SwePub - sökning: L773:2100 014X

Numrering	Referens	Omslagsbild	Hitta
1.	Acharya, Govatsa, et al. (författare) Investigation of a self-actuated, gravity-driven shutdown system in a small lead-cooled reactor 2020 Ingår i: International Conference on Physics of Reactors. - : EDP Sciences. ; , s. 1456-1463 Konferensbidrag (refereegranskat)abstract Passive safety systems in a nuclear reactor allow to simplify the overall plant design, beside improving economics and reliability, which are considered to be among the salient goals of advanced Generation IV reactors. This work focuses on investigating the application of a self-actuated, gravity-driven shutdown system in a small lead-cooled fast reactor and its dynamic response to an initiating event. The reactor thermal-hydraulics and neutronics assessment were performed in advance. According to a first-order approximation approach, the passive insertion of shutdown assembly was assumed to be influenced primarily by three forces: gravitational, buoyancy and fluid drag. A system of kinematic equations were formulated a priori and a MATLAB program was developed to determine the dynamics of the assembly. Identifying the delicate nature of the balance of forces, sensitivity analysis for coolant channel velocities and assembly foot densities yielded an optimal system model that resulted in successful passive shutdown. Transient safety studies, using the multi-point dynamics code BELLA, showed that the gravity-driven system acts remarkably well, even when accounting for a brief delay in self-actuation. Ultimately the reactor is brought to a sub-critical state while respecting technological constraints.
2.	Al-Adili, Ali, et al. (författare) Isomer yields in nuclear fission 2021 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 256 Tidskriftsartikel (refereegranskat)abstract The generation of angular momentum in the fission process is still an open question. To shed light on this topic, we started a series of measurements at the IGISOL-JYFLTRAP facility in Finland. Highprecision measurements of isomeric yield ratios (IYR) are performed with a Penning trap, partly with the aim to extract average root-mean-square (rms) quantities of fragment spin distributions. The newly installed Phase-Imaging Ion-Cyclotron Resonance (PI-ICR) technique allows the separation of masses down to tens of keV, which is suffcient to disentangle many isomers. In this paper, we first summarize the previous measurements on the neutron and proton-induced fission of uranium and thorium, e.g. the odd cadmium and indium isotopes (119 ≤ A ≤ 127). The measurements revealed systematic trends as function of mass number, which stimulated further exploration. A recent measurement was performed at IGISIOL and several new IYR data will soon be published, for the first time. Secondly, we employ the TALYS nuclear-reaction code to model one of the newly measured isomer yields. Detailed GEF and TALYS calculations are discussed for the fragment angular momentum distribution in 134I.
3.	Alberdi, Antxon, et al. (författare) The jet of the Low Luminosity AGN of M81. Evidence of Precession 2013 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 61 Konferensbidrag (refereegranskat)abstract In this contribution, we summarize our main results of a big campaign of global VLBI observations of the AGN in M81 (M81) phase-referenced to the radio supernova SN 1993J. Thanks to the precise multi-epoch and multi-frequency astrometry, we have determined the normalized core-shift of the relativistic jet of M81 and estimated both the magnetic field and the particle density at the jet base. We have also found evidence of jet precession in M81* coming from the systematic time evolution of the jet orientation correlated with changes in the overall flux density.
4.	Atomassa, Ermias, et al. (författare) Feasibility studies for nucleon structure measurements with PANDA 2014 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 81 Tidskriftsartikel (refereegranskat)abstract The study of nucleon structure is one of the main physics goals of PANDA to be built at the FAIR accelerator complex. The excellent particle identification performance of the PANDA detector will enable measurements of exclusive channels p̄ p -> e^+e^- and p̄ p -> pi^0 J/psi -> pi^0e^+e^- to extract the electromagnetic form factors of protons and pi-nucleon Transition Distribution Amplitudes (pi-N TDAs). After a brief description of the PANDA apparatus and a method to handle momentum resolution degradation due to Bremsstrahlung, the physics of pi-N TDAs is discussed. An estimate for the expected signal to background ratio for p̄ p -> pi^0 J/psi -> pi^0e^+e^- that takes into account the main background source is given.
5.	Audouin, L., et al. (författare) High-precision measurement of isotopic fission yields of 236 U 2018 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 193 Konferensbidrag (refereegranskat)abstract We report on the second SOFIA experiment, dedicated to the fission yields of 236U∗, analog to 235U(n,f). The measurement is based on the inverse kinematics method, using a relativistic, secondary beam of 236U. Both fission fragments are identified in mass and charge in the SOFIA recoil spectrometer. The obtained isotopic yields are compared with existing spectroscopy measurements and the elemental yields are used to discuss the treatment of the even-odd effect with energy in nuclear data libraries.
6.	Babaahmadi, Arezou, 1985, et al. (författare) Electrochemical migration technique to accelerate ageing of cementitious materials 2013 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759810468 ; 56 Konferensbidrag (refereegranskat)abstract Durability assessment of concrete structures for constructions in nuclear waste repositories requires long term service life predictions. As deposition of low and intermediate level radioactive waste (LILW) takes up to 100 000 years, it is necessary to analyze the service life of cementitious materials in this time perspective. Using acceleration methods producing aged specimens would decrease the need of extrapolating short term data sets. Laboratory methods are therefore, needed for accelerating the ageing process without making any influencing distortion in the properties of the materials. This paper presents an electro-chemical migration method to increase the rate of calcium leaching from cementitious specimens. This method is developed based on the fact that major long term deterioration process of hardened cement paste in concrete structures for deposition of LILW is due to slow diffusion of calcium ions. In this method the cementitious specimen is placed in an electrochemical cell as a porous path way through which ions can migrate at a rate far higher than diffusion process. The electrical field is applied to the cell in a way to accelerate the ion migration without making destructions in the specimen's micro and macroscopic properties. The anolyte and catholyte solutions are designed favoring dissolution of calcium hydroxide and compensating for the leached calcium ions with another ion like lithium.
