Description of the payload

TS93 was a balloon-borne magnetic spectrometer designed to measure electrons and positrons in the energy range from 4 to about 50 GeV, being the upper value limited only by the exposure factor.

The instrument design -as many others of those years- was an adaptation of the basic configuration of the Balloon-Borne Magnet Facility (BBMF), a payload developed by New Mexico State University and NASA's Goddard Space Flight Center to perform research on high energy particles using a magnet spectrometer.

A schematic drawing of the TS93 instrument is shown at left (click to enlarge). It was composed by a single-coil superconducting magnet, providing a magnetic field varying from 0.1 to 2.1 Teslas. The tracking system was formed by a combination of drift chambers (DC) and multiwire proportional chambers (MWPC). The DC subsystem consisted of two DC modules with a hexagonal close-packed structure, which provided 12 measurements in the bending direction (x) and eight in the nonbending direction (y). Eight MWPC layers were used: three above the top DC, three at the center of the magnet between the DCs, and two below the lower DC. This configuration of the spectrometer was the same flown in the IMAX instrument a year before. For TS93, two completely new instruments were added to the magnet spectrometer: a transition radiation detector and a silicon-tungsten imaging calorimeter. These two detectors provided a much better proton rejection factor.

The transition radiation detector was positioned at the top of the sealed gondola and was composed of ten modules, each one made of a carbon fiber radiator followed by a multiwire proportional chamber (MWPC) filled with a mixture of Xenon and Methane. Each radiator consisted of an aluminium frame containing four bags, each filled with carbon fiber segments. The MWPCs were equipped with 256, 3 mm spaced, wires having an active area of 76 X 80 cm2.

The calorimeter was positioned at the bottom of the gondola and was composed of 5 silicon planes, sensitive both in the X and Y coordinates, interleaved with 4 tungsten planes. The sampling layer of the calorimeter was composed by an array of 8 X 8 pairs of detectors. Each sampling layer consisted of two arrays having 128 + 128 readout channels. A built-in system equipped with analog to digital converters and digital processors accomplished the data acquisition.

An aluminium cylindrical gondola measuring 3.67 meters in height and 1,52 meters of diameter enclosed the magnet, detectors and all systems that processed the incoming data.

Details of the balloon flight and scientific outcome

Launch site: Scientific Flight Balloon Facility, New Mexico, US  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon SF3-459.37-080-NSXCHR-ST
Balloon serial number: W39.57-3-02
Flight identification number: 368N

The balloon was launched by dynamic method with assistance of a crane acting as launch vehicle on September 8, 1993.

After an initial ascent phase it reached float altitude of 36 km and maintained a more or less stable altitude during the 25 hours of leveled flight.

During this unique flight of the instrument were obtained near 25 hours of useful scientific data.

External references and bibliographical sources

Images of the mission