bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative study of photo-produced ionosphere in the close environment of comets
Authors: Beth A. , Galand M. , Heritier K. L.
Published: November 2018

Context.TheGiottoand Rosetta missions gave us the unique opportunity of probing the close environment of cometary ionospheres of 1P/Halley (1P) and 67P/Churyumov-Gerasimenko (67P). The plasma conditions encountered at these two comets were very different from each other, which mainly stem from the different heliocentric distances, which drive photoionization rates, and from the outgassing activities, which drive the neutral densities.

Aims.We asses the relative contribution of different plasma processes that are ongoing in the inner coma: photoionization, transport, photoabsorption, and electron–ion dissociative recombination. The main goal is to identify which processes are at play to then quantitatively assess the ionospheric density.

Methods.We provide a set of analytical formulas to describe the ionospheric number density profile for cometary environments that take into account some of these processes. We discuss the validity of each model in the context of the Rosetta andGiottomissions.

Results.We show that transport is the dominant loss process at large cometocentric distances and low outgassing rates. Chemical plasma loss throughe−-ion dissociative recombination matters around 67P near perihelion and at 1P during theGiottoflyby: its effects increase as the heliocentric distance decreases, that is, at higher outgassing activity and higher photoionization frequency. Photoabsorption is of importance for outgassing rates higher than 1028s−1and only close to the cometary nucleus, well below the location of both spacecraft. Finally, regardless of the processes we considered, the ion number density profile always follows a 1∕rlaw at large cometocentric distances.
Chromospheric condensations and magnetic field in a C3.6-class flare studied via He I D3 spectro-polarimetry
Authors: Libbrecht Tine , de la Cruz Rodríguez Jaime , Danilovic Sanja , Leenaarts Jorrit , Pazira Hiva
Published: November 2018

Context. Magnetic reconnection during flares takes place in the corona, but a substantial part of flare energy is deposited in the chromosphere. However, high-resolution spectro-polarimetric chromospheric observations of flares are very rare. The most used observables are Ca II 8542 Å and He I 10830 Å.

Aims. We aim to study the chromosphere during a C3.6 class flare via spectro-polarimetric observations of the He I D3 line.

Methods. We present the first SST/CRISP spectro-polarimetric observations of He I D3. We analyzed the data using the inversion code HAZEL, and estimate the line-of-sight velocity and the magnetic field vector.

Results. Strong He I D3 emission at the flare footpoints, as well as strong He I D3 absorption profiles tracing the flaring loops are observed during the flare. The He I D3 traveling emission kernels at the flare footpoints exhibit strong chromospheric condensations of up to ∼60 km s−1 at their leading edge. Our observations suggest that such condensations result in shocking the deep chromosphere, causing broad and modestly blueshifted He I D3 profiles indicating subsequent upflows. A strong and rather vertical magnetic field of up to ∼2500 G is measured in the flare footpoints, confirming that the He I D3 line is likely formed in the deep chromosphere at those locations. We provide chromospheric line-of-sight velocity and magnetic field maps obtained via He I D3 inversions. We propose a fan-spine configuration as the flare magnetic field topology.

Conclusions. The He I D3 line is an excellent diagnostic to study the chromosphere during flares. The impact of strong condensations on the deep chromosphere has been observed. Detailed maps of the flare dynamics and the magnetic field are obtained.
Heating of the solar photosphere during a white-light flare
Authors: Jurčák Jan , Kašparová Jana , Švanda Michal , Kleint Lucia
Published: November 2018

Context. The Fe I lines observed by the Hinode/SOT spectropolarimeter were always seen in absorption, apart from the extreme solar limb. Here we analyse a unique dataset capturing these lines in emission during a solar white-light flare.

Aims. We analyse the temperature stratification in the solar photosphere during a white-light flare and compare it with the post-white-light flare state.

Methods. We used two scans of the Hinode/SOT spectropolarimeter to infer, by means of the LTE inversion code Stokes Inversion based on Response function (SIR), the physical properties in the solar photosphere during and after a white-light flare. The resulting model atmospheres are compared and the changes are related to the white-light flare.

Results. We show that the analysed white-light flare continuum brightening is probably not caused by the temperature increase at the formation height of the photospheric continuum. However, the photosphere is heated by the flare approximately down to log τ = −0.5 and this results in emission profiles of the observed Fe I lines. From the comparison with the post-white-light flare state of the atmosphere, we estimate that the major contribution to the increase in the continuum intensity originates in the heated chromosphere.
A VLT/FLAMES survey for massive binaries in Westerlund 1
Authors: Clark J. S. , Najarro F. , Negueruela I. , Ritchie B. W. , González-Fernández C. , Lohr M. E.
Published: November 2018

Context. Recent observational studies indicate that a large number of OB stars are found within binary systems which may be expected to interact during their lifetimes. Significant mass transfer or indeed merger of both components is expected to modify evolutionary pathways, facilitating the production of exceptionally massive stars which will present as blue stragglers. Identification and characterisation of such objects is crucial if the efficiency of mass transfer is to be established; a critical parameter in determining the outcomes of binary evolutionary channels.

Aims. The young and coeval massive cluster Westerlund 1 hosts a rich population of X-ray bright OB and Wolf–Rayet stars where the emission is attributed to shocks in the wind collision zones of massive binaries. Motivated by this, we instigated a study of the extremely X-ray luminous O supergiants Wd1-27 and -30a.

