 tests was ran for 20 minutes.

__Thursday: July 22, 2010__ We began testing the new paddles we had created using the performance study. We did similar tests as the pulsar to compare the difference between actual counters and the pulsar. We also did an angular study using a set of plastic shelves. We angled each of the counters to 45° to detect particles coming from a particular direction. We did two of these tests, each running for an hour. The last test of the day was a similar set up, but rather than being at an angle, the paddles lay flat. We wanted to compare the difference between angular and flat paddles.

__Friday: July 23, 2010__ We continued the tests from Thursday. The new paddle tests were the same but they ran for only 10 minutes rather than 20 minutes. We also reconfigured the set up of the angle study so that a 45° angle was created with the counters laying flat. This was done so that only particles coming in at a 45° angle would be counted. It is continuously running until we get near 1000 hits. So far, we have 391 hits after two hours.