Structure of particle-hole nuclei around 100Sn

We have performed shell-model calculations for the three odd-odd nuclei 100In, 102In, and 98Ag, with neutron particles and proton holes around 100Sn. We have used a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential, the neutron-proton channel being explicitly treated in the particle-hole formalism. Particular attention has been focused on the particle-hole multiplets, which are a direct source of information on the neutron-proton effective interaction. We present our predictions for the two lowest lying multiplets in 100In, for which no spectroscopic data are yet available. For 98Ag and 102In comparison shows that our results are in very good agreement with the available experimental data.Comment: 5 pages, published in Physical review

Similarity of nuclear structure in 132Sn and 208Pb regions: proton-neutron multiplets

Starting from the striking similarity of proton-neutron multiplets in 134Sb and 210Bi, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the V-low-k approach. The calculated results for 136Sb, 212Bi, 136I, and 212At are in very good agreement with the available experimental data. The similarity between 132Sn and 208Pb regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.Comment: 4 pages, 3 figures, 2 table

Low-momentum nucleon-nucleon interaction and shell-model calculations

We discuss the use of the low-momentum nucleon-nucleon NN interaction V-low-k in the derivation of the shell-model effective interaction and emphasize its practical value as an alternative to the Brueckner G-matrix method. We present some selected results of our current study of exotic nuclei around closed shells, which have been obtained starting from the CD-Bonn potential. We also show some results of calculations performed with different phase-shift equivalent NN potentials, and discuss the effect of changes in the cutoff momentum which defines the V-low-k potential.Comment: 5 pages, 5 figures, 1 table, Talk presented at CDN05, 31 Jan - 4 Feb 2005, University of Tokyo, Japa

Realistic shell-model calculations: current status and open problems

The main steps involved in realistic shell-model calculations employing two-body low-momentum interactions are briefly reviewed. The practical value of this approach is exemplified by the results of recent calculations and some remaining open questions and directions for future research are discussed.Comment: 12 pages, 2 figures, contribution to J. Phys G, Special Issue, Focus Section: Open Problems in Nuclear Structur

Neutron-proton interaction in rare-earth nuclei: Role of tensor force

We investigate the role of the tensor force in the description of doubly odd deformed nuclei within the framework of the particle-rotor model. We study the rare-earth nuclei 174Lu, 180Ta, 182Ta, and 188Re using a finite-range interaction, with and without tensor terms. Attention is focused on the lowest K=0 and K=1 bands, where the effects of the residual neutron-proton interaction are particularly evident. Comparison of the calculated results with experimental data evidences the importance of the tensor-force effects.Comment: 8 pages, 5 figures, to be published on Physical Review

Low momentum nucleon-nucleon potential and shell model effective interactions

A low momentum nucleon-nucleon (NN) potential V-low-k is derived from meson exhange potentials by integrating out the model dependent high momentum modes of V_NN. The smooth and approximately unique V-low-k is used as input for shell model calculations instead of the usual Brueckner G matrix. Such an approach eliminates the nuclear mass dependence of the input interaction one finds in the G matrix approach, allowing the same input interaction to be used in different nuclear regions. Shell model calculations of 18O, 134Te and 135I using the same input V-low-k have been performed. For cut-off momentum Lambda in the vicinity of 2 fm-1, our calculated low-lying spectra for these nuclei are in good agreement with experiments, and are weakly dependent on Lambda.Comment: 5 pages, 5 figure

Low Momentum Nucleon-Nucleon Interactions and Shell-Model Calculations

In the last few years, the low-momentum nucleon-nucleon (NN) interaction V-low-k derived from free-space NN potentials has been successfully used in shell-model calculations. V-low-k is a smooth potential which preserves the deuteron binding energy as well as the half-on-shell T-matrix of the original NN potential up to a momentum cutoff Lambda. In this paper we put to the test a new low-momentum NN potential derived from chiral perturbation theory at next-to-next-to-next-to-leading order with a sharp low-momentum cutoff at 2.1 fm-1. Shell-model calculations for the oxygen isotopes using effective hamiltonians derived from both types of low-momentum potential are performed. We find that the two potentials show the same perturbative behavior and yield very similar results.Comment: 8 pages, 8 figures, to be published in Physical Review

Bonn Potential and Shell-Model Calculations for 206,205,204Pb

The structure of the nuclei 206,205,204Pb is studied interms of shell model employing a realistic effective interaction derived from the Bonn A nucleon-nucleon potential. The energy spectra, binding energies and electromagnetic properties are calculated and compared with experiment. A very good overall agreement is obtained. This evidences the reliability of our realistic effective interaction and encourages use of modern realistic potentials in shell-model calculations for heavy-mass nuclei.Comment: 4 pages, 4 figures, submitted to Physical Review

Periprocedural and Short-Term Outcomes of Transfemoral Transcatheter Aortic Valve Implantation With the Sapien XT as Compared With the Edwards Sapien Valve

ObjectivesThe aim of this study was to analyze the short-term outcomes after transcatheter aortic valve implantation with the Edwards Sapien THV (ESV), compared with the Sapien XT THV (SXT) (Edwards Lifesciences, Irvine, California).BackgroundThe SXT has been recently commercialized in Europe, but there are no studies analyzing the efficacy and safety of SXT, compared with ESV.MethodsAll consecutive patients (n = 120) who underwent transcatheter aortic valve implantation in our center via the transfemoral approach with either ESV (n = 66) or SXT (n = 54). Valve Academic Research Consortium endpoints were used.ResultsMean age was 80 ± 8 years, and mean Logistic-European System for Cardiac Operative Risk Evaluation was 24.9 ± 17.0. The ilio-femoral artery minimal lumen diameter was smaller in patients treated with the SXT (7.27 ± 1.09 mm vs. 7.94 ± 1.08 mm, p = 0.002). Device success was high in both groups (96.3% vs. 92.4%, p = 0.45). Major vascular events were 3-fold lower in the SXT group (11.1% vs. 33.3%, relative risk: 0.40, 95% confidence interval: 0.28 to 0.57; p = 0.004). Life-threatening and major bleeding events were not significantly different between groups (18.5% vs. 27.3% and 35.2% vs. 40.9%, respectively). The SXT group had a lower 30-day Valve Academic Research Consortium combined safety endpoint (20.4% vs. 45.5%; relative risk: 0.44, 95% confidence interval: 0.24 to 0.80; p = 0.004). The 30-day mortality was 1.7% (n = 2). At 30 days, mean transaortic gradient was approximately 10 mm Hg in both groups and the aortic regurgitation was mild-to-moderate in 70.2% of SXT and 76.3% of ESV.ConclusionsThe new SXT valve has the same short-term performance as the ESV but seems to be associated with a lower risk of major vascular complications and thus has a broader clinical application