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There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on 220 Rn and 224 Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental studies of atomic electric-dipole moments that might reveal extensions to the standard model. An experimental study of certain short-lived isotopes of radon and radium has found clear octupole deformation in the nuclei of the latter — that is, these nuclei are pear-shaped; the results enable discrimination between differing theoretical approaches to octupole correlations. Pear-shaped atomic nuclei The atomic nucleus is a many-body quantum system with a shape determined by the number of nucleons that it contains and the interactions between them. Most of the several thousand known stable and radioactive atomic nuclei, with differing numbers of protons and neutrons, are spherical or rugby-ball shaped. But there is circumstantial evidence that some heavy, unstable nuclides are distorted into a pear shape through the phenomenon of octupole deformation. Samples of these rare atomic species can be accelerated to 8% of the speed of light in the REX-ISOLDE facility at CERN, and now Coulomb excitation experiments on beams of the short-lived isotopes radium-224 and radon-220 have demonstrated clear octupole deformation in the former. The results make it possible to discriminate between the various theoretical models of octupole-deformed nuclei, and are also relevant to the pursuit of physics beyond the Standard Model.

The first cluster of the constructed PARIS calorimeter was assembled and tested at the γELBE facility at HZDR, Dresden, Germany. The experiment was aimed at the evaluation of the performance of each detector separately as well as the whole PARIS cluster with discrete γ-ray energies seen by the PARIS ranging up to 8.9 MeV. As the detectors use phoswich configuration, with 2\" × 2\" × 2\" LaBr3(Ce) crystal coupled to 2\" × 2\" × 6\" NaI(Tl) one, great care must be taken during the data analysis process to obtain the best possible values for energy resolution. Two algorithms for data transformation from matrices created with slow vs fast pulse shaping to energy spectra were tested from which one was chosen for further analysis. An algorithm for adding back energies of γ-rays scattered inside the cluster was prepared, as well. Energy resolution for γ-rays in 2-8 MeV range was estimated and is presented in this paper.

The IS475 collaboration conducted Coulomb-excitation experiments with postaccelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam ≈ 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted ⟨3−||Ê3||0+⟩ matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. An observation that has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nuclei.

The IS475 collaboration conducted Coulomb-excitation experiments with post-accelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam: 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted ‹3−||E3||0+› matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. This finding has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nuclei.

Floodplain lakes are important elements of landscapes with large rivers. In this study we compared planktonic communities of two oxbow lakes of the Vistula River. We investigated how the inflow of the river's water affected their physicochemical and biological conditions including water temperature, water transparency, oxygen concentration, and macrophyte coverage of the bottom. These parameters in turn affected plankton community. The average phytoplankton abundance in the isolated lake was over two times lower than in the lake connected to the river. Cryptophyta dominated in the phytoplankton community in the isolated lake and diatoms – in the lake supplied with water from the river. The average abundance of zooplankton in the isolated lake was more than twice as high as that in the lake which was connected to the river. The first lake proved to be more attractive for zooplankton due to its stable living conditions (similar to the conditions observed in ponds), higher temperature in summer, and nutrient availability due to the high abundance of small phytoplankton. The results of our research indicate that species composition, plankton abundance, and Chl-a concentration depended on whether there was water exchange between the particular lake and the Vistula River. Hydrological conditions shaped the relationships between the components of the biota.

Spectroscopic data, such as precise γ-ray branching and E2/M1 multipole-mixing ratios, provide vital constraints when performing multi-dimensional Coulomb-excitation analyses. Consequently, as part of our new Coulomb-excitation campaign aimed at investigating the role of exotic non-axial (triaxial) deformations in the unstable refractory Ru-Mo isotopes, additional beta-decay data was obtained. These measurements make use of ANL's CARIBU facility, which provides intense beams of radioactive refractory isotopes along with the excellent efficiency and angular resolution of the GRETINA γ-ray tracking array. In this article, we report on the analysis of the A = 110 decay chain, focussing on the identification of previously unreported states in 110Ru following the decay of 110Tc.

A hypothesis of the chiral symmetry breaking opened a new opportunity for the study of spontaneous time-reversal symmetry breaking in an atomic nucleus. The occurence of chirality has been found in 126,128Cs nuclei for which specific electromagnetic selection rules have been found in Doppler Shift Attenuation experiments. Here, recent DSA measurements in the 124Cs nucleus are presented. The 124Cs nucleus was produced in the 114Cd(14N,4n)124Cs reaction at Heavy Ion Laboratory of the University of Warsaw. The obtained results agree with basic expectations deduced from the chiral symmetry breaking. A connection between the chirality phenomenon and the time-reversal symmetry is discussed and a possibility of using chiral doublets for studies of fundamental time reversal symmetry is suggested.

The planning, history of construction, description of the equipmentand the expected activity program of the University ofWarsaw Radiopharmaceuticals Production and Research Centreare presented.

The different data-sorting modes of the phoswich detector array PARIS used for detecting high-energy (4\\(-\\)10 MeV) \\(\\gamma\\) rays are investigated. The characteristics including time resolution, energy resolution and detection efficiency under various modes are studied. The present study shows that PARIS has capabilities of rejecting escape and pileup events when used for decay spectroscopy. Notably, the methods presented in this work refer specifically to the \\(\\beta\\)-decay experiment of \\(^{80g+m}\\)Ga conducted with three PARIS clusters comprising 27 phoswich detectors, rather than to a general report on the PARIS array or its overall performance for in-beam spectroscopy. Compared with the 2\"\\(\\times\\)2\"\\(\\times\\)2\" LaBr\\(_3\\)(Ce) detector (Ciemała et al., 2009), even in individual mode, PARIS provides significant suppression of single- and double-escape peaks and reduces background via vetoing function of the outer-volume NaI(Tl) crystals. In contrast to the common approach of adding back the energies in LaBr\\(_3\\)(Ce) and NaI(Tl) to increase the detection efficiency of the full-energy peak, using NaI(Tl) as a veto shield provides a superior trade-off for applications where spectral purity is essential. Employing add-back analysis within each cluster of nine phoswiches or between all phoswiches could enhance full-energy peak efficiency and further suppress escape peaks and background. Applying a multiplicity condition provides a further suppression but simultaneously lowers the statistics of full-energy peaks.