The Rosat Pspc

With a continuous operational life time of 4 years and an additional life of 4 years with alternating hibernation and operation (due to the nearly exhausted gas supply), the ROSAT PSPC (Fig. 4.5) was one of the most successful imaging X-ray detectors [18,19]. Because of a high mechanical accuracy of the wire grids of the order of micrometer, the detector gain was uniform within 3% over the sensitive area. The position resolution, mainly limited by the size of the primary electron cloud arriving at the anode, was 250 |0,m at 930 eV Cu-La and about 400 |0,m at 280 eV C-Ka. A five-sided anticoincidence counter system in connection with an event

Table 4.1 Performance of imaging proportional counters aboard several X-ray astronomy satellites

Satellite

Einstein

EXOSAT

ROSAT

INTEGRAL

Telescope

Imaging

Imaging

Imaging

Coded mask

Focal length

340 cm

110 cm

240 cm

-

Detector

IPC

PSD

PSPC

JEM-X

Active area

58 cm2

6.2 cm2

50 cm2

500 cm2

Energy range

0.2-4 keV

0.1-2 keV

0.1-2.4 keV

3-35 keV

Window

Lexan

Lexan

Lexan

Be 250 |im

1.8 |im PP

0.5 |im PP

1 |im PP

C

0.8 |im PP+C

C

Gas

84% Ar

80% Ar

65% Ar

90% Xe

6% Xe

20% Xe

Quench gas

10% CO2

20% CH4

15% CH4

10% ch4

Pressure

1.05 bar

1.1 bar

1.46 bar

1.5 bar

Sealed/Flow

F

F

F

S

aE/E % (FWHM)

122

42

41

40

V£(keV)

E (keV)

\/E(keV)

V£(keV)

AX mm (FWHM)

1.0

0.25

0.25

1.94

V£(keV)

VE(keV)

VE(keV)

VE(keV)

Ang. Res. (HPD)

Det. + Mirror

1 arcmin

0.75 arcmin

0.42 arcmin

3.4 arcmin

NXB

arcmin-2 s-1 keV-1

3 x 10-5

Not available

5 x 10~6

1 x10-5 *

NXBxRE

s-1keV-1

2.4 x 10~5

Not available

1 x 10~6

-

Reference

[8,9]

[7,13]

[18,21]

[3,11]

PP, polypropylene; C, carbon; NXB, non X-ray background; HPD, half power diameter; RE, angular resolution element arcmin2 * = mm-2 s-1 keV-1

PP, polypropylene; C, carbon; NXB, non X-ray background; HPD, half power diameter; RE, angular resolution element arcmin2 * = mm-2 s-1 keV-1

selection logic, based on the cathode pattern signature of the events, resulted in a background rejection efficiency of 99.8%. The excellent background rejection efficiency of the PSPC allowed deep observations with high contrast. Radiation hardness of the detector against heavy ionizing particle events was tested on a heavy ion tandem accelerator. A careful prelaunch calibration was carried out concerning quantum efficiency, energy resolution, and spatial resolution. [5,6]

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