Methods. We subjected a multi-wavelength and -epoch photometric and spectroscopic dataset to quantitative non-LTE model atmosphere and time-series analysis in order to determine fundamental stellar parameters and search for evidence of binarity. A detailed examination of the second Gaia data release was undertaken to establish cluster membership.

Results. Both stars were found to be early/mid-O hypergiants with luminosities, temperatures and masses significantly in excess of other early stars within Wd1, hence qualifying as massive blue stragglers. The binary nature of Wd1-27 remains uncertain but the detection of radial velocity changes and the X-ray properties of Wd1-30a suggest that it is a binary with an orbital period ≤10 days. Analysis of Gaia proper motion and parallactic data indicates that both stars are cluster members; we also provide a membership list for Wd1 based on this analysis.

Conclusions. The presence of hypergiants of spectral types O to M within Wd1 cannot be understood solely via single-star evolution. We suppose that the early-B and mid-O hypergiants formed via binary-induced mass-stripping of the primary and mass-transfer to the secondary, respectively. This implies that for a subset of objects massive star-formation may be regarded as a two-stage process, with binary-driven mass-transfer or merger yielding stars with masses significantly in excess of their initial “birth” mass.
Effect of GIS parameters on modelling runoff from river basin. The case study of catchment in the Puck District
Authors: Kalinowska Dominika , Wielgat Paweł , Kolerski Tomasz , Zima Piotr
Published: November 2018

The study was preceded to check the impact of the adopted digital elevation model resolution on the determination of catchment parameters and the further influence of the received information on calculations related to the hydrograph at the closing point of the basin after a synthetic 100-year precipitation episode. The study area are river basins located in the Puck commune convoying water directly to the Puck Bay. These studies allowed the formulation of the basic assumptions for the research project (in short called WaterPuck) supported by the National Centre for Research and Development.
Reconstruction of an architectural object. Case study: Citadel fort No. 33 “Krakus” in Krakow
Authors: Piech Izabela , Kwoczynska Boguslawa , Ciszewski Artur
Published: November 2018

The aim of the study was to recreate, in the form of a 3D model, the Citadel fort No. 33 “Krakus” in Krakow. The data on the basis of which the three-dimensional model was made were obtained using a Leica ScanStation P40 terrestrial laser scanner, which is owned by the Faculty of Environmental Engineering and Geodesy of the University of Agriculture Hugona Kollataj in Krakow. The scope of field work included performing laser measurements, and then processing the point cloud in the Leica Cyclone 3D program and creating a full architectural model in SketchUp 2016.
Accuracy analysis of 3D model obtained by photogrammetric method on the example of historic room from Wisłoujście Fortress
Authors: Widerski Tadeusz , Daliga Karol
Published: November 2018

The article presents a comparison of obtained models of a test object. Close range photogrammetry was used to obtain 3D models. As test object was used one of the rooms located in Wisłoujście Fortress in Gdańsk, Poland. Different models were obtained by using different distribution and number of reference points. Article contains analysis of differences between coordinates of control points obtained from total station measurements and estimated from different 3D models.
Application of ALS data for GNSS terrain obstacles inventory
Authors: Pelc-Mieczkowska Renata , Tomaszewski Dariusz , Jurgielewicz Karolina
Published: November 2018

Current constellation of global navigation satellite system (GNSS) ensures signal availability even in severe observational conditions like urban canyon or under tree canopy. However, positioning in such environment remains a challenge because obstacles can block, reflect and diffract GNSS signals which significantly affects accuracy. Those errors are strongly sight dependent and cannot be mitigated in differential positioning that is why, knowledge of the shape and spatial distribution of terrain obstacles is essential. In this paper using of airborne laser scanning (ALS) data for terrain obstacles inventory is presented and evaluated. In proposed method terrain obstacle models have been derived from ASCII ALS data file using open source QGIS with LAStools software suite and dedicated ALSObstModel plugin. Test models were developed for three geodetic control points with different environmental characteristics. For each point reference model from direct tachometry measurements have been obtained. An average error in determining the elevation of the terrain obstacles from ALS based models was 0.6° to 1.7°. This distance corresponds to 3 to 6 minutes of satellite in orbit.
Archaeological monuments of the Warmian-Masurian voivodeship – spatial analysis using GIS tools
Authors: Rząsa Krzysztof , Ciski Mateusz
Published: November 2018

Archaeological monuments are one of the forms of monument protection in Poland. It includes various objects, among which one can distinguish: field remnants of prehistoric and historical settlements, graveyards, burial mounds and single graves, as well as relics of industrial, religious and artistic activity. All these objects are of great importance in spatial planning, and its location possess a big impact on the possibilities of land development. According to The National Heritage Board of Poland database for September 2018, there are 7 672 archaeological monuments registered in the polish register of objects of cultural heritage. The number of archaeological objects entered in the register in individual voivodeships is varied. The majority of monuments is located in the Lower Silesian voivodeship, the least in Łódź voivodeship. In this article, archaeological monuments in the Warmian-Masurian voivodeship were analysed, in which there are 286 of such objects. Identification with regard to function was carried out, and a detailed location was specified. With the use of GIS tools, a series of maps was created, which after analysing became the basis for formulating final conclusions. Some of it can be used in the preparation of planning documents at the voivodeship and municipal level.
OPE in Wilson lines with sub-eikonal spin corrections for TMDs and g1 structure function
Authors: Chirilli Giovanni Antonio
Published: November 2018

