38 research outputs found
Three-body effects in the Hoyle-state decay
We use a sequential -matrix model to describe the breakup of the Hoyle
state into three particles via the ground state of . It
is shown that even in a sequential picture, features resembling a direct
breakup branch appear in the phase-space distribution of the
particles. We construct a toy model to describe the Coulomb interaction in the
three-body final state and its effects on the decay spectrum are investigated.
The framework is also used to predict the phase-space distribution of the
particles emitted in a direct breakup of the Hoyle state and the
possibility of interference between a direct and sequential branch is
discussed. Our numerical results are compared to the current upper limit on the
direct decay branch determined in recent experiments
Experimental study of the reaction at MeV
Our understanding of the low-lying resonance structure in C remains
incomplete. We have used the reaction at
proton energies of MeV as a selective probe of the excitation
region above the threshold in C. Transitions to individual
levels in C were identified by measuring the 3 final state with
a compact array of charged-particle detectors. Previously identified
transitions to narrow levels were confirmed and new transitions to broader
levels were observed for the first time. Here, we report cross sections, deduce
partial -decay widths and discuss the relative importance of direct and
resonant capture mechanisms.Comment: 9 pages, 7 figures, 5 tables; added details on data analysi
Fusion cross section measurements of astrophysical interest for light heavy ions systems within the STELLA project
This contribution is focused on the STELLA project (STELlar LAboratory), which aims at the measurement of fusion cross sections between light heavy ions like 12C+12C, 12C+16O or 16O+16O at deep subbarrier energies. The gamma-particle coincidence technique is used in order to reduce background contributions that become dominant for measurements in the nanobarn regime. The experimental setup composed of an ultra high vacuum reaction chamber, a set of 3 silicon strip detectors, up to 36 LaBr3(Ce) scintillators from the UK FATIMA collaboration, and a fast rotating target system will be described. The 12C+12C fusion reaction has been studied from Elab = 11 to 5.6 MeV using STELLA at the AndromĂšde facility in Orsay, France. Preliminary commissioning results are presented in this article
Improving Short-Term Heat Load Forecasts with Calendar and Holiday Data
The heat load in district heating systems is affected by the weather and by human behavior, and special consumption patterns are observed around holidays. This study employs a top-down approach to heat load forecasting using meteorological data and new untraditional data types such as school holidays. Three different machine learning models are benchmarked for forecasting the aggregated heat load of the large district heating system of Aarhus, Denmark. The models are trained on six years of measured hourly heat load data and a blind year of test data is withheld until the final testing of the forecasting capabilities of the models. In this final test, weather forecasts from the Danish Meteorological Institute are used to measure the performance of the heat load forecasts under realistic operational conditions. We demonstrate models with forecasting performance that can match state-of-the-art commercial software and explore the benefit of including local holiday data to improve forecasting accuracy. The best forecasting performance is achieved with a support vector regression on weather, calendar, and holiday data, yielding a mean absolute percentage error of 6.4% on the 15–38 h horizon. On average, the forecasts could be improved slightly by including local holiday data. On holidays, this performance improvement was more significant
Recurrent Neural Networks with Stochastic Layers for Acoustic Novelty Detection
International audienc
Patients to Peers: Barriers and Opportunities for Doctors with Disabilities
Electron capture on Ne is thought to play a crucial role in the final
evolution of electron-degenerate ONe stellar cores. Recent calculations suggest
that the capture process is dominated by the second-forbidden transition
between the ground states of Ne and F, making an experimental
determination of this transition strength highly desirable. To accomplish this
task we are refurbishing an intermediate-image magnetic spectrometer capable of
focusing 7 MeV electrons, and designing a scintillator detector surrounded by
an active cosmic-ray veto shield, which will serve as an energy-dispersive
device at the focal plane.Comment: 4 pages, 1 figure, NIC-XI
Impact of forbidden electron capture in intermediate-mass stars
International audienceIntermediate-mass stars (7-11 Mâ) form degenerate ONe cores following carbon burning. In some cases the cores grow dense enough to trigger electron capture on various nuclei. The double electron capture 20Ne(e-, v e)20F(e-, Îœe )20O releases enough heat to trigger runaway oxygen burning. Depending on the conditions at ignition the outcome is either a collapse to a neutron star or a thermonuclear explosion with an ONeFe remnant. We have investigated the impact of two forbidden transitions on the ignition conditions using the MESA stellar evolution code. The 0+ â 2+ transition between the ground states of 20Ne and 20F has been measured experimentally and is found to decrease the ignition density while pushing the point of ignition off-centre. We have also studied the 2+ â 4+ transition between 24Na and 24Ne through a shell model calculation. Its impact is found to be marginal in our simulations, but it might play a role in the development of convectional instabilities