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"Developing a Two-Dimensional Event Display for Tracking Mode of Qweak"



In nuclear physics research, several different types of apparatus are used to detect scattered particles.  The computer programs that are often developed to analyze data taken from the detectors are frequently very complex and use so much computing time that the acquisition of new data is reduced or even lost.  The Qweak Collaboration at Jefferson Lab uses gas electron multipliers, horizontal drift chambers, vertical drift chambers, and trigger scintillators for calibration. The purpose of this project was to develop a graphical user interface that displays Qweak tracking mode data in analyzable projections with scaled geometry to show hit patterns in real time for each event. By plotting the triggered elements in the tracking hardware for each event, collaborators may be able to derive a viable interpolation of the particle track(s) for each event by using the drawn patterns. The new macro was created with C++ primarily using the ROOT library. Geant4 Monte Carlo simulated data and raw experimental data were used to troubleshoot the program. Gathering data for beam production analysis was controlled by the CEBAF Online Data Acquisition system and stored into ROOT files to be read by the event display.  Orthographic projections and tracking data were organized to move between events and beam-line regions to depict hit patterns of the particles for each event. Through effective collaboration and testing, hit patterns were successfully displayed with practical features in a user-friendly environment.  The macro may also be used by collaborators to provide hardware diagnostics during production. It may be run independently or within the larger Qweak Data Analysis Graphical User Interface.

Qweak Collaboration (2010)

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