7.	Backs, Alex, et al. (författare) Development and first results of a magnetic sample environment for polarized neutron imaging of thin metal sheets 2023 Ingår i: EPJ Web of Conferences. - 2100-014X. ; 286 Tidskriftsartikel (refereegranskat)abstract Polarized neutron imaging brings the great advantage of analyzing bulk magnetic properties with good spatial resolution. The technique is based on the interaction of the neutron spin with magnetic samples or free magnetic fields and observing the changes to a spin-polarized neutron beam. The high sensitivity to even small magnetic fields is a benefit in obtaining magnetization information but simultaneously a challenge in instrumentation, since magnetic environments for the polarized neutron beam and for the sample, as well as the fringe field from the magnetic sample itself all affect the measurement and can give rise to unwanted effects. We have used finite element simulations and ray tracing simulations, to design and analyze a magnetic sample environment devised for the measurement of ferromagnetic metal sheets. Here we show an analysis of performance of the experimental setup based on the simulation results and compare them to first experimental results on a grain oriented silicon steel sample.
8.	Balibrea-Correa, J., et al. (författare) First measurement of the 94Nb(n,γ) cross section at the CERN n_TOF facility 2023 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 279 Tidskriftsartikel (refereegranskat)abstract One of the crucial ingredients for the improvement of stellar models is the accurate knowledge of neutron capture cross-sections for the different isotopes involved in the s-,r- and i- processes. These measurements can shed light on existing discrepancies between observed and predicted isotopic abundances and help to constrain the physical conditions where these reactions take place along different stages of stellar evolution.In the particular case of the radioactive 94Nb, the 94Nb(n,γ) cross-section could play a role in the determination of the s-process production of 94Mo in AGB stars, which presently cannot be reproduced by state-of-the-art stellar models. There are no previous 94Nb(n,γ) experimental data for the resolved and unresolved resonance regions mainly due to the difficulties in producing highquality samples and also due to limitations in conventional detection systems commonly used in time-of-flight experiments.Motivated by this situation, a first measurement of the 94Nb(n,γ) reaction was carried out at CERN n_TOF, thereby exploiting the high luminosity of the EAR2 area in combination with a new detection system of small-volume C6D6-detectors and a high quality 94Nb-sample. The latter was based on hyper-pure 93Nb material activated at the high-flux reactor of ILL-Grenoble. An innovative ring-configuration detection system in close geometry around the capture sample allowed us to significantly enhance the signal-to-background ratio. This set-up was supplemented with two conventional C6D6-detectors and a highresolution LaCl3(Ce)-detector, which will be employed for addressing reliably systematic effects and uncertainties.At the current status of the data analysis, 18 resonance in 94Nb+n have been observed for the first time in the neutron energy range from thermal up to 10 keV.
9.	Beck, Christian, et al. (författare) Notes on Fitting and Analysis Frameworks for QENS Spectra of (Soft) Colloid Suspensions 2022 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 272, s. 01004-01004 Tidskriftsartikel (refereegranskat)abstract With continuously improving signal-to-noise ratios, a statistically sound analysis of quasi-elasticneutron scattering (QENS) spectra requires to fit increasingly complex models which poses several challenges.Simultaneous fits of the spectra for all recorded values of the momentum transfer become a standard approach.Spectrometers at spallation sources can have a complicated non-Gaussian resolution function which has to bedescribed most accurately. At the same time, to speed up the fitting, an analytical convolution with this resolutionfunction is of interest. Here, we discuss basic concepts to efficient approaches for fits of QENS spectra basedon standard MATLAB and Python fit algorithms. We illustrate the fits with example data from IN16B, BASIS,and BATS.
10.	Bensby, Thomas, et al. (författare) Chemical constraints on the formation of the Galactic thick disk 2012 Ingår i: Assembling the Puzzle of the Milky Way. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 19 Konferensbidrag (refereegranskat)abstract We highlight some results from our detailed abundance analysis study of 703 kinematically selected F and G dwarf stars in the solar neighbourhood. The analysis is based on spectra of high-resolution (R = 45 000 to 110 000) and high signal-to-noise (S/N approximate to 150 to 300). The main findings include: (1) at a given metallicity, the thick disk abundance trends are more alpha-enhanced than those of the thin disk; (2) the metal-rich limit of the thick disk reaches at least solar metallicities; (3) the metal-poor limit of the thin disk is around [Fe/H] approximate to -0.8; (4) the thick disk shows an age-metallicity gradient; (5) the thin disk does not show an age-metallicity gradient; (6) the most metal-rich thick disk stars at [Fe/H] approximate to 0 are significantly older than the most metal-poor thin disk stars at [Fe/H] approximate to -0.7; (7) based on our elemental abundances we find that kinematical criteria produce thin and thick disk stellar samples that are biased in the sense that stars from the low-velocity tail of the thick disk are classified as thin disk stars, and stars from the high-velocity tail of the thin disk are classified as thick disk stars; (8) age criteria appears to produce thin and thick disk stellar samples with less contamination.
