We present a measurement of the total cross section σ t in proton-proton collisions at the CERN ISR. The method involves determination of the total interaction rate and machine luminosity. A two-arm scintillation hodoscope observes ∼ 90% of the total interaction rate, while a streamer chamber is employed for event topologies missed by the main trigger. An increase of about 10% in σ t is observed in the energy range √ s = 23.6 to √ s = 62.8 GeV/ c in agreement with previous experiments.
VAN DER MEER METHOD.
We report the measurements of the inclusive μ-pair production by 150-GeV protons and π+ mesons on beryllium. Absolute cross sections as well as the Feynman-x and PT dependence are presented in the mass region between 0.211 and 3.5 GeV/c2. Upper limits are also given for the inclusive production of η and ρ′(1600) mesons.
DATA OBTAINED FROM FIGURE BY A.A. LEBEDEV.
DATA OBTAINED FROM FIGURE BY A.A. LEBEDEV.
No description provided.
Data from a study of muon pairs produced in hadron-nucleus collisions are compared with the Drell-Yan model. Comparison of dimuon production by π+ and π− mesons on an isoscalar target shows evidence for a charge asymmetry characteristic of an isospin-nonconserving electromagnetic process. The average transverse momentum of the pairs increases smoothly with pair mass. Data taken on carbon and tin targets are used to extract the dependence on target atomic weight.
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We present results of a large-acceptance experiment in which muon pairs were observed in the mass range 0.6 to 6.0 GeV/c2. Emphasis is given to features of the production of Jψ and ψ′(3.7) particles. We find [Bσ]ψ′(3.7)[Bσ]Jψ to be 0.007±0.004 for p-C and 0.018±0.007 for π+-C interactions. Comparison with results from e+e− storage rings indicates that both the Jψ and the ψ′(3.7) are produced strongly rather than electromagnetically in our experiment.
No description provided.
The data on the total inelastic and partial cross sections in pNe interactions at 300 GeV are presented. It is found that the total cross section, σin(pNe)=356±13 mb, and multiplicity distributions of the number of negative and relativistic charged particles are in good agreement with predictions of a multiple-scattering model based on Glauber's approach. The multiplicity of negative particles obeys the Koba-Nielsen-Olesen (KNO) scaling, but it is observed that the KNO function depends on the atomic mass number of the target. From an analysis of the average multiplicities of secondary particles, it is shown that approximately 10 percent of the fast (p≳1.2 GeV) positive secondaries are protons, which are derived from the nucleons in the neon nucleus.
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Using a double arm electromagnetic calorimeter we have searched for narrow states produced in the exclusive reaction π − p→γγn at 13 GeV/c. No enhancements were observed in the mass range 2.0–4.0 GeV/c 2 . For example, the 90% confidence limit on η c production is σ ( π − p→ η c n)× B ( η c → γγ ) < 44 pb.
UPPER LIMIT (90 PCT CL) FOR SIG*BR(ETA/C --> 2 GAMMA).
We have searched for exclusive hadronic J/ψ production by looking for narrow resonances in the e+e− mass spectrum of the reaction π−p→e+e−n. No events were observed in the region around 3.1 GeV/c2. The cross section for the reaction π−p→J/ψ n at 13 GeV/c is no more than 103 pb at the 90% confidence level.
Corrected cross section based on 7.4 pct branching ratio.
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In a sample of 670 000 charged-current neutrino events, 101 μ−μ− events have been observed, with 30 GeV<Eν<600 GeV and Pμ>9 GeV/c for both muons. After background subtraction, 18.5±13.9 events remain, yielding a prompt rate of (5.5±4.1)×10−5 per charged-current event. A sample of 124 000 antineutrino events yields 15 μ+μ+ events, giving 6.4±4.2 events after background subtraction and a prompt rate of (1.0±0.7)×10−4 per charged-current event. The numbers and kinematic distributions of these events are consistent with standard model sources.
No description provided.
The ratio of sea to valence quarks for nucleons in tungsten has been measured for the fractional momentum range 0.04<xN<0.36. The determination is based on the relative production rate of muon pairs by π+ and π− beams on a tungsten target. The results provide the most accurate determination to date of this ratio in the region xN<0.1 and Q2>20 GeV2, and are in good agreement with earlier measurements.
No description provided.