Measurement of tensor analyzing powers in deuteron photodisintegration

A new accurate measurement of the tensor analyzing powers T20, T21, and T22 in deuteron photodisintegration has been performed. Wide-aperture nonmagnetic detectors allowed broad kinematic coverage in a single set up: E(gamma)=25 to 600 MeV, and theta(p)(cm)=24 degrees to 48 degrees and 70 degrees to 102 degrees . The new data provide a significant improvement over the few existing measurements. The angular dependency of the tensor asymmetries in deuteron photodisintegration is extracted for the first time.     

Tagging system for almost-real photons at VEPP-3 storage ring

At BINP the construction of the tagging system for almost-real photons (TS) is in progress. The energy of tagging photons can be up to 1.5 GeV. The projected energy resolution of TS is better then 1%. For at least a half of photons the linear polarization can be determined. The tagging system will extend the possibilities for photoreaction studying at VEPP-3 significantly. TS would allow to perform a complete kinematics reconstruction, thus permitting a reliable rejection of the background processes; to extend the measurements to higher photon energy; to enabling Σ-asymmetry measurements and double polarization experiments.     

The number of photons emitted by a channeled electron

A discussion is presented of the influence of photon multiplicity in the emission from channeled electrons on the radiation spectrum measured by a total-absorption spectrometric device. It is shown that as the maximum in the spectrum shifts with increasing crystal thickness, in the absence of further information it is impossible to determine the multiplicity of the emission. A method is proposed for determining the presence of multiple emission from channeled electrons with a total-absorption spectrometer by using an absorber covering a specified portion of the -ray aperture. The presence of multiplicity is identified in emission from channeled electrons with energy E₀=900 MeV in a tungsten single crystal of 1.18 mm. Previously the presence of multiplicity in the radiation from channeled electrons had been detected for electron energies above 4.5 GeV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 88–105, June, 1991.     

Experimental study of the albedo of a beam of γ rays produced by ultrarelativistic electrons

A study has been carried out of the spectral dependence of -radiation scattered from targets irradiated with beams of rays produced by relativistic electrons in crystals. It is shown that the change in the spectral composition of the beam of rays incident on the target changes considerably the spectral properties of the scattered radiation. The spectra of the scattered radiation are studied as a function of the thickness and atomic number of the scatterer. It is shown that the atomic number of the scattering material can be determined from the ratio of the spectral components of the scattered radiation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 106–119, June, 1991.     

Tensor analyzing capacity of the γd → Δp reaction

The relativistic momentum approximation has been used to calculate the tensor analyzing capacity F₂₀ of the d p reaction. At high proton moments (p50 MeV/sec), the dependence of F₂₀ of the parameters of the n vertex becomes substantial, which shows that experiments on F₂₀ can provide information on the electromagnetic form factor of the n transition.Research performed with financial support from the Russian Fundamental Research Fund (project code 93-02-3514).Nuclear Physics Research Institute, Tomsk Polytechnical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 35–38, October, 1994.     

Effect of rescattering on polarization observables of the reaction γd → ppπ in the delta-resonance region

The effect of pion-nucleon and nucleon-nucleon rescatterings on polarization observables of the reaction γd → ppπ^? are calculated in the delta-isobar region. Pion-nucleon and nucleon-nucleon rescatterings are considered on the basis of a diagrammatic approach. Lorentz invariant expressions are used for the operators of photoproduction and of pion scattering on a free nucleon. A unitarization procedure in the K-matrix approximation is used for resonance partial-wave amplitudes. It is shown that, in the delta-resonance region, rescattering has a sizable effect on polarization observables of the reaction γd → ppπ^? at high momenta of final protons.     

Exchange effects during δ-isobar photoproduction on a polarized deuteron

Within the framework of the relativistic impulse approximation and the nucleon spectator model we have investigated the influence of exchange effects in the photoproduction of δ isobars on a polarized deuteron with subsequent decay into a proton and a π⁻-meson. We used two forms of propagator for the spinor-vector field of an δ isobar in the calculations. Nuclear Physics Research Institute, Tomsk Polytechnic University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. 2, pp. 3–8, February, 1999.     

Investigation of the reaction D(e, pp)e′ π − on a tensorpolarized deuterium target at high proton momenta

The differential cross section of the reaction D(e,pp)e′ π ⁻ is measured in the range of proton momenta 300–720 MeV/c and proton emergence angles 64–83° for invariant masses of the pp system ranging from 2m _p to 2220 MeV/c ². The measured values of the cross section are found to differ substantially from single-particle model calculations. The components of the analyzing power for this reaction are measured. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 10, 730–736 (25 May 1998) Deceased.     

Neutral pion photoproduction on tensor-polarized deuterium on the VEPP-3 storage ring

An experiment to measure component T ₂₀ of the tensor analyzing power for the coherent photo-production of neutral pions on polarized deuterons is described. The measurements cover the photon energies in the ranges E _γ = 200–500 MeV and E _γ = 300–600 MeV, and the emission angles of neutral pions in the ranges = \(\theta _{\pi ^0 }^{c.m.} \) = 100°–140° and = \(\theta _{\pi ^0 }^{c.m.} \) = 60°–65°, respectively. The experiment uses a hyperfine internal gas polarized target. Detectors of neutral pions and deuterons register these particles in coincidence. The target’s degree of polarization and luminosity is measured by detecting elastic electron-deuteron scattering at low momentum transfer. A selection of the preliminary results is presented.