Low-x evolution of spin-dependent TMDs and spin g1 structure function are relevant for the future Electron Ion Collider. To study spin-dynamics at high energies it is necessary to extend the eikonal approximation to include sub-eikonal corrections. I will discuss the Operator Product Expansion (OPE) in terms of Wilson lines with sub-eikonal corrections and derive the sub-eikonal quark propagator.
Nuclear modification of prompt and non-prompt J/Ψ production in p-Pb collisions at √SNN = 5.02 TeV with ALICE
Authors: Trombetta Giuseppe
Published: November 2018

Various Cold Nuclear Matter (CNM) effects, such as nuclear shadowing or partonic energy loss, can modify the production of J/Ψ in heavy-ion collisions with respect to what is measured in elementary colliding systems. The study of p-Pb collisions at the Large Hadron Collider (LHC) energy scale represents a crucial tool to assess the influence of Cold Nuclear Matter on J/Ψ production in order to achieve a more correct interpretation of Pb-Pb collision results. The ALICE detector at the LHC is capable of reconstructing J/Ψ mesons at central rapidity through their e+e- decay channel down to zero transverse momentum (pT), and has measured the fraction of J/Ψ produced from the decay of beauty-flavoured hadrons (non-prompt J/Ψ) in p-Pb collisions down to pT = 1:3 GeV/c. In this paper, the results obtained by ALICE from the measurement of the prompt and non-prompt J/Ψ yields at mid-rapidity in p-Pb collisions at √SNN = 5.02 TeV will be discussed in comparison to different theoretical predictions including CNM effects.
Dual chiral density waves in nuclear matter
Authors: Abuki Hiroaki , Takeda Yusuke , Harada Masayasu
Published: November 2018

We study inhomogeneous chiral phases in nuclear matter using a hadronic model with the parity doublet structure. With an extended ansatz for the dual chiral density wave off the chiral limit, we numerically determine the phase structure. A new type of dual chiral density wave where the condensate has nonvanishing space average is confirmed and it comes to occupy a wide range of low density region as the chiral invariant mass parameter is lowered.
Measurement of hadron form factors at BESIII
Authors: Redmer Christoph Florian
Published: November 2018

The BESIII experiment, operated at the BEPCII e+e- collider in Beijing, has acquired large data sets at center-of-mass energies between 2.0 GeV and 4.6 GeV. One of the key aspects of the physics program of the BESIII collaboration is to test the understanding of QCD at intermediate energies. Applying different experimental techniques, form factors of hadrons are measured. Among these are the pion form factor, as an important input to the (g - 2)μ puzzle, and the electro-magnetic form factors of nucleons and hyperons in the time-like regime. An overview of the recent results and some ongoing studies at BESIII is provided.
Recent results from NA62 and NA48
Authors: Fantechi Riccardo
Published: November 2018

This paper reviews recent results form the NA62 and NA48 experiments at CERN. NA62 has searched for the K → πνν¯ with an in-flight decay technique. The analysis of 1.2 · 1011 decays has found one event compatible with the Standard Model prediction, giving an upper limit for the branching ratio of 1.4 · 10-9 (95% CL) in the background assumption. Prospects for improvements in the measurement are given. Results on the Kl3 decay form factors from NA48/2 are presented as well as the first observation of the decay K± → π ± π0e+e- and the measurement of its branching ratio from the same experiment.
Extra Quarks and Bileptons in BSM Physics in a 331 Model
Authors: Corianò Claudio , Costantini Antonio
Published: November 2018

We describe some salient features of the 331F (Frampton-Pisano-Pleitez) bilepton model, in which the constraints of anomaly cancelation require the number of generations to be three. In a class of six models, four of which characterised by a β parameter describing the embedding of the hypercharge in the SU(3)L symmetry, a specific choice for β allows bileptons in the spectrum, i.e. vectors and scalars of lepton numbers ±2. At the same time the model allows exotic quarks, with the third quark generation treated asymmetrically respect to the other two. Bileptons generate specific signatures in the form of multilepton final states in Drell-Yan like processes, with and without associated jets, which can be searched for at the LHC.
Exotic Tetraquark Mesons in Large-Nc Limit: an Unexpected Great Surprise
Authors: Lucha Wolfgang , Melikhov Dmitri , Sazdjian Hagop
Published: November 2018

Two-ordinary-meson scattering in large-Nc QCD implies consistency criteria for intermediate-tetraquark contributions. Their fulfilment at Nc-leading order constrains the nature of the spectrum of genuinely exotic tetraquark states.
Search for a Λnn bound state in Pb-Pb collisions with ALICE at the LHC
Authors: Mastroserio Annalisa
Published: November 2018

