A portable spark-chamber range spectrometer and data acquisition system

Abstract

A portable spark-chamber range spectrometer and electronic data acquisition system is described for acquiring spectral data on energetic charged particles. The instrument system consists of a uni-directional spark-chamber range telescope with pulse-height analysis of the specific energy loss ( dE dx of a charged particle that passes through a triggering telescope. The range telescope consists of a stack of sealed double-gap spark-discharge modules with absorbers sandwiched between them. A Cherenkov counter discriminates against electrons and muons. Cherenkov and dE dx signals are gated by the coincidence circuit. Data, either telemetered or recorded in situ, include the number of coincidences, a clock signal, system voltage levels, and the dE dx , Cherenkov, and spark-discharge module signals. Power consumption of the self-contained system is about 10 W at an event rate of 20 per second and 17 W at an event rate of 100 per second. The standby power is about 8 W. This instrument system can measure primary protons and alphas at balloon altitudes and secondary protons at lower altitudes. A particular configuration with a geometric factor of about 1 cm 2 sr has been assembled for measuring atmospheric proton intensities and spectra in the range from MeV to 300 MeV and at altitudes ranging from the altitude of high-flying aircraft to balloon altitudes near the top of the atmosphere.