Roger Wallace

SHIELDING AND ACTIVATION CONSIDERATIONS FOR A MESON FACTORY

The shielding and activations of a meson factory are estimated by computing the emission spectra of the neutrons produced, and using these spectra to estimate the necessary shielding and the probable activation of the accelerator caused by the captured neutrons. The technique used in making these estimates is explained. It is assumed that a meson factory has an internal circulating beam current of 100 μA of 450-, 600-, or 850-MeV protons. This beam will be assumed to hit an aluminium target of 100 g/cm 2 .

LEAD GLASS CERENKOV RADIATION PHOTON SPECTROMETER

A spectrometer for analyzing photons of energies extending up to several Bev has been constructed and used successfully. This instrument essentially consists of a cylinder of glass, 12‐in. diam and 14‐in. long containing 52% of PbO, viewed by four 5‐in. diam photomultipliers. High‐energy photons incident along the spectrometer axis produce electron showers in the transparent high‐Z glass. The total Cerenkov radiation emitted by these electrons and detected by the phototubes is nearly proportional to the energy of the incident photon, from 50 Mev to at least 1.4 Bev. The spectrometer has been calibrated over this range of photon energies by the pulses produced by electrons of the same energies. Above 200 Mev the measured energy resolution of the spectrometer is 30% and is approximately independent of energy. For elimination of incident charged particles during the analysis of γ rays the spectrometer is operated in coincidence with a preceding photon‐identifying counter system.