High Altitude Radiation Detector (HARD): Integration of Undergraduate Research into Senior Design and Lessons Learned

An interdisciplinary undergraduate research project conducted as part of an ECE senior design is discussed. The focus of the research project was on aspects of physics, particularly on arrivals of cosmic rays in the so-called “east‐west” angular asymmetry. In collaboration with NASA’s Columbia Scientific Balloon Facility (CSBF) and other universities developing scientific ballooning payloads, a sophisticated scientific payload was designed to study how the angular asymmetry and intensity of cosmic rays changes with altitude, as well as conducting a high‐quality, long‐exposure measurement at balloon-float altitudes for about 10 hours. The payload was designed by following a top-down design approach: initially establishing engineering requirements of the payload for the experiment, carrying out functional decomposition, and actual laboratory design of subsystems by student team members enrolled in the Electrical and Computer Engineering (ECE) program at the University. The project team consisted of six undergraduate students (three seniors and three sophomores) from the ECE department and two faculty advisors from the ECE and Physics departments. The payload was certified flight-ready after integration and vacuum testing at CSBF with all modules functioning properly. Unfortunately, the payload failed to collect the desired cosmic-ray data during flight; however, all other parts of the design functioned as expected. Overall, adopted as a senior design project for an academic year, this project was a considerable success from a student education standpoint. Further details are provided on project design, team structure and collaboration, experimental details, and lessons learned, particularly on promoting student learning and improving its outcomes. 1. Overview of the Project The Earth’s magnetic field deflects cosmic‐ray trajectories from a straight line. Due to the fact that cosmic rays are predominantly positively charged, this results in more particles arriving from the west than from the east. This “east‐west” asymmetry has been investigated in the past at ground level. The goal of the project was to design and launch a small experimental payload to investigate how the “east-west” angular asymmetry changes with altitude, as the cosmic ray flux transitions from mostly secondary particles near the ground level to mostly primary cosmic rays near balloonfloat altitudes. Additionally, this project intended to study how the intensity of cosmic rays changes with altitude, based on measurements of cosmic ray intensity from multiple arrival directions, providing a more complete picture of the high‐altitude radiation environment caused by cosmic rays. To achieve the project goal, a payload integrating various subsystems for cosmic-ray detection and event processing has been designed in a top-down design approach: initially establishing engineering requirements of the payload for the experiment, carrying out functional decomposition, and actual laboratory design of subsystems by student team members from the Electrical and Computer Engineering (ECE) department. Figure 1 shows the functional block diagram of the payload for the experiment, and Figure 2 shows a completed, sealed payload P ge 23660.2 waiting for thermal and vacuum testing at NASA’s Columbia Scientific Balloon Facility (CSBF) site. An exploded view of the recovered payload after flight is shown in Figure 3. The student team primarily consisted of a total of six ECE undergraduate students including three seniors and three sophomores, and two faculty advisors from ECE and Physics department. For a short period of time during the summer 2011, a graduate student participated in the laboratory experiment to assist the team. This project was initiated and formulated as a response to the Call for Payloads from one of NASA’s State Space Grant Consortia. As such, to some extent, the final project deadline and key design requirements for proper integration into the High Altitude Student Platform (HASP) were set. Along the course of the design activities, the team followed the schedule posted by the program director for the launch vehicle, HASP in Louisiana. As part of the requirements, the team delivered all monthly status reports from January 2012 to November 2012 on design activities for payload subsystems, a Payload Specification & Integration Plan (PSIP), Flight Operation Plan (FLOP), and on-site payload integration at the CSBF lab, as well as post-balloon launch activities. 2. Payload Subsystems The key subsystems of the payload are the detector module, comparator module, coincidence detector, micro-processor/CPU, and power module. A brief description of each module is given below.