Design and testing of a compact X-ray diode. 1998 summer research program for high school juniors at the University of Rochester`s Laboratory for Laser Energetics: Student research reports

Omega, the University of Rochester`s high powered laser dedicated to fusion research gives off x-rays with different energy levels. Measuring the number of x-rays and the energy of each is important in understanding what happens in the target chamber when Omega is fired. Existing x-ray detectors are expensive, big, and cumbersome. Imaging detectors such as x-ray pinhole cameras which record onto film, x-ray framing cameras which make videos, and most often, x-ray streak cameras which measure time dependences of x-rays. They require a lot of maintenance and are difficult to keep operational. Lawrence Livermore National Laboratory has developed the Dante Diode. The Dante diode array on Omega functions as a group of 12 diodes which take up a 24 inch port in the target chamber, making it space-consuming and difficult to move for alternate views. In designing a new detector, space was the main issue. The smallest possible functional diode, without losing accuracy was desired. Since the laser pulse only lasts a few nanoseconds it is important that the x-ray detector have a response time of a few tenths of a nanosecond. Other criteria include that it be easy to use for measuring the energy and number of x-ray photons and that cost be kept down. This report discusses the design process and testing of the new diode