Investigation of the mixed-symmetric one-quadrupole phonon 2+ 1,ms state of the heavy nucleus 204Hg

Low-energy quadrupole-collective excitations of isovector character, the so-called states with proton-neutron mixed-symmetric character (MSS), have been investigated in 204Hg which is the sole stable nucleus in the straight vicinity of 208Pb exhibiting a 2π - 2ν structure. A 12C(204Hg,204Hg∗)12C projectile Coulomb-excitation experiment at 890MeV was performed at Argonne National Laboratory using the ATLAS accelerator. γ-rays originating from the decay of the excited states of 204Hg were detected using the GAMMASPHERE spectrometer. The measured Coulomb-excitation yields provide the B(M1) and the B(E2) strength distributions which unambiguously reveal the 23 + state at 1948 keV as the one-phonon MSS of 204Hg

Factors Affecting European Farmers’Participation in Biodiversity Policies

This article reports the major findings from an interdisciplinary research project that synthesises key insights into farmers’ willingness and ability to co-operate with biodiversity policies. The results of the study are based on an assessment of about 160 publications and research reports from six EU member states and from international comparative research.We developed a conceptual framework to systematically review the existent literature relevant for our purposes. This framework provides a common structure for analysing farmers’ perspectives regarding the introduction into farming practices of measures relevant to biodiversity. The analysis is coupled and contrasted with a survey of experts. The results presented above suggest that it is important to view support for practices oriented towards biodiversity protection not in a static sense – as a situation determined by one or several influencing factors – but rather as a process marked by interaction. Financial compensation and incentives function as a necessary, though clearly not sufficient condition in this process

Wheat bran valorisation: Towards photocatalytic nanomaterials for benzyl alcohol photo-oxidation

In this work, we have successfully synthesized a set of titania photocatalytic nanocomposites by the incorporation of different TiO2 content on wheat bran residues. The obtained catalysts were characterized by different techniques including UVeVis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Transmission Electron Microscopy (TEM) while their photocatalytic activity was investigated in the oxidation of benzyl alcohol under UV light irradiation. Benzaldehyde yields were ca. 20%, with conversion in the systems of ca. 33% of benzyl alcohol by using 10%Ti-Bran catalyst, as compared to 33% yield to the target product (quantitative conversion of benzyl alcohol) using commercial pure TiO2 (P-25). The photocatalytic activity results indicate that designed waste-derived nanomaterials with low TiO2 content can efficiently photocatalyze the conversion of benzyl alcohol with relative high selectivity towards benzaldehyde

Nuclear isovector valence-shell excitation of Hg 202

Excited states of Hg202 have been studied via the C12(Hg202,Hg∗202) Coulomb excitation reaction at a beam energy of 890 MeV. The γ-ray transitions from the excited states of Hg202 were detected by the Gammasphere array. The intensities of the observed γ rays determined the relative populations of the excited states which were used to extract the absolute M1 and E2 transition strength distributions for excited 2+ states of Hg202 up to 2 MeV. The measured absolute B(M1;27+→21+) strength of 0.18(8)μN2 indicates that the 27+ level of Hg202 is the main fragment of the proton-neutron mixed-symmetry 21,ms+ state. Upper limits for the F-spin mixing matrix elements of 202,204Hg are determined as well

Identification of the one-quadrupole phonon 21,ms + state of 204Hg

One-phonon states of vibrational nuclei with mixed proton–neutron symmetry have been observed throughout the nuclear chart besides the mass A≈200 region. Very recently, it has been proposed that the 22 + state of 212Po is of isovector nature. This nucleus has two valence protons and two valence neutrons outside the doubly-magic 208Pb nucleus. The stable isotope 204Hg, featuring two valence-proton and valence-neutron holes, with respect to 208Pb, is the particle-hole mirror of 212Po. In order to compare the properties of low-lying isovector excitations in these particle-hole mirror nuclei, we have studied 204Hg by using the projectile Coulomb-excitation technique. The measured absolute B(M1;22 +→21 +) strength of 0.20(2)μN 2 indicates that the 22 + level of 204Hg is at least the main fragment of the 21,ms + state. For the first time in this mass region, both lowest-lying, one-quadrupole phonon excitations are established together with the complete set of their decay strengths. This allows for a microscopic description of their structures, achieved in the framework of the Quasi-particle Phonon Model

Identification of the one-quadrupole phonon 21,ms + state of 204Hg

One-phonon states of vibrational nuclei with mixed proton–neutron symmetry have been observed throughout the nuclear chart besides the mass A≈200 region. Very recently, it has been proposed that the 22 + state of 212Po is of isovector nature. This nucleus has two valence protons and two valence neutrons outside the doubly-magic 208Pb nucleus. The stable isotope 204Hg, featuring two valence-proton and valence-neutron holes, with respect to 208Pb, is the particle-hole mirror of 212Po. In order to compare the properties of low-lying isovector excitations in these particle-hole mirror nuclei, we have studied 204Hg by using the projectile Coulomb-excitation technique. The measured absolute B(M1;22 +→21 +) strength of 0.20(2)μN 2 indicates that the 22 + level of 204Hg is at least the main fragment of the 21,ms + state. For the first time in this mass region, both lowest-lying, one-quadrupole phonon excitations are established together with the complete set of their decay strengths. This allows for a microscopic description of their structures, achieved in the framework of the Quasi-particle Phonon Model

Isospin dependence of electromagnetic transition strengths among an isobaric triplet

Electric quadrupole matrix elements, M, for the J=2→0, ΔT=0, T=1 transitions across the A=46 isobaric multiplet Cr-V-Ti have been measured at GSI with the FRS-LYCCA-AGATA setup. This allows direct insight into the isospin purity of the states of interest by testing the linearity of M with respect to T. Pairs of nuclei in the T=1 triplet were studied using identical reaction mechanisms in order to control systematic errors. The M values were obtained with two different methodologies: (i) a relativistic Coulomb excitation experiment was performed for Cr and Ti; (ii) a “stretched target” technique was adopted here, for the first time, for lifetime measurements in V and Ti. A constant value of M across the triplet has been observed. Shell-model calculations performed within the fp shell fail to reproduce this unexpected trend, pointing towards the need of a wider valence space. This result is confirmed by the good agreement with experimental data achieved with an interaction which allows excitations from the underlying sd shell. A test of the linearity rule for all published data on complete T=1 isospin triplets is presented.Peer Reviewe

Study of Isomeric States in ^{198,200,202,206}Pb and ²⁰⁶Hg Populated in Fragmentation Reactions

Isomeric states in isotopes in the vicinity of doubly-magic 208Pb were populated following reactions of a relativistic 208Pb primary beam impinging on a 9Be fragmentation target. Secondary beams of 198;200;202;206Pb and 206Hg were isotopically separated and implanted in a passive stopper positioned in the focal plane of the GSI Fragment Separator. Delayed γ rays were detected with the Advanced GAmma Tracking Array (AGATA). Decay schemes were re-evaluated and interpreted with shell-model calculations. The momentum-dependent population of isomeric states in the two-nucleon hole nuclei 206Pb/206Hg was found to differ from the population of multi neutron-hole isomeric states in 198;200;202Pb