11.	Bierlich, Christian (författare) Rope Hadronization and Strange Particle Production 2018 Ingår i: 17th International Conference on Strangeness in Quark Matter, SQM 2017. - : EDP Sciences. - 9782759890330 ; 171 Konferensbidrag (refereegranskat)abstract Rope Hadronization is a model extending the Lund string hadronization model to describe environments with many overlapping strings, such as high multiplicity pp collisions or AA collisions. Including effects of Rope Hadronization drastically improves description of strange/non-strange hadron ratios as function of event multiplicity in all systems from e+e- to AA. Implementation of Rope Hadronization in the MC event generators Dipsy and Pythia8 is discussed, as well as future prospects for jet studies and studies of small systems.
12.	Bijnens, Johan (författare) ChPT loops for the lattice : Pion mass and decay constant, HVP at finite volume and nn̄ -oscillations 2018 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 175 Tidskriftsartikel (refereegranskat)abstract I present higher loop order results for several calculations in Chiral perturbation Theory. 1) Two-loop results at finite volume for hadronic vacuum polarization. 2) A three-loop calculation of the pion mass and decay constant in two-flavour ChPT. For the pion mass all needed auxiliary parameters can be determined from lattice calculations of ππ-scattering. 3) Chiral corrections to neutron-anti-neutron oscillations.
13.	Bijnens, Johan (författare) Hadronic light-by-light contribution to aμ : Extended Nambu-Jona-Lasinio, chiral quark models and chiral Lagrangians 2016 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 118 Konferensbidrag (refereegranskat)abstract This talk discusses our old work on the hadronic light-by-light contribution to the muon anomalous magnetic moment and some more recent contributions. I discuss the various contributions starting with pseudoscalar meson exchange, the quark-and pion-loop, as well as scalar and a1-exchange. For the π0-exchange I point out a possible large enhancement when only connected contributions are included. For the quark-loop I include some comments about the more recent estimates of this contribution. The pion-loop is discussed in more detail, in particular I discuss our unpublished work on including effects from a1 and the polarizability.
14.	Bijnens, Johan (författare) On the Hadronic light-by-light contribution to the muon g-2 2018 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 179 Tidskriftsartikel (refereegranskat)abstract This talk is about the hadronic light-by-light contribution to the muon anomalous magnetic moment, mainly our old work but including some newer results as well. It concentrates on the model calculations. Most attention is paid to pseudo-scalar exchange and the pion loop contribution. Scalar, a1-exchange and other contributions are shortly discussed as well. For the π0-exchange a possible large cancellation between connected and disconnected diagrams is expected.
15.	Bijnens, Johan, et al. (författare) The hadronic light-by-light contribution to the muon anomalous magnetic moment and renormalization group for EFT 2012 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 37 Tidskriftsartikel (refereegranskat)abstract We give a short overview of the theory of the muon anomalous magnetic moment with emphasis on the hadronic light-by-light and the pion loop contribution. We explain the difference between the hidden local symmetry and full VMD pion loop and discuss leading logarithms in the anomalous sector of 2-flavour chiral perturbation theory.
16.	Biscarat, Catherine, et al. (författare) New developments in cost modeling for the LHC computing 2020 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 245, s. 03014-03014 Tidskriftsartikel (refereegranskat)abstract The increase in the scale of LHC computing during Run 3 and Run 4 (HL-LHC) will certainly require radical changes to the computing models and the data processing of the LHC experiments. The working group established by WLCG and the HEP Software Foundation to investigate all aspects of the cost of computing and how to optimise them has continued producing results and improving our understanding of this process. In particular, experiments have developed more sophisticated ways to calculate their resource needs, we have a much more detailed process to calculate infrastructure costs. This includes studies on the impact of HPC and GPU based resources on meeting the computing demands. We have also developed and perfected tools to quantitatively study the performance of experiments workloads and we are actively collaborating with other activities related to data access, benchmarking and technology cost evolution. In this contribution we expose our recent developments and results and outline the directions of future work.
17.	Boca, Gianluigi, et al. (författare) The experiment PANDA: physics with antiprotons at FAIR 2015 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 95 Tidskriftsartikel (refereegranskat)abstract PANDA is an experiment that will run at the future facility FAIR, Darmstadt, Germany. A high intensity and cooled antiproton beam will collide on a fixed hydrogen or nuclear target covering center-of-mass energies between 2.2 and 5.5 GeV. PANDA addresses various physics aspects from the low energy non-perturbative region towards the perturbative regime of QCD. With the impressive theoretical developments in this field, e.g. lattice QCD, the predictions are becoming more accurate in the course of time. The data harvest with PANDA will, therefore, be an ideal test bench with the aim to provide a deeper understanding of hadronic phenomena such as confinement and the generation of hadron masses. A variety of physics topics will be covered with PANDA, for example: the formation or production of exotic non-qqbar charm meson states connected to the recently observed XYZ spectrum; the study of gluon-rich matter, such as glueballs and hybrids; the spectroscopy of the excited states of strange and charm baryons, their production cross section and their spin correlations; the behaviour of hadrons in nuclear matter; the hypernuclear physics; the electromagnetic proton form factors in the timelike region.
18.	Boca, Gianlugi, et al. (författare) The PANDA experiment: physics goals and experimental setup 2014 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 72 Tidskriftsartikel (refereegranskat)
19.	Borovoi, Anatoli, et al. (författare) Retrieving microphysics of cirrus clouds from data measured with raman lidar ramses and a tilted ceilometer 2018 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 176 Tidskriftsartikel (refereegranskat)abstract To develop a microphysical model of cirrus clouds, data obtained by Raman lidar RAMSES and a tilted ceilometer are studied synergistically. The measurements are interpreted by use of a data archive containing the backscattering matrixes as well as the depolarization, color and lidar ratios of ice crystals of different shapes, sizes and spatial orientations calculated within the physical-optics approximation.
