CERENKOV COUNTER

The purpose of the experiment was to measure the flux of cosmic-ray alpha particles and to investigate the usefulness of a Cerenkov counter for flux measurements on the more heavily charged cosmic-ray components.

The equipment onboard this flight consisted of a Geiger counter telescope to define a solid angle in space from which particles will be accepted, a Cerenkov counter to determine their charge, some devices to identify background events, and apparatus to record the information obtained.

Trays A, B, and C, which are shown in solid black in the figure at left, formed the Geiger counter telescope. The equipment recorded only those events which caused a coincidence between these three trays. Thin-wall counters were used in tray A to reduce the number of nuclear interactions occurring just above the radiator. Between trays A and B was the Cerenkov counter. The radiator was a cylindrical slab of Lucite 4 inches in diameter and 1 inch thick. The Lucite was optically coupled by a film of Canada balsam to the cathode of a Dumont K1198 photomultiplier.

There were 8 Geiger counters in each tray so the bottom 64 square inches were effectively divided into 64 separate units, and the detector could tell whenever particles passed through more than one of these units simultaneously. To determine which events were really due to alphas and which to background, four guard counters were placed alongside the Lucite radiator to detect side showers.

All the equipment was mounted in a spherical gondola whose diameter was 30 inches and whose wall thickness was 0.03 inches. The gondola was pressure tight, and thus the equipment remained in one atmosphere of pressure during the flight, to prevent corona discharge.

Balloon launched on: 2/2/1954
Launch site: Goodfellow Air Force Base, San Angelo, Texas, US  
Balloon launched by: Winzen Research Inc.
Balloon manufacturer/size/composition: Zero Pressure Balloon Winzen
Balloon serial number: 90-2x100-V-64
Flight identification number: WRI 339
End of flight (L for landing time, W for last contact, otherwise termination time): 2/2/1954 at 15:28 cst
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 8 h
Overall weight: 562

The balloon was launched from Goodfellow AFB, in San Angelo, Texas, on Februrary 2, 1954. It reached an altitude of 16 g/cm2 at 9:30 CST and remained within 1 g/cm2 of this altitude until 15:28 when the flight was terminated. The equipment was recovered in good condition.

• Cerenkov Counter Flux Measurement of Cosmic-Ray Alphas at 41º Phys. Rev. 98, 165
• Cerenkov Counter Flux Measurement of Cosmic-Ray Alphas at 41º Technical Report - University of Minnesota Physics group, August 1954
• Flight Summary Log Winzen Research Inc. report (1963)