335 research outputs found
Neutrino-less Double Electron Capture - a tool to research for Majorana neutrinos
The possibility to observe the neutrino-less double decay and thus
to prove the Majorana nature of neutrino as well as provide a sensitive measure
of its mass is a major challenge of to-day's neutrino physics. As an attractive
alternative we propose to study the inverse process, the radiative
neutrino-less double electron capture . The associated monoenergetic
photon provides a convenient experimental signature. Other advantages include
the favourable ratio of the to the competing capture
rates and, very importantly, the existence of coincidence trigger to suppress
the random background. These advantages partly offset the expected longer
lifetimes. Rates for the process are calculated. High Z atoms are
strongly favoured. A resonance enhancement of the capture rates is predicted at
energy release comparable to the atomic level difference. The resonance
conditions are likely to be met for decays to excited states in final nuclei.
Candidates for such studies are considered. The experimental feasibility is
estimated and found highly encouraging.Comment: New figure added, table updated, physical background discusse
A first search of excited states double beta and double electron capture decays of Pd110 and Pd102
A search for double beta decays of the palladium isotopes 110Pd and 102Pd
into excited states of their daughters was performed and first half-life limits
for the 2{\nu}{\beta}{\beta} and 0{\nu}{\beta}{\beta} decays into first excited
0+ and 2+ states of 5.89e19 yr and 4.40e19 yr (95% CL) for the 110Pd decay were
obtained. The half-life limits for the corresponding double electron capture
transition of 102Pd are 7.64e18 yr and 2.68e18 yr (95% CL) respectively. These
are the first measurements for 102Pd.Comment: Updated to published version. Refined analysis and minor text
changes. Half-life limits change
Sestrins are evolutionarily conserved mediators of exercise benefits.
Exercise is among the most effective interventions for age-associated mobility decline and metabolic dysregulation. Although long-term endurance exercise promotes insulin sensitivity and expands respiratory capacity, genetic components and pathways mediating the metabolic benefits of exercise have remained elusive. Here, we show that Sestrins, a family of evolutionarily conserved exercise-inducible proteins, are critical mediators of exercise benefits. In both fly and mouse models, genetic ablation of Sestrins prevents organisms from acquiring metabolic benefits of exercise and improving their endurance through training. Conversely, Sestrin upregulation mimics both molecular and physiological effects of exercise, suggesting that it could be a major effector of exercise metabolism. Among the various targets modulated by Sestrin in response to exercise, AKT and PGC1α are critical for the Sestrin effects in extending endurance. These results indicate that Sestrin is a key integrating factor that drives the benefits of chronic exercise to metabolism and physical endurance
Search for EC and ECEC processes in Se
For the first time, limits on double-beta processes in Se have been
obtained using a 400 cm HPGe detector and an external source consisting of
natural selenium powder.
At a confidence level of 90%, they are y for the
EC transition to the ground state,
y for the ECEC() transition to the excited state in Ge
(595.8 keV), y for the ECEC() transition to the
excited state in Ge (595.8 keV) and y for
the ECEC() and ECEC() transitions to the excited state in
Ge (1204.2 keV). The last transition is discussed in association with a
possible enhancement of the decay rate, in this case by several orders of
magnitude, because the ECEC process is nearly degenerate with an
excited state in the daughter nuclide. Prospects for investigating such
processes in future experiments are discussed.Comment: 13 pages, 2 figures; presented at the 2-nd Symposium on "Neutrino and
Dark Matter in Nuclear Physics" (Paris, September 3-9, 2006); v3: minor
change
dFatp regulates nutrient distribution and long‐term physiology in Drosophila
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94477/1/acel864.pd
LES NOYAUX DE TRANSITION 189Ir ET 187Ir SONT-ILS TRIAXIAUX ?
Les niveaux excités des noyaux 189Ir et 187Ir ont été étudiés par réaction (α, 2nγ) sur le faisceau du cyclotron de Grenoble. Les schémas détaillés qui ont été établis mettent en évidence : 1) des états de parité positive qui s'interprètent comme appartenant aux deux bandes 3/2+ | 402 | (fondamental) et 1/2+ | 400 | mélangées par interaction de Coriolis (noyaux a symétrie axiale de déformation positive) ; 2) une bande découplée construite sur un état 9/2- (h 9/2) décrite de manière équivalente par un modèle à symétrie axiale et déformation positive ou par un modèle a particule-plus-rotor asymétrique ; 3) une structure complexe pour les niveaux de parité négative associés à l'isomère 11/2- (h 11/2). Ce système est correctement prédit par le modèle à rotor asymétrique
Compound and precompound γ-ray entry lines from measured multiplicities and energies in α-induced reactions
Multiplicities of quasi-continuum γ-rays have been measured for the 160Gd(α, xnγ) reactions as a function of bombarding energy and for the 4n exit channel also as a function of γ-ray energy. Increase of beam energy causes initially an increase of the energy and angular momentum of the entry line in the residual nucleus until the neutron “drip line” is reached. This can be understood in terms of competing compound and precompound processes
K X-ray multiplicities for rare earth atoms produced in (H.I., xn) nuclear reactions
K X-ray multiplicities are determined for a number of nuclear reaction products in the rare earth region. It is shown that if certain conditions are fulfilled the values of these multiplicities can be considered as characteristic for the reaction residues independently of the reaction used. They can thus be used for the quantitative determination of cross sections
Selection of heavy ion reaction channels via particle K X-ray coincidences
To identify the residual nuclei in very asymmetric heavy-ion reactions heavy-ion K X-ray coincidences have been measured. The usefulness and limitations of this method are discussed, and its feasibility is demonstrated in a study of the 14N+197Au reaction at 140 MeV
- …