 |
SODART - XSPECT |
XSPECT is the general term for the Danish part of the SODART telescope.
XSPECT consist of the SODART mirror modules (MM
), the Bragg panel - called the Objective Crystal Spectrometer (OXS) and the 4 proportional counters HEPC/LEPC.
- Mirror Modules
- There are two sets of mirror modules. The MM is designed as a conical
approximation to the Wolter I Xray telescope geometry. The outer
diameter of the MMs are 600 mm and inner radius is 82 mm. The focal
length is 8000 mm. The MMs have each 143 laquered and AU-coated 0.4 mm
thick Al-foils, nested to completely fill the opening. The design goal
is an angular resolution of 2 arcmin HPW.

Scanned in from MOR v2.3 Dec 1994 (for complete document go here)
Field of view (arcmin) |
60 |
Half power width (arcmin) |
< 3 |
Focal length (m) |
8 |
Diameter: Inner Shell (cm)
Outer Shell (cm)
|
16 60 |
Reflecting surface (Å gold) |
400 |
Effective area cm2
@2 keV cm2@8 keV
cm2@20 keV
|
1460 1120 94 |
Shell material (mm aluminium) |
0.4 |
Shell separation (min -( mm)) |
0.52 |
Shell length (cm) |
20 |
Number of shells |
143 |
Mass per telescope (kg) |
101 |
Total mirrored surface (m2) |
62 |
Taken from the MOR v1.9 (for complete document go here)
- OXS - Objective Crystal Spectrometer
- The OXS is situated in front of one of the MMs (MM no. B). The OXS
concept separates the processes of energy dispersion and imaging. The
large mosaic panel of flat crystals in front of the telescope acts as
a narrow bandpass filter and as a mirror. Each pixel in the reflected
field of view of the telescope satisfies a specific Bragg angle on
the crystal and, therefore, each pixel in the detector can be
identified with a particular energy. Scans which involve repositioning
of the telescope axis and the angle between the crystal panel and the
telescope axis (45��15�) yield either the spectrum of a point
source or energy resolved images of an extended source. Multilayer (ML)
structures will be deposited on the polished surfaces of the LiF and
Si crystals to allow simultaneous measurements of the Fe L and other
prominent lines in the energy range below the C K-edge.
The following table shows the main parameters for the OXS, implying
the performance of the spectrometer.
>
NATURAL CRYSTALS | LiF (220) | Si (111) |
RAP (001) |
Lines: H- and He-like | Fe | S & Ar | O
|
Bragg Angle (He-like) deg | ~41 | ~50 & ~39 |
~57 |
Wavelength Range � | 1.7 - 2.5 | 2.7 - 5.4
| 15.4 - 22.6 |
Energy Range keV | 5.0 - 7.4 | 2.3 - 4.6 |
0.55 - 0.81 |
Rocking Curve Width arcmin | ~2.5 | ~1.6 |
~7 |
Resolution (point source) E/dE | ~1250 | ~3200 |
~770 |
Peak Reflectvity % | ~21 | ~35 | ~2 |
MULTILAYER CRYSTALS | ML (001) on LiF |
ML (001) on Si |
Composition | Ni/C | Co/C |
Wavelength Range � | 56 - 83 | 44 - 71 |
Energy Range keV | 0.15 - 0.22 | 0.175 - 0.28 |
2d Spacing � | 96 | 79 |
Number of Layers | ~60 | 65-80 |
Peak Reflectivity % | ~20 | 12-22 |
Resolution (point source) E/dE | ~55 | 52 |
- HEPC/LEPC
- The HEPC/LEPC detectors are Microstrip Proportional Counters. The MSPC
is a novel approach, in which the wire grids in conventional
proportional counters are replaced by narrowly spaced, conducting
microstrips which are accurately deposited to 0.1 micron on an
insulating substrate. A high- and a low-energy (HEPC and LEPC) detector
will be provided for each telescope. Figure 1 shows the Mirror Module
(MM) plus the HEPC/LEPC effective area.

Figure 1. The HEPC and LEPC effective area
HEPC/LEPC: Instrument performance
Energy resolution | 0.32 x (E/1 kev)� keV |
Background rejection | > 99 per cent |
Time resolution | < 10 microsec |
Gas | Xe 90%, CH4 10% |
| HEPC | LEPC |
Field of view (arcmin) | 60 | 30 |
Diameter of active area (mm) | 150 | 75 |
Diameter of window (mm) | 140 | 70 |
Position resolution (mm) | <1 | <2 |
Energy range (keV) | 2 - 25 | 0.2 - 8 |
Gas thickness (cm) | 4 | 4 |
Gas pressure (atm) | 1 | 0.5 |
Window : Polyimide (microns) | 7.5 | 0.85 |
Al (nm) | 52 | 38 |
Taken from the MOR v1.9 (for complete document go here)
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This page is maintained by
Dr. Jonathan Mittaz
Last modified 9 June 1997.
on is
the reduction of the limiting brightness by one or two magnitudes.
The fast photometry mode allows measurement of the UV brightness of up to
two source