Search results for "ENERGIE"
showing 10 items of 215 documents
New accurate measurements of neutron emission probabilities for relevant fission products
2017
We have performed new accurate measurements of the beta-delayed neutron emission probability for ten isotopes of the elements Y, Sb, Te and I. These are fission products that either have a significant contribution to the fraction of delayed neutrons in reactors or are relatively close to the path of the astrophysical r process. The measurements were performed with isotopically pure radioactive beams using a constant and high efficiency neutron counter and a low noise beta detector. Preliminary results are presented for six of the isotopes and compared with previous measurements and theoretical calculations. peerReviewed
Radiative neutron capture on 242Pu in the resonance region at the CERN n_TOF-EAR1 facility
2018
The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with uranium to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. However, an extensive use of MOX fuels, in particular in fast reactors, requires more accurate capture and fission cross sections for some Pu isotopes. In the case of 242Pu there are sizable discrepancies among the existing capture cross-section measurements included in the evaluations (all from the 1970s) resulting in an uncertainty as high as 35% in the fast energy region. Moreover, post-irradiation experiments evalua…
Precision Measurement of the Mass and Lifetime of the Ξ[0 over b] Baryon
2014
Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 $\Xi_b^0\to\Xi_c^+\pi^-$, $\Xi_c^+\to pK^-\pi^+$ signal decays are reconstructed. From this sample, the first measurement of the $\Xi_b^0$ baryon lifetime is made, relative to that of the $\Lambda_b^0$ baryon. The mass differences $M(\Xi_b^0)-M(\Lambda_b^0)$ and $M(\Xi_c^+)-M(\Lambda_c^+)$ are also measured with precision more than four times better than the current world averages. The resulting values are $\frac{\tau_{\Xi_b^0}}{\tau_{\Lambda_b^0}} = 1.006\pm0.018\pm0.010$, $M(\Xi_b^0) - M(\Lambda_b^0) = 172.44\pm0.39\pm…
Possible neutron and proton halo structure in the isobaric analog states of A=12 nuclei
2020
The differential cross sections of the 11B(3He,d)12C reaction leading to formation of the 0+ ground state and the 15.11-MeV 1 +, 16.57-MeV 2−, and 17.23-MeV 1− excited states of 12C are measured at Elab=25 MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct proton transfer to the bound and unbound states. The rms radii of the last proton in all states studied are determined. A comparison of the rms radii of the 12B, 12C, and 12N nuclei in the isobaric analog states (IASs) with isospin T=1 determined by different methods allows us to arrive at a conclusion that these nuclei in the 1− excited states at Ex=2.62, 17.23, and 1.80 MeV, respectiv…
Mirror and triplet displacement energies within nuclear DFT: : numerical stability
2017
Isospin-symmetry-violating class II and III contact terms are introduced into the Skyrme energy density functional to account for charge dependence of the strong nuclear interaction. The two new coupling constants are adjusted to available experimental data on triplet and mirror displacement energies, respectively. We present preliminary results of the fit, focusing on its numerical stability with respect to the basis size.
Collectivity in ${}^{\mathrm{196,198}}$Pb isotopes probed in Coulomb-excitation experiments at REX-ISOLDE
2017
The neutron-deficient ${}^{\mathrm{196,198}}$Pb isotopes have been studied in Coulomb-excitation experiments employing the Miniball γ-ray spectrometer and radioactive ion beams from the REX-ISOLDE post-accelerator at CERN. The reduced transition probabilities of the first excited 2+ states in 196Pb and 198Pb nuclei have been measured for the first time. Values of $B(E2)={18.2}_{-4.1}^{+4.8}$ W.u. and $B(E2)={13.1}_{-3.5}^{+4.9}$ W.u., were obtained, respectively. The experiment sheds light on the development of collectivity when moving from the regime governed by the generalised seniority scheme to a region, where intruding structures, associated with different deformed shapes, start to com…
Neutron measurements for advanced nuclear systems: The n_TOF project at CERN
2012
A few years ago, the neutron time-of-flight facility n_TOF was built at CERN to address some of the urgent needs of high-accuracy nuclear data for Accelerator Driven Systems and other advanced nuclear energy systems, as well as for nuclear astrophysics and fundamental nuclear physics. Thanks to the characteristics of the neutron beam, and to state-of-the-art detection and acquisition systems, high quality neutron cross-section data have been obtained for a variety of isotopes, many of which radioactive. Following an important upgrade of the spallation target and of the experimental area, a new measurement campaign has started last year. After a brief review of the most important results obt…
Latest predictions from the EbyE NLO EKRT model
2019
We present the latest results from the NLO pQCD + saturation + viscous hydrodynamics (EbyE NLO EKRT) model. The parameters in the EKRT saturation model are fixed by the charged hadron multiplicity in the 0-5 \% 2.76 TeV Pb+Pb collisions. The $\sqrt{s}$, $A$ and centrality dependence of the initial particle production follows then from the QCD dynamics of the model. This allows us to predict the $\sqrt{s}$ and $A$ dependence of the particle production. We show that our results are in an excellent agreement with the low-$p_T$ data from 2.76 TeV and 5.02 TeV Pb+Pb collisions at the LHC as well as with the data from the 200 GeV Au+Au collisions at RHIC. In particular, we study the centrality de…
Lateral distribution of muons in IceCube cosmic ray events
2013
In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high pT (>2 GeV/c) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard pT component that can be described by perturbative quantum chromodynamics. However, the ra…
Measurement of high energy resolution inelastic proton scattering at and close to zero degrees
2009
13 pages, 15 figures.-- Printed version published Jul 1, 2009.