GAMMA RAY DETECTOR

Developed by University of Minnesota

Balloon launched on 9/19/1967, from Columbia Scientific Balloon Facility, Palestine, Texas, US

Purpose of the flight and payload description

The objective of the flight was to measure the intensity and energy spectrum of cosmic ray electrons with energies above Gev, using a nuclear emulsion-spark chamber combination detector triggered by scintillation and Cherenkov counters.

A schematic diagram of the detector is shown in the figure at left. The geometry of the telescope was defined by the middle scintillator S1, the gas Cherenkov counter C1, the bottom scintillation S2, and a hole cut in the anticoincidence shield S3. These elements give a factor of 38 cm2 ster after correcting for non usable portions of the emulsion stack. The major detector element is the stack of emulsions (Ilford G-5) flanked on top and bottom by two thin-plate spark chambers with 6 and 2 gaps, respectively. The top spark chamber picture is used to locate the primary track entering the emulsions; the bottom chamber picture reveals whether the primary has produced an electromagnetic or a nuclear interaction in the emulsion stack. The emulsion block consisted of a vertical stack 49 X 12.6 X 6.5 cm and horizontal steel-emulsion-lead sandwiches, making up a total of 6.5 radiation lengths (rl). A triple coincidence between S1, C1, and S2 with no S3 triggers the spark chambers, and a camera takes stereoscopic pictures using folded optics.

Details of the balloon flight

Balloon launched on: 9/19/1967 at 3:20 utc
Launch site: Columbia Scientific Balloon Facility, Palestine, Texas, US  
Balloon launched by: National Center for Atmospheric Research (NCAR)
Balloon manufacturer/size/composition: Zero Pressure Balloon Winzen 10.600.000 cuft (0.5 MIL. Stratofilm)
Flight identification number: 348P
End of flight (L for landing time, W for last contact, otherwise termination time): 9/19/1967 at 20:31 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 17 h 15 m
 Payload weight: 990 kgs

External references

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