.
The electric dipole (
E
1 response of
208
Pb has been precisely determined by measuring Coulomb excitation induced by proton scattering at very forward angles. The electric dipole polarizability, ...defined as inverse energy-weighted sum rule of the
E
1 strength, has been extracted as
fm
3
. The data can be used to constrain the neutron skin thickness of
208
Pb to
fm, where the subscript “expt” refers to the experimental uncertainty, “theor” to the theoretical confidence band and “est” to the uncertainty associated with the estimation of the symmetry energy at the saturation density. In addition, a constraint band has been extracted in the plane of the symmetry energy (
J
and its slope parameter (
L
at the saturation density.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A gas target system has been developed for nuclear scattering experiments with a highly dispersive spectrometer at small scattering angles including 0°. The system is equipped with a gas cell that ...has a wide beam window of 44mm in width and 14mm in height. The size is sufficient to pass a dispersed beam, which is essential for high energy-resolution measurement. A gas handling system allows target gas that is often limited in quantity, to be collected for reuse. Typical areal density is 1mg/cm2 for 20Ne or 36Ar gas. The target can be operated either at room temperature or at the liquid nitrogen temperature. The gas target has been employed in a proton inelastic-scattering experiment at 295MeV with the Grand Raiden spectrometer at the Research Center for Nuclear Physics. A good energy resolution of 20keV (FWHM) has been achieved at scattering angles of 0–4.5°.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Abstract
We searched for the $\alpha$ condensed state in $^{13}$C by measuring the $\alpha$ inelastic scattering at $E_\alpha = 388$ MeV at forward angles including 0$^\circ$. We performed a ...distorted-wave Born approximation calculation with the single-folding potential and multipole decomposition analysis to determine the isoscalar transition strengths in $^{13}$C. We found a bump structure around $E_x = 12.5$ MeV due to the isoscalar monopole ($IS0$) transition. A peak-fit analysis suggested that this bump consisted of several $1/2^-$ states. We propose that this bump is due to the mirror state of the 13.5 MeV state in $^{13}$N, which dominantly decays to the $\alpha$ condensed state in $^{12}$C. It was speculated that the $1/2^-$ states around $E_x = 12.5$ MeV were candidates for the $\alpha$ condensed state, but the $3\alpha + n$ orthogonality condition model suggests that the $\alpha$ condensed state is unlikely to emerge as the negative parity states. We also found two $1/2^+$ or $3/2^+$ states at $E_x = 14.5$ and 16.1 MeV excited with the isoscalar dipole ($IS1$) strengths. We suggest that the 16.1 MeV state is a possible candidate for the $\alpha$ condensed state predicted by the cluster model calculations on the basis of the good correspondence between the experimental and calculated level structures. However, the theoretical $IS1$ transition strength for this state is significantly smaller than the measured value. Further experimental information is strongly desired to establish the $\alpha$ condensed state in $^{13}$C.
The Gamow–Teller strength distributions of
116
Sb
and
122
Sb
were measured with the
116
,
122
Sn
(
3
He
,
t
)
116
,
122
Sb
charge-exchange reactions at
140
MeV/u
. The measurements were carried out ...at the Research Center for Nuclear Physics (RCNP) at Osaka University in Osaka, Japan using the Grand Raiden spectrometer. The data were analysed by Multipole-Decomposition Analysis (MDA). The Gamow–Teller strengths summed up to
28
MeV
are
(
38
±
7
)
%
and
(
48
±
6
)
%
of the Ikeda sum rule for
116
Sb
and
122
Sb
, respectively, if the quasi-free scattering (QFS) contribution is not subtracted. These percentages are
(
29
±
7
)
%
and
(
35
±
5
)
%
, respectively, if the QFS contribution is maximally subtracted. These results were compared to those from previous measurements of the same isotopes, to recent measurements of
150
Pm
, and to a Quasi-particle Random-Phase Approximation (QRPA) calculation with Quasi-Particle Vibration Coupling (QPVC). The data suggest that the true QFS contribution is small for
116
Sb
, but are inconclusive about whether the QFS contribution is small or significant for
122
Sb
. Therefore, these data may provide an interesting test for the general quenching phenomenon of the Gamow–Teller Resonance (GTR). However, more research to reveal the nature of the QFS contribution is still needed on both the experimental and the theoretical side.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We have measured the β -decay half-lives of 16 neutron-deficient nuclei with T z = - 1 / 2 and -1 , ranging from chromium to germanium. They were produced in an experiment carried out at GANIL and ...optimized for the production of 58Zn , for which in addition we present the decay scheme and absolute Fermi and Gamow-Teller transition strengths. Since all of these nuclei lie on the rp -process pathway, the T 1 / 2 values are important ingredients for the rp -process reaction flow calculations and for models of X-ray bursters.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Isospin symmetry is expected for the T(z)=+/-1-->0 isobaric analogous transitions in isobars with mass number A, where T(z) is the z component of isospin T. Assuming this symmetry, strengths of ...analogous Gamow-Teller (GT) transitions within A = 50 isobars were determined from a high energy-resolution study at 0 degrees in combination with the decay Q value and lifetime from the beta decay. This method can be applied to other pf-shell nuclei and can be used to study GT strengths of astrophysical interest.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
.
A survey of the fine structure of the Isovector Giant Dipole Resonance (IVGDR) was performed, using the recently commissioned Zero-degree Facility of the K600 magnetic spectrometer at iThemba LABS. ...Inelastic proton scattering at an incident energy of 200MeV was measured on
27
Al ,
40
Ca ,
56
Fe ,
58
Ni and
208
Pb . A high energy-resolution (
Δ
E
≃
40
keV FWHM) could be achieved after utilising faint-beam and dispersion-matching techniques. A considerable fine structure is observed in the energy region of the IVGDR and characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The comparison with Quasiparticle-Phonon Model (QPM) calculations provides insight into the relevance of different giant resonance decay mechanisms. Photoabsorption cross sections derived from the data assuming a dominance of relativistic Coulomb excitation are in fair agreement with previous work using real photons.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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