Jet-X at MSSL

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.

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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 Å	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 Å	56 - 83	44 - 71
Energy Range keV	0.15 - 0.22	0.175 - 0.28
2d Spacing Å	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)½ 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

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This page is maintained by Dr. Jonathan Mittaz
Last modified 9 June 1997.

The fast photometry mode allows measurement of the UV brightness of up to two source