20.	Bott, Lukas Thomas, et al. (författare) Coulomb dissociation of O-16 into He-4 and C-12 2023 Ingår i: NUCLEAR PHYSICS IN ASTROPHYSICS - X, NPA-X 2022. - : EDP Sciences. - 2100-014X. ; 279 Konferensbidrag (refereegranskat)abstract We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4.
21.	Bouzid, Mehdi, et al. (författare) Non-local rheology of dense granular flows 2017 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 140 Tidskriftsartikel (refereegranskat)abstract The rheology of dense granular flows is studied numerically in a shear cell controlled at constant pressure and shear stress, confined between two granular shear flows. We show that a liquid state can be achieved even far below the yield stress, whose flow can be described with the same rheology as above the yield stress. A non-local constitutive relation is derived from dimensional analysis through a gradient expansion and calibrated using the spatial relaxation of velocity profiles observed under homogeneous stresses. Both for frictional and frictionless grains, the relaxation length is found to diverge as the inverse square root of the distance to the yield point, on both sides of that point. We also make use of a micro-rheometer to determine the influence of a distant shear band on the local rheological behaviour. Finally, we compare various approaches based on different non-local constitutive relations and choices for the fluidity parameter. We emphasise that, to discriminate between the different approaches proposed in the literature, one has to go beyond the predictions derived from linearisation around a uniform stress profile, such as that obtained in a simple shear cell. We argue that future tests can be based on the nature of the chosen fluidity parameter, and the related boundary conditions, as well as the hypothesis made to derive the models and the dynamical mechanisms underlying their dynamics.
22.	Bovo, Mirko, 1979, et al. (författare) Measurements of a single pulse impinging jet. A CFD reference 2014 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9788026053750 ; 67 Konferensbidrag (refereegranskat)abstract This paper reports three sets of measurements of a single pulse impinging jet. The purpose is to serve as a reference for CFD validation. A gas injector generates a single pulse jet at Re ~90000. The jet impinges on a temperature controlled flat target at different angles (0̈, 30̈, 45̈ and 60̈). The jet velocity field is measured with PIV. The evolution of the jet velocity profile in time is reported at two different locations (suitable as CFD inlet conditions). At the same locations also turbulence quantities are reported. The impingement wall temperature is measured with fast responding thermocouples and infrared camera. These give high time and space resolution respectively. Results are reported in a format suitable for comparison with CFD simulations. The results show that the heat transfer effects are highest for the jet impinging normally on the target. Target inclination has remarkable effects on the jet penetration rate and repeatability. Even small target inclinations result creates a preferential direction for the jet flow and cause a shift in the position of the stagnation region.
23.	Broeg, C., et al. (författare) CHEOPS: A transit photometry mission for ESA's small mission programme 2013 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759809851 ; 47 Konferensbidrag (refereegranskat)abstract Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to detect Earth sized transits. It will be able to detect transits of RV-planets by photometric monitoring if the geometric configuration results in a transit. For Hot Neptunes discovered from the ground, CHEOPS will be able to improve the transit light curve so that the radius can be determined precisely. Because of the host stars' brightness, high precision RV measurements will be possible for all targets. All planets observed in transit by CHEOPS will be validated and their masses will be known. This will provide valuable data for constraining the mass-radius relation of exoplanets, especially in the Neptune-mass regime. During the planned 3.5 year mission, about 500 targets will be observed. There will be 20% of open time available for the community to develop new science programmes.
24.	Brydegaard, Mikkel, et al. (författare) Daily Evolution of the Insect Biomass Spectrum in an Agricultural Landscape Accessed with Lidar 2016 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 119 Tidskriftsartikel (refereegranskat)abstract We present measurements of atmospheric insect fauna intercepted by a static lidar transect over arable and pastoral land over one day. We observe nearly a quarter million of events which are calibrated to optical cross section. Biomass spectra are derived from the size distribution and presented against space and time. We discuss detection limits and instrument biasing, and we relate the insect observations to relevant ecological landscape features and land use. Future directions and improvements of the technique are also outlined.
25.	Brydegaard, Mikkel, et al. (författare) Short-Wave infrared atmospheric scheimpflug lidar 2018 Ingår i: EPJ Web of Conferences. - : EDP Sciences. ; 176 Konferensbidrag (refereegranskat)abstract Atmospheric dual-band Scheimpflug lidar is demonstrated at 980 and 1550 nm. Signals are compared during three weather conditions, and the spatio-temporal resolution of the atmospheric structure is considered. The potential for aerosol classification is evaluated, and future directions are discussed.
26.	Butkus, Vytautas, et al. (författare) Phase relationships of spectral oscillations in 2D molecular spectroscopy 2013 Ingår i: 18th International Conference on Ultrafast Phenomena, UP 2012. - : EDP Sciences. - 9782759809561 ; 41 Konferensbidrag (refereegranskat)abstract Spectral oscillations in 2D molecular spectroscopy of the displaced oscillator system and their phase relationships are analyzed. The phase maps of the dispersive and absolute-valued signals give hints for experimental probing of peak oscillations.
