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Solar X-Ray Monitor

NSSDCA ID: 1972-014A-06

Mission Name: TD 1A
Principal Investigator:Prof. Cornelis de Jager


The solar hard X-ray, integrating, pulse-counting spectrometer measured 24 to 900 keV X rays in 12 approximately logarithmically-spaced energy channels. The instrument consisted essentially of a scintillation counter. A CSi (na) crystal of sensitive area of 5 sq cm and of thickness 15 mm was optically coupled to an EMR photomultiplier tube. Impulse height analysis was done by means of discriminators, because of low dead-time and redundancy advantages in comparison with a multi-channel analyzing system. The energy channel limits were 24, 34, 45, 63, 90, 125, 175, 270, 320, 420, 540, 670, and 900 keV, which were sufficient for the analysis of the flare-photon spectral distribution. The sampling rate was 1.2 s for the four low-energy channels and 4.8 s for the others. To absorb the background X rays from various sources a lead-tin-copper shield-collimator was placed around the counter. The full width at half maximum of the collimator was 26 deg. To minimize the effects of background particles, inside the collimator were two solid-state detectors mounted in front of and completely masking the scintillation crystal. All particles entering the scintillator within the field of view were detected by these two solid-state devices. Thus, pulses in the scintillator, which were coincident with particles detected in the solid-state units, could be rejected. In-flight calibration of the whole system utilized the detection of the decay products from the two radioactive sources SR(90) and AM(241).

Alternate Names

  • S100
  • Solar X-Ray Monitor in the Energy Range 20 to 300 KeV
  • TD1A/SolarX-RayMonitor

Facts in Brief

Mass: 4.4 kg
Power (avg): 3.3 W
Bit rate (avg): 0.1 kbps

Funding Agency

  • Unknown (The Netherlands)


  • Solar Physics: X-Ray

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Prof. Cornelis de JagerPrincipal InvestigatorUniversity of
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