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