The extreme energy densities reached at the LHC lead to the production of a significant amount of baryons and strangeness. Such a regime allows for an increased production of potentially existing exotic QCD bound states containing nuclei and strange hadrons. An interesting measurement for the phenomenology of the nuclear interaction is the presence of a neutral bound state constituted by one Λ and two neutrons. The excellent particle identification, tracking and vertexing performance of the ALICE experiment allow for the search of this exotic bound state in the decay channel Λnn →3H+π- in Pb-Pb collisions. In order to improve detection of this state despite the presence of a huge combinatorial background, the extraction of the signal is performed by means of a multivariate approach with the TMVA (Toolkit for Multivariate Data Analysis with ROOT). So far the indication for the existence of the Λnn state was reported only by the HypHI Collaboration, so the observation by ALICE would crucially contribute to the study of such an exotic state.
The Dual QCD @ Work: 2018
Authors: Buras Andrzej J.
Published: November 2018

The Dual QCD (DQCD) framework, based on the ideas of ’t Hooft and Witten, and developed by Bill Bardeen, Jean-Marc Gérard and myself in the 1980s is not QCD, a theory of quarks and gluons, but a successful low energy approximation of it when applied to K → ππ decays and K¯0 - K0 mixing. After years of silence, starting with 2014, this framework has been further developed in order to improve the SM prediction for the ratio ε'/ε, the ΔI = 1/2 rule and B^K. Most importantly, this year it has been used for the calculation of all K → ππ hadronic matrix elements of BSM operators which opened the road for the general study of ε'/ε in the context of the SM effective theory (SMEFT). This talk summarizes briefly the past successes of this framework and discusses recent developments which lead to a master formula for ε'/ε valid in any extension of the SM. This formula should facilitate the search for new physics responsible for the ε'/ε anomaly hinted by 2015 results from lattice QCD and DQCD.
Impact of FIFRELIN input parameters on fission observables
Authors: Chebboubi Abdelaziz , Litaize Olivier , Serot Olivier
Published: November 2018

Evaluated nuclear data are essential for nuclear reactor studies. In order to significantly improve the precision of nuclear data, more and more fundamental fission models are used in the evaluation processing. Therefore, tests of fission models become a central issue. In this framework, FIFRELIN (FIssion Fragments Evaporation Leading to an Investigation of Nuclear data) is a Monte Carlo code developed in order to modelize fission fragments de-excitation through the emission of neutrons, γ and conversion e-. To be performed, a FIFRELIN calculation relies on several models such as gamma strength function and nuclear level density and of more empirical hypothesis such as total excitation energy repartition or angular momentum given by the fission reaction. Moreover, pre-emission mass yield and kinetic energy distribution per mass are necessary to process the simulation. A set of five free parameters are chosen to reproduce a target observable. Often this observable corresponds to the mean neutron multiplicity for heavy and light fragment. In this work, the impact of the set of parameters on different output observables (neutron emission probability, neutron multiplicity as function of the fission fragment mass) is investigated.
Impact of nuclear inertia momenta on fission observables
Authors: Tamagno P. , Litaize O.
Published: November 2018

Fission is probably the nuclear process the less accurately described with current models because it involves dynamics of nuclear matter with strongly coupled manybody interactions. It is thus diffcult to find models that are strongly rooted in good physics, accurate enough to reproduce target observables and that can describe many of the nuclear fission observables in a consistent way. One of the most comprehensive current modeling of the fission process relies on the fission sampling and Monte-Carlo de-excitation of the fission fragments. This model is implemented for instance in the FIFRELIN code. In this model fission fragments and their state are first sampled from pre-neutron fission yields, angular momentum distribution and excitation energy repartition law then the decay of both initial fragments is simulated. This modeling provides many observables: prompt neutron and gamma fission spectra, multiplicities and also fine decompositions: number of neutrons emitted as a function of the fragment mass, spectra per fragments, etc. This model relies on nuclear structure databases and on several basic nuclear models describing for instance gamma strength functions or level densities. Additionally some free parameters are still to be determined, namely two parameters describing the excitation energy repartition law, the spin cutoff of the heavy and light fragments and a rescaling parameter for the rotational inertia momentum of the fragments with respect of the rigid-body model. In the present work we investigate the impact of this latter parameter. For this we mainly substitute the corrected rigid-body value by a quantity obtained from a microscopic description of the fission fragment. The independent-particle model recently implemented in the CONRAD code is used to provide nucleonic wave functions that are required to compute inertia momenta with an Inglis-Belyaev cranking model. The impact of this substitution is analyzed on different fission observables provided by the FIFRELIN code.
High-statistics reactor anti-neutrino energy spectra for fission and beta-decay studies
Authors: Letourneau Alain
Published: November 2018

With the availability of high-statistics and high-resolution anti-neutrino energy spectra, measured in experiments dedicated to the study of the neutrino oscillation in proximity of a nuclear reactor, we can now envisage to use these data as integral measurements to constrain fission and beta-decay models and nuclear data libraries. In this paper we present the ingredients for the simulation of an anti-neutrino energy spectrum and their sensitivity to the constraint by measured energy spectrum.
Direct observation of slow fission from the width of K x-ray line
Authors: Ray Amlan , Sikdar A. K. , Pandit D. , Bhattacharyya Sarmishtha , Bhattacharya Soumik , De A. , Paul S. , Chatterjee A.
Published: November 2018

