Please join us for an informal seminar sponsored by the Atomic and Molecular Physics Division, Harvard-Smithsonian Center for Astrophysics. (Complete schedule at http://www.cfa.harvard.edu/amp/events.html) 2:00 PM Thursday, June 7, 2012 Phillips Auditorium 60 Garden St, Cambridge, MA Near-IR imaging and UV-Vis spectroscopy of high-speed ejecta using the Caltech hypervelocity impact range Jon Tandy (Caltech) The Small Particle Hypervelocity Impact Range (SPHIR) facility at the California Institute of Technology recently added two spectrographs coupled with high-speed cameras to measure short-lived (~20 microsec) ejecta emission. Currently, this facility utilizes a 1.8 mm bore, two-stage light-gas gun to launch 5.2 mg nylon 6/6 impactors into 15 x15 cm aluminum targets at typical speeds ranging from 5-7 km/s. The facility now features a comprehensive set of in situ diagnostics that enable simultaneous observation of various phenomena in each experiment. High-speed photography is used to determine impact speed in each experiment. A second high-speed camera is used to implement an optical technique that creates "shadowgraph" images of the impact phenomena (front ejecta and debris cloud behind the target). The aforementioned spectrograph/camera systems are able to record either a single image or spectrum of the impact ejecta emission. Preliminary results from the near-IR imaging show an emitting ejecta "cloud" expanding from the impact site followed by a second, darker region of expanding material. UV-vis spectroscopy measurements of the emitting ejecta show several strong molecular emission bands between 380 nm and 650 nm. Preliminary assignments of these spectral bands show evidence of small molecular fragments originating from both the projectile and target material. _______________________________________________ Aspuru-meetings-list mailing list Aspuru-meetings-list(a)lists.fas.harvard.edu https://lists.fas.harvard.edu/mailman/listinfo/aspuru-meetings-list