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1.	Barbier, Antoine, et al. (författare) Editorial 2016 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 85, s. 1-3 Tidskriftsartikel (refereegranskat)abstract Editorial comments about the proceedings of EMRS Symposium C: In situ studies of functional nano materials at large scale facilities: From model systems to applications, EMRS Spring Meeting.
2.	Billnert, Robert, 1981, et al. (författare) Novel Scintillation Detectors for Prompt Fission γ-Ray Measurements 2012 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 29-34 Konferensbidrag (refereegranskat)abstract In this work we present first results from measurements of prompt fission γ-rays from the spontaneous fission in 252Cf. New and accurate data on corresponding γ-rays from the reactions 235U(nth,f) and 239Pu(nth,f) are highly demanded for the modeling of new Generation-IV nuclear reactor systems. For these experiments we employed scintillation detectors made out of new materials (LaBr3, LaCl3 and CeBr3), whose properties were necessary to know in order to obtain reliable results. Hence, we have characterized these detectors. In all the important properties these detectors outshine sodium-iodine detectors that where used in the 1970s, when the existing data had been acquired. Our finding is that the new generation of scintillation detectors is indeed promising, as far as an improved precision of the demanded data is concerned.
3.	Billnert, R., et al. (författare) Prompt γ-ray spectral data from 252Cf(SF), 235U(nth, f) and 241Pu(nth,f) 2014 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 17-23 Konferensbidrag (refereegranskat)abstract In this paper we talk about our work in developing a method to measure and analyze prompt fission γ-rays, as well as our results from the measurement of three different reactions, namely 252Cf(SF), 235U(nth,f) and 241Pu(nth,f). The first two had, at the beginning of our measurements, not been examined since the early 1970s, and the last reaction had never been measured. Our results show a slight improvement over evaluated data-tables in comparison with benchmark experiments, but can still not explain all of the underestimation witnessed. Our results also show that new evaluations is needed, especially for 252Cf(SF) and 241Pu(nth,f).
4.	Boutoux, G., et al. (författare) The SOFIA Experiment 2013 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 47, s. 166-171 Konferensbidrag (refereegranskat)abstract SOFIA (Study On FIssion with Aladin) is an innovative experimental programme on nuclear fission carried out at GSI. In August 2012, we used relativistic secondary beams of neutron-deficient actinides and pre-actinides provided by the FRS and studied their fission, induced by electromagnetic interaction, in inverse kinematics. This experiment will provide for the first time complete isotopic yields (nuclear charge and mass) for both fragments over a broad range of fissioning nuclei from 238Np down to 183Hg. In this article, we discuss the experimental set-up and present promising preliminary results.
5.	Dragić, A.L., et al. (författare) Shape-isomer studies with resonance neutron capture 2014 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 125-131 Konferensbidrag (refereegranskat)abstract An experiment searching for formation of super-deformed shape isomers in odd uranium isotopes following neutron capture is designed at the GELINA neutron source of IRMM. We focus on neutron energies around the so-called intermediate structure in the fission cross-section, where the coupling between compound states above the first and the second minimum is largest. The experimental arrangement is described. The results of a feasibility study on the population of the shape isomer in 235U, using a 234U target, together with the results from first run with a 238U target are presented.
6.	Eckardt, C., et al. (författare) Development of an Active 238UF6 Gas Target 2012 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 141-146 Konferensbidrag (refereegranskat)abstract At the superconducting 130 MeV Darmstadt electron linac S-DALINAC a new source of spin-polarized electrons using a GaAs cathode has been installed, opening the path for experiments with polarized electron and photon beams for nuclear structure studies at low momentum transfers, e.g., the search for forward-backward asymmetries originating from parity non-conservation (PNC) in the photon-induced fission process of 238U.Detailed studies of different properties, e.g., the energy dependence of fission modes, the population of fission isomers, or the search for (PNC) effects in the photon-induced fission process of 238U, depends on high quality data, therefore needing high luminosities. An active gas target containing uranium may overcome the problem that large solid target thicknesses cause poor energy and angular resolution.A single Frisch-grid ionization chamber has been built to test a mixture of standard counting gases (e.g., argon) with depleted uraniumhexafiliguoride (238UF6) using a triple alpha source, evaluating signal quality and drift velocity. For mass fractions up to 2 percent of 238U in the counting gas. The drift velocity increases with rising UF6 content, while a good signal quality and energy resolution is preserved.
