Hard X-ray/soft gamma-ray astronomy is on the threshold of a major technological advance: the introduction of focussing optics above 20 keV. This advance will provide dramatic improvements in sensitivity and angular resolution not achievable with the current generation of background-limited non-focussing hard X-ray instruments. The advent of focussing optics at hard X-ray energies will have the same impact that the introduction of grazing incidence X-ray telescopes had at energies below 10 keV. In particular, entire new classes of hard X-ray observations will become possible, such as the detailed study of large samples of extragalactic objects, and the mapping of non-thermal diffuse emission.
The High Energy Focusing Telescope (HEFT) is a balloon-borne experiment that uses depth-graded multilayer optics and cadmium zinc telluride pixel detectors to image astrophysical sources in the hard X-ray (20–100 keV) band. Its maiden flight of 25 hours took place in May 2005 from Fort Sumner, New Mexico.
Graduate student Hubert Chen presented an overview of HEFT in an Everhart Lecture at Caltech on 24th May, 2007. The lecture is now streaming online at the Caltech Streaming Theater (realplayer required to view).
The focal-plane detectors on HEFT were featured in a NASA Tech Briefs article in April 2005.
An enthusiast of stratospheric balloons (with no relation to us) has written this page documenting our 2005 balloon launch.