From: "Michael McGuirk" To: "Dan Dewey"
Cc: Subject: RE: rad gratings - acoustic test? Date: Thu, 24 Jan 2002 16:34:59 -0500 Hi Dan, Pre- and post radiation tests were performed by Olivier Mongrard, who was a MS candidate in Mechanical Engineering, and did his thesis on the resonant frequencies and deflections of Mark's foil optics. I believe his measurements are accurate. There was no significant change in the resonant frequency of any grating. Even if material were knocked out of the polyimide, I would think that ACIS subtends such a small solid angle that not much would be collected. If there are hydrocarbons collecting on ACIS, I would think that the 900 lbs of epoxy in the optical bench would be a more likely source than the 1E-6 lbs of polyimide in HETG. Michael McGuirk, Ph.D. Voice: 617-253-3722 Research Technical Staff Fax: 617-253-0861 MIT 37-491 Cellular Phone: 508-735-6927 77 Massachusetts Avenue Cambridge, MA 02139-4307 -----Original Message----- From: Dan Dewey [mailto:dd] Sent: Thursday, January 24, 2002 4:00 PM To: mm Cc: hermanm Subject: rad gratings - acoustic test? Hi Mike, Do you know if our little lab acoustic test was performed on the rad-tested gratings as part of their post-exposure testing? Herman's thinking some of the polyimide could have been blasted away from the gratings that are in orbit (and deposited on the ACIS?!)... and we're wondering if we can test for such a thing either from visual inspection of post-rad gratings and/or acoustic test (change in res frequ, destruction of membrane...) thanks for any thoughts, - Dan