Search results for " Decay"
showing 10 items of 1838 documents
A novel approach to β-decay: PANDORA, a new experimental setup for future in-plasma measurements
2022
International audience; Theoretical predictions as well as experiments performed at storage rings have shown that the lifetimes of β-radionuclides can change significantly as a function of the ionization state. In this paper we describe an innovative approach, based on the use of a compact plasma trap to emulate selected stellar-like conditions. It has been proposed within the PANDORA project (Plasmas for Astrophysics, Nuclear Decay Observation and Radiation for Archaeometry) with the aim to measure, for the first time in plasma, nuclear β-decay rates of radionuclides involved in nuclear-astrophysics processes. To achieve this task, a compact magnetic plasma trap has been designed…
The Hamburg/ESO R-process Enhanced Star survey (HERES)
2004
We report on a dedicated effort to identify and study metal-poor stars strongly enhanced in r-process elements ([r/Fe] > 1 dex; hereafter r-II stars), the Hamburg/ESO R-process Enhanced Star survey (HERES). Moderate-resolution (~2A) follow-up spectroscopy has been obtained for metal-poor giant candidates selected from the Hamburg/ESO objective-prism survey (HES) as well as the HK survey to identify sharp-lined stars with [Fe/H] < -2.5dex. For several hundred confirmed metal-poor giants brighter than B~16.5mag (most of them from the HES), ``snapshot'' spectra (R~20,000; S/N~30 per pixel) are being obtained with VLT/UVES, with the main aim of finding the 2-3% r-II stars expected to be a…
Simultaneous measurement of β-delayed proton and γ decay of 27P
2016
This is the first study of 27P to measure both the β-delayed proton and β-delayed γ decays. While no new proton groups in the astrophysically interesting energy region of 300–400 keV were observed, a new upper limit on the proton branching of 0.16% was estimated. Several new γ -ray lines were observed, mainly coming from the isobaric analog state in 27Si, which has been assigned a more accurate energy value of 6638(1) keV. peerReviewed
High-spin states beyond the proton drip-line: Quasiparticle alignments in Cs-113
2015
Excited states have been studied in the deformed proton emitter 113Cs. Gamma-ray transitions have been unambiguously assigned to 113Cs by correlation with its characteristic proton decay, using the method of recoil-decay tagging. Two previously identified rotational bands have been observed and extended to tentative spins of 45/2 and 51/2 h¯, with excitation energies over 8 MeV above the lowest state. These are the highest angular momenta and excitation energies observed to date in any nucleus beyond the proton drip-line. Transitions in the bands have been rearranged compared to previous work. A study of aligned angular momenta, in comparison to the predictions of Woods–Saxon cranking calcu…
Neutrinos in GUTs and left right symmetry
2014
215 páginas. Tesis Doctoral del Departamento de Física Teórica de la Universidad de Valencia y del Instituto de Física Corpuscular (IFIC).
Proton dripline studies at ISOLDE: 31Ar and 9C
2002
In this contribution examples of the application of new technologies to disentangle the mechanism of beta-delayed multiparticle emission are given. In particular the mechanism of β-delayed two-proton emission from 31Ar has be resolved and proved to be sequential, a preview of 9C-decay data is discussed. peerReviewed
Azimuthal Anisotropy of Heavy-Flavor Decay Electrons in p-Pb Collisions at √sNN = 5.02 TeV
2019
Angular correlations between heavy-flavor decay electrons and charged particles at midrapidity (|η|<0.8) are measured in p-Pb collisions at √sNN=5.02 TeV. The analysis is carried out for the 0%–20% (high) and 60%–100% (low) multiplicity ranges. The jet contribution in the correlation distribution from high-multiplicity events is removed by subtracting the distribution from low-multiplicity events. An azimuthal modulation remains after removing the jet contribution, similar to previous observations in two-particle angular correlation measurements for light-flavor hadrons. A Fourier decomposition of the modulation results in a positive second-order coefficient (v2) for heavy-flavor decay ele…
Comparison of Microscopic Interacting Boson Model and Quasiparticle Random Phase Approximation 0νββ Decay Nuclear Matrix Elements
2021
The fundamental nature of the neutrino is presently a subject of great interest. A way to access the absolute mass scale and the fundamental nature of the neutrino is to utilize the atomic nuclei through their rare decays, the neutrinoless double beta (0νββ) decay in particular. The experimentally measurable observable is the half-life of the decay, which can be factorized to consist of phase space factor, axial vector coupling constant, nuclear matrix element, and function containing physics beyond the standard model. Thus reliable description of nuclear matrix element is of crucial importance in order to extract information governed by the function containing physics beyond the standard m…
First observation and study of the K± → π±π0e+e− decay
2018
The NA48/2 experiment at CERN reports the first observation of the K-+/- -> pi(+/-)pi(0)e(+)e(-) decay from an exposure of 1.7 x 10(11) charged kaon decays recorded in 2003-2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region, BR(K-+/- -> pi(+/-)pi(0)e(+)e(-)) = (4.24 +/- 0.14) x 10(-6). The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated.
Rare beta decays and the spectrum-shape method
2017
This is a thesis consisting of seven publications and an introductory part on theoretical studies on rare single beta decays. Firstly, the theoretical framework is applied to the computation of partial half-lives for few selected cases of rare single beta-decay transitions. This includes the study on a possible ultra-low-Q-value decay branch of 115Cd as well as the highly forbidden beta decays of 48Ca and 50V. The double magic 48Ca is one of the few experimentally verified nuclei that decay via the two-neutrino mode of double beta decay. A theoretical study on the single beta-decay branches was used to inspect the competition between the single and double beta-decay channels. In the case of…