257 research outputs found
Structure of 10N in 9C+p resonance scattering
The structure of exotic nucleus 10N was studied using 9C+p resonance
scattering. Two L=0 resonances were found to be the lowest states in 10N. The
ground state of 10N is unbound with respect to proton decay by 2.2(2) or 1.9(2)
MeV depending on the 2- or 1- spin-parity assignment, and the first excited
state is unbound by 2.8(2) MeV.Comment: 6 pages, 4 figures, 1 table, submitted to Phys. Lett.
Nuclear structure beyond the neutron drip line: the lowest energy states in He via their T=5/2 isobaric analogs in Li
The level structure of the very neutron rich and unbound He nucleus has
been the subject of significant experimental and theoretical study. Many recent
works have claimed that the two lowest energy He states exist with spins
and and widths on the order of hundreds of keV.
These findings cannot be reconciled with our contemporary understanding of
nuclear structure. The present work is the first high-resolution study with low
statistical uncertainty of the relevant excitation energy range in the
He system, performed via a search for the T=5/2 isobaric analog states
in Li populated through He+p elastic scattering. The present data show
no indication of any narrow structures. Instead, we find evidence for a broad
state in He located approximately 3 MeV above the neutron
decay threshold
Structure of 8B from elastic and inelastic 7Be+p scattering
Motivation: Detailed experimental knowledge of the level structure of light
weakly bound nuclei is necessary to guide the development of new theoretical
approaches that combine nuclear structure with reaction dynamics.
Purpose: The resonant structure of 8B is studied in this work.
Method: Excitation functions for elastic and inelastic 7Be+p scattering were
measured using a 7Be rare isotope beam. Excitation energies ranging between 1.6
and 3.4 MeV were investigated. An R-matrix analysis of the excitation functions
was performed.
Results: New low-lying resonances at 1.9, 2.5, and 3.3 MeV in 8B are reported
with spin-parity assignment 0+, 2+, and 1+, respectively. Comparison to the
Time Dependent Continuum Shell (TDCSM) model and ab initio no-core shell
model/resonating-group method (NCSM/RGM) calculations is performed. This work
is a more detailed analysis of the data first published as a Rapid
Communication. [J.P. Mitchell, et al, Phys. Rev. C 82, 011601(R) (2010)]
Conclusions: Identification of the 0+, 2+, 1+ states that were predicted by
some models at relatively low energy but never observed experimentally is an
important step toward understanding the structure of 8B. Their identification
was aided by having both elastic and inelastic scattering data. Direct
comparison of the cross sections and phase shifts predicted by the TDCSM and ab
initio No Core Shell Model coupled with the resonating group method is of
particular interest and provides a good test for these theoretical approaches.Comment: 15 pages, 19 figures, 3 tables, submitted to PR
Molecular Structures in T=1 states of 10B
Multi-center (molecular) structures can play an important role in light
nuclei. The highly deformed rotational band in 10Be with band head at 6.179 MeV
has been observed recently and suggested to have an exotic alpha:2n:alpha
configuration. A search for states with alpha:pn:alpha two-center molecular
configurations in 10B that are analogous to the states with alpha:2n:alpha
structure in 10Be has been performed. The T=1 isobaric analog states in 10B
were studied in the excitation energy range of E=8.7-12.1 MeV using the
reaction 1H(9Be,alpha)6Li*(T=1, 0+, 3.56 MeV). An R-matrix analysis was used to
extract parameters for the states observed in the (p,alpha) excitation
function. Five T=1 states in 10B have been identified. The known 2+ and 3-
states at 8.9 MeV have been observed and their partial widths have been
measured. The spin-parities and partial widths for three higher lying states
were determined. Our data support theoretical predictions that the 2+ state at
8.9 MeV (isobaric analog of the 7.54 MeV state in 10Be) is a highly clustered
state and can be identified as a member of the alpha:np:alpha rotational band.
The next member of this band, the 4+ state, has not been found. A very broad 0+
state at 11 MeV that corresponds to pure alpha+6Li(0+,T=1) configuration is
suggested and it might be related to similar structures found in 12C, 18O and
20Ne.Comment: 10 pages, 10 figures, accepted in Physical Review
Effect of Cr Layer on the Structure and Properties of Cr/DLC Films
This paper focuses on the Cr interlayer effect on the structure and properties of Cr/DLC films. To improve structural, mechanical and chemical properties of a-C films, we developed two layer chromium-carbon films produced by cathode magnetic filtered arc deposition. Microstructure and properties of these films are explained depending on the Cr-interlayer size. The structure is analyzed by Raman spectroscopy. Moreover, we also estimated residual stress, the friction coefficient, hardness, the elastic modulus and corrosion parameters by X-ray double crystal surface profilometry, tribotesting, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of the comparative analysis, we revealed a substantial improvement in the characteristics of the produced two layer films. The results provide theoretical basis for the application of these films
Low-lying states in 8B
Excitation functions of elastic and inelastic 7Be+p scattering were measured
in the energy range between 1.6 and 2.8 MeV in the c.m. An R-matrix analysis of
the excitation functions provides strong evidence for new positive parity
states in 8B. A new 2+ state at an excitation energy of 2.55 MeV was observed
and a new 0+ state at 1.9 MeV is tentatively suggested. The R-matrix and Time
Dependent Continuum Shell Model were used in the analysis of the excitation
functions. The new results are compared to the calculations of contemporary
theoretical models.Comment: 6 pages, 5 figures, accepted as Rapid Communication in Phys. Rev.
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