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Grids
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Fine grids are being fabricated using new, innovative technology for Fourier-transform
imaging in X-rays and gamma rays. The square grids are manufactured by Van Beek Consultancy, the round
grids by Tecomet. The grid mounts are manufactured by Goddard Space Flight Center. Optical and x-ray tests
were performed by Goddard Space Flight Center.
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| HESSI Grid
Specifications - Nominal (as of 6/24/99) |
| Grid # |
1
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2
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3
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4
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| Nominal FWHM Resolution (arcsec) |
2.26
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3.92
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6.79
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11.8
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| Angular Pitch (arcsec) |
4.52
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7.84
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13.57
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23.5
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| Pitch (mm) |
0.034
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0.059
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0.102
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0.177
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| Source |
Tecomet
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Tecomet
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Tecomet
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Tecomet
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| Slit (mm) |
0.020
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0.035
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0.061
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0.106
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| Slat (mm) |
0.014
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0.024
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0.041
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0.071
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| Maximum Fractional Transmission |
0.60
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0.60
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0.60
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0.60
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| Total Grid Thickness (mm) |
1.2
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2.1
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3.6
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6.2
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| Field of View (degrees) |
1.0
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1.0
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1.0
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1.0
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| Shape |
Round
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Round
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Round
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Round
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| Mount Material |
Titanium
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Titanium
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Titanium
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Titanium
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| High-Z Absorber |
Molybdenum
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Tungsten
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Tungsten
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Tungsten
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| High-Z Absorber Density (g mm-3) |
0.0102
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0.0180
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0.0180
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0.0180
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| High-Z Absorber Layer Thickness (mm) |
0.018
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0.025
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0.0508
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0.0762
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| Epoxy Thickness (per layer) |
0.0026
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0.0026
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0.0026
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0.0026
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| Nominal Layer Count |
58
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76
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67
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79
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| Diameter (mm) |
90
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90
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90
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90
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| Outer Diameter (mm) |
110
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110
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110
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110
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| Rim Width (mm) |
10
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10
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10
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10
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| Rim (+ring) Material |
Moly+Kovar
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Tungsten+Kovar
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Tungsten
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Tungsten
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| Rim (+ring) Height |
1.2+4.0
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2.1+3.0
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3.6
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6.2
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| Mass (g) (incl. ring estimate) |
173
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288
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379
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626
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| Grid # |
5
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6
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7
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8
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9
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| Nominal FWHM Resolution (arcsec) |
20.4
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35.3
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61.1
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105.8
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183.2
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| Angular Pitch (arcsec) |
40.7
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70.5
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122.2
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211.6
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366.5
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| Pitch (mm) |
0.306
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0.530
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0.918
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1.590
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2.754
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| Source |
VBC
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VBC
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VBC
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VBC
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VBC
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| Slit (mm) |
0.184
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0.318
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0.477
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0.811
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1.487
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| Slat (mm) |
0.122
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0.212
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0.441
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0.779
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1.267
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| Maximum Fractional Transmission |
0.60
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0.60
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0.52
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0.51
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0.54
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| Total Grid Thickness (mm) |
10.7
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18.6
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6.2
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6.2
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30.0
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| Field of View (degrees) |
1.0
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1.0
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4.4
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7.5
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2.8
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| Shape |
Square
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Square
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Square
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Square
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Square
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| Mount Material |
Aluminum
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Aluminum
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Aluminum
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Aluminum
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Aluminum
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| High-Z Absorber |
Tungsten
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Tungsten
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Tungsten
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Tungsten
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Tungsten
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| High-Z Absorber Density (g mm-3) |
0.0190
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0.0190
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0.0185
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0.0190
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0.0190
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| High-Z Absorber Layer Thickness (mm) |
10.7
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18.6
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6.2
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6.2
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30.0
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| Epoxy Thickness (per layer) |
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| Nominal Layer Count |
1
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1
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1
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1
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1
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| Diameter (mm) |
90
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90
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90
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90
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90
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| Outer Diameter (mm) |
110
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110
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110
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110
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110
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| Rim Width (mm) |
10
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10
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10
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10
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10
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| Rim (+ring) Material |
Aluminum
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Aluminum
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Aluminum
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Aluminum
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Aluminum
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| Rim (+ring) Height |
20.7
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28.6
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16.2
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16.2
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40.0
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| Mass (g) (incl. ring estimate) |
1031
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1517
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681
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706
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2672
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