Objective Crystal Spectrometer OXS

The OXS is a two flat sides 65*61 cm2 panel placed in front of one of the high throughput SODART telescopes. One side of this panel is completely covered with 23x63 mm2 LiF(220) crystals, while the other side is covered partly with 20*60 mm2 RAP(001) crystals and partly with 60*60 mm2 Si(111) crystals coated with ~70 periods Co/C. The 36 coated Si-crystals will allow simultaneous spectroscopy in two separate wavelength bands; while the softer x-ray wavelengths are reflected in the multilayer coatings, the harder x-ray wavelengths are reflected in the substrate (Si-111). The composition of this panel allows high resolution spectroscopy in the energy bands that encompass the H- and He-like emission line features from the cosmically important elements Fe, S, Ar and O. An estimation of the effective area in the 4 energy windows yields >100cm2 from 5 to 7.4 keV, >200 cm2 from 2.3 to 4.6 keV, ~10 cm2 from 0.55 to 0.81 keV and ~100 cm2 from 0.175 tp 0.28 keV.

The below table lists the specifications of the OXS

BRAGG CRYSTALS                LiF(220)  Si(111)   RAP(001)
lines: H- & He-like           Fe        S  & Ar   O
Bragg angle (He-like)deg      41        50 & 39   57
Wavelength Range    nm        0.17-0.25 0.27-0.54 1.54-2.26
Energy Range        keV       5.0-7.4   2.3-4.6   0.55-0.81
Rocking Curve width arcmin    2.5       1.6       7
Energy Resolution   E/(del)E  1250      3200      770
Peak Reflectivity   %         21        35        2

MULTILAYER COATING            ML(001) on Si(111)
Composition                   Co/C
Wavelength Range    nm        4.4-7.1
Energy Range        keV       0.175-0.28
2d Spacing          nm        7.9
# periods                     60-70
Peak Reflectivity   %         12-22
Rocking Curve width arcmin    40
Energy Resolution   E/(del)E  80