Yu. M. Antipov

Measurement of π−-meson polarizability in pion compton effect

Abstract About 7 × 10 3 events of Compton effect on pion in the reaction π − A → A π − γ st 40 GeV/ c were detected and for the first time the charged pion polarizability was obtained α π = (6.8 ± 1.4) × 10 −43 cm 3 .

Elastic scattering of π−p, K−p and pp at 25 and 40 GeV/c

Elastic diffraction scattering of π−, K− and pon protons has been measured at 25 and 40 GeV/c at the Serpukhov Proton Accelerator. Differential elastic cross sections and diffraction slopes are presented in the momentum-transfer interval 0.07–0.80 (GeV/c)2 and compared with existing data at lower energies.

A1, A2 and A3 production in π−p→π−π−π+p at 25 and 40 GeV/c

A sample of ∼ 70 000 fitted events of the reaction of π−p→π−π−π+p at 25 and 40 GeV/c has been obtained with the CERN-IHEP boson spectrometer at the Serpukhov accelerator. A partial-wave analysis shows that (i) A1 and A3 cannot be described by a Breit-Wigner amplitude, (ii) the A2 can be well described by a Breit-Wigner amplitude, (iii) although A1, A3 and A2 have different properties, the energy dependence of their production cross section is similar.

Elastic scattering of pi- p, K- p and anti-p p at 25-GeV/c and 40-GeV/c

Elastic diffraction scattering of π−, K− and pon protons has been measured at 25 and 40 GeV/c at the Serpukhov Proton Accelerator. Differential elastic cross sections and diffraction slopes are presented in the momentum-transfer interval 0.07–0.80 (GeV/c)2 and compared with existing data at lower energies.

The reaction π−p → π−π−π+p at 25 and 40 GeV/c

The reaction pp→pπ−π+p has been studied at 25 and 40 GeV/c at the Serpukhov proton synchroton using the CERN-IHEP spectrometer. The differential cross section has been determined as a function of four-momentum transfer to the proton (0.05–0.30 (GeV/c)2) and pππ mass (up to 2.2 and 2.6 GeV/c2). At both energies there is a broad low-mass maximum with an enhancement at 1.6–1.8 GeV/c2. The cross section in a given mass band falls rapidly with |t|, with an exponential slope that decreases with increasing mass. In both the background and the 1.7 GeV/c2 peak there is a strong Δ−−π+ component. Possible spin-parity (JP) contributions to it are discussed. Throughout the range 1.5–2.2 GeV there is at least one state of J ⩾ 32 and there is interference between states of opposite P, |ΔJ| ⩽ 1. At the peak there is a J ⩾ 52 component. There are striking parallels between this reaction and the boson reactions π−p→π−π−π+p and K− → K−π−π+p.

Experimental estimation of the sum of pion electrical and magnetic polarizabilities

The pion radiative scattering πZ→πZγ at 40 GeV was investigated. Coulomb scattering-i.e. pion Compton-effect-dominates for small fourmomentum transfers in this reaction. In our previous paper we found the pion polarizability to beβπ=(−6.8±1.4)·10−43, cm3, where we assume following the theory that the sum of electrical and magnetic polarizabilities (απ+βπ)≃0. More complete analysis of our data is done in order to test this assumption. The result for (απ+βπ) is in agreement with theoretical predictions.

J/ψ particle production by 70 GeV/c protons

Abstract Invariant mass spectrum of μ + μ − pairs produced by 70 GeV/ c protons in Be target are presented. Distinct enhancements in the mass regions of ϱ, ω mesons, φ meson and J/ψ particle are observed. For J/ψ production x and p ⊥ 2 distributions are given. The total cross section for the reaction p + Be → ( J ψ → μ + μ − ) + … is equal to 9.5 ± 2.5 nb/nucleus .

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.

Missing-mass spectra observed in π- + p → p + X- at 25 and 40 GeV/c

Abstract Missing-mass spectra were obtained in the reaction π − p → p X − at 25 and 40 GeV/ c at the Serpukhov Accelerator. At low masses a strong peak at 1.3 and a smaller one near 1.7 GeV are observed. In the mass region above 2 GeV no structure exceeding 3μb/(geV/ c 2 is seen.

The A-dependence of J/ψ-particle inclusive distributions

Abstract The differential cross sections d σ d x and d σ d p t 2 of inclusive J/ψ production by 43 GeV/ c π − off Be, Cu and W nuclei have been measured. Fitting d σ d p t 2 ∼ A α (p t 2 ) we observed the increase of α with p t 2 .