Search results for "[formula omitted] decay"

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…

Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Antineutrino Spectra and Decay Heat Calculations

2016

Beta decay of fission products is at the origin of decay heat and antineutrino emission in nuclear reactors. Decay heat represents about 7% of the reactor power during operation and strongly impacts reactor safety. Reactor antineutrino detection is used in several fundamental neutrino physics experiments and it can also be used for reactor monitoring and non-proliferation purposes. 92,93Rb are two fission products of importance in reactor antineutrino spectra and decay heat, but their β-decay properties are not well known. New measurements of 92,93Rb β-decay properties have been performed at the IGISOL facility (Jyväskylä, Finland) using Total Absorption Spectroscopy (TAS). TAS is complemen…

Cross section for bb¯ production via dielectrons in d + Au collisions at √sNN = 200 GeV

2015

We report a measurement of e+e− pairs from semileptonic heavy-flavor decays in d + Au collisions at √sNN = 200 GeV. By exploring the mass and transverse-momentum dependence of the yield, the bottom decay contribution can be isolated from charm, and quantified by comparison to PYTHIA and MC@NLO simulations. The resulting bb¯-production cross section is σdAu bb¯ = 1.37 ± 0.28 (stat) ± 0.46 (syst) mb, which is equivalent to a nucleon-nucleon cross section of σ NN bb = 3.4 ± 0.8 (stat) ± 1.1 (syst) μb. peerReviewed

"Table 7" of "Cross section for $b\bar{b}$ production via dielectrons in d$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV"

2023

$b\bar{b}$ cross section

Occupation probabilities of single particle levels using the microscopic interacting boson model: Application to some nuclei of interest in neutrinol…

2016

We have developed a new method to calculate the occupancies of single particle levels in atomic nuclei. This method has been developed in the context of the microscopic interacting boson model, in which neutron and proton degrees of freedom are treated explicitly. The energies of the single particle levels constitute a very important input for the calculation of the occupancies in this method. In principle these energies can be considered as input parameters that can be fitted to reproduce the experimental occupancies. Instead of fitting, in this study we have extracted the single particle energies from experimental data on nuclei with a particle more or one particle less than a shell closu…

The NUMEN project @ LNS: Status and perspectives

2017

The NUMEN project aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ), by high-accuracy measurements of Heavy Ion (HI) induced Double Charge Exchange (DCE) reaction cross sections. In particular, the (18O,18Ne) and (20Ne,20O) reactions are used as tools for β+β+ and β−β− decays, respectively. In the experiments, performed at INFN - Laboratory Nazionali del Sud (LNS) in Catania, the beams are accelerated by the Superconducting Cyclotron (CS) and the reaction ejectiles are detected the MAGNEX magnetic spectrometer. The measured cross sections are challengingly low (a few nb), being the tota…

Total absorption γ -ray spectroscopy of niobium isomers

2019

15 pags. 17 figs., 5 tabs.

High-sensitivity study of levels in 30Al following β decay of 30Mg

2016

Branching Ratios and Spectral Functions of $\tau$ Decays: final ALEPH measurements and physics implications

2005

The full LEP-1 data set collected with the ALEPH detector at the $Z$ pole during 1991-1995 is analysed in order to measure the $\tau$ decay branching fractions. Extensive systematic studies are performed, in order to match the large statistics of the data sample corresponding to over 300 000 measured and identified $\tau$ decays. Branching fractions are obtained for the two leptonic channels and eleven hadronic channels defined by their respective numbers of charged particles and $\pi^0$'s. Using previously published ALEPH results on final states with charged and neutral kaons, corrections are applied to the hadronic channels to derive branching ratios for exclusive final states without kao…