An atomic clock based on the measurement of the intrinsic width of K x-ray lines has been used to obtain evidence of long-lived fission of the highly excited plutonium nuclei produced in the fusion of 4He+238U at E(4He)Lab=60 MeV. The mean fission time of the long-lived fission could be obtained from the increase of the intrinsic width of plutonium K x-ray line using quantum energy-time uncertainty principle. The presence of long-lived fission (mean fission time >1×10-18 s) has been found and the fluorescence yield per fission event shows that most of the fission events are slow (~10-18 s).
Charting Terra Incognita at Alto and S3
Authors: Franchoo Serge , Cheikh Mhamed Maher , Li Ruohong , Minaya Ramirez Enrique , Vazquez-Rodriguez Liss , Yordanov Deyan
Published: November 2018

Charting Terra Incognita is a project grant that brings together the IPN Orsay, CSNSM Orsay and Irfu-SPHN laboratories around the common development of knowhow, equipment and techniques for mass spectrometry and nuclear spectroscopy at the low-energy branch of the new S3 spectrometer at Ganil, where likewise the Reglis set-up for intrajet laser spectroscopy is entering its final phase of construction. At the same time its concerted action initiates and sets the pace for the corresponding precursor physics programme at the Alto on-line isotope-separation facility, based on the photofission of uranium. We also collect a review of the Alto laser ion source, which is an essential instrument at any low-energy facility for the production of purified isotopic beams.
Nuclear structure of superheavy nuclei - state of the art and perspectives (@ S3)
Authors: Ackermann Dieter
Published: November 2018

Decay spectroscopy is a powerful tool to study the low lying nuclear structure of heavy and superheavy nuclei (SHN). Single particle levels and other structure features like K isomerism, being important in the fermium-nobelium region as well as for the spherical shell stabilized SHN, can be investigated. The new separator-spectrometer combination S3, presently under construction at the new SPIRAL2 facility of GANIL, Caen, France, together with the high intensity beams of SPIRAL2’s superconducting linear accelerator (SC LINAC), will offer exciting perspectives for a wide spectrum of nuclear and atomic physics topics. The installation is designed to employ nuclear physics methods like decay spectroscopy after separation or atomic physics methods like laser spectroscopy and mass measurements. The nuclear physics studies will include particle and photon correlation studies, attacking the open questions in the field, which have been revealed in earlier studies at facilities like e.g. GSI in Darmstadt, Germany, with the velocity filter SHIP and the gas-filled separator TASCA, the cyclotron accelerator laboratory of the University of Jyväskylä, Finland, with RITU and its numerous auxiliary detection set-ups, and FLNR/JINR in Dubna with the DGFRS and VASSILISSA/SHELS separators.
Excited States and Collectivity in 88Se
Authors: Simpson G. , Grachev I. , Thiamova G. , Ramdhane M. , Sieja K. , Blanc A. , Jentschel M. , Köster U. , Mutti P. , Soldner T. , de France G. , Ur C.A. , Urban W.
Published: November 2018

The γ decays of excited states in the very neutron-rich nucleus 88Se have been observed following the cold neutron-induced fission of 235U at the PF1B facility of the Institut Laue-Langevin (ILL), Grenoble. The EXILL array was used to measure γ - γ - γ coincidences, which were then analysed to build a level scheme of 88Se. A low (2+1) energy hints at the onset of quadrupole deformation and the identification of possible members of a (2+2) band provide evidence for γ vibrations. Shell-model calculations using a 78Ni core reproduce the experimental decay scheme well, implying that interactions between particles in the π f5/2 p and vsd orbits are responsible for much of the collectivity present. The algebraic collective model has also been used to interpret the experimental data, showing that that the experimental spectrum is consistent with 88Se being a transitional nucleus, possessing weak static β deformation and γ instability.
Fast-timing measurements in neutron-rich odd-mass zirconium isotopes using LaBr3:Ce detectors coupled with Gammasphere
Authors: Gamba E.R. , Lalkovski S. , Rudigier M. , Bruce A.M. , Bottoni S. , Carpenter M.P. , Zhu S. , Ayangeakaa A.D. , Anderson J.T. , Berry T.A. , Burrows I. , Carroll R.J. , Copp P. , Carmona Gallardo M. , Cullen D.M. , Daniel T. , Greene J.P. , Gurgi L.A. , Hartley D.J. , Ilieva R. , Ilieva S. , Janssens R.V.F. , Kondev F.G. , Kröll T. , Lane G.J. , Lauritsen T. , Lazarus I. , Lotay G. , Fernández Martínez G. , Podolyák Zs. , Pucknell V. , Reed M. , Regan P.H. , Rohrer J. , Sethi J. , Seweryniak D. , Shand C.M. , Simpson J. , Smolen M. , Stefanova E.A. , Vedia V. , Yordanov O.
Published: November 2018

