B. Baldin

D∅ muon system with proportional drift tube chambers

Abstract The muon detection system for the Fermilab D∅ detector is described. It has better muon detection performance than other existing hadron collider detectors, with respect to both hadron attenuation length and position resolution. In the large angle region there are three large magnetized toroids and a total of 10 planes of proportional drift tube chambers made of 10 cm wide cells. At both small angles there are magnetized toroids and 9 planes of proportional drift tubes made of 3 cm diameter stainless steel tubes. The 10 cm wide cell structure is made of specially designed aluminum extrusions, which make the assembly of a whole chamber easy. The chamber is provided with vernier pads so that the position of a charged particle can be simultaneously detected in both directions perpendicular and parallel to the sense wire. The system resolution goal along the wire is ±2.0 mm and perpendicular to the wire ±0.5 mm.

Study of fast gases, resolutions and contaminants in the DØ muon system

Abstract Studies of the operating parameters of the DO muon chambers are reported. The choice of operating gas was such to find a nonexplosive gas with properties similar to those of argon-ethane. Faster gases were also studied. The resolutions of the chambers in two coordinates were determined. Finally, systematic effects due to variations in voltage, gas mix, O 2 contamination and H 2 O contamination were determined.

Production of vector mesons in hadron‐A interactions

Total and differential cross sections for production of the ρ, ω, φ, and J/ψ vector mesons were measured in the Feynman‐x region 0.1≤xF≤0.8 with a 530 GeV/cπ− beam incident on beryllium and copper targets. Using the cross‐section parametrization Aα, we find α=0.76±0.02, 0.81±0.04, 0.87±0.04, and 0.97±0.06 for the ρ/ω, φ, Jψ and Drell‐Yan continuum, respectively. No statistically significant dependence of α on either xF or transverse momentum pT is observed. We have also studied the relative production rates of vector mesons as a function of the event inelasticity, as measured by transverse energy, ET. ET is defined as the scalar sum of transverse momenta for centrally produced charged particles. The relative rate of J/ψ’s and continuum muon pairs does not change with event inelasticity, contrary to the findings of a heavy‐ion collision experiment. On the other hand, the production rate of φ mesons as compared to ρ/ω increases with ET. We argue that the observed increase reflects a simple momentum conserva...

The A‐dependenc of ψ production in π− nucleus collisions at 530 GeV/c

The E672/E706 Spectrometer, located in the MW beam at Fermilab, was used to collect data on events containing a pair of muons in the final state with large effective mass. The momentum of incident pions and protons was 530 GeV/c. Nuclear targets included Be, C, Al, Cu and Pb. We report on a preliminary measurement of the A‐dependence of the per nucleus cross section for forward J/ψ production. The apparatus also detected charged particles and γ’s produced in association with the muon pair. The expected physics results on the hadroproduction of χ states and beauty particles are discussed.