STACK OF NUCLEAR EMULSIONS

Between 1971-1974 the University of Bristol along with the collaboration of the Dublin Institute for Advanced Studies performed a series of exposures with thick sandwich stacks of nuclear emulsions. The objective of the flights was to obtain tracks in the emulsions of heavy nucleonic cosmic rays. For this purpose the balloons were launched from Sioux Falls, South Dakota where the geomagnetic latitude was such that both high energy and low energy cosmic ray nuclei were present.

The stacks were assembled from modules which varied in configuration from flight to flight and included both pure Lexan modules containing up to 200 sheets of 250 microns Lexan with one or two sheets of 200 microns G5 emulsion and composite modules in which Lexan sheets were interleaved with copper or iron degraders of thickness typically 0.12 g/cm 2. This latter type of module included up to four layers of emulsion. In all cases the total stopping power of the modules exceeded 4 g/cm 2 Lexan equivalent. The stacks were thus thick in comparison with most others which have been exposed, enabling comparatively high energy nuclei (up to 800 MeV/N) to be brought to rest in the stack so that their tracks could be studied over a wide band of energy. A thick stack also allows to determine the energy of penetrating particles with greater confidence.

Balloon launched on: 9/22/1974 at ~ 12:30 cdt
Launch site: Joe Foss field, Sioux Falls, South Dakota, US  
Balloon launched by: Raven Industries Inc.
Balloon manufacturer/size/composition: Zero Pressure Balloon Winzen - 20.900.000 cuft (Natural Shape 0.7 mil - Two caps 0.8 mil)
Balloon serial number: S/N: 1
Flight identification number: RAVEN Nº 1519
End of flight (L for landing time, W for last contact, otherwise termination time): 9/27/1974 at ~ 18:00 cdt
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 127 h 30 m
Landing site: Near Eau Claire, Wisconsin, US

The Winzen Research Inc. 20.9-million-cubic-foot balloon was launched by Raven Industries Flight Operations Division personnel under the direction of Tom Pappas from Sioux Falls, South Dakota, on 22 September 1974. The dynamic launch was made with a scientific payload with a weight of 1.319 pounds, plus 414 pounds of control instrumentation, parachute, rigging, etc. and 1,600 pounds of ballast. A gross lift of 6.297 pounds was obtained from an inflation with 95,400 cubic feet of helium.

The flight was terminated five days later to prevent the independent backup timers from initiating descent during the approaching hours of darkness. Termination occurred near Eau Claire, Wisconsin. The complete flight trajectory was within a 230-nautical-mile arc to the east of Sioux Falls.

This flight set a new record duration of almost 123 hours at 125.000 feet of altitude.

• Apparent cause of many UFO sightings lands Eau Claire Leader Telegram , September 30, 1974, p.3
• Charge and Energy Spectra of Ultra Heavy Cosmic Ray Nuclei 15th International Cosmic Ray Conference, Vol. 11 p.165 (1977)
• High resolution study of nucleonic cosmic rays with Z=34 Nuclear Instruments and Methods, 147(1), 195-199
• Measurement of the cosmic ray element abundances between in the region from nickel to krypton using lexan track detectors Nuclear Instruments and Methods, 147(1), 201-203