7.	Gorbinet, T., et al. (författare) A sample of the results of the first SOFIA experiment 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 101-106 Konferensbidrag (refereegranskat)abstract The first SOFIA experiment (Studies On FIssion with Aladin) was performed in August 2012 at GSI. The fission of several neutron-deficient actinides and pre-actinides was induced in flight at 700 A MeV by electromagnetic excitation. The use of inverse kinematics provides both high detection and high geometrical efficiency. The complete identification of both fission fragments in coincidence (nuclear charge and mass) was obtained over a broad range of fissioning nuclei. After a short introduction and description of the experimental setup, the quality of the charge and mass separation is presented, followed by some results concerning the Coulex-induced fission of U-234 and U-235. (C) 2015 Published by Elsevier B.V.
8.	Oberstedt, Andreas, 1961, et al. (författare) Gamma-ray Measurements with LaBr3: Ce Detectors – thinking Outside the Box 2012 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 31, s. 21-28 Konferensbidrag (refereegranskat)abstract Recently developed cerium-doped lanthanum bromide (LaBr3: Ce) scintillation detectors have shown to possess promising properties with respect to the detection of γ-rays compared to previously known materials. In this work however, we demonstrate how these detectors may be used to obtain information not only about γ-rays, but also about neutrons, i.e. thinking "inside" and "outside" the box, respectively. For this purpose γ-rays were detected in coincidence with fission fragments and both their energy and their time-of-flight relative to the instant of a fission event is recorded. By evaluating the time-of-flight distributions of γ-rays, identified as decays of excited states after population by inelastically scattered neutrons inside the scintillation crystal as well as other surrounding materials, we show that it is possible to acquire knowledge from and about the spectrum of incident neutrons. We give three examples for conceivable applications, used to determine geometrical profiles, cross sections and neutron spectra, respectively.
9.	Oberstedt, Andreas, 1960-, et al. (författare) New prompt fission gamma-ray spectral data and its implication on present evaluated nuclear data files 2013 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892 .- 1875-3884. ; 47, s. 156-165 Tidskriftsartikel (refereegranskat)abstract In this paper we report on new spectral prompt gamma-ray measurements from the spontaneous fission of Cf-252 and thermal neutron-induced fission of U-236. In both experiments, fission of U-236. In both experiments, gamma-ray multiplicities, average and total gamma-energies were extracted. gamma-ray multiplicities, average and total.-energies were extracted. Apart from one recent measurement on Cf-252, about four decades have passed since the last dedicated experiments were reported in literature. Hence, there was a need for a revision, not only with respect to high priority nuclear data requests by the Nuclear Energy Agency (NEA). In the first mentioned experiment we have measured prompt fission gamma-rays with both cerium-doped LaBr3 and CeBr3 scintillation detectors, which both exhibit excellent timing and good energy resolution. The results from both detectors are in excellent agreement with each other and confirm the historical data. In the experiment on U-235(n(th), f) we employed cerium-doped LaCl3 detectors, together with the lanthanum bromide detectors mentioned above. Even here the first results indicate a good agreement with data from the early 1970' s. They are also in accordance with data in evaluated libraries like ENDF/B-VII.0, while this is not the case for Cf-252(SF). Hence, here an update is strongly recommended.
