From: "Michael McGuirk" To: "Lavoie, Tony" , "O'Dell, Steve" , "'William F Mayer'" , "'Eugene B Galton'" Cc: "Weisskopf, Martin" ,
Subject: RE: The envelope, please. Date: Tue, 22 May 2001 14:14:14 -0400 Three of the four gratings we identified had been irradiated. MB1148, HB2104, and HF2517. HC2259, which has unexplained changes, was not irradiated. MA1025 was irradiated, but not identified. Dan's comments: (smiley face indicates no "unexplained" changes) >MA1025 (010301/001207) > OK - zero jump at 0.93 keV (high zo Chi2) > 4/4-OK: SSD/fitting problem, reanalyzed, lowered Chi2 > OK - first second-order point consistently ~12% low in all regions > 5/8-OK: fits look good. Error on ref ratio is 6% one sigma - > ref stat error could create this easily. Note that the Chi2 > is not large for the regions. > :) , MB1158 was irradiated, but not identified. Dan's comments: >MB1158 (010302/001117) > OK - second order Chi2 large - poor fitting of small signals > 4/4 exclude poor fits/measurements > :) HE2426 was irradiated, but not identified.. Dan's comments: >HE2426 (010309/001115) > OK - large second-order Chi2 in m8 (Al-K +1 order) > 5/7 re-analysis reduced the Chi2. > :) The thickness of the bars is chosen to minimize the second order, so the counting statistics are poor. A small change in thickness or bar shape would change the second order response, but might not be believable by itself. It is interesting, but not conclusive, that all three gratings which were irradiated showed changes in the second order. The bottom line is still: "Any proton induced performance change is small, and will be accommodated by the normal recalibration schedule." We will be producing a more complete report, but didn't want to keep everyone in suspense. 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