27.	Butler, Peter, et al. (författare) Coulomb excitation of pear-shaped nuclei 2019 Ingår i: - : EDP Sciences. ; , s. 01007-01007 Konferensbidrag (refereegranskat)abstract There is a large body of evidence that atomic nuclei can undergo octupole distortion and assume the shape of a pear. This phenomenon is important for measurements of electric-dipole moments of atoms, which would indicate CP violation and hence probe physics beyond the Standard Model of particle physics. Isotopes of both radon and radium have been identified as candidates for such measurements. Here, we have observed the low-lying quantum states in 224Rn and 226Rn by accelerating beams of these radioactive nuclei. We show that radon isotopes undergo octupole vibrations but do not possess static pear-shapes in their ground states. We conclude that radon atoms provide less favourable conditions for the enhancement of a measurable atomic electric-dipole moment.
28.	Cabelllos, Oscar, et al. (författare) GRE@T-PIONEeR: teaching the nuclear data pipeline using innovative pedagogical methods 2023 Ingår i: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - 2100-014X. ; 284 Konferensbidrag (refereegranskat)abstract GRE@T-PIONEeR - GRaduate Education Alliance for Teaching the PhysIcs and safety Of NuclEar Reactors - is a project funded by the Euratom – Horizon 2020 Framework Programme which aims at developing and providing specialised and advanced courses in computational and experimental reactor physics at the graduate level (MSc and PhD levels) and post-graduate level, as well as the staff members working in the nuclear industry. One of the work packages of GRE@T-PIONEeR is devoted to developing a specific course on the nuclear data pipeline processes and to present the role of nuclear data to play in calculations of innovative reactor systems. This course covers all steps in the nuclear data life cycle, starting from the measurements to their validation and final use in nuclear reactor calculations. Beyond the technical contents of the courses being developed, the paper describes the use of innovative pedagogical methods and active learning techniques, such as flipped classes, aimed at promoting student learning.
29.	Carlsson, Gillis, et al. (författare) How to calculate α-decay rates in the future? 2016 Ingår i: Nobel Symposium NS 160 - Chemistry and Physics of Heavy and Superheavy Elements. - : EDP Sciences. - 9782759890118 ; 131 Konferensbidrag (refereegranskat)abstract New elements discovered during past decades have been created in fusion reactions where a lighter nucleus is collided with a heavier one. The new elements created often decay by emitting α particles. From the half-lives of the decays and the energies of the emitted particles one may extract some properties of the new elements. In this talk the recent work performed by the Lund group to model α decay starting from nuclear density-functional theory is reviewed and a possible extension is mentioned.
30.	Casagrande, Luca, et al. (författare) The SAGA so far : Reading the history of the Galaxy with asteroseismology 2015 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 101 Tidskriftsartikel (refereegranskat)abstract Asteroseismology has the capability of delivering stellar properties which would otherwise be inaccessible, such as radii, masses and thus ages of stars. When this information is coupled with classical determinations of stellar parameters, such as metallicities, effective temperatures and angular diameters, powerful new diagnostics for stellar and Galactic studies can be obtained. The ongoing Strömgren survey for Asteroseismology and Galactic Archaeology (SAGA) is pursuing such a goal, by determining photometric stellar parameters for stars with seismic oscillations measured by the Kepler satellite. As the survey continues and expands in sample size, SAGA will provide an unprecedented opportunity to constrain theories of the evolution of the Milky Way disc.
31.	Chakraborty, S., et al. (författare) Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb breakup 2014 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 66 Konferensbidrag (refereegranskat)abstract Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup model calculation with neutron in p3/2 orbital favours 34Al(g.s) - νp3/2 as ground state configuration of 35Al. But ground state configuration of 34Al is complicated as evident from γ-ray spectra of 33Al after Coulomb breakup of 34Al. © Owned by the authors, published by EDP Sciences, 2014.
32.	Chatillon, A., et al. (författare) Accurate measurements of fission-fragment yields in U-234,U-235,U-236,U-238(gamma,f) with the SOFIA set-up 2016 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759819706 ; 111 Konferensbidrag (refereegranskat)abstract SOFIA (Studies On Fission with Aladin) is a new experimental set-up dedicated to accurate measurement of fission-fragments isotopic yields. It is located at GSI, the only place to use inverse kinematics at relativistic energies in order to study the (gamma,f) electromagnetic-induced fission. The SOFIA set-up is a large-acceptance magnetic spectrometer, which allows to fully identify both fission fragments in coincidence on the whole fission-fragment range. This paper will report on fission yields obtained in U-234,U-235,U-236,U-238(gamma,f) reactions.
33.	Chatillon, A., et al. (författare) Fission-fragment yields measured in Coulomb-induced fission of U-234,U-235,U-236,U-238 and Np-237,Np-238 with the (RB)-B-3/SOFIA setup 2023 Ingår i: 15TH INTERNATIONAL CONFERENCE ON NUCLEAR DATA FOR SCIENCE AND TECHNOLOGY, ND2022. - 2100-014X. ; 284 Konferensbidrag (refereegranskat)abstract Low energy fission of (234,235,236,238)u and Np-237,Np-381 radioactive beams, provided by the GSI/FRS facility, has been studied using the (RB)-B-3/SOFIA setup. The latter allows, on an event-by-event basis, to simultaneously identify, in terms of their mass and atomic numbers, the fissioning nucleus in coincidence with both fission fragments after prompt-neutron emission. This presentation reports on new results on elemental, isobaric and isotopic yields.