10.	Oberstedt, Andreas, 1961, et al. (författare) Prompt fission gamma-ray spectra characteristics - systematics and predictions 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 91-100 Konferensbidrag (refereegranskat)abstract Revised systematics for prompt fission gamma-ray spectra (PFGS) characteristics as function of both atomic and mass number of the compound system, derived from recent experiments on thermal-neutron induced and spontaneous fission, is presented and applied to fission induced by fast neutrons. Results from these calculations for U-238(n, f) and U-235(n, f) for incident neutron energies from 0 to 20 MeV are compared to new experimental results, exhibiting nice agreement. Very recent PFGS measurements for Pu-240(sf) and Pu-242(sf) have been evaluated and the determined PFGS characteristics are shown to also fit well with the systematics. From this we conclude that the obtained systematics, although purely empirical, is indeed a useful tool for the prediction of average total gamma-ray energy released in prompt fission, mean energy per photon as well as average photon multiplicity for fissioning systems, which are difficult or even impossible to study experimentally. (C) 2015 The Authors. Published by Elsevier B.V.
11.	Oberstedt, Andreas, 1961, et al. (författare) Systematics of prompt fission γ-ray spectra characteristics 2014 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 59:C, s. 24-30 Konferensbidrag (refereegranskat)abstract Systematics from 2001, describing prompt fission γ-ray spectra (PFGS) characteristics as function of mass and atomic number of the fissioning system, has been revisited and parameters have been revised, based on recent experimental results. Although originally expressed for spontaneous and thermal neutron induced fission, validity for fast neutrons was assumed and applied to predict PFGS characteristics for the reaction n + 238U up to incident neutron energies of En = 20 MeV. The results from this work are compared with preliminary experimental results.
12.	Oberstedt, S., et al. (författare) Prompt fission gamma-ray spectra characteristics - a first summary 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 83-90 Konferensbidrag (refereegranskat)abstract In this work we give an overview of our investigations of prompt gamma-ray emission in nuclear fission. This work was conducted during the last five years in response to a high priority nuclear data request formulated by the OECD/NEA. The aim was to reveal data deficiencies responsible for a severe under-prediction of the prompt gamma heating in nuclear reactor cores. We obtained new prompt fission gamma-ray spectral (PFGS) data for Cf-252(SF) as well as for thermal-neutron induced fission on U-235(nth,f) and Pu-241(nth,f). In addition, first PFGS measurements with a fast-neutron beam were accomplished, too. The impact of the new data and future data needs are discussed.
13.	Ramzi, Abelaziz, et al. (författare) Niobium and Aluminum Josephson Junctions Fabricated with a Damascene CMP Process 2012 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 36, s. 211-216 Konferensbidrag (refereegranskat)abstract We report on the fabrication of Josephson junction and superconducting bridges using a damascene CMP process applied for a first time to superconductors. The demonstrated industrial reliability of damascene CMP processes on large scale semiconductor circuits is a major incentive for our research that should allow large numbers of nanometric Josephson junctions to be fabricated in both Nb and Al, the two main material employed in superconducting quantum computing (qubit) and RSFQ electronics fabrication.We carried out a Chemical-Mechanical Polishing (CMP) process on Nb and Al films deposited on a SiO2 layer patterned with trenches of 100 to 300 nm of nominal depth. The process formed long bridges, 1 to 4 μm wide. The susceptibility and resistive transitions showed that CMP has no observable influence on superconductivity.We have also developed a hybrid technique that uses Al/Al2O3/Al shadow evaporation in the trenches before the damascene CMP process. This allows for high quality “in-situ” junction oxidation with the size reduction benefit provided by the damascene CMP process. We easily reach junctions sizes near 0.5 μm2 which are difficult to fabricate by other methods.We describe these techniques and report on measurements on large bridges and junctions and on the fabrication and measurements of Al and Nb nanobridges.
14.	Rodriguez-Sanchez, J. L., et al. (författare) Transient effects in fission investigated with proton-on-lead reactions in complete kinematic measurements 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 64, s. 157-162 Konferensbidrag (refereegranskat)abstract Proton-induced fission of Pb-208 has been investigated at 370, 500 and 650 A MeV in complete kinematic measurements. The experiment was performed at GSI Darmstadt where the combined use of the inverse kinematics technique with an efficient detection setup allowed to measure for the first time the atomic and mass number of both fission fragments. The performed measurement together with different model calculations allow us to investigate dissipative and transient effects in the fission process and the dependence on temperature and deformation of the dissipation strength beta. The use of spallation reactions with lead projectiles favours this study due to its high excitation energy and low angular momentum. (C) 2015 The Authors. Published by Elsevier B.V.
