On the measurement of the momentum of 19 GeV/c electrons in a heavy liquid bubble chamber

The Fermilab 15-ft bubble chamber was exposed to an electron beam of 19 GeV/c momentum. The chamber was filled with a heavy neon-hydrogen mixture (64% atomic Ne, 36% atomic H) and operated with a magnetic field of 3 T. The momentum of the electrons was determined from the bubble chamber pictures using two methods: (a) the measurement of the curvature of the electrons and their shower products, and (b) the measurement of the total track length of the electron and its shower. The momentum, as determined from curvature measurement of the primary electron and the e+e− pairs from the radiated gammas was 19.1±7.6 GeV/c.