HODOSCOPE

The objective of the flight was to obtain measurements of the energy spectrum of electrons between 1 GeV and 25 GeV present in cosmic rays at stratospheric altitudes using an hodoscope. The term hodoscope is derived from the Greek root ''hodos", meaning path, and ''scopes", meaning to watch. Thus that denomination is used in particle physics to describe any device (usually electronic) that determines and displays the trajectory of a charged particle. The flight was part of a yearly program carried out at high and intermediate latitudes by the Department of Physics and Astronomy of the University of Maryland.

An schematic diagram of the hodoscope can be seen in the figure at left (click to enlarge). It was composed of six crossed trays of Geiger tubes which gave a crude stereoscopic description of particle trajectories, served as a guard element able to identify multiple incident particles, and provided information on the number of particles emerging downward from the absorber in association with electromagnetic cascades or nuclear interactions. Each tray contained 9 tubes of 1.58 cm outside diameter and 14.2 cm sensitive length.

Triggering particles were selected by coincidence requirements among tubes in the top four trays chosen so as to define straight line trajectories passing completely through all absorbers and exiting through Tray 6. This was accomplished by combining a selected set of eleven two-fold coincidences between tubes in Trays 1 and 3 with a similar set of eleven coincidences based on discharges in Trays 2 and 4. Thus, a group of 121 four-fold coincidences defined incident trajectories suitable for analysis while discriminating against trajectories not suited to unambiguous interpretation. This scheme was denominated the directional filter.

The Geiger-tube discharges were processed in the flight apparatus, telemetered to a ground station and tape recorded for post-flight analysis by computer.

Balloon launched on: 9/7/1966 at 00:02 utc
Launch site: Fleming Field Airport, South St.Paul, Minnesota, US  
Balloon launched by: Winzen Research Inc.
Balloon manufacturer/size/composition: Zero Pressure Balloon Winzen 749.000 cuft (0.5 Mil. Stratofilm)
Flight identification number: 1058W
End of flight (L for landing time, W for last contact, otherwise termination time): 9/7/1966 at 23:00 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 23 h 33 m
Landing site: 1 km E of Cable, Winsconsin, US
Payload weight: 250 lbs.

• Balloon Flight Record Facilities for Atmospheric Research Nº 3 - Spring 1967
• Balloon Measurements of the Energy Spectrum of Cosmic Electrons Between 1 Gev and 25 Gev. Technical Report Nº 72-038, University of Maryland
• Report on Skyhook 1966 Final report for ONR - Winzen Research Inc.
• Solar and geomagnetic modulation of low-energy secondary cosmic ray electrons J. Geophys. Res., 78(10), 1502-1514