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The spontaneous chiral symmetry breaking was experimentally studied at the Heavy Ion Laboratory of the University of Warsaw by use of the DSAM and DCO analysis. Obtained lifetimes, branching ratios and E2/M1 mixing ratios were used to determine B(M1) and B(E2) values. The preliminary results for 124Cs confirm spontaneous chiral symmetry breaking hypothesis in the 15ħ-20ħ spin range. [ABSTRACT FROM AUTHOR]

Electromagnetic transition strengths and spectroscopic quadrupole moments for 140Sm were measured by means of multi-step Coulomb excitation with radioactive beam at the ISOLDE facility at CERN. A complementary experiment was performed at the Heavy Ion Laboratory inWarsaw to assign spins for non-yrast states using the angular correlation technique. Based on the new experimental data previous spin assignments need to be revised. [ABSTRACT FROM AUTHOR]

Search for a new kind of superfluidity built on collective proton-neutron pairs with aligned spin is performed studying the Gamow-Teller decay of the T=1, Jπ=0+ ground state of 62Ge into excited states of the odd-odd N=Z nucleus 62Ga. The experiment is performed at GSI Helmholtzzentrum für Shwerionenforshung with the 62Ge ions selected by the fragment separator and implanted in a stack of Si-strip detectors, surrounded by the RISING Ge array. A half-life of T1/2=82.9(14)??ms is measured for the 62Ge ground state. Six excited states of 62Ga, populated below 2.5 MeV through Gamow-Teller transitions, are identified. Individual Gamow-Teller transition strengths agree well with theoretical predictions of the interacting shell model and the quasiparticle random phase approximation. The absence of any sizable low-lying Gamow-Teller strength in the reported beta-decay experiment supports the hypothesis of a negligible role of coherent T=0 proton-neutron correlations in 62Ga. [ABSTRACT FROM AUTHOR]

The decay of the Iπ = Kπ = 8- isomeric state in 130Ba was investigated using the 122Sn(12C,4n)130Ba reaction. The measurement was carried out in e-γ and γ-γ coincidence modes using an electron spectrometer coupled to the EAGLE gamma-ray array at the Heavy Ion Laboratory, University of Warsaw. Multipolarities and mixing ratios for the 8- → 6+ and 8- → 5+ transitions in 130Ba were derived from experimentally obtained internal conversion coefficients. [ABSTRACT FROM AUTHOR]

Abstract: The lifetimes of the excited states belonging to the chiral partner bands built on the configuration in 126Cs have been measured using the DSA technique. For the first time the large set of the experimental transition probabilities is in qualitative agreement with all selection rules predicted for the strong chiral symmetry breaking limit. The selection rules originate from two general features of a chiral nucleus, namely, from the existence of well separated left- and right-handed systems built of three angular momentum vectors and extra symmetries appearing in addition to the chiral symmetry breaking. The staggering resulting from these additional symmetries is sensitive to triaxiality of odd–odd nuclei as well as configuration of valence particles. [Copyright &y& Elsevier]

The decay of the $\ensuremath I^{\pi}=K^{\pi}=8^{-}$ isomeric state at 2340keV in 132Ce has been investigated in the 120Sn(16O, 4n)132Ce reaction. The measurements were carried out in e - $ \gamma$ and $ \gamma$ - $ \gamma$ coincidence modes using an electron spectrometer coupled to the OSIRIS II gamma-ray array at the Heavy Ion Laboratory of the University of Warsaw. Experimentally obtained internal conversion coefficients for the $\ensuremath 8^{-} \rightarrow 6^{+}$ and $\ensuremath 8^{-} \rightarrow 5^{+}$ transitions allowed the multipolarities, mixing ratios, reduced transition probabilities and hindrance factors to be determined. [ABSTRACT FROM AUTHOR]

Lifetimes of the yrast levels with spins I π = 23/2− to 39/2− in 129La produced via the 120Sn(14N, 5 n) reaction at a beam energy of 77MeV have been measured by the Doppler shift attenuation method. The properties of the studied levels belonging to the πh11/2 band were compared with the theoretical predictions obtained in the framework of the core quasi-particle coupling model. It is suggested that the rigid-rotor model used to describe the cores is too simplified as the even-even nuclei from the A ∼ 130 region are susceptible to shape deformation. Reasonable agreement was obtained with the phenomenological cores based on the experimental data of 128Ba. [ABSTRACT FROM AUTHOR]

The phenomenon of chiral symmetry breaking is discussed and a review of a wide spectrum of the experimental data is given. In addition to the basic description of this phenomenon an analysis of the level schemes and electromagnetic properties observed in nuclei expected to show the chiral symmetry breaking is presented. [ABSTRACT FROM AUTHOR]

It is emphasised that the chiral symmetry operator, RyT, commutes not only with the Hamiltonian but also with the electromagnetic transition operators M(σλ) for σλ =M1, E2, etc. This fact is used to illustrate possible differences in electromagnetic properties between the two chiral partner bands. On the basis of the 132La lifetime data an example is shown where differences in the transition probabilities observed in the partner and in the yrast band can be described in the chiral picture. [ABSTRACT FROM AUTHOR]

