28 research outputs found
A doorway to Borromean halo nuclei: the Samba configuration
We exploit the possibility of new configurations in three-body halo nuclei -
Samba type - (the neutron-core form a bound system) as a doorway to Borromean
systems. The nuclei Be, B, N and F are of such
nature, in particular N with a half-life of 37.7 s and a halo radius of
6.07 fm is an excellent example of Samba-halo configuration. The fusion below
the barrier of the Samba halo nuclei with heavy targets could reveal the so far
elusive enhancement and a dominance of one-neutron over two-neutron transfers,
in contrast to what was found recently for the Borromean halo nucleus He +
U.Comment: Accepted for publication in Modern Physics Letters
Halo Excitation of He in Inelastic and Charge-Exchange Reactions
Four-body distorted wave theory appropriate for nucleon-nucleus reactions
leading to 3-body continuum excitations of two-neutron Borromean halo nuclei is
developed. The peculiarities of the halo bound state and 3-body continuum are
fully taken into account by using the method of hyperspherical harmonics. The
procedure is applied for A=6 test-bench nuclei; thus we report detailed studies
of inclusive cross sections for inelastic He(p,p')He and
charge-exchange Li(n,p)He reactions at nucleon energy 50 MeV. The
theoretical low-energy spectra exhibit two resonance-like structures. The first
(narrow) is the excitation of the well-known three-body resonance. The
second (broad) bump is a composition of overlapping soft modes of
multipolarities whose relative weights depend on
transferred momentum and reaction type. Inelastic scattering is the most
selective tool for studying the soft dipole excitation mode.Comment: Submitted to Phys. Rev. C., 11 figures using eps
New Discrete Basis for Nuclear Structure Studies
A complete discrete set of spherical single-particle wave functions for
studies of weakly-bound many-body systems is proposed. The new basis is
obtained by means of a local-scale point transformation of the spherical
harmonic oscillator wave functions. Unlike the harmonic oscillator states, the
new wave functions decay exponentially at large distances. Using the new basis,
characteristics of weakly-bound orbitals are analyzed and the ground state
properties of some spherical doubly-magic nuclei are studied. The basis of the
transformed harmonic oscillator is a significant improvement over the harmonic
oscillator basis, especially in studies of exotic nuclei where the coupling to
the particle continuum is important.Comment: 13 pages, RevTex, 6 p.s. figures, submitted to Phys. Rev.
Three-body continuum energy correlations in Borromean halo nuclei. III. Short-range external fields
Recommended from our members
A New phenomenological tau-alpha interaction
We present a potential model, with distinctive features, reproducing angular distributions and analyzing power data for tau-alpha scattering from 20 to 30 MeV energy with regular variation of the parameters. The distinctive features are: (1) a spin-orbit term which incorporates the influence of central depression in the nucleus, and, (2) central terms which are strongly parity dependent. The parity dependence of the real central term is such that the odd-parity component has both a greater rms radius and greater volume integral than the even-parity component. These parity dependence characteristics had been predicted by the inversion of the RGM S-matrix. Our result supports a considerable contribution from three-nucleon exchange processes. The predicted 1/2- level of 7Be is shifted 3 MeV relative to a previous one-level R-matrix formula fit, and depends strongly on the geometry of the spin-orbit potential
19-C: the heaviest one-neutron halo nucleus?
We have investigated the loosely bound halo candidate
in a neutron + core coupling model. A deformed
Woods-Saxon potential is used for the neutron-core interaction and the
coupled channels equations are solved with Sturmian expansions of the
relative motion wave functions for experimental neutron separation energy.
Longitudinal momentum distributions, the r.m.s. matter
radius, the neutron stripping cross-section and the electromagnetic
dissociation cross-section are calculated
and compared with the sparse available data. An assessment of
the possible character
of is made, and
in particular, of the role of
s-orbital motion between halo-neutron and core
Hvordan formidle dÄrlige nyheter pÄ en god mÄte?
Sammendrag
Bakgrunn: Formidling av dÄrlige nyheter er en krevende oppgave, som utfordrer legen pÄ et personlig og mellommenneskelig plan. Man har i stadig stÞrre grad blitt bevisst pÄ at klinisk kommunikasjon bÞr fÄ stÞrre plass i legeutdannelsen. Samtidig ser man at helsevesenet i Þkende grad preges av krav til effektivitet og mindre tid til den enkelte pasient.
Kunnskapsgrunnlag: Vi gjorde et systematisk litteratursÞk. SÞk i Cochrane Library og PubMed Clinical Queries gav noen relevante resultater. Generelt ser de ut til at det er vanskelig Ä studere effekt av tiltak som gÄr pÄ situasjonen rundt det Ä gi en dÄrlig beskjed. Det er liten dokumentasjon pÄ tiltak som bedrer pasientnÊre indikatorer.
Begrunnet tiltak og metode: Tiltaket vi valgte Ä innfÞre var basert pÄ avdelingens egne erfaringer og Þnsker. Avdelingen vi undersÞkte hadde fra fÞr gode rutiner for denne typen utfordringer, men ingen av rutinene var skrevet ned. Som tiltak valgte vi derfor Ä skriftliggjÞre de allerede eksisterende rutinene, slik at de ble lettere tilgjengelige for nye leger og andre pÄ avdelingen. PÄ denne mÄten hÄpet vi Ä kunne kvalitetssikre at de allerede eksisterende gode rutinene ivaretas ogsÄ i fremtiden. Som indikator valgte vi Ä utarbeide et spÞrreskjema som sykepleierne skal fylle ut ved alle konsultasjonene hver februar og september mÄned.
Implementering: Avdelingsoverlege har ansvar for Ä dele ut retningslinjene til nye leger. For Ä vurdere om retningslinjene fÞlges, og sikre fortsatt fokus pÄ kommunikasjon av dÄrlige nyheter, vil det bli gjennomfÞrt en evaluering to mÄneder i Äret der sykepleieren som er med pÄ samtalen vurderer kommunikasjonen ved hjelp av et spÞrreskjema.
Vurdering: VÄr mening er at et manglende kunnskapsgrunnlag ikke bÞr vÊre til hinder for at man forsÞker Ä gjennomfÞre et forbedringsarbeid. Vi tror at vÄrt tiltak kan ha effekt ved Ä etablere en minimumsramme for kommunikasjonen ved formidling av dÄrlige nyheter, og pÄ den mÄten hindre at de mest alvorlige feilene begÄs. Dessuten hÄper vi at disse retningslinjene og dette forbedringsarbeidet kan vÊre til hjelp for andre avdelinger som Þnsker Þkt fokus pÄ dette omrÄdet