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We have measured the behaviour or charged-particle multiplicities as a function of the transverse momentum of photons produced at 90° in proton-proton collisions. The data were obtained at the CERN Intersecting Storage Rings (ISR) at a centre-of-mass energy of 53 GeV and cover the transverse momentum range 0

The effects of varying independently the inter-dinode voltages of Philips photomultipliers types 56 AVP and 58 AVP on the linearity and maximum gain obtainable are described. It is found that great improuvements are possible over the performances obtainable with the voltage distributions recommended by the manufacturers and that with voltage distributions optimized separately for each tube it is always possible to at least achieve the maximum performances claimed by the manufacturers. The distributions recommended by them do not fulfill these claims.

Two standard voltage distributions, differing from those recommended by the manufactures, to be used for Philips 56 and 58 AVP photomultipliers in conditions of high gain or of high linearity have been determined. Measurements are given in which there is considerable improvement in gain or in linearity obtained with such distributions as compared with those recommended by the manufacturers. A new apparatus for independently varying the interdynode voltages is described, with which the optimum distributions for any particular photomultiplier can be easily found.

Presents the first results of a measurement of the total cross section sigma /sub T/ in proton-proton collisions at equivalent laboratory momenta between 291 and 1480 GeV/c at the CERN Intersecting Storage Rings (ISR). The method is based on the measurement of the ratio of the total interaction rate and the machine luminosity. The data show an increase of about 10% in sigma /sub T/ in this energy interval. (11 refs).

We present the first results of an experiment at the CERN intersecting storage rings, which measures the total cross-section in proton-proton collisions. The equivalent laboratory momenta are 291, 496, 1068 and 1480 GeV/c. We have made a direct measurement of αT as the ratio between the total interaction rate and the machine luminosity. The present paper gives a detailed description of the experimental apparatus and of the analysis procedure. We find that αT increases by about 10% in the energy region studied.