3/28/01, 4/4/01, 5/7/01, 5/21/01 dd

To test for effects of radiation exposure on HETG gratings,
**a sample of 12 facets**
were provided to MSFC for proton irradiation
at energies of 40 keV to 640 keV. Six of the 12 facets received
proton exposures and the other 6 did not. The facets were
pre- and post- tested at MIT and only after
**analyzing the test data**
were the identities of the irradiated gratings
provided to MIT personnel. There was no clear correlation
between irradiation and any change in grating properties,
we concluded:

*Any proton induced performance change is small,
and will be accommodated by the normal recalibration schedule.
There was no significant change in the resonant frequency of any grating.
*

**mm_010522.txt**<-- Summary note when rad gratings revealed

(**Ressonant Frequency note**)**proton_hetg.pdf**<-- The irradiated gratings!**rad_note_010521.txt**<-- Final note, includes rad_anom.txt**rad_note_010507.txt****mmdd_010405.txt****odell_notes.txt****rad_note_010313.txt****rad_note_010307.tx**

Plots comparing the pre and post exposure diffraction efficiencies were made for each of the five regions of each of the 12 possibly-exposed gratings and are available here:

**rad_anom.txt**<--- Anomalies noted in the comparison plots

and the status of investigating them.**rad_allrad.ps**and**rad_allrad.pdf**<--- Plots Compare Post/Pre Radiation Exposed Gratings- Earlier versions of these products
**010507 -- rad_anom.txt****010404 -- rad_allrad.ps**,**rad_allrad.pdf**,**rad_anom.txt****010328 -- rad_allrad.ps**,**rad_allrad.pdf**

A brief explanation of the two types of plots on these pages is given here...

Plot of the absolute efficiencies measured by X-GEF for
a specific grating and region. For each closely spaced pair of points, the left one is the "pre" value and the right one is the "post" value. The diffraction order is indicated by "1st", "2nd", and "zo". The second-order points are: MEG: m= + - + - + - + - (8) E= 1.25 1.49 2.29 4.51 HEG: m= - - - + - + - (7) E= 1.25 1.49 2.29 4.51 6.40 | |

Plot of the Ratio of "post"/"pre" exposure values. The X-GEF date codes are given as well as the Chi-squared value for each order set. The error bars shown are plus/minus one sigma. |

The plots above give the reduced Chi-squared value:

Chi^2/N = TOTAL{ ( Ratio - 1.0 )^2 / Error_in_ratio^2 } / N_pointsfor each region and type of data (zeroth, first, second orders). This value indicates the agreement of the measurements with the "no change" hypothesis (ratio = 1.0) for first-order (fo), second order (so) and zeroth-order (zo) measurements. For the 10 or 12 first-order ratio points, a value greater than about 2.2 would occur statistically only 1 per cent of the time.

The 5-region-averaged reduced Chi-squared values for each grating are given in the tables below. In this case, for the 50 to 60 first-order measurements, values greater than 1.5 would occur randomly in only about 1 per cent of the cases.

MA1025 Chi^2 fo: 1.3, so: 1.2, zo: 2.1 MA1026 Chi^2 fo: 0.95, so: 1.0, zo: 2.1 MB1148 Chi^2 fo: 1.4, so: 0.80, zo: 2.6 MB1158 Chi^2 fo: 0.66, so: 2.3, zo: 0.73 MA1022 Chi^2 fo: 0.71, so: 1.3, zo: 1.2 ME1409 Chi^2 fo: 1.2, so: 2.8, zo: 0.41 HC2214 Chi^2 fo: 0.59, so: 2.5, zo: 0.0 HC2259 Chi^2 fo: 0.90, so: 7.2, zo: 0.0 HB2104 Chi^2 fo: 2.3, so: 3.8, zo: 5.2 HE2426 Chi^2 fo: 0.71, so: 2.1, zo: 0.22 HE2412 Chi^2 fo: 0.45, so: 2.8, zo: 1.2 HF2517 Chi^2 fo: 1.3, so: 2.0, zo: 4.3

