CTOBEB 1974 p p interactions at 300 Gev / c : Measurement of the charged-particle multiylicity and the total and elastic cross sections *

We present data on a determination of the charged-particle multiplicity distribution and of the total and elastic cross sections for 300-GeV/c proton-proton interactions. Precise determinations of these cross sections and of the shape of the multiplicity distribution are of importance to high-ener gy strong-interaction dynamics. The data presented here represent approximately 5.4 times the number of events previously reported at this ener gy. ' The primary proton beam was extracted from the Fermi National Accelerator Laboratory proton synchrotron and reduced to a suitable intensity for the 30-in. hydrogen bubble chamber. The intensity of the beam was suitably attenuated by closing collimators and defocusing magnets, and by the insertion of an aluminum target approximately 1 km upstream of the bubble chamber. The target was viewed at an angle of 1.5 mrad. Measurements indicated that the beam momentum spread was less than 0.5$. The proton beam entered the bubble chamber with an angular spread of 1.3 mrad, and within this angular region the fraction of contaminating particles is &0.2%. The bubble chamber operated with the following parameters: B=27 kG, 35-mm film, four views, bubble size on film -15 p.m, and a bubble density for minimum-ionizing particles of 10-12 bubbles/ cm. The entrance window was -18 cm high by %.5 cm wide. In the first scan the chamber was imaged at 75% of its true size, and all the film was scanned by teams of two physicists working together. In this scan a decision was made as to whether a picture was acceptable based on two criteria: (1) All beam tracks entering the chamber had to be parallel to the beam to s1.3 mrad. Frames with up to three off-angle incident tracks were flagged and mere also included in the analysis. (2) The number of beam tracks entering through the window as projected in view 2 had to be ~15.