SOLAR NEUTRON DETECTOR

The experiment was a neutron detector with no directional properties but with high efficiency. The goal was to use the detector to search for time variations of the high altitude neutron flux. Such time variations include when the sun emits neutrons continuously and also if neutrons are produced in association with solar activity.

A schematic drawing of the detector system is shown at left. It consisted of a cylindrical NE 102 plastic scintillator which was viewed by three photomultiplier tubes, and these components were all completely surrounded by a 1.9 cm thick plastic scintillator charged particle shield. The output pulse height distribution of the neutron detector was cruder determined by recording the counting rates above three integral discrimination levels. A second detector included in the experiment was a Csl(Na) scintillator also completely surrounded by its own plastic charged particle shield. It was also equipped with three integral level discriminators.

The operation of the two detectors, except for common low voltage power supplies and the recording system, was completely independent. Each detector along with its complete electronics circuitry and high voltage DC-DC converter was in its own pressurized container. The rates from the three integral level discriminators and the charged particle shield of each detector were electronically sealed and recorded on photographic film. A clock pulse and the temperature in each pressure shield were also recorded during the flight. The total thíckness of matter between the basic neutron or gamma ray detectors and the atmosphere was 4 to 5 g/cm2 and consisted of the plastic charged particle shields, fiber glass pressure containers and polystyrene thermal insulation.

Balloon launched on: 7/18/1967
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 2.940.000 cuft (0.5 MIL.)
Flight identification number: 326P
End of flight (L for landing time, W for last contact, otherwise termination time): ??/??/1967
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 1 h
Landing site: Balloon reached 50.000 ft and started to descend
Payload weight: 385 kgs

The balloon rose to 50,000 feet and floated for 40 minutes before starting to descend. Usable data was obtained on the altitude dependence of the neutron flux and gamma ray spectrum up to the maximum altitude achieved.

• A search for high energy solar neutrons Ph.D Thesis by David John Forrest, University of New Hampshire, 1969
• NCAR Scientific Balloon Facility Annual Report, 1967 National Center for Atmospheric Research, January 1968