15.	Rodriguez-Tajes, C., et al. (författare) Isotopic distributions of fission fragments from transfer-induced fission 2013 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3884 .- 1875-3892. ; 47, s. 125-130 Konferensbidrag (refereegranskat)abstract Fissioning systems from U to Cm as well as 250Cf were produced by 238U+12C transfer and fusion reactions. The detection of the target-like transfer partner made the characterization of the fissioning systems in (Z, A) and excitation energy possible. The isotopic identification of the fission fragments was achieved by using the VAMOS spectrometer combined to with reactions in inverse kinematics. Results regarding the populated transfer channels and excitation of the target-like transfer partner are presented, as well as the 240Pu fission probability. Isotopic yields of the fission-fragments for 240,*241Pu and 250Cf, having excitation energies of about 10 and 45 MeV, respectively, are discussed.
16.	Volpp, Joerg, et al. (författare) Analytical modeling of the keyhole including multiple reflections for analysis of the influence of different laser intensity distributions on keyhole geometry 2013 Ingår i: Lasers in Manufacturing (LIM 2013). Physics Procedia. - : Elsevier. - 1875-3884. ; 41, s. 460-468 Tidskriftsartikel (refereegranskat)abstract An analytical model of the keyhole for deep penetration welding is presented. Based on a pressure and energy equilibrium the initial keyhole radii in different depths are calculated depending on different incident beam intensity distributions. Multiple reflections are included by using a ray tracing method in a second step to improve calculation of the keyhole shape. A Gaussian and a top hat beam profile are used for evaluation and show similar resulting keyhole geometries and different pressure gradients.
17.	Al-Adili, Ali, et al. (författare) Corrections of Prompt-neutron Emission in Fission-fragment Experiments 2013 Ingår i: Physics Procedia, Vol 47, 2013. - : Elsevier BV. ; , s. 131-136 Konferensbidrag (refereegranskat)
18.	Alam, Md. Minhaj, et al. (författare) Analysis of the rapid central melt pool flow in hybrid laser-arc welding 2012 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 39, s. 853-862 Tidskriftsartikel (refereegranskat)abstract Hybrid laser arc welding creates a long weld pool tail. By high speed imaging the melt velocity behind the keyhole was measured to be very high, of the order of meters per second. Fluid dynamics simulation was carried out locally in the central axial plane of the pool tail. The high speed melt layer redistributes its momentum to slow movement of the deeper bulk. The consequences of initially high melt speed and its mass flow redistribution on the formation of the central reinforcement peak are discussed.
19.	Bunaziv, Ivan, et al. (författare) Hybrid Welding of 45 mm High Strength Steel Sections 2017 Ingår i: Physics Procedia. - : Elsevier. - 1875-3892. ; 89, s. 11-22 Tidskriftsartikel (refereegranskat)abstract Thick section welding has significant importance for oil and gas industry in low temperature regions. Arc welding is usually employed providing suitable quality joints with acceptable toughness at low temperatures with very limited productivity compared to modern high power laser systems. Laser-arc hybrid welding (LAHW) can enhance the productivity by several times due to higher penetration depth from laser beam and combined advantages of both heat sources. LAHW was applied to join 45 mm high strength steel with double-sided technique and application of metal cored wire. The process was captured by high speed camera, allowing process observation in order to identify the relation of the process stability on weld imperfections and efficiency. Among the results, it was found that both arc power and presence of a gap increased penetration depth, and that higher welding speeds cause unstable processing and limits penetration depth. Over a wide range of heat inputs, the welds where found to consist of large amounts of fine-grained acicular ferrite in the upper 60-75% part of welds. At the root filler wire mixing was less and cooling faster, and thus found to have bainitic transformation. Toughness of deposited welds provided acceptable toughness at -50 °C with some scattering.
