2014 Annual Report - U Penn

Summary of the Penn 2014 QuarkNet Program

This year we had an exceptional crew of High School researchers: N. Zavanelli, D. Ells, M. Macerato and D. Grabovsky.  They came to us armed with curiosity and tons of expectation pursuing High Energy Physics along lines that they had learned about in high school physics courses, physics club and on the internet: primarily Particle theory and Quantum physics principles.  They seemed a bit taken back when looking at pile of equipment they would use to make real world measurements of sub-atomic particles. The connections to theory and basic science weren't so clear at least for a while.  As they learned about the program through daily seminars and about the work in Experimental High Energy Physics going on at Penn, their enthusiasm grew. They seemed especially pleased by our concept that the QuarkNet project is a multi-year development where year by year student researchers sophisticate a Cosmic Ray tower that has been built, rebuilt and improved over the past 7 years. The students start by re-assembling the basic components according to documentation archived by QuarkNet groups from previous years and become familiar with the apparatus. The Cosmic Ray Tower includes two scintillator paddles to establish a readout coincidence reference time, 64 proportional drift tubes housed in 4 - 16 tube planes with readout electronics designed at Penn for use in CDF and Data Acquisition elements very similar to what is used in high energy physics experiments: An Xilinx FPGA coded for readout by the students that feeds data to a Raspberry Pi computer with resident track re construction programs again written by the students themselves. 

They are initially given the job of reading and evaluating the documentation written by students in previous years that describes the equipment left to them and using it as reference documentation to understand how to re-assemble the cosmic ray tower and calibrate the operating voltages and thresholds. As they go they are encouraged to re-write the descriptions as part of their archive for the following year. This year's group felt they didn't have enough pictures of the assembled equipment, and that the FPGA code they inherited could be written with more comments and in a different way. They responded by leaving a relatively complete description of their setup with detailed pictures and descriptions.  They gave us three presentations at two week intervals and were encouraged to pose questions to us and themselves about the equipment and completion strategies to get to something reading out if not the whole system.  They were collaborative, self-organized and accomplished a lot on their own.  Along the way developed a deep appreciation of how to write FPGA code, validate the signals from proportional drift tubes, set front end electronics thresholds and write Python code to deal with the data as it arrived.     

Towards the end of the program we went on a field trip to Brookhaven National Laboratory where Helio Takai took us on a guided tour.  We visited the BNL Instrumentation group where Paul O'Connor led the tour and then went for a guided tour of the Star Detector. We returned late in the evening with time for plenty of discussion during the three hour ride each way.

Finally they have left us with a short presentation to be sent to next year's QuarkNet students in advance of the start of the program to give them a head start on the project. 

I was most impressed by their adaptability in all forms during the program, leaving old expectations behind and allowing new ideas and simple realities focus their work.  Most interesting was a complete change in the way that data was acquired by the FPGA code and sent to the Raspberry Pi. With some encouragement from us, they went from a simple leading edge initiated timing readout to a counter driven scope like acquisition reporting the state of the FPGA inputs from all tubes for a fixed number of 10ns system clock periods.  This time sequenced array of 0's and 1's  provided a way to find the arrival of the earliest signals from the drift tubes without having to know (with significant precision) when to expect them.   This approach required reprogramming the FPGA and the Raspberry Pi and was written exclusively by them in the last three days of the QuarkNet program and it worked!  While no time was left for physics analysis, they were able to get sensible signals from the drift tubes and left ideas for the next year's students to carry on.  You may notice in their comments that there wasn’t enough time to make the Cosmic Ray Tower perform its expected track finding function, but all in all this year’s program was a great success.

Mitch Newcomer