A fast-timing experiment was performed at the Argonne National Laboratory to measure the lifetimes of the lowest lying states of nuclei belonging to the deformed regions around mass number A≃110 and A≃150. These regions were populated via spontaneous fission of 252Cf and the gamma radiation following the decay of excited states in the fission fragments was measured using 51 Gammasphere detectors coupled with 25 LaBr3:Ce detectors. A brief description of the acquisition system and some preliminary results from the fast-timing analysis of the fission fragment 100Zr are presented. The lifetime value of τ = 840(65) ps was found for the 2+ state in 100Zr consistent within one standard deviation of the adopted value with 791 +26 -35ps. This is associated with a quadrupole deformation parameter of 0.36(2) which is within one standard deviation of the literature value of 0.3556+82 -57.
The γ-ray spectroscopy studies of low-spin structures in 210Bi and 206Tl using cold neutron capture reactions
Authors: Cieplicka-Oryńczak Natalia , Leoni Silvia , Fornal Bogdan , Bazzacco Dino , Blanc Aurelien , Benzoni Giovanna , Bottoni Simone , Bracco Angela , Crespi Fabio C. L. , de France Gilles , Iskra Łukasz W. , Jentschel Michael , Köster Ulli , Michelagnoli Caterina , Mutti Paolo , Pietralla Norbert , Simpson Gary , Soldner Torsten , Ur Calin , Urban Waldemar , Werner Volker
Published: November 2018

The γ-coincidence studies of low-spin structures of 210Bi and 206Tl are presented. The 210Bi nucleus, populated in thermal neutron capture reaction, was investigated using EXILL HPGe array at Institut Laue-Langevin in Grenoble. The experimental results were compared to the shell-model calculations allowing to draw the conclusions on the nature of the low-spin excitations populated below the neutron binding energy in 210Bi (4.6 MeV). It has been found that some levels cannot be described by the valence proton and neutron couplings, but may arise from couplings of valence particles to the 3- octupole phonon of the doubly magic 208Pb core. Moreover, preliminary results of a low-spin structure measurements of 206Tl by the γ-coincidence technique, making use of the 205Tl(n,γ)206Tl reaction at the FIPPS prompt γ-ray spectroscopy facility of ILL are shown. The population of a large number of excited states of 206Tl above the ground state up to the neutron binding energy (at 6.5 MeV), within a few units of spin is expected. The analysis involving double and triple γ-coincidences and γγ-angular correlations will allow to significantly extend the experimental information on the energy and spin-parity of the levels in 206Tl. This will help shedding light on the proton-hole and neutron-hole couplings near the doubly magic core 208Pb.
Effects of the shape and Coriolis interaction in nuclear electromagnetic properties
Authors: Minkov Nikolay
Published: November 2018

We study the manifestation of collective vibrations and rotations coupled to single-particle motion in odd-mass nuclei with the presence of axial quadrupole-octupole deformations. Our model incorporates K-mixing effects stemming from the Coriolis interaction between the odd nucleon and the even-even core and thus takes into account the probabilities for otherwise forbidden due to the axial symmetry electromagnetic transitions between excited states built on different intrinsic configurations. We demonstrate these effects in the quasi-parity-doublet spectrum of the nucleus 221Fr in which a strong Coriolis interaction manifests. The model successfully describes the available intra- and interband E1, E2 and M1 transition rates giving an insight into the mechanism which allows the K-suppressed transitions in axially symmetric nuclei.
Nuclear structure of 82Kr and 82Se relevant for neutrinoless double-beta decay
Authors: Gayer Udo , Werner Volker , Beck Tobias , Finch Sean , Kleemann Jörn , Krishichayan  , Löher Bastian , Papst Oliver , Pietralla Norbert , Ries Philipp Christian , Savran Deniz , Weinert Michael , Tornow Werner
Published: November 2018

Nuclear Resonance Fluorescence (NRF) experiments on the nuclei 82Kr and 82Se were performed, that are a candidates for a mother-daughter pair for the hypothetical neutrinoless double-beta (0νββ) decay. The experiment aimed at providing high-precision data to benchmark theoretical calculations of the nuclear matrix elements involved in this exotic decay mode. We have investigated the excitation energy range from 2.3MeV to 4.2MeV, where the nuclear scissors mode is expected to be located in nuclei of this mass region. Our experiment was able to constrain decay branches of the scissors mode down to a level of a few percents, comparable to previous experiments on heavy deformed 0νββ decay candidates. Reduced transition strengths of the magnetic dipole-excited states have been determined by a method that exploits the non-resonant background in the NRF spectra. They are compared to a calculation within the nuclear shell model for 82Se, which reveals their mixed orbital and spin character, hinting at a more complex microscopic structure of low-lying 1+ states.
Symmetries in mirror nuclei 31S and 31P
Authors: Tonev D. , de Angelis G. , Goutev N. , Iliev S. , Orlandi R. , Deloncle I. , Demerdjiev A. , Gadea A. , Geleva E. , He C. , Laftchiev H. , Lunardi S. , Marginean N. , Nikolov A. , Pavlov P. , Pantaleev I.L. , Penttilä H. , Recchia F. , Sahin E. , Singh R.P. , Slavchev B. , Wirth H.–F. , Yavahchova M.S.
Published: November 2018

Excited states in mirror nuclei 31S and 31P were populated in the 1n and 1p exit channels, respectively, of the reaction 20Ne + 12C. The beam of 20Ne, with an energy of 33 MeV, was delivered for the first time by the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. Angular correlations of coincident pairs and Doppler-shift attenuation lifetime measurements in 31S and 31P were performed using the multidetector array GASP in conjunction with the EUCLIDES charged particle detector. A comparison of the determined B(E1) strengths of the analog mirror 7/2- → 5/2+ transitions indicates the presence of a violation of isospin symmetry.
Lifetimes and electromagnetic transition strength in 124Ba
Authors: Trichkova Mariya , Beckers Marcel , Gladnishki Kalin , Dewald Alfred , Blazhev Andrey , Müller-Gatermann Claus , Fransen Christoph , Jolie Jan , Kalaydjieva Desislava , Rainovski Georgi , Zell Karl-Oskar
Published: November 2018

