GAMMA RAY SPECTROMETER

Developed by Instituto Nacional de Pesquisas Espaciais (INPE)

Balloon launched on 12/20/1983, from Balloon Launch Sector, Cachoeira Paulista, Brazil

Purpose of the flight and payload description

The instrument flown in this balloon mission was a double coaxial Ge(Li) spectrometer aimed to observe and measure the nuclear gamma-ray lines of cosmic origin. A simplified cutaway view of the instrument is shown at left.

The heart of the gamma-ray spectrometer is a system of two coaxial Ge(Li) diodes separated from each one by 12,5 mm. The diodes are right circular cylinders 47 mm in diameter and 25 mm in height corresponding to a volume of 44 cm3 each. They are polarized by the same high voltage power supply at 2100 volts negative bias. Detectors, high voltage and charge amplifiers (Canberra 970D and 2001) are enclosed in pressurized aluminium vessels which maintain the subsystems at atmospheric pressure.

The Ge(Li) diodes are cooled to a temperature of about 77 K by liquid nitrogen contained in a dewar, which was enough to keep the detector at operating temperature during all flight time.

The diodes are surrounded by a three-section Nal anticoincidence shield. The lower part of the shield consists in two semi-circular cylinders of dimensions 8" diameter by 2" height (LM1 and LN2), which are viewed by two 2060 RCA photomultiplier tubes. The upper section is a circular cylinder of dimensions 8" diameter by 6" height (UN), viewed by four 2060 RCA photomultiplier tubes.

The diodes are placed approximatively at half of the upper section's height, providing a field of view of ~50º.

Details of the balloon flight

Balloon launched on: 12/20/1983 at 01:52
Launch site: Balloon Launch Sector, Cachoeira Paulista, Brazil  
Balloon launched by: Instituto Nacional de Pesquisas Espaciais (INPE)
Balloon manufacturer/size/composition: Zero Pressure Balloon Raven - 184.000 m3
End of flight (L for landing time, W for last contact, otherwise termination time): 12/20/1983 at ~ 13:00
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 11 h
Landing site: In Santa Fe do Sul, Sao Paulo, Brazil

External references

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