20.	Carlson, Johan, et al. (författare) Monitoring local solids fraction variations in multiphase flow using pulse-echo ultrasound 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 70, s. 376-379 Tidskriftsartikel (refereegranskat)abstract This paper presents an ultrasonic pulse-echo technique for on-line monitoring of variations in solids concentrations in particlesuspensions. The method is based on time-frequency analysis of the backscatter signals, exploring variations in spectral content ofthe backscatter as function of depth in the suspension. Experiments on a settling of magnetite particles in water, at varying solidsconcentrations, show that the settling process can be followed by studying the energy of backscattered ultrasound.
21.	Cutrarolo, Stefano, et al. (författare) Thermodynamics of carbon in iron nanoparticles at low temperature : reduced solubility and size-induced nucleation of cementite 2010 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 6, s. 16-26 Tidskriftsartikel (refereegranskat)abstract In this manuscript we present the thermodynamics of iron-carbon nano particles at low temperature. By combining classical molecular dynamics simulations, ab initio calculations, finite temperature thermodynamics modeling, and the “size/pressure approximation”, we address carbon-induced fluidization, size-induced eutectic point shift, and reduced solubility at the nanoscale. The results are used to describe, as functions of particle size, three scenarios in the catalytic chemical vapor deposition growth of single single-walled carbon nanotubes, corresponding to steady state-, limitedand no-growth.
22.	Dadbakhsh, Sasan, et al. (författare) Effect of Powder Size and Shape on the SLS Processability and Mechanical Properties of a TPU Elastomer 2016 Ingår i: Physics Procedia. - 1875-3892. ; 83, s. 971-980 Tidskriftsartikel (refereegranskat)
23.	Delaney, Paul, et al. (författare) Small cluster model of the NV centre in diamond 2010 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 3:4, s. 1533-1537 Tidskriftsartikel (refereegranskat)abstract The singlet 1E and 1A 1 energy levels of the Nitrogen-Vacancy centre's ground state configuration each need two Slater determinants in theoretical models, posing difficulties for Density-Functional Theory (DFT) and Hartree-Fock approaches. Configuration Interaction (CI) can handle such states, but not the C 284H 144N - and C 163H 100N - clusters of our recent DFT study as CI computer time and memory scale worse than DFT with system size. Using smaller clusters to model bulk diamond introduces size errors. We examine the smaller diamond cluster C 42H 42N - using DFT to quantify the size error: if not too large it opens the way to CI calculations of these states.
24.	Eriksson, Ingemar, et al. (författare) Guidelines in the choice of parameters for hybrid laser arc welding with fiber lasers 2013 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 41, s. 119-127 Tidskriftsartikel (refereegranskat)abstract Laser arc hybrid welding has been a promising technology for three decades and laser welding in combination with gas metal arc welding (GMAW) has shown that it is an extremely promising technique. On the other hand the process is often considered complicated and difficult to set up correctly. An important factor in setting up the hybrid welding process is an understanding of the GMAW process. It is especially important to understand how the wire feed rate and the arc voltage (the two main parameters) affect the process. In this paper the authors show that laser hybrid welding with a 1 μm laser is similar to ordinary GMAW, and several guidelines are therefore inherited by the laser hybrid process.
25.	Farricker, A., et al. (författare) Beam Dynamics in the ESS Linac under the Influence of Monopole and Dipole HOMs 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 79, s. 21-29 Tidskriftsartikel (refereegranskat)abstract The European Spallation Source (ESS), planned to be operational in 2019, is anticipated to be the worlds most intense neutron source. The total beam power will be 5 MW. We focus on the impact of manufacturing errors on the beam quality. In particular we assess the emittance dilution which occurs due to Higher Order Modes (HOMs) excited at a harmonic of the bunch frequency. We also discuss some alignment issues pertaining to the cavities.