*** OLD 010404 Values *** Rad-exposed Gratings "Post- / Pre-" MA1025 Chi^2 fo: 1.3, so: 1.2, zo: 2.1 MA1026 Chi^2 fo: 0.95, so: 1.0, zo: 2.1 MB1148 Chi^2 fo: 1.4, so: 0.80, zo: 2.6 MB1158 Chi^2 fo: 0.66, so: 2.3, zo: 0.73 MA1022 Chi^2 fo: 0.71, so: 1.3, zo: 1.2 ME1409 Chi^2 fo: 1.2, so: 2.8, zo: 0.41 HC2214 Chi^2 fo: 0.62, so: 3.2, zo: 0.0 HC2259 Chi^2 fo: 1.3, so: 1.7, zo: 0.0 HB2104 Chi^2 fo: 2.5, so: 4.3, zo: 5.2 HE2426 Chi^2 fo: 0.76, so: 3.2, zo: 0.22 HE2412 Chi^2 fo: 0.54, so: 1.2, zo: 1.2 HF2517 Chi^2 fo: 1.5, so: 1.9, zo: 4.3

*** OLD 010328 Values *** Rad-exposed Gratings "Post- / Pre-" MA1025 Chi^2 fo: 1.3, so: 1.2, zo: 21. MA1026 Chi^2 fo: 0.95, so: 1.0, zo: 2.1 MB1148 Chi^2 fo: 1.4, so: 5.5, zo: 2.6 MB1158 Chi^2 fo: 0.66, so:4.5E+04, zo: 0.73 MA1022 Chi^2 fo: 0.71, so: 1.3, zo: 1.2 ME1409 Chi^2 fo: 1.2, so: 2.8, zo: 0.41 HC2214 Chi^2 fo: 0.62, so: 3.2, zo: 0.0 HC2259 Chi^2 fo: 1.3, so: 1.7, zo: 0.0 HB2104 Chi^2 fo: 2.5, so: 4.3, zo: 5.2 HE2426 Chi^2 fo: 0.76, so: 3.2, zo: 0.22 HE2412 Chi^2 fo: 0.54, so: 1.2, zo: 1.2 HF2517 Chi^2 fo: 1.5, so: 1.9, zo: 4.3

Similar plots were made by comparing the
**
HETG Vacuum Storage Gratings** at different
(sequential) epochs:

**rad_allvsg1.ps**and**rad_allvsg1.pdf**<--- Compares "Dec.00" to "July 99"**rad_allvsg2.ps**and**rad_allvsg2.pdf**<--- Compares "July 99" to "Oct.98"

MA1019 Chi^2 fo: 1.1, so: 1.5, zo: 0.51 MA1040 Chi^2 fo: 0.95, so: 1.5, zo: 1.8 MC1212 Chi^2 fo: 2.5, so: 2.6, zo: 1.9 ME1408 Chi^2 fo: 0.94, so: 2.1, zo: 1.3 MB1165 Chi^2 fo: 1.5, so: 1.8, zo: 1.6 MD1367 Chi^2 fo: 1.8, so: 1.5, zo: 1.2 HA2003 Chi^2 fo: 0.94, so: 2.2, zo: 0.60 HD2334 Chi^2 fo: 0.61, so: 0.94, zo: 1.4 HA2045 Chi^2 fo: 3.8, so: 12., zo: 10. HC2251 Chi^2 fo: 0.71, so: 1.3, zo: 98. HB2121 Chi^2 fo: 0.96, so: 1.2, zo: 0.0 HF2503 Chi^2 fo: 1.6, so: 2.2, zo: 0.71 HE2423 Chi^2 fo: 2.9, so: 1.1, zo: 18. H2102 Chi^2 fo: 1.3, so: 2.0, zo: 0.0

MA1019 Chi^2 fo: 1.5, so: 0.92, zo: 0.92 MA1040 Chi^2 fo: 1.6, so: 1.3, zo: 1.9 MC1212 Chi^2 fo: 1.4, so: 1.2, zo: 0.87 ME1408 Chi^2 fo: 0.98, so: 3.4, zo: 0.73 MB1165 Chi^2 fo: 1.8, so:4.8E+02, zo: 1.2 MD1367 Chi^2 fo: 0.84, so: 1.3, zo: 1.6 HA2003 Chi^2 fo: 0.99, so: 1.8, zo: 0.37 HD2334 Chi^2 fo: 1.1, so: 1.1, zo: 2.9 HA2045 Chi^2 fo: 1.1, so: 3.2, zo: 2.5 HC2251 Chi^2 fo: 0.96, so: 1.2, zo: 8.4 HB2121 Chi^2 fo: 1.1, so: 1.1, zo: 0.79 HF2503 Chi^2 fo: 0.93, so: 0.85, zo: 1.2 HE2423 Chi^2 fo: 0.97, so: 1.1, zo: 0.49 H2102 Chi^2 fo: 1.3, so: 1.6, zo: 0.95

For reference, the tables and plots presented here were created by the IDL routines:

- xgef_test/
**rad_compare.pro** - xgef_test/
**rad_loop.pro**