1,084 research outputs found
Relativistic continuum-continuum coupling in the dissociation of halo nuclei
A relativistic coupled-channels theory for the calculation of dissociation
cross sections of halo nuclei is developed. A comparison with non-relativistic
models is done for the dissociation of B projectiles. It is shown that
neglecting relativistic effects leads to seizable inaccuracies in the
extraction of the astrophysical S-factor for the proton+beryllium radiative
capture reaction.Comment: 4 pages, 2 figures, version accepted for publication at Physics
Review Letter
Theoretical photo-disintegration of O
The photodisintegration of O is predicted to be dominated by 2
excitation in the vicinity of the -particle threshold.
The reaction rates of C(,)O are expected to be
determined from this reaction.Comment: 3 pages, 2 figures, Proceedings of Nuclei in the Cosmos (NIC-XIV).
19-24 June 2016, Niigata, Japa
Resonances and the thermonuclear reaction rate
We present an approximate analytic expression for thermonuclear reaction rate
of charged particles when the cross section contains a single narrow or wide
resonance described by a Breit-Wigner shape. The resulting expression is
uniformly valid as the effective energy and resonance energy coalesce. We use
our expressions to calculate the reaction rate for
C(p,)N.Comment: 4 pages, 1 figure, presented at the VIII International Conference on
Nucleus-Nucleus in Moscow (Russia) on June 17-21, 200
Study of the 12C+12C fusion reactions near the Gamow energy
The fusion reactions 12C(12C,a)20Ne and 12C(12C,p)23Na have been studied from
E = 2.10 to 4.75 MeV by gamma-ray spectroscopy using a C target with ultra-low
hydrogen contamination. The deduced astrophysical S(E)* factor exhibits new
resonances at E <= 3.0 MeV, in particular a strong resonance at E = 2.14 MeV,
which lies at the high-energy tail of the Gamow peak. The resonance increases
the present non-resonant reaction rate of the alpha channel by a factor of 5
near T = 8x10^8 K. Due to the resonance structure, extrapolation to the Gamow
energy E_G = 1.5 MeV is quite uncertain. An experimental approach based on an
underground accelerator placed in a salt mine in combination with a high
efficiency detection setup could provide data over the full E_G energy range.Comment: 4 Pages, 4 figures, accepted for publication in Phys. Rev. Let
Solving the two-center nuclear shell-model problem with arbitrarily-orientated deformed potentials
A general new technique to solve the two-center problem with
arbitrarily-orientated deformed realistic potentials is demonstrated, which is
based on the powerful potential separable expansion method. As an example,
molecular single-particle spectra for C + C Mg are
calculated using deformed Woods-Saxon potentials. These clearly show that
non-axial symmetric configurations play a crucial role in molecular resonances
observed in reaction processes for this system at low energy
Correspondence between W. J. Kerr, A. E. Stene, F. M. Rolfs, L. H. Bailey, and Charles F. Curtiss
Correspondence concerning a position in Horticulture Botany at Utah Agricultural College
Two important cotton diseases and their control
The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311
Thermal neutron induced (n,p) and (n,alpha) reactions on 37Ar
The 37Ar(n_th,alpha)34S and 37Ar(n_th,p)37Cl reactions were studied at the
high flux reactor of the ILL in Grenoble. For the 37Ar(n_th,alpha_0) and
37Ar(n_th,p) reaction cross sections, values of (1070+/-80)b and (37+/-4)b,
respectively, were obtained. Both values are about a factor 2 smaller than
results of older measurements. The observed suppression of the 37(n_th,alpha_1)
transition could be verified from theoretical considerations. Finally, evidence
was found for the two-step 37Ar(n_th,gamma-alpha) process.Comment: 11 pages, 5 figures, accepted for publication in Nuclear Physics
Atomic effects in astrophysical nuclear reactions
Two models are presented for the description of the electron screening
effects that appear in laboratory nuclear reactions at astrophysical energies.
The two-electron screening energy of the first model agrees very well with the
recent LUNA experimental result for the break-up reaction , which so far defies all available theoretical models.
Moreover, multi-electron effects that enhance laboratory reactions of the CNO
cycle and other advanced nuclear burning stages, are also studied by means of
the Thomas-Fermi model, deriving analytical formulae that establish a lower and
upper limit for the associated screening energy. The results of the second
model, which show a very satisfactory compatibility with the adiabatic
approximation ones, are expected to be particularly useful in future
experiments for a more accurate determination of the CNO astrophysical factors.Comment: 14 RevTex pages + 2 ps (revised) figures. Phys.Rev.C (in production
Activation measurement of the 3He(alpha,gamma)7Be cross section at low energy
The nuclear physics input from the 3He(alpha,gamma)7Be cross section is a
major uncertainty in the fluxes of 7Be and 8B neutrinos from the Sun predicted
by solar models and in the 7Li abundance obtained in big-bang nucleosynthesis
calculations. The present work reports on a new precision experiment using the
activation technique at energies directly relevant to big-bang nucleosynthesis.
Previously such low energies had been reached experimentally only by the
prompt-gamma technique and with inferior precision. Using a windowless gas
target, high beam intensity and low background gamma-counting facilities, the
3He(alpha,gamma)7Be cross section has been determined at 127, 148 and 169 keV
center-of-mass energy with a total uncertainty of 4%. The sources of systematic
uncertainty are discussed in detail. The present data can be used in big-bang
nucleosynthesis calculations and to constrain the extrapolation of the
3He(alpha,gamma)7Be astrophysical S-factor to solar energies
- …