Lifetimes of excited states of 124Ba were measured by the Recoil Distance Doppler Shift (RDDS) technique. The γ-ray coincidence data were analysed by the Differential Decay Curve method (DDCM). The trend of the experimentally deduced normalized B(E2) values reveals a drop at the 8+1 state, which may be caused by structural changes in the backbending region.
On direct one-neutron decay of the giant dipole resonance
Authors: Tulupov Boris , Urin Mikhail
Published: November 2018

The newly developed particle-hole dispersive optical model is implemented to evaluate the partial and total branching ratios for direct one-neutron decay of the giant dipole resonance in a few neutron-closedshell nuclei. The calculation results obtained for 48Ca, 90Zr, 140Ce and 208Pb with no specific model parameters are compared with available experimental data.
Cluster structures, ellipsoidal shapes and nuclear molecules in light A = 12-50 nuclei
Authors: Afanasjev A.V.
Published: November 2018

The transition from cluster structures to extremely elongated ellipsoidal shapes and nuclear molecules in light A=12-50 (N~Z) nuclei has been studied within the framework of covariant density functional theory. Nodal structure of the occupied single-particle states plays a critical role in microscopic understanding of this transition. This is illustrated by the analysis of dominant types of single-particle density distributions and their evolution (from the bottom of nucleonic potential) with deformation and particle number. The microscopic mechanism of the transition from clustered structures to ellipsoidal shapes and nuclear molecules and between them is discussed.
Proton-induced pre-equilibrium composite-particle emission
Authors: Cowley Anthony
Published: November 2018

The reaction mechanism of proton-induced composite particle pre-equilibrium emission as an intrinsic part a statistical multistep process was confirmed long ago. Nevertheless, until fairly recently it was still not clear how pickup and knockout processes compete in the multistep sequence to produce a composite ejectiles. An overview of results and conclusions based on recent (p,α) studies at incident energies from 65 to 200 MeV are presented and evaluated. It is shown how analyzing power is a valuable observable for unravelling the details of the reaction mechanism. Future avenues of investigation are discussed.
Current status and research activity at the INRNE cyclotron laboratory
Authors: Demerdjiev Anguel , Tonev Dimitar , Goutev Nikolay , Asova Galina , Artinyan Ary
Published: November 2018

A review and update on the status of the Cyclotron Physics Laboratory at the Institute for Nuclear Research and Nuclear Energy as well as related research activity is presented. The main part of the research activities at the Cyclotron Physics Laboratory is directed to simulations for design considerations, for the cyclotron vault for some of the target radioisotopes. In this paper, a review on the simulations, conducted at the laboratory, related to 18F production is included. A model for studying the effect of attenuation and absorption of neutron radiation, emitted by a point source with fixed energy of 14.1 MeV is developed. Preliminary results from this study are shown.
Cross section covariances: a user perspective
Authors: Palmiotti Giuseppe , Salvatores Massimo
Published: November 2018

This paper makes a brief historical review, from the user point of view, of the impact of the different covariance data made available during this period, then look at today current situation in the different evaluated files, using practical examples. In particular, the performance, in terms of C/E, of two of the most recent and reliable evaluate files, CIELO and CIELO-2, is presented for a set of selected integral experiments. Moreover, this performance is compared for consistency against the uncertainty computed with two of the current most used covariance data (COMMARA-2.0 and COMACV1). A limited number of comparisons are also shown relative to the JENDL-4 data. Of specific interest is the observed difference due separately to the diagonal and off-diagonal (correlations) contributions. Finally, some perspective and future needs are discussed.
Checking, processing and verification of nuclear data covariances
Authors: Cabellos Oscar , Dyrda James , Soppera Nicolas
Published: November 2018

The aim of this paper is to present the activities carried out by NEA Data Bank on checking, processing and verification of JEFF-3.3T4 covariances. A picture of the completeness and status of the JEFF-3.3T4 covariances is addressed. The verification of JEFF-3.3T4 covariances is performed with nuclear data sensitivity tool providing thekeffuncertainty as a function of the contributing nuclide-reaction pairings including cross-reaction covariances. A total number of 4501 ICSBEP benchmarks is used in this analysis. This exercise is also extended to covariance libraries such as JENDL-4.0 updated files, ENDF/B-VII.1, SCALE-6.2rev8 and ENDF/B-VIII.0β5, allowing comparison of these results with both the experimental criticality benchmark and different methodologies of evaluation.
From fission yield measurements to evaluation: status on statistical methodology for the covariance question
Authors: Voirin Brieuc , Kessedjian Grégoire , Chebboubi Abdelaziz , Julien-Laferrière Sylvain , Serot Olivier
Published: November 2018

