X-RAY DETECTOR

This flight was an enginnering flight of short duration to test the components of a X-ray/gamma-ray burst experiment specially developed to be transported under a balloon in a Transatlantic flight from Italy to USA.

The detector was composed by an array of six 100-cm2 NaI(Tl) detectors along with four passive collimators to separate X-ray sources. The counts of each detector were sampled in four energy channels for equal periods of time. The data handling as well as the film recording were designed to suit the apparatus on the future transatlantic flight.

The detector was mounted in a gondola orientated by an azimuth control system.

Balloon launched on: 11/4/1975
Launch site: Columbia Scientific Balloon Facility, Palestine, Texas, US  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon Winzen 157.346 m3 (12.70 Microns - Stratofilm)
Flight identification number: 938P
End of flight (L for landing time, W for last contact, otherwise termination time): 11/4/1975
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): F 7 h 30 m
Payload weight: 490 kgs.

During the flight was performed an observation of the hard X-ray spectrum (25-150 keV range) of Cyg X-l during the third upward transition of the source in 1975.

• National Scientific Balloon Facility Annual Report FY 1976 National Center for Atmospheric Research, March 1977
• The hard X-ray spectrum of Cyg X-1 during the transition in November 1975 Nature 263, 752 - 753 (28 October 1976)