T. Czosnyka

Experimental test of the polarization direction correlation method (PDCO)

Abstract The study of the polarization direction correlation method (PDCO) for γ quanta emitted from the nuclear states oriented in fusion-evaporation reactions is discussed with emphasis on making unique multipolarity assignments. The method is applied to the data coming from a typical experiment performed with the EUROGAM II array, where polarization-sensitive CLOVER detectors were used. The accuracy obtained in the experiment for the studied transitions was high enough to exclude, using the PDCO method, most of the ambiguities which occur if the assignments are made on the basis of angular correlation measurements alone.

Coulomb excitation of 226Ra

Abstract Radioactive targets of 226 Ra were Coulomb excited by 4 He projectiles (particle spectroscopy), and 16 O, 32 S and 208 Pb projectiles (particle-γ coincidences). The K = 0± rotational bands could be followed up to spin 18 + and 17 − , respectively. All experiments were simultaneously analyzed in terms of E1, E2, E3 and E4 matrix elements coupling the positive- and negative-parity rotational states. The systematics of level energies, as well as dipole, quadrupole and octupole matrix elements are discussed in the framework of models assuming stable octupole deformation.

Information on antiprotonic atoms and the nuclear periphery from the PS209 experiment

A. Trzcińska, J. Jastrzȩbski, T. Czosnyka, T. von Egidy, K. Gulda, F. J. Hartmann, J. Iwanicki, B. Ketzer, M. Kisieliński, B. K los, W. Kurcewicz P. Lubiński, P. J. Napiorkowski, L. Pieńkowski, R. Schmidt, E. Widmann Heavy Ion Laboratory, Warsaw University, PL-02-093 Warsaw, Poland Physik-Department, Technische Universität München, D-85747 Garching, Germany Institute of Experimental Physics, Warsaw University, PL-00-681, Warsaw, Poland Institute of Physics, University of Silesia, PL-40-007 Katowice, Poland CERN, CH-1211 Geneva 23, Switzerland

Neutron density distributions from antiprotonic Pb 208 and Bi 209 atoms

The x-ray cascade from antiprotonic atoms was studied for 208 Pb and 209 Bi. Widths and shifts of the levels due to the strong interaction were determined. Using modem antiproton-nucleus optical potentials, the neutron densities in the nuclear periphery were deduced. Assuming two-parameter Fermi distributions (2pF) describing the proton and neutron densities, the neutron rms radii were deduced for both nuclei. The difference of neutron and proton rms radii Δr nP equal to 0.16 ± (0.02) stat ± (0.04) syst fm for 208 Pb and 0.14 ± (0.04) stat ± (0.04) syst fm for 209 Bi were determined, and the assigned systematic errors are discussed. The Δr nP values and the deduced shapes of the neutron distributions are compared with mean field model calculations.

The decay of128Cs to levels in128Xe

The level structure of128Xe has been studied from theβ+ decay of128Cs by observing gamma rays and gamma-gamma coincidences. The128Cs isotope was produced in the128Xe(p, n)128Cs reaction at a proton energy ofE∼9.5 MeV. A decay scheme has been proposed for this nucleus.

Quadrupole and octupole collectivity in 148Nd

Abstract The role of quadrupole and octupole collectivity in the shape-transitional nucleus 148 Nd has been studied by Coulomb excitation using beams of 58 Ni and 92 Mo, and a beam of 148 Nd (using a 208 Pb target). The extracted E1, E2 and E3 matrix elements involving states up to 12 + ·in the ground band and 13 − in the negative-parity band are presented, and compared to calculations that assume a vibrational and rotational octupole nature for the negative-parity band. The positive-parity ground-band states are well described in terms of a prolate deformed shape with Q 20 ≈ 400 e fm 2 ( β 2 rms ≈ +0.18). The present results suggest a vibrational octupole nature for the low-spin negative-parity states, with an intrinsic moment Q 30 ≈ 1500 e fm 3 ( β 3 rms ≈ 0.12). The E2 and E3 matrix elements connecting these bands to the β- and γ-vibrational bands (and within these bands) are also presented, and compared to calculations incorporating the coupling between the rotational and vibrational modes. These calculations describe reasonably well the E2 matrix elements involving the gamma band, but do not reproduce the measured E2 matrix elements for the beta band, implying a complicated intrinsic structure for the beta band. The strong enhancement of the measured E3 matrix elements connecting the negative-parity band to the beta band could be indicative of a significant component of the two-phonon octupole vibration in the wavefunction of the so-called beta band.

El, E2, E3 and M1 information from heavy ion coulomb excitation

Abstract The richness of information pertaining to El, E2, E3 and M1 interaction deduced from Coulomb excitation experiments is illustrated. E2 and particularly M1 transition probabilities in 128 Xe are presented. Large set of E3 and E1 additionally to E2 transition probabilities in 226 Ra are shown.

Antiprotonic investigation of the nuclear periphery

Some results inferred from a program devoted to the study of the nuclear periphery using antiprotonic atoms are presented.

Neutron density distributions from antiprotonic 208 Pb and 209 Bi atoms

The x-ray cascade from antiprotonic atoms was studied for 208 Pb and 209 Bi. Widths and shifts of the levels due to the strong interaction were determined. Using modem antiproton-nucleus optical potentials, the neutron densities in the nuclear periphery were deduced. Assuming two-parameter Fermi distributions (2pF) describing the proton and neutron densities, the neutron rms radii were deduced for both nuclei. The difference of neutron and proton rms radii Δr nP equal to 0.16 ± (0.02) stat ± (0.04) syst fm for 208 Pb and 0.14 ± (0.04) stat ± (0.04) syst fm for 209 Bi were determined, and the assigned systematic errors are discussed. The Δr nP values and the deduced shapes of the neutron distributions are compared with mean field model calculations.

Unified analytical approximation of Gaussian and Voigtian lineshapes

Abstract Analytical approximation of the Voigt function has been derived. The Voigtian lineshape is reproduced without numerical integration or recourse to special functions. The formula derived contains also the Gaussian lineshape as a limiting case, thus allowing for pattern recognition if the appropriate lineshape is not a priori known.