Studies on fission yields have a major impact on the characterization and the understanding of the fission process and are mandatory for reactor applications. Fission yield evaluation represents the synthesis of experimental and theoretical knowledge to perform the best estimation of mass, isotopic and isomeric yields. Today, the output of fission yield evaluation is available as a function of isotopic yields. Without the explicitness of evaluation covariance data, mass yield uncertainties are greater than those of isotopic yields. This is in contradiction with experimental knowledge where the abundance of mass yield measurements is dominant. These last years, different covariance matrices have been suggested but the experimental part of those are neglected. The collaboration between the LPSC Grenoble and the CEA Cadarache starts a new program in the field of the evaluation of fission products in addition to the current experimental program at Institut Laue-Langevin. The goal is to define a new methodology of evaluation based on statistical tests to define the different experimental sets in agreement, giving different solutions for different analysis choices. This study deals with the thermal neutron induced fission of 235U. The mix of data is non-unique and this topic will be discussed using the Shannon entropy criterion in the framework of the statistical methodology proposed.
Recent advances in beta decay measurements
Authors: Estienne Magali , Fallot Muriel , Giot Lydie , Le Meur Loïc , Porta Amanda
Published: November 2018

Three observables of interest for present and future reactors depend on the β decay data of the fission products: the reactor decay heat, antineutrinos from reactors and delayed neutron emission. Concerning the decay heat, significant discrepancies still exist between summation calculations in − their two main ingredients: the decay data and the fission yields − performed using the most recent evaluated databases available. It has been recently shown that the associated uncertainties are dominated by the ones on the decay data. But the results subtantially differ taking into account or not the correlations between the fission products. So far the uncertainty propagation does not include as well systematic effects on nuclear data such as the Pandemonium effect which impacts a large number of nuclei contributing to the decay heat. The list of nuclei deserving new TAGS measurements has been updated recently in the frame of IAEA working groups. The issues listed above impact in the same way the predicted energy spectra of the antineutrinos from reactors computed with the summation method, the interest of which has been recently reinforced by the Daya Bay latest publication. Nuclear data should definitely contribute to refine and better control these calculations. Lastly, a lot of nuclear data related to delayed neutrons are missing in nuclear databases. Despite the progresses already done these last years with new measurements now requiring to be included in evaluated databases, the experimental efforts which still need to be done are significant. These different issues will be addressed here before to comment on recent experimental results and on their impacts on the quoted observables. Some perspectives will also be presented. Solving the issues listed above will require to bring together experimental, simulation, evaluation and theoretical activities.
Bayesian optimization of generalized data
Authors: Arbanas Goran , Feng Jinghua , Clifton Zia J. , Holcomb Andrew M. , Pigni Marco T. , Wiarda Dorothea , Chapman Christopher W. , Sobes Vladimir , Liu Li Emily , Danon Yaron
Published: November 2018

Direct application of Bayes' theorem to generalized data yields a posterior probability distribution function (PDF) that is a product of a prior PDF of generalized data and a likelihood function, where generalized data consists of model parameters, measured data, and model defect data. The prior PDF of generalized data is defined by prior expectation values and a prior covariance matrix of generalized data that naturally includes covariance between any two components of generalized data. A set of constraints imposed on the posterior expectation values and covariances of generalized data via a given model is formally solved by the method of Lagrange multipliers. Posterior expectation values of the constraints and their covariance matrix are conventionally set to zero, leading to a likelihood function that is a Dirac delta function of the constraining equation. It is shown that setting constraints to values other than zero is analogous to introducing a model defect. Since posterior expectation values of any function of generalized data are integrals of that function over all generalized data weighted by the posterior PDF, all elements of generalized data may be viewed as nuisance parameters marginalized by this integration. One simple form of posterior PDF is obtained when the prior PDF and the likelihood function are normal PDFs. For linear models without a defect this PDF becomes equivalent to constrained least squares (CLS) method, that is, the χ2 minimization method.
Application of the EGPT methodology in the analysis of small-sample reactivity worth experiments
Authors: Leconte Pierre , Tommasi Jean , Santamarina Alain , Blaise Patrick , Ros Paul
Published: November 2018

In the current paper, we investigate the application of the Equivalent Generalized Perturbation Theory (EGPT) to derive trends and associated covariances on the neutron capture cross section of one major fission product for both light water reactors and sodium-cooled fast reactors which is Rhodium-103. To do so, we have considered the ERMINE-V/ZONA1 & ZONA3 fast spectrum experiment and the MAESTRO thermal-spectrum experiment, where samples of these materials were oscillated in the MINERVE facility. In the paper, the theoretical formulation of EPGT is described and its derivation in the special case of the close loop oscillation technique where the reactivity worth is determined thanks to a power control system. A numerical benchmark is presented to assess the relevance of sensitivity coefficients provided by EGPT against direct perturbations where the microscopic cross sections are manually changed before calculating the adjoint and forward flux. The breakdown between direct and indirect contributions in the sensitivity analysis of the sample reactivity worth is presented and discussed, with the impact of using a calibration reference sample to normalize the measured reactivity worth. Finally, the assimilation of integral trends is done with the CONRAD code, using C/E comparisons between TRIPOLI4/JEFF3.2 calculations and experimental results and the sensitivity coefficients provided by the EGPT. Preliminary results of this study are showing that the JEFF3.2 evaluation of 103Rh gives satisfactory agreements in both thermal and fast spectrum experiments and that the combination of them can lead to a significant uncertainty reduction on the capture cross section, from ±5% to ±3% in the resolved resonance range (1 eV–10 keV) and from ±8% to ±5% in the unresolved resonance range (10 keV–1 MeV).