34.	Csörgő, Tamás, et al. (författare) Convergence properties of Lévy expansions: implications for Odderon and proton structure 2019 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 206, s. 06007-06007 Tidskriftsartikel (refereegranskat)abstract We detail here the convergence properties of a new model-independent imaging method, the Lévy expansion, that seems to play an important role in the analysis of the diﬀerential cross section of elastic hadron-hadron scattering.We demonstrate, how our earlier results concerning the Odderon eﬀects in the diﬀerential cross-section of elastic proton-proton and proton-antiproton scattering as well as those related to apparent sub-structures inside the protons were obtained in a convergent and stable manner.
35.	Cubero, M., et al. (författare) Scattering of 9Li on 208Pb at energies around the Coulomb barrier 2011 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759806935 ; 17, s. Art. no. 16002- Konferensbidrag (refereegranskat)abstract In order to study the dynamics of 11Li and 9Li beams in a strong electric field at energies around the Coulomb barrier, we measured at the ISACII-TRIUMF Facility the angular distribution of elastic and inelastic scattering of 11Li+208Pb at 24.2 and 29.7 MeV and 9Li+208Pb at 24, 29.5 and 33 MeV laboratory energies. We present here the first determination of the angular distribution of the cross section of 9Li+208Pb. The results are compared with theoretical calculations using the double-folding São Paulo Potential (SPP) for the real part and a for the imaginary part a Woods-Saxon potential. A good overall agreement is obtained.
36.	D'Ammando, F., et al. (författare) Relativistic jets in narrow-line Seyfert 1 galaxies. New discoveries and open questions 2013 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; , s. 05006- Konferensbidrag (refereegranskat)abstract Before the launch of the Fermi satellite only two classes of AGNs were known to produce relativistic jets and thus emit up to the γ-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first four years of observations by the Large Area Telescope on board Fermi confirmed that these two are the most numerous classes of identified sources in the extragalactic γ-ray sky, but the discovery of γ-ray emission from 5 radio-loud narrow-line Seyfert 1 galaxies revealed the presence of a possible emerging third class of AGNs with relativistic jets. Considering that narrow-line Seyfert 1 galaxies seem to be typically hosted in spiral galaxy, this finding poses intriguing questions about the nature of these objects, the onset of production of relativistic jets, and the cosmological evolution of radio-loud AGN. Here, we discuss the radio-to-γ-rays properties of the γ-ray emitting narrow-line Seyfert 1 galaxies, also in comparison with the blazar scenario.
37.	Deen, Pascale, et al. (författare) A design study of VOR: A versatile optimal resolution chopper spectrometer for the ESS 2015 Ingår i: QENS/WINS 2014 - 11th International Conference on Quasielastic Neutron Scattering and 6th International Workshopon Inelastic Neutron Spectrometers. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 83, s. 03002-03002 Konferensbidrag (refereegranskat)abstract VOR, the versatile optimal resolution chopper spectrometer, is designed to probe dynamic phenomena that are currently inaccessible for inelastic neutron scattering due to flux limitations. VOR is a short instrument by the standards of the European Spallation Source (ESS), 30.2m moderator to sample, and provides instantaneous access to a broad dynamic range, 1-120 meV within each ESS period. The short instrument length combined with the long ESS pulse width enables a quadratic flux increase, even at longer wavelengths, by relaxing energy resolution from Delta E/E = 1% up to Delta E/E = 7%. This is impossible both on a long chopper spectrometer at the ESS and with instruments at short pulsed sources. In comparison to current day chopper spectrometers, VOR can offer an order of magnitude improvement in flux for equivalent energy resolutions, Delta E/E = 1-3%. Further relaxing the energy resolution enables VOR to gain an extra order of magnitude in flux. In addition, VOR has been optimised for repetition rate multiplication (RRM) and is therefore able to measure, in a single ESS period, 6-14 incident wavelengths, across a wavelength band of 9 angstrom with a novel chopper configuration that transmits all incident wavelengths with equivalent counting statistics. The characteristics of VOR make it a unique instrument with capabilities to access small, limited-lifetime samples and transient phenomena with inelastic neutron scattering.
38.	Dehlin, Fredrik, 1994-, et al. (författare) Implementation of an autonomous reactivity control system in a small lead-cooled fast reactor 2021 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. Konferensbidrag (refereegranskat)abstract This paper describes the design, implementation and characterisation of an Autonomous Reactivity Control (ARC) system in a small modular lead-cooled fast reactor. The aim of this work was to demonstrate the applicability of the ARC system and to study its dynamic behaviour during an anticipated transient without scram. A simplified one-dimensional model was developed to calculate the heat transfer within the ARC system, and the reactivity worth as a function of the neutron poison’s insertion into the active core was obtained via static neutronic calculations. By coupling the aforementioned models, the ARC’s time-dependent reactivity was derived as a function of the coolant outlet temperature variation. This model was implemented into the BELLA multi-point dynamics code and transient simulations were run. A control rod ejection accident was studied leading to an unprotected transient overpower scenario, in which 350 pcm reactivity was inserted during one second. It was shown that the ARC system provides a forceful negative reactivity feedback and that steady-state temperatures after the transient were reduced by almost 300 K compared to an identical transient without its action. In this scenario, the ARC system managed to stabilise the coolant outlet temperature at a value 100 K above nominal conditions. The implementation of an ARC system provided the reactor with a passively actuated self-regulating reactivity control system able to insert large amounts of negative reactivity in a short amount of time.
