418 research outputs found
No-Core shell model for A = 47 and A = 49
We apply an {\it ab-initio} approach to the nuclear structure of odd-mass
nuclei straddling . Starting with the NN interaction, that fits
two-body scattering and bound state data we evaluate the nuclear properties of
and nuclei in a no-core approach. Due to model space
limitations and the absence of 3-body interactions, we incorporate
phenomenological terms determined by fits to nuclei in a previous
effort. Our modified Hamiltonian produces reasonable spectra for these odd mass
nuclei. In addition to the differences in single-particle basis states, the
absence of a single-particle Hamiltonian in our no-core approach obscures
direct comparisons with valence effective NN interactions. Nevertheless, we
compare the fp-shell matrix elements of our initial and modified Hamiltonians
in the harmonic oscillator basis with a recent model fp-shell interaction, the
GXPF1 interaction of Honma, Otsuka, Brown and Mizusaki. Notable differences
emerge from these comparisons. In particular, our diagonal two-body
matrix elements are, on average, about 800-900keV more attractive. Furthermore,
while our initial and modified NN Hamiltonian fp-shell matrix elements are
strongly correlated, there is much less correlation with the GXPF1 matrix
elements.Comment: 17 pages including 14 figure
Unveiling the intruder deformed 0 state in Si
The 0 state in Si has been populated at the {\sc Ganil/Lise3}
facility through the -decay of a newly discovered 1 isomer in
Al of 26(1) ms half-life. The simultaneous detection of pairs
allowed the determination of the excitation energy E(0)=2719(3) keV and
the half-life T=19.4(7) ns, from which an electric monopole strength of
(E0)=13.0(0.9) was deduced. The 2 state is
observed to decay both to the 0 ground state and to the newly observed
0 state (via a 607(2) keV transition) with a ratio
R(2)=1380(717). Gathering all
information, a weak mixing with the 0 and a large deformation parameter
of =0.29(4) are found for the 0 state, in good agreement with
shell model calculations using a new {\sc sdpf-u-mix} interaction allowing
\textit{np-nh} excitations across the N=20 shell gap.Comment: 5 pages, 3 figures, accepted for publication in Physical Review
Letter
Interaction potential between dynamic dipoles: polarized excitons in strong magnetic fields
The interaction potential of a two-dimensional system of excitons with
spatially separated electron-hole layers is considered in the strong magnetic
field limit. The excitons are assumed to have free dynamics in the -
plane, while being constrained or `polarized' in the direction. The model
simulates semiconductor double layer systems under strong magnetic field normal
to the layers. The {\em residual} interaction between excitons exhibits
interesting features, arising from the coupling of the center-of-mass and
internal degrees of freedom of the exciton in the magnetic field. This coupling
induces a dynamical dipole moment proportional to the center-of-mass magnetic
moment of the exciton. We show the explicit dependence of the inter-exciton
potential matrix elements, and discuss the underlying physics. The unusual
features of the interaction potential would be reflected in the collective
response and non-equilibrium properties of such system.Comment: REVTEX - 11 pages - 1 fi
Prolate-Spherical Shape Coexistence at N=28 in S
The structure of S has been studied using delayed and
electron spectroscopy at \textsc{ganil}. The decay rates of the 0
isomeric state to the 2 and 0 states have been measured for the
first time, leading to a reduced transition probability
B(E2~:~20= 8.4(26)~efm and a monopole
strength (E0~:~00
=~8.7(7)10. Comparisons to shell model calculations point
towards prolate-spherical shape coexistence and a phenomenological two level
mixing model is used to extract a weak mixing between the two configurations.Comment: 5 pages, 3 figures, accepted for publication in Physical Review
Letter
Spectroscopy of F
The structure of the weakly-bound F odd-odd nucleus,
produced from Na nuclei, has been investigated at GANIL by means of
the in-beam -ray spectroscopy technique. A single -line is
observed at 657(7) keV in F which has been ascribed to the decay of
the excited J= state to the J=1 ground state. The possible presence of
intruder negative parity states in F is also discussed.Comment: 3 pages, 1 figure, accepted for publication in Physical Review
Collapse of the N=28 shell closure in Si
The energies of the excited states in very neutron-rich Si and
P have been measured using in-beam -ray spectroscopy from the
fragmentation of secondary beams of S at 39 A.MeV. The low 2
energy of Si, 770(19) keV, together with the level schemes of
P provide evidence for the disappearance of the Z=14 and N=28
spherical shell closures, which is ascribed mainly to the action of
proton-neutron tensor forces. New shell model calculations indicate that
Si is best described as a well deformed oblate rotor.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. let
Study on the One-Proton Halo Structure in Al
The Glauber theory has been used to investigate the reaction cross section of
proton-rich nucleus Al. A core plus a proton structure is assumed for
Al. HO-type density distribution is used for the core while the density
distribution for the valence proton is calculated by solving the eigenvalue
problem of Woods-Saxon potential. The transparency function in an analytical
expression is obtained adopting multi-Gaussian expansion for the density
distribution. Coulomb correction and finite-range interaction are introduced.
