287 research outputs found
Precise half-life measurement of 110Sn and 109In isotopes
The half-lives of 110Sn and 109In isotopes have been measured with high
precision. The results are T1/2 =4.173 +- 0.023 h for 110Sn and T1/2 = 4.167
+-0.018 h for 109In. The precision of the half-lives has been increased by a
factor of 5 with respect to the literature values which makes results of the
recently measured 106Cd(alpha,gamma)110Sn and 106Cd(alpha,p)109In cross
sections more reliable.Comment: 3 pages, 2 figures, accepted for publication in Phys. Rev C as brief
repor
The Equivalence Problem for Deterministic MSO Tree Transducers is Decidable
It is decidable for deterministic MSO definable graph-to-string or
graph-to-tree transducers whether they are equivalent on a context-free set of
graphs
Alpha-induced reactions for the astrophysical p-process: the case of 151Eu
The cross sections of 151Eu(alpha,gamma)155Tb and 151Eu(alpha,n)154Tb
reactions have been measured with the activation method. Some aspects of the
measurement are presented here to illustrate the requirements of experimental
techniques needed to obtain nuclear data for the astrophysical p-process
nucleosynthesis. Preliminary cross section results are also presented and
compared with the predictions of statistical model calculations.Comment: Accepted for publication in Journal of Physics Conference Series,
proceeding of the Nuclear Physics in Astrophysics IV. conferenc
Proton capture cross section of Sr isotopes and their importance for nucleosynthesis of proton-rich nuclides
The (p,) cross sections of three stable Sr isotopes have been
measured in the astrophysically relevant energy range. These reactions are
important for the -process in stellar nucleosynthesis and, in addition, the
reaction cross sections in the mass region up to 100 are also of importance
concerning the -process associated with explosive hydrogen and helium
burning. It is speculated that this -process could be responsible for a
certain amount of -nuclei in this mass region. The (p,) cross
sections of Sr isotopes were determined using an activation
technique. The measurements were carried out at the 5 MV Van de Graaff
accelerator of the ATOMKI, Debrecen. The resulting cross sections are compared
with the predictions of statistical model calculations. The predictions are in
good agreement with the experimental results for Sr(p,)Y
whereas the other two reactions exhibit differences that increase with mass
number. The corresponding astrophysical reaction rates have also been computed.Comment: Phys. Rev. C in pres
On reducing inconsistency of pairwise comparison matrices below an acceptance threshold
A recent work of the authors on the analysis of pairwise comparison matrices
that can be made consistent by the modification of a few elements is continued
and extended. Inconsistency indices are defined for indicating the overall
quality of a pairwise comparison matrix. It is expected that serious
contradictions in the matrix imply high inconsistency and vice versa. However,
in the 35-year history of the applications of pairwise comparison matrices,
only one of the indices, namely CR proposed by Saaty, has been associated to a
general level of acceptance, by the well known ten percent rule. In the paper,
we consider a wide class of inconsistency indices, including CR, CM proposed by
Koczkodaj and Duszak and CI by Pel\'aez and Lamata. Assume that a threshold of
acceptable inconsistency is given (for CR it can be 0.1). The aim is to find
the minimal number of matrix elements, the appropriate modification of which
makes the matrix acceptable. On the other hand, given the maximal number of
modifiable matrix elements, the aim is to find the minimal level of
inconsistency that can be achieved. In both cases the solution is derived from
a nonlinear mixed-integer optimization problem. Results are applicable in
decision support systems that allow real time interaction with the decision
maker in order to review pairwise comparison matrices.Comment: 20 page
Impact of a revised Mg(p,)Al reaction rate on the operation of the Mg-Al cycle
Proton captures on Mg isotopes play an important role in the Mg-Al cycle
active in stellar H-burning regions. In particular, low-energy nuclear
resonances in the Mg(p,)Al reaction affect the production
of radioactive Al as well as the resulting Mg/Al abundance ratio.
Reliable estimations of these quantities require precise measurements of the
strengths of low-energy resonances. Based on a new experimental study performed
at LUNA, we provide revised rates of the Mg(p,)Al
and the Mg(p,)Al reactions with corresponding
uncertainties. In the temperature range 50 to 150 MK, the new recommended rate
of the Al production is up to 5 times higher than previously
assumed. In addition, at T MK, the revised total reaction rate is a
factor of 2 higher. Note that this is the range of temperature at which the
Mg-Al cycle operates in an H-burning zone. The effects of this revision are
discussed. Due to the significantly larger Mg(p,)Al
rate, the estimated production of Al in H-burning regions is less
efficient than previously obtained. As a result, the new rates should imply a
smaller contribution from Wolf-Rayet stars to the galactic Al budget.
Similarly, we show that the AGB extra-mixing scenario does not appear able to
explain the most extreme values of Al/Al, i.e. , found
in some O-rich presolar grains. Finally, the substantial increase of the total
reaction rate makes the hypothesis of a self-pollution by massive AGBs a more
robust explanation for the Mg-Al anticorrelation observed in Globular-Cluster
stars
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
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