M. Corden

Experimental comparison of Jψ production by π±, K±, p and p̄ beams at 39.5 GeV/c

Abstract Measurements have been made of relative production cross sections of the J ψ by π±, K±, p and p at 39.5 GeV/c incident on copper. J ψ production rates from π−, K− and p are similar. The J ψ relative particle/anti-particle production cross sections for x>0 are σ(π + ) σ(π − )=(0.87±0.14) , σ(K+)/σ(K−)=(0.85±0.5) and σ( p ) σ( p )=(0.15 ±0.08) . The small p/p cross section ratio disagrees with models of J/ψ production by gluon amalgamation.

A measurement of the A-dependence of the J/ψ cross section by comparing data on hydrogen and tungsten targets at 39.5 GeV/c

Abstract J/ψ production on hydrogen and tungsten targets has been compared at 39.5 GeV/ c and the variation of the A -dependence of the J/ψ cross section as a function of p t 2 and x F has been measured. The A -dependence parameter, α, rises with increasing p t 2 and falls with increasing x F . Both effects are shown not to be due to the Fermi motion of nucleons in the tungsten nucleus.

Some Hadron Calorimeter Properties Relevant to Storage Rings

At wide angles in a storage ring environment, a substantial part of the energy seen by a hadron calorimeter can be in the form of very low momentum particles such as jet fragments or resonance cascade decay products. Data are presented on the deviations from Gaussian resolution and linear response for such low momentum particles. The differing responses to incident e-, μ-, π+-, K+-, p and at momenta below 10 GeV/c are also compared. In addition, we discuss the significance of angle effects for a 4π calorimeter, and the problems of combining data from calorimeters with different physical characteristics. Experimental data are presented on the difference in hadron response between a fine grain (electromagnetic) lead calorimeter and a coarser (hadron) iron calorimeter, and on the dependence of the response on the energy sharing between the two calorimeters.

Experimental results on J/ψ production by π±, K±, p and p incident on hydrogen at 39.5 GeV/c

Abstract J/ ψ production at 40 GeV/ c by π ± , K ± , p and p incident on hydrogen has been studied and results compared with those obtained on tungsten in the same experiment. On hydrogen, J/ψ cross-section ratios relative to π − have been measured to be (for x F > 0) σ(π − ) : σ(π + ) : σ( p ) : σ( p ) = 1 : (0.78 ± 0.09) : (0.83 ± 0.35) : (0.07 ± 0.04) . The suppression of the proton induced cross sections shows the importance of calence quark-antiquark fusiin J/ψ production at this energy (i.e. M J 2 / ψ / s =0.13).

Performance of a UA1 Hadron Calorimeter Prototype

The hadron calorimeter for the UA1 experiment at the CERN SPS proton-antiproton collider consists of a lead-scintillator sandwich plus an iron-scintillator sandwich with wavelength shifter readout. We have tested prototype modules in muon and hadron beams in the momentum range from 0.7 to 90 GeV/c. For several angles of incidence, we have studied the uniformity of the response to hadrons as a function of position. This has included regions where there is reduced sensitivity due to mechanical constraints and the presence of the wavelength shifter readout. The response, resolution and degree of shower containment were measured as a function of incident momentum.

Experimental results on J/ψ production by π±, K±, p and p¯ beams at 39.5 GeV

Abstract The production of J/ψ by π ± , K ± , p and p¯ incident on tungsten at 39.5GeV/ c beam momentum has been studied. Production of ψ (3700) by π ± was also observed. The J/ψ relative particle/a ntiparticle cross-sections for x F 0 are σ(σ + ) σ(σ − =( are σ(σ ± )/σ(σ − )=(1.01±0.06), σ(K + )/σ(K) − )=(0.29±0.07) and σ(p) /σ(p¯)= (0.1+-0.03). The small p/p¯ and K + /K − cross-section ratios indicate the importance of valence quarks in the production process.

Production of A20 and ω∗ (1675) in the reaction π−p → π+π−π0n at 12 and 15 GeV/c

Abstract Data on the reaction π−p → π+π−π0 have been taken at 12 and 15 GeV/c with the CERN Omega multiparticle spectrometer. In a 3-pion partial-wave analysis strong production of A 2 0 (1310) and ω ∗ (1675) is observed. Total and differential cross sections are determined and density matrix elements presented as a function of t in the t- and s-channel frames. The energy dependence of A20 production is studied, and a comparison of ω(780), A 2 0 (1310) and ω ∗ (1675) production is made.

Production of muon pairs in the continuum region by 39.5 GeV/c π±, K±, p and p¯ beams incident on a tungsten target

Abstract Inclusive dimuon production by 39.5 GeV/ c π ± , K ± , p and p¯ is described for masses greater than 2.0 GeV/ c 2 . The π − , π + and (π − − π + ) continuum cross-sections exceed the naive Drell-Yan predictions by a factor ∼2.4. The pion valence structure function has been measured and is consistent with a corresponding measurement at 200 GeV/ c .

Central Hadron Calorimeter of UA1

Abstract An iron—scintillator sampling calorimeter is described, which measures hadronic energy in proton-antiproton interactions at the CERN 540 GeV SPS collider. Construction details are given of the instrumentation of the magnet pieces of the UA1 experiment and of the methods used to measure the calorimeter response and resolution. The system of lasers and quartz fibres, which allows long term monitoring of the calorimeter response, is also described.

An amplitude analysis of ππ scattering from new data on the reaction π−p→π+π−n

Abstract We have carried out a partial-wave analysis of ππ scattering in the mass range 1.0 to 2.08 GeV/ c 2 . We find solutions similar to those obtained in previous analyses below 1.8 GeV/ c 2 but, in addition, we obtain a new solution which does not suffer from violations of unitarity and is compatible with data from other channels. This solution, when continued to 2.08 GeV/ c 2 , shows a g meson with mass and width of 1.734± 0.010 GeV/ c 2 and 0.322±0.035 GeV/ c 2 respectively, and an h meson with mass 1.935±0.013 GeV/ c 2 and width 0.263±0.057 GeV/ c 2 . The L = 2 partial wave contains the f meson and an additional resonance with parameters m = 1.502±0.025 Gev/ c 2 , Γ = 0.165±0.042 GeV/ c 2 and x = 0.19±0.03. If we associate this state with the f′(1514), our ππ branching fraction is considerably higher than previous determinations. An SU(3) fit to the 2 + nonet yields a mixing angle of 38.4± 1.3°.