Post #1: Correcting for Beam Effects in the Qweak Experiment

First of all, I want to start off with a summary and explanation of my abstract and purpose: I am working to correct data measured by the Qweak experiment at Jefferson Lab for natural beam imperfections which create ‘false asymmetries’ in the data. This is done by calculating correlations between different beam properties and the data (asymmetries measured by the main detectors) and removing these correlations from the data. Correlations are not calculated in the same way that one might in a stats class. They are calculated for each successive event (there are some 90,000 events in each data file that I use) so that precision is not lost as one calculates over such a large set of data. These values are then used to correct the main detector data, removing the ‘false asymmetries’ due to the beam motion. Greater explanation of this process and results will follow in subsequent blog posts.

I have been now working on my project for over a month now. In order to accomplish this goal, I have learned to use ROOT, a C++ based data analysis package and written scripts to calculate the correlations between the beam properties and do the correction. This past Monday, I gave a 10 minute presentation of my preliminary results for other students participating in the REU (Research Experience for Undergraduates) program.

In addition to this work for the Monroe Program and the physics department, I have informally participated in the REU program. While not actually a member of the program, I have had the opportunity to work with REU students by presenting my findings and attending lectures by my peers and faculty. Additionally, we have had the opportunity to visit local physics-related facilities, including the Proton Therapy Institute and NASA Langley.

I participated in a ropes course with other students working for Dr. Deconinck, which was an excellent team-building and ‘heights desensitization’ experience. Additionally, I was able to work in the experimental hall where Qweak is/used to be by participating in the deconstruction of the Qweak experiment (data collection is now over, and the hall will be used to house new experiments). While somewhat tedious (I bundled cables that carried signals from the detectors), it was a very cool experience to actually work hands-on at the experiment site.


  1. arhartley says:

    Very interesting–I’d love to see a summary of the presentation of your preliminary results!