26.	Frostevarg, Jan, et al. (författare) Embedding Carbon Fibre Structures in Metal Matrixes for Additive Manufacturing 2017 Ingår i: Physics Procedia. - : Elsevier. - 1875-3892. ; 89, s. 39-48 Tidskriftsartikel (refereegranskat)abstract It is possible to reinforce structures and components using carbon fibres for applications in electronics and medicine, but most commonly used in reinforcing resin fibre composites for personal protection equipment and light weight constructions. Carbon fibres act as stress redistributors while having increased electrical and thermal conductivities. These properties could also be utilized in metal matrixes, if the fibres are properly fused to the metal and the structure remains intact. Another recently developed high potential carbon structure, carbon nanotube- (CNT) yarns, has similar but even greater mechanical properties than common carbon fibres. Via laser cladding, these reinforcing materials could be used in a plethora of applications, either locally (or globally) as surface treatments or as structural reinforcements using multi-layer laser cladding (additive manufacturing). The challenges of embedding carbon fibres or CNT-yarns in a CuAl mixture and SnPb solder wire using lasers are here investigated using high speed imaging and SEM. It is revealed that the carbon fibres have very high buoyancy in the molten metal and quickly degrades when irradiated by the laser. Wetting of the fibres is shown to be improved by a Tungsten coating and embedding of the structures after processing are evaluated using SEM and Raman spectroscopy.
27.	Frostevarg, Jan, et al. (författare) Undercuts in Laser Arc Hybrid Welding 2014 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 56, s. 663-672 Tidskriftsartikel (refereegranskat)abstract Undercuts are usually an imperfection in welding that either continuously or sporadically form, especially when welding at high speed. Efforts, usually lowering the welding speed or overfilling, are applied to avoid undercuts as they can significantly lower the fatigue properties of the welded workpiece. Undercut formation is complex and occurs by various means, mainly based on temperature and melt flow mechanisms. When having two power sources as in laser arc hybrid welding, the melt flow can be tailored to suppress undercut formation. This can be done e.g. by narrowing the width of the gouge or by optimum positioning of the power sources relative to each other. The present paper shows and explains the main reasons of various types of undercut formation. By following the herein generated guidelines, the critical welding speed during laser arc hybrid welding can be further increased, free of undercuts
28.	Garofalo, F., et al. (författare) Optimal design of silicon-based chips for piezo-induced ultrasound resonances in embedded microchannels 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 70, s. 50-54 Konferensbidrag (refereegranskat)abstract We present a variational formulation of the governing equations and introduce global indicators to describe the behavior of acoustofluidic devices driven at resonance frequencies by means of a piezoelectric transducer. The individuation of the correct Lagrangian densities for the different parts constituting the device (the piezo transducer, the silicon walls, the fluid-filled microchannel, and the glass lid) allows for the introduction of the weak formulation used in the finite element discretization of the equations describing the system in its oscillatory regime. Additionally, the knowledge of the Lagrangian density leads to the derivation of the correct structure of the Hamiltonian density, i.e. the energy density, which is important for the quantification of the energy content of the whole system and its individual parts. Specifically, the energy content of the embedded microchannel is quantified by means of the acoustofluidic yield η defined as the ratio between the energy in the channel and the total energy. From the standpoint of acoustophoretic application, the introduction of the acoustophoretic mean orientation allows us to identify the frequencies for which an acoustophoretic effect, i.e. the lateral motion of particle dragged by the axial main flow, is particularly strong. Finally, the connection between the mechanical and electrical degrees of freedom of the system is addressed. This is important for proper determination of the dissipated power, and it may lead to the detection of resonance states by means of purely electrical measurements. Numerical simulations and preliminary experimental results show some features of the model introduced.
29.	Hall-Wilton, Richard, et al. (författare) Status of the European Spallation Source ESS AB, the instrument selection process, and a fundamental physics beamline at the ESS. 2014 Ingår i: ESS Science Symposium on Neutron Particle Physics at Long Pulse Spallation Sources (NPPATLPS 2013). - : Elsevier BV. - 1875-3892. ; 51, s. 8-12 Konferensbidrag (refereegranskat)abstract A general introduction to the status of the European Spallation Source ESS AB is given. As well as a general overview, the status of instruments and instrument design is presented. Particular attention is given to the instrument selection process, and how a proposal for a fundamental neutron physics beamline should be submitted. The contents of this presentation closely reflect the recently completed Technical Design Report for the ESS. (C) 2013 The Authors. Published by Elsevier B.V.