39.	del Rio, J. S., et al. (författare) CEPA: A LaBr 3 (Ce)/LaCl 3 (Ce) phoswich array for simultaneous detection of protons and gamma radiation emitted in reactions at relativistic energies 2014 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 66 Konferensbidrag (refereegranskat)abstract A prototype CEPA4, made of four optically isolated phoswich-crystals of LaBr3(Ce)+LaCl3(Ce) packed together in one can of Al, was tested with high energy protons (70-230 MeV) at the cyclotron of Krakow. Further, the response to different gamma radiation standard sources and cosmic muons was determined. Shape analysis of the pulses derived from the four individually coupled PM-tubes was performed and were used as input functions for Monte Carlo simulations in order to simulate the efficiencies and resolutions of a final detector design consisting of 750 such phoswich crystals arranged in a cylindrical disc. © Owned by the authors, published by EDP Sciences, 2014.
40.	Demaziere, Christophe, 1973, et al. (författare) Monte Carlo-based dynamic calculations of stationary perturbations 2020 Ingår i: International Conference on Physics of Reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020. - : EDP Sciences. ; 2020-March Konferensbidrag (refereegranskat)abstract Capitalizing on some earlier work, this paper presents a novel Monte Carlo-based approach that allows estimating the neutron noise induced by stationary perturbations of macroscopic cross-sections in the frequency domain. This method relies on the prior computation using Monte Carlo of modified Green’s functions associated to the real part of the dynamic macroscopic cross-sections, mimicking equivalent subcritical problems driven by external neutron sources. Once such modified Green’s functions are estimated, the neutron noise induced by any type of perturbations can be recovered, by solving a linear algebra problem accounting for the interdependence between the real and imaginary parts of the governing balance equations. The newly derived method was demonstrated on a large homogeneous test system and on a small heterogeneous test system to provide results comparable to a diffusion-based solver specifically developed for neutron noise applications. The new method requires the specification by the user of the real part of the Fourier transform of the macroscopic cross-sections. This is accomplished using ACE-formatted cross-section files defined by the user. Beyond this input data preparation, no change to the Monte Carlo source code is necessary. This represents the main advantage of the proposed method as compared to similar efforts requiring extensive modifications to the Monte Carlo source code.
41.	Demaziere, Christophe, 1973, et al. (författare) Neutron noise-based anomaly classification and localization using machine learning 2020 Ingår i: International Conference on Physics of Reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020. - : EDP Sciences. ; 2020-March, s. 2913-2921 Konferensbidrag (refereegranskat)abstract A methodology is proposed in this paper allowing the classification of anomalies and subsequently their possible localization in nuclear reactor cores during operation. The method relies on the monitoring of the neutron noise recorded by in-core neutron detectors located at very few discrete locations throughout the core. In order to unfold from the detectors readings the necessary information, a 3-dimensional Convolutional Neural Network is used, with the training and validation of the network based on simulated data. In the reported work, the approach was also tested on simulated data. The simulations were carried out in the frequency domain using the CORE SIM+ diffusion-based two-group core simulator. The different scenarios correspond to the following cases: a generic “absorber of variable strength”, axially travelling perturbations at the velocity of the coolant flow (due to e.g. fluctuations of the coolant temperature at the inlet of the core), fuel assembly vibrations, control rod vibrations, and core barrel vibrations. In all those cases, various frequencies were considered and, when relevant, different locations of the perturbations and different vibration modes were taken into account. The machine learning approach was able to correctly identify the different scenarios with a maximum error of 0.11%. Moreover, the error in localizing anomalies had a mean squared error of 0.3072 in mesh size, corresponding to less than 4 cm. The proposed methodology was also demonstrated to be insensitive to parasitic noise and will be tested on actual plant data in the near future.
42.	Demaziere, Christophe, 1973 (författare) Using active learning in hybrid learning environments 2020 Ingår i: International Conference on Physics of Reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020. - : EDP Sciences. ; 2020-March, s. 2419-2429 Konferensbidrag (refereegranskat)abstract In this paper, an innovative pedagogical approach relying on flipped classroom and offered in a hybrid learning environment combining on-site and off-site attendees is proposed. The set-up is furthermore tested on two short courses offered at Chalmers University of Technology and analyzed using student course evaluation questionnaires. Several elements constitute the backbone of the courses. Such elements are either offered in an asynchronous fashion or in a synchronous fashion. The asynchronous elements are made of textbooks specifically written for the respective courses, pre-recorded short webcasts explaining the key concepts of the textbooks and on-line quizzes giving formative feedback to the students. Such elements should thus be studied by the students before attending the synchronous sessions. Because of the preparatory work made by the students, the synchronous sessions can focus on much more active forms of learning under the teacher’s supervision. The success of the pedagogical approach entirely depends on the contents of the synchronous sessions, which need to be carefully planned and designed so that they promote student learning. Although the hybrid learning environment gives rise to some additional challenges from a teacher’s perspective, it also gives much more flexibility in attracting students from remote locations, without compromising the learning experience.
