A high precision 1 GeV/c spectrometer

Abstract A combination π − beam transport system and momentum spectrometer was constructed at the Bevatron of the University of California Lawrence Radiation Laboratory. The use of thin Al and Be foil wide gap spark chambers without beam windows, a one radian deflection of the beam, and a beam channel filled with helium to a pressure of 250 Torr allowed for a 0.05% precision measurement of the momenta of individual pions. The maximum usable particle intensity was 10 4 π − /sec.