736 research outputs found
Double beta decay versus cosmology: Majorana CP phases and nuclear matrix elements
We discuss the relation between the absolute neutrino mass scale, the
effective mass measured in neutrinoless double beta decay, and the Majorana CP
phases. Emphasis is placed on estimating the upper bound on the nuclear matrix
element entering calculations of the double beta decay half life. Consequently,
one of the Majorana CP phases can be constrained when combining the claimed
evidence for neutrinoless double beta decay with the neutrino mass bound from
cosmology.Comment: 11 pages, 3 figure
Conditions for detecting CP violation via neutrinoless double beta decay
Neutrinoless double beta decay data together with information on the absolute
neutrino masses obtained from the future KATRIN experiment and/or astrophysical
measurements give a chance to find CP violation in the lepton sector with
Majorana neutrinos. We derive and discuss necessary conditions which make
discovery of such CP violation possible for the future neutrino oscillation and
mass measurements data.Comment: 15 pages, 4 figures, RevTe
Results of a search for 2-decay of Xe with high-pressure copper proportional counters in Baksan Neutrino Observatory
The experiment for the 2-decay of Xe search with two
high-pressure copper proportional counters has been held in Baksan neutrino
observatory. The search for the process is based on comparison of spectra
measured with natural and enriched xenon. No evidence has been found for
2(2)- and 2(0)-decay. The decay half lifetime limit
based on data measured during 8000 h is Tyr for
2-mode and Tyr for 0-mode (90%C.L.).Comment: 9 pages, 8 figures; talk at the NANP'05 Conference; submitted to
Phys. At. Nuc
Direct neutron capture of 48Ca at kT = 52 keV
The neutron capture cross section of 48Ca was measured relative to the known
gold cross section at kT = 52 keV using the fast cyclic activation technique.
The experiment was performed at the Van-de-Graaff accelerator, Universitaet
Tuebingen. The new experimental result is in good agreement with a calculation
using the direct capture model. The 1/v behaviour of the capture cross section
at thermonuclear energies is confirmed, and the adopted reaction rate which is
based on several previous experimental investigations remains unchanged.Comment: 9 pages (uses Revtex), 2 postscript figures, accepted for publication
as Brief Report in Phys. Rev.
Properties of Be and C deduced from the folding--potential model
The -- differential cross sections are analyzed in the
optical model using a double--folded potential. With the knowledge of this
potential bound and resonance--state properties of --cluster states in
Be and C as well as astrophysical S--factors of
He(,)Be and Be(,)C are
calculated. --widths and B(E2)--values are deduced.Comment: 2 pages LaTeX, 2 figures can be obtained from the author
Theoretical Aspects of Science with Radioactive Nuclear Beams
Physics of radioactive nuclear beams is one of the main frontiers of nuclear
science today. Experimentally, thanks to technological developments, we are on
the verge of invading the territory of extreme N/Z ratios in an unprecedented
way. Theoretically, nuclear exotica represent a formidable challenge for the
nuclear many-body theories and their power to predict nuclear properties in
nuclear terra incognita. It is important to remember that the lesson learned by
going to the limits of the nuclear binding is also important for normal nuclei
from the neighborhood of the beta stability valley. And, of course, radioactive
nuclei are crucial astrophysically; they pave the highway along which the
nuclear material is transported up in the proton and neutron numbers during the
complicated synthesis process in stars.Comment: 26 ReVTeX pages, 11 Postscript figures, uses epsf.sty, to be
published in: Theme Issue on Science with Beams of Radioactive Nuclei,
Philosophical Transactions, ed. by W. Gelletl
Comparison of low--energy resonances in 15N(alpha,gamma)19F and 15O(alpha,gamma)19Ne and related uncertainties
A disagreement between two determinations of Gamma_alpha of the astro-
physically relevant level at E_x=4.378 MeV in 19F has been stated in two recent
papers by Wilmes et al. and de Oliveira et al. In this work the uncertainties
of both papers are discussed in detail, and we adopt the value
Gamma_alpha=(1.5^{+1.5}_{-0.8})10^-9eV for the 4.378 MeV state. In addition,
the validity and the uncertainties of the usual approximations for mirror
nuclei Gamma_gamma(19F) approx Gamma_gamma(19Ne), theta^2_alpha(19F) approx
theta^2_alpha(19Ne) are discussed, together with the resulting uncertainties on
the resonance strengths in 19Ne and on the 15O(alpha,gamma)19Ne rate.Comment: 9 pages, Latex, To appear in Phys. Rev.
Limits on the Majorana neutrino mass in the 0.1 eV range
The Heidelberg-Moscow experiment gives the most stringent limit on the
Majorana neutrino mass. After 24 kg yr of data with pulse shape measurements,
we set a lower limit on the half-life of the neutrinoless double beta decay in
76Ge of T_1/2 > 5.7 * 10^{25} yr at 90% C.L., thus excluding an effective
Majorana neutrino mass greater than 0.2 eV. This allows to set strong
constraints on degenerate neutrino mass models.Comment: 6 pages (latex) including 3 postscript figures and 2 table
Shell Model Study of the Double Beta Decays of Ge, Se and Xe
The lifetimes for the double beta decays of Ge, Se and
Xe are calculated using very large shell model spaces. The two neutrino
matrix elements obtained are in good agreement with the present experimental
data. For eV we predict the following upper bounds to the
half-lives for the neutrinoless mode: , and . These results are the first from a new generation of Shell
Model calculations reaching O(10) dimensions
- âŠ