Results of the DSAM lifetime measurements in supposed chiral partner bands of 128Cs and 132La are presented. Experimental reduced transition probabilities in 128Cs are compared with theoretical calculations done in the frame of the Core-QuasiParticle Coupling model. The electromagnetic properties and energy pattern of partner bands show that 128Cs is the best candidate revealing the chiral symmetry breaking phenomenon. [ABSTRACT FROM AUTHOR]

Lifetimes of yrast levels with spins I π = 23/2--43/2- in 131La populated in the 122Sn(14N, 5n) reaction at a beam energy of 70MeV are measured by the Doppler Shift Attenuation method. A model of side-feeding population is presented. The model parameters are determined in an experiment based on the lineshape of γ-transitions from two highest spin levels and from the intensity distribution along the yrast band. The properties of the h 11/2 band in 131La are compared with the theoretical predictions obtained in the framework of the Core-Quasi-Particle Coupling and the self-consistent Total Routhian Surface models. [ABSTRACT FROM AUTHOR]

The lifetime of levels in 128Cs and 132La have been measured in-beam of the Warsaw University Cyclotron using DSA method. The absolute M1 and E2 transition probabilities have been deduced. Two cases have been found: 132La where the B(E2) values in yrast and partner bands differ up to 30 times and 128Cs - the B(E2) values in both bands differ only few times. It seems that bands in 128Cs are better candidates for chiral partner bands than the ones in 132La. [ABSTRACT FROM AUTHOR]

Lifetimes of the h[sub 11/2] decoupled band in [sup 131]La and supposed chiral bands in odd-odd [sup 132]La have been measured using the Doppler Shift Atenuation method. The properties of all bands have been calculated in terms of the Core Quasi Particle Coupling and Core Particle Hole Coupling models by using in both cases the same phenomenological core of [sup 130]Ba. A new band in [sup 132]La has been found. [ABSTRACT FROM AUTHOR]

The very neutron-deficient isotope 50Ni was produced in fragmentation reactions between a 650 A MeV 58Ni beam and a 9Be target. For the first time the decay of this nucleus was investigated, leading to the determination of the half-life as 12+3 -2 ms and the branching ratio for β-delayed proton emission of (70 ± 20)%. [ABSTRACT FROM AUTHOR]

The g factor of the 56 ns half-life isomeric state in 128Cs has been measured using the time-differential perturbed angular distribution method. This state is the bandhead of the positive-parity chiral rotational band, which emerges when an unpaired proton, an unpaired neutron hole, and an even-even core are coupled such that their angular momentum vectors are aplanar (chiral configuration). g-factor measurements can give important information on the relative orientation of the three angular momentum vectors. The measured g factor g=+0.59(1) shows that there is an important contribution of the core rotation in the total angular momentum of the isomeric state. Moreover, a quantitative theoretical analysis supports the conclusion that the three angular momentum vectors lie almost in one plane, which suggests that the chiral configuration in 128Cs demonstrated in previous works by characteristic patterns of electromagnetic transitions appears only above some value of the total nuclear spin. [ABSTRACT FROM AUTHOR]

The previously accepted spin values of the 991 and 1599 keV levels in 140Sm have been revised and established as 2+ and 0(+), respectively. The γ-γ angular correlation method was used to determine the new spin values. The excited low-spin levels in 140Sm were populated in the 140Eu→ 140Sm and 140Gd 140Eu→ 140Sm decays. The 140Gd and 140Eu nuclei were produced in the 112Cd + 32S reaction at a beam energy of 155 MeV. [ABSTRACT FROM AUTHOR]

The properties of the K-isomer decays in the 134Nd and 184Pt nuclei have been investigated. Measurements were carried out in e-γ and γ-γ coincidence modes using electron spectrometers coupled to the central European Array for Gamma Levels Evaluations at the Heavy Ion Laboratory of the University of Warsaw. Internal conversion coefficients were obtained for transitions relevant to the decay of the isomeric states, allowing the determination of multipolarities and mixing ratios as well as hindrance factors. Two possible causes of the weakening of the K forbiddenness, namely rotational K mixing (Coriolis interaction) and triaxiality, are briefly discussed using schematic theoretical models. [ABSTRACT FROM AUTHOR]

The lifetimes of the first excited states of the N = 30 isotones (50)Ca and (51)Sc have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f_{7/2} shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus (48)Ca, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.

The results of the Doppler-shift attenuation method lifetime measurements in partner bands of 128Cs and 132La are presented. Experimental reduced transition probabilities in 128Cs are compared with theoretical calculations done in the frame of the core-quasiparticle coupling model. The electromagnetic properties, energy and spin of levels belonging to the partner bands show that 128Cs is the best known example revealing the chiral symmetry breaking phenomenon.