This modified Glauber model is apt for halo nuclei. A dominate s-wave is
suggested for the last proton in Al from our analysis which is possible
in the RMF calculation.Comment: 4 pages, 4 figure
Strong field physics and QED experiments with ELI-NP 2×10PW laser beams
The ELI-NP facility will focus a 10 PW pulsed laser beam at intensities of ∼10 23 W/cm 2 for the first time, enabling investigation of the new physical phenomena at the interfaces of plasma, nuclear and particle physics. The electric field in the laser focus has a maximum value of ∼10 15 V/m at such laser intensities. In the ELI-NP Experimental Area E6, we propose the study of Radiation Reaction, Strong Field Quantum Electrodynamics (QED) effects and resulting production of Ultra-bright Sources of Gamma-rays which could be used for nuclear activation. Two powerful, synchronized 10 PW laser beams will be focused in the E6 Interaction Chamber on either gas or solid targets. One 10 PW beam is the Pump-beam and the other is the Probe-beam. The focused Pump beam accelerates the electrons to relativistic energies. The accelerated electron bunches interact with the very high electro-magnetic field of the focused Probe beam. The layout of the experimental area E6 will be presented with several options for the experimental configurations
Recurrence of hepatocellular carcinoma
Clinica I Chirurgie, Spitalul “Sf.Spiridon”, Departamentul de Chirurgie, Universitatea de Medicină și Farmacie
“Gr.T.Popa”, Iași, România, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Rezecția hepatică rămâne “standardul de aur” în tratamentul cancerului hepatocelular (CHC). Alegerea variantei
de rezecție hepatică depinde de mai mulți factori: localizarea tumorii, dimensiunile tumorii, starea parenchimului hepatic
nontumoral, scorul Child-Pugh. Problema recurenței locoregionale în funcție de tipul de rezecție rămâne controversată.
Scopul studiului: Ne-am propus să comparăm rata recurenței loco-regionale a CHC în funcție de tipul de rezecție hepatică
(anatomică versus non-anatomică).
Material și metode: Am analizat 64 de pacienți cu CHC, care au beneficiat de rezecție hepatică curativă în perioada 2005-
2013. Pacienții au fost împărțiți în două loturi: lotul A – 26 de pacienți la care s-a practicat o rezecție hepatică anatomică și lotul
B – 38 de pacienți la care s-a practicat o rezecție hepatică non-anatomică.
Rezultate: Pe o perioadă de urmărire postoperatorie cuprinsă între 12 și 60 de luni, rata recurenței CHC în cele două loturi a
fost de 32% în grupul A și 31,4% în grupul B (P=0,963). Durata medie de apariție a recurenței a fost de 15,63±7,46 luni (între 5
și 25 luni) în lotul A și 16,91±9,35 luni (între 5 și 33 luni) în lotul B (P=0,753).
Concluzii: Tipul de rezecție hepatică (anatomică sau non-anatomică) nu influențează apariția recurenței CHC, dacă se
respectă limitele oncologice de rezecție.Introduction: Liver resection remains the gold standard in the treatment of hepatocellular cancer (HCC). Choosing liver
resection depends on several factors: tumor location, tumor size, condition nontumoral liver parenchyma, Child-Pugh score. The
locoregional recurrence problem depending on the type of resection remains controversial.
The purpose of the study: We aimed to compare loco-regional recurrence rate of HCC according to the type of hepatic
resection (anatomic versus non-anatomical).
Material and methods: We analyzed 64 patients with HCC who received curative liver resection during the period 2005-2013.
Patients were divided into two groups: group A – 26 patients who underwent hepatic anatomical resection and group B – 38
patients who underwent non-anatomical hepatic resection.
Results: On a postoperative follow-up period between 12 and 60 months, HCC recurrence rate in the two groups was 32% in
group A and 31.4% in group B (P=0.963). The average length of developing appellant was 15.63±7.46 months (between 5 and
25 months) in group A and 16.91±9.35 months (between 5 and 33 months) in group B (P=0.753).
Conclusions: The type of liver resection (anatomical or non-anatomical) does not influence the occurrence of HCC recurrence,
if we respect the oncologic limits resection
Experimental investigation of the effect of ionization on the 51V(p,n)51Cr reaction
The investigation of the effects of average atomic ionization on nuclear
reactions is of prime importance for nuclear astrophysics. No direct
experimental measurement using a plasma target has been done yet. In this
regard, we measured for the first time the neutron production of a (p,n)
reaction in different states of ionization. The studied nuclear reaction was
51V(p,n)51Cr. We measured a significantly lower neutron production than
expected when the target was ionized, even when taking into account existing
electron screening theory or the effect of the stopping power in the target on
the injected proton beam. This experiment is a first step in the process to
characterize the influence of ionization at astrophysically relevant energies.Comment: 20 pages, 10 figures, submitted to EP
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