30.	Hashemzadeh, M., et al. (författare) The Application of Specific Point Energy Analysis to Laser Cutting with 1 μm Laser Radiation 2014 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 56, s. 909-918 Tidskriftsartikel (refereegranskat)abstract Specific point energy (SPE) is a concept that has been successfully used in laser welding where SPE and power density determine penetration depth. This type of analysis allows the welding characteristics of different laser systems to be directly compared. This paper investigates if the SPE concept can usefully be applied to laser cutting. In order to provide data for the analysis laser cutting of various thicknesses of mild steel with a 2 kW fibre laser was carried out over a wide range of parameter combinations. It was found that the SPE concept is applicable to laser cutting within the range of parameters investigated here.
31.	Ilar, Torbjörn, et al. (författare) Root humping in laser welding : an investigation based on high speed imaging 2012 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 39, s. 27-32 Tidskriftsartikel (refereegranskat)abstract Regular drop formation (humping) along the weld root during laser welding was studied by high speed imaging of the melt pool underneath the workpiece. The formation of droplets towards the rear of this weld pool was seen to be primarily caused by the pumping of melt from the bottom of the keyhole and the influence of gravity drawing melt into a sagging hump. This is a different process from the one which creates humps on the top surface of welds.
32.	Jiang, Biao, et al. (författare) Ultrasonic Imaging Through Thin Reverberating Materials 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 70, s. 380-383 Tidskriftsartikel (refereegranskat)abstract Imaging through anisotropic or highly heterogeneous materials is challenging for the existence of strong boundary and volume reverberations. To image small cracks or flaws in a reverberating thin layers, high resolution techniques are needed in both temporal and spatial domain, so that the reverberation can be suppressed to some level. In this paper, the reverberation suppression performance of the total focusing beamforming method (TFM) was evaluated by simulation and real data processing. The results showed that the more the focusing point moves away from the array central line, the more multi-reflections can be suppressed. Furthermore, TFM combined with adaptive processing greatly improves the small flaw detection performance. Test results on real samples confirmed the robustness and reverberation suppression capability of the TFM imaging method.
33.	Jonsson, Sigurdur, et al. (författare) Monte Carlo studies of protein aggregation 2012 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 34, s. 49-54 Konferensbidrag (refereegranskat)abstract The disease-linked amyloid beta (A beta) and alpha-synuclein (alpha S) proteins are both fibril-forming and natively unfolded in free monomeric form. Here, we discuss two recent studies, where we used extensive implicit solvent all-atom Monte Carlo (MC) simulations to elucidate the conformational ensembles sampled by these proteins. For alpha S, we somewhat unexpectedly observed two distinct phases, separated by a clear free-energy barrier. The presence of the barrier makes alpha S, with 140 residues, a challenge to simulate. By using a two-step simulation procedure based on flat-histogram techniques, it was possible to alleviate this problem. The barrier may in part explain why fibril formation is much slower for alpha S than it is for A beta.
34.	Kampf, Karol (författare) On decays of light unflavoured pseudoscalar mesons 2011 Ingår i: 2nd International Workshop on the Physics of Fundamental Symmetries and Interactions (PSI). - : Elsevier BV. - 1875-3892. ; 17 Konferensbidrag (refereegranskat)abstract The ongoing and planned experimental activities with direct reference to light unflavoured pseudoscalar mesons motivate a new theoretical study regarding their properties. An overview including details on new precise calculations is presented.