43.	Demchenko, P., et al. (författare) Study of influence of densification on control of conductivity and spectral characteristics of thin films of carbon nanotubes in terahertz frequency range 2018 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. Konferensbidrag (refereegranskat)
44.	Destefanis, Marco, et al. (författare) Spin studies via Drell-Yan processes at PANDA 2014 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 73 Tidskriftsartikel (refereegranskat)abstract The nucleon structure is still not completely understood. A transverse momentum dependent description of the nucleon structure is a crucial milestone for several forthcoming studies in a wide range of experimental scenarios. By means of antiproton beams, possibly polarized in a later stage of the project, with a beam momentum up to 15 GeV/c, which will be available at the future FAIR facility, the nonperturbative region of QCD is planned to be investigated. One of the main goals of the forthcoming experiments at FAIR is the study of Drell-Yan lepton pairs by means of proton-antiproton annihilations, taking also advantage of the expected high luminosity. The Drell-Yan production is a unique tool to access the spin dependent properties of the nucleon, and in particular its transverse degrees of freedom. Transverse Momentum Dependent (TMD) Parton Distribution Functions (PDFs), i.e. the Boer-Mulders function, the Sivers function, and the Transversity, could be deeply investigated by means of experimental angular asymmetries. In later stages of FAIR, single- and double-spin asymmetries could be investigated as well. The Drell-Yan physics program which could be accessed at FAIR with the PANDA experiment will be discussed in details, in the light of existing results in the field.
45.	Diakaki, M., et al. (författare) Towards the high-accuracy determination of the 238U fission cross section at the threshold region at CERN -€“ n_TOF 2016 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. Konferensbidrag (refereegranskat)abstract The U-238 fission cross section is an international standard beyond 2 MeV where the fission plateau starts. However, due to its importance in fission reactors, this cross-section should be very accurately known also in the threshold region below 2 MeV. The U-238 fission cross section has been measured relative to the U-235 fission cross section at CERN - n_TOF with different detection systems. These datasets have been collected and suitably combined to increase the counting statistics in the threshold region from about 300 keV up to 3 MeV. The results are compared with other experimental data, evaluated libraries, and the IAEA standards.
46.	Dittmeier, Sebastian, et al. (författare) Wireless data transmission for high energy physics applications 2017 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 150 Tidskriftsartikel (refereegranskat)abstract Silicon tracking detectors operated at high luminosity collider experiments pose a challenge for current and future readout systems regarding bandwidth, radiation, space and power constraints. With the latest developments in wireless communications, wireless readout systems might be an attractive alternative to commonly used wired optical and copper based readout architectures.The WADAPT group (Wireless Allowing Data and Power Transmission) has been formed to study the feasibility of wireless data transmission for future tracking detectors. These proceedings cover current developments focused on communication in the 60 GHz band. This frequency band offers a high bandwidth, a small form factor and an already mature technology. Motivation for wireless data transmission for high energy physics application and the developments towards a demonstrator prototype are summarized. Feasibility studies concerning the construction and operation of a wireless transceiver system have been performed. Data transmission tests with a transceiver prototype operating at even higher frequencies in the 240 GHz band are described. Data transmission at rates up to 10 Gb/s have been obtained successfully using binary phase shift keying.
47.	Dostal, Jakub, et al. (författare) Fast Exciton Dynamics and Coherent Oscillations Revealed by Coherent 2D Spectroscopy in Chlorosomes 2013 Ingår i: XVIIITH International Conference on Ultrafast Phenomena. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 41 Konferensbidrag (refereegranskat)abstract In this study ultrafast energy transfer dynamics in chlorosomes from sulphur bacterium Chlorobaculum tepidum were explored by means of coherent electronic two-dimensional spectroscopy. Observed sub-100 fs dynamics were attributed to incoherent downhill excitation diffusion between disordered domains within chlorosomes. At the same time vibrational coherent oscillations were investigated on the longer timescales.
48.	Dufek, Jan, 1978-, et al. (författare) Optimisation of Monte Carlo burnup simulations 2020 Ingår i: International Conference on Physics of Reactors. - : EDP Sciences. ; , s. 804-810 Konferensbidrag (refereegranskat)abstract We show here that computing efficiency of Monte Carlo burnup simulations depends on chosen values of certain free parameters, such as the length of the time steps and the number of neutron histories simulated at each Monte Carlo criticality run. The efficiency can thus be improved by optimising these parameters. We have set up a simple numerical model that made it possible for us to test a large number of combinations of the free parameters, and suggest a way to optimise their selection.
49.	Ederth, Thomas, 1969- (författare) Neutrons for scattering : What they are, where to get them, and how to deal with them 2018 Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 188 Tidskriftsartikel (refereegranskat)abstract In neutron scattering studies of soft matter, a diverse array of methods and instruments are used, providing information on structure and dynamics on various length and energy scales. However, much of the infrastructure needed for neutron scattering is common for many instruments. After a brief historical retrospect of neutron scattering, this chapter introduces the basic infrastructure needed to conduct scattering experiments. This includes equipment that is used to produce, spectrally adjust and purify, and to deliver neutrons to the instruments where scattering experiments are conducted. The basics of the interaction of neutrons with matter is also introduced, as a preparation for the final sections on the different means at hand for neutron detection.
50.	Ehlers, G., et al. (författare) Neutron xyz - polarization analysis at a time-of-flight instrument 2015 Ingår i: QENS/WINS 2014 - 11th International Conference on Quasielastic Neutron Scattering and 6th International Workshopon Inelastic Neutron Spectrometers. - : EDP Sciences. - 2101-6275 .- 2100-014X. ; 83, s. 03004-03004 Konferensbidrag (refereegranskat)abstract When implementing a dedicated polarization analysis setup at a neutron time-of-flight instrument with a large area detector, one faces enormous challenges. Nevertheless, significant progress has been made towards this goal over the last few years. This paper addresses systematic limitations of the traditional method that is used to make these measurements, and a possible strategy to overcome these limitations. This will be important, for diffraction as well as inelastic experiments, where the scattering occurs mostly out-of-plane.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "L773:2100 014X "

Avgränsa träffmängd

År