K. Heinloth

Electroproduction of singke π+ mesons on hydrogen

The electroproduction of single π+ mesons on hydrogen, ep → e′π+n, has been investigated by measuring coincidences between the scattered electron and the produced π+ meson. The differential cross sections as functions of so, q2, t and φπq were determined in the following kinematical region: so = (π+ + n)2 = 4.0 − 6.0 GeV2; |q2| = |(e − e′)2| = 0.1 − 0.9 GeV2/c2; |t| = |(p − n)2| = |tmin| − 0.15 GeV2/c2; φπq = 0 − 2π; (φπq = angle between polarizatin plane (e, e′) and production plane (π+, n); e, e′, π+, p, n = four-momenta of primary and scattered electron, π+ meson, target proton and recoil neutron).

Electroproduction of ϱo-mesons on protons

Abstract The electroproduction of transversely polarized ϱ o -mesons on protons has been measured detecting the scattered electron and the two decay π-mesons in spark-chamber spectrometers. The differential cross sections d σ u /d t and d σ u /d( t – t min ) have been determined as functins of W , q 2 and t and W , q 2 and t − t min in the kinematical region 2.60 ⩽ W ⩽ 2.95 GeV, −0.12 ⩾ q 2 ⩾ −0.40 GeV 2 / c 2 , t min ⩾ t ⩾ −0.15 GeV 2 / c 2 .

Tagging System for High Energy Photons

An apparatus has been built to determine the energy of each photon in a bremsstrahlung spectrum which produces an interaction of interest in a hydrogen target. The technique was applied specifically to charged pion photoproduction with photons of 2 to 5 BeV. The tagging system utilized a monoenergetic (to ± 1%) positron beam which produced photons and associated recoil positrons in a thin radiator. The recoil positrons were momentum analyzed and detected by a 19‐counter hodoscope. The difference between the energies of an incident and a recoil positron is the photon energy, and this was determined to ±2.5%. Since the photon beam is relatively weak, the interactions it produces must be detected with good efficiency. Such a large‐solid‐angle spark chamber, magnet, and counter system, which was used to measure the photoproduced pions, is also described.

Inclusive π+ and π− distributions in electroproduction on protons

We investigate thes inclusive pion spectra in the electroproduction reaction ep → eπ±+ anything in a coincidence experiment at DESY. Data are presented from the kinematical region 0.1 < |q2| < 0.8 GeV2 and 3.15 < W < 2.8 GeV as a function of the transverse momentum squared pT2, the Feynman variable x2, and the azimuth angle φ. The charge ratio π+π− is given in terms of the variables q2 and x. The inclusive spectra are compared with results from photoproduction.

Electroproduction of π°-mesons on protons in the backward direction

Electroproduction of π°-mesons on protons at backward angles was investigated by measuring the scattered electron and the recoiling proton in coincidence. The differential cross section was determined as a function of W, q2, θπoucms and u respectively, in the following kinematical region: W = √(πo + p′)2 = 1.5 − 2.1 GeV, |q2| = |(e − e′)2| = 0.3 − 1.0 GeV2/c2, 100° ⩽ θπocms ⩽ 180°, − 60° ⩽ Φπo ⩽ + 60°.

Electroproduction of π−Δ++ (1236) and of π+Δ0 (1236) on hydrogen

The electroproduction of a π-meson and of a Δ(1236) nucleon resonance on hydrogen, ep → eπΔ (1236), was investigated in the two charge states π−Δ++ and π+Δ0 by measuring the scattered lepton and the produced π-meson in coincidence. The differential cross sections as funcions of W, q2, t−tmin and oπq were determine in the following kinematical region: w = (π + δ)2 = 2.0 − 3.0 GeV , |q2| = |(e−e′)2 | = 0.15 − 0.8 GeV2/c2 , |t − tmin| = 0-0.5GeV2/c2 with t = (p − δ)2 , φπq = 0 − 360° .

BACKWARD PRODUCTION OF VECTOR MESONS IN INELASTIC ELECTRON SCATTERING.

Electroproduction of the vector mesons π0 and Ω on protons at backward angles was investigated by measuring the scattered electron and the recoiling proton in coincidence. The differential cross section was determined as function of W, q2, u−umin and ϕV in the following kinematical region: 1.9 ⩽ W ⩽ 2.6 Gev , 0.1 ⩽ |;q2| ⩽ 0.9 GeV2/c2 , −0.13 ⩽ u−umin ⩽0 GeV2/c2 , 00 ⩽ ϕV ⩽ 360° .