35.	Kaplan, Alexander, et al. (författare) CYCLAM : Recycling by a Laser-driven Drop Jet from Waste that Feeds AM 2017 Ingår i: Physics Procedia. - : Elsevier. - 1875-3892. ; 89, s. 187-196 Tidskriftsartikel (refereegranskat)abstract Additive manufacturing of metal parts is supplied by powder or wire. Manufacturing of this raw material causes additional costs and environmental impact. A new technique is proposed where the feeding directly originates from a metal sheet, which can even be waste. When cutting is done by laser-induced boiling, melt is continuously ejected downwards underneath the sheet. The ejected melt is deposited as a track on a substrate, enabling additive manufacturing by substrate movement along a desired path. The melt first flows downwards as a column and after a few millimeters separates into drops, here about 500 micrometer in diameter, as observed by high speed imaging. The drops incorporate sequentially and calmly into a long melt pool on the substrate. While steel drops formed regular tracks on steel and aluminium substrates, on copper substrate periodic drops solidified instead. For this new technique, called CYCLAM, the laser beam acts indirectly while the drop jet becomes the main tool. From imaging, properties like the width or fluctuations of the drop jet can be statistically evaluated. Despite oscillation of the liquid column, the divergence of the drop jet remained small, improving the precision and robustness. The melt leaves the cut sheet as a liquid column, 1 to 4 mm in length, which periodically separates drops that are transferred as a liquid jet to the substrate. For very short distance of 2 to 3 mm between the two sheets this liquid column can transfer the melt continuously as a liquid bridge. This phenomenon was observed, as a variant of the technique, but the duration of the bridge was limited by fluid mechanic instabilities.
36.	Kaplan, Alexander, et al. (författare) Evolution of a Laser Hybrid Welding Map 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 78, s. 2-13 Tidskriftsartikel (refereegranskat)abstract Laser arc hybrid welding combines the advantages but also the complex physical mechanisms of gas metal arc welding and laser keyhole welding. From manifold mainly experimental but also theoretical research results a map with versatile functions was initiated for the first time. The purpose is to survey the overall context and to facilitate navigation to the various phenomena that are shown through case studies accompanied by theoretical explanations and guidelines for optimization. Though not complete, the map enables systematic and graphical navigation to relevant publications. Based on a fundamental structure of the map, which was decided early, it is inherently extendable in the future by adding existing and new knowledge, also from other research groups, enabling evolution. The fundament of the map structure comprises gouge thickness, joint type and metal grade, in coherence with product and weld designers’ starting points. The next hierarchy level of the map offers options in the joint type as well as in hybrid welding techniques. The latter contains techniques like double-sided welding, pulse shaping management of the arc or laser, CMT arcs, tandem arcs, or remelting of undercuts. In addition to laser-arc hybrid welding, other hybrid laser techniques like multilayer hot-wire laser welding of narrow gaps or hybrid laser friction stir welding can be taken into account. At the other end of the hierarchy, the map offers via a database-like archive electronic navigation to research results like weld macrographs, high speed imaging or numerical simulation results of the welding process.
37.	Kaplan, Alexander (författare) Modelling the Primary Impact of an Yb:Fibre Laser Beam Profile on the Keyhole Front 2011 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 12:1, s. 627-637 Tidskriftsartikel (refereegranskat)abstract During laser materials processing the direct interaction between the laser beam and the processing zone essentially determines the process. A self-regulating processing front develops. A simplified mathematical model was applied to describe this first order mechanism. In particular, a high power Yb:fibre laser beam was characterized and modelled. The dependence of the keyhole shape on different beam models was studied. While a top-hat beam would cause a very different interaction, the impact from the more accurate beam model hardly differed from a Gaussian beam, as can be explained by interaction solely with selected peripheral domains of the beam.
38.	Karlsson, Jan, et al. (författare) Parameter influence on the laser weld geometry documented by the matrix flow chart 2010 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 5:2, s. 183-192 Tidskriftsartikel (refereegranskat)abstract Three variants of fibre laser welding of corner joints where studied. In service a welded piece experiences fatigue load in a complex manner. The peak stress responsible for the fatigue life of the product is mainly determined by positioning and the geometry of the resulting weld. Some top and root shapes where identified for the joints studied. While parameter documentation is straightforward, generalization and combination of knowledge is a challenge. A new documentation method, the Matrix Flow Chart, MFC, turned out to be a powerful solution for large scale documentation, combination and generalization. Three variants of fibre laser welding of corner joints where studied. The peak stress responsible for the fatigue life of the product is mainly determined by the geometry of the resulting weld. Different top and root shape classes were identified for the joints studied. The shapes mainly depend on geometrical laser beam parameters and govern the peak stress. While parameter documentation used to be straightforward, generalization