High Energy Astrophysics with STACEE

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This proposal requests funds to support the Barnard College group in expanding their efforts in the STACEE project. STACEE (Solar Tower Atmospheric Cherenkov Effect Experiment) is a ground-based detector sensitive to gamma-rays in the energy range between 50 and 1000 GeV. Gamma-ray observations provide one of the most direct ways to learn about the highest energy astrophysical accelerators in the Universe. By studying sources of very high-energy (VHE) radiation, one may glimpse astrophysical situations in which physics operates under extreme conditions of gravitational or magnetic fields. A unique feature of STACEE is that it operates at energies below 250 GeV, a regime that is out of the scope of current atmospheric Cherenkov telescopes (ACTs). Due to its low energy threshold, STACEE will be able to observe AGN and GRBs out to redshifts of Z ~ 1. The construction of STACEE started in 1997 and is now complete. Results obtained during the construction phase have been very encouraging. The Crab nebula was detected in 1998 with a significance of greater than six standard deviations and the active galaxy Markarian 421 was detected in 2001 during an outburst. During the 2001 campaign, STACEE was the only instrument to detect the source at energies below 250 GeV, an important region in the spectral energy distribution of the source. Prior NSF funding was used to support the PI's participation in STACEE, particularly in the calibration system and analysis efforts. Funding is now requested, at a time when STACEE is functioning as an observatory, to support a graduate student and to enable the PI to make a major contribution to the project, including: 1) participating in the observing program, 2) playing a leading role in the development of the data analysis, 3) obtaining scientific results using new observational data, and 4) maintaining the laser calibration system.Broader Impact: This research has broader impact on several areas outside of particle astrophysics. Areas of broader impact include (1) the use of heliostats to support remote sensing for earth-viewing satellites, (2) design and implementation of new types of non-imaging optical systems, (3) the development of mirror measurement techniques for solar energy applications, and (4) software development for high-speed data acquisition. Finally, the PI has been involved in outreach efforts to K-12 students and the broader public. Activities have included public lectures, week-long activities for K-12 students (summer schools) and individual student mentorships.