M. Gmitro

Towards a better understanding of 16O nuclear structure: Muon capture and radiative pion capture reactions

Abstract Muon capture and radiative pion capture reactions on 16 O have been analysed with the aim to extract more information on the importance of higher components of the A = 16 nuclear ground and excited states. Good agreement with the experimental data for both reactions may be achieved if at least 2p2h components of the nuclear wave functions are taken into account. The positive parity excited states in 16 N are shown to contribute 43 % to the radiative π − capture but only ≈ 10 % to the muon capture rate.

Pion photoproduction and inelastic scattering in A=12 nuclei: Transitions to the lowest isovector 1+ and 2+ levels

Abstract The continuity equation for the nuclear electric charge and convection current ▿ · j N = −α ρ N ρt has been used in an analysis of nuclear transition densities in 12 C. The results differ considerably from the former derivations. The standard M1 and newly-calculated E2 nuclear structure input is applied to estimate the pionic cross sections. A consistent improvement in several instances over the earlier results has been achieved; the calculations agree nicely with data both in the (3, 3) resonance region and at lower pion energies.

Ordinary and radiative muon capture on 12C

Abstract Rates of the ordinary and radiative muon capture on 12 C have been calculated with shell-model wave functions (0 h ω and 1 h ω) of the nuclear initial and final states. Compa experimental data suggests an upward renormalisation of the induced pseudoscalar weak coupling constant, g P g A ≈ 16 .

On the Sensitivity of Nucleon-nucleon Correlations to the Form of Short Range Potential

Nucleon-nucleon correlation characteristics are calculated for several phenomenological and realistic strong potentials. The results show that a square-well potential reasonably well approximates the nucleon-nucleon interaction if one calculates the correlations between nudeons generated in a region with an r.m.s. radius larger than 1·5–2 fm. And vice versa, the correlations of nucleons emitted from a smaller generation region are sensitive to the form of assumed nucleon-nucleon potential.

Radiative capture of polarised muons on 16O and 40Ca

Abstract The coefficient of asymmetry Γ γ ( k ) of the photon angular distribution (with respect to the muon spin) and photon circular polarisation P γ ( k ) have been calculated for the radiative muon capture (RMC) on 16 O and 40 Ca and compared with the data. Nuclear states are treated in a microscopic model; the RMC characteristics are obtained by summing the contributions of individual partial transitions rather than by using the closure approximation.

(e, e′), (γ, π+ and (π−, γ) on12C and13C

A detailed theoretical analysis of spin degrees of freedom in carbon isotopes is performed, probing them by electron scattering, pion photoproduction and radiative pion capture from the mesoatomic orbits.

Continuity equation constraint in the transverse quadrupole electric-type form factors

The analysis of nuclear convection-current contributions to the transverseE 2 isoscalar and isovector form factors in12C initiated by Flanz et al. has been extended. It is shown that the continuity equation of the nuclear electromagnetic current provides the constraint needed to explain the behaviour of the form factors studied in the range 0

One- and two-nucleon emission following the nuclear radiative pion capture

Decay channels in the radiative pion capture reactions are discussed and their respective yields calculated. Specific consequences of a recently suggested quadrupole excitation mode in the (π−,γ) reaction are found and their experimental investigation is urged. A yield of about 19% of the total decay was estimated for the two-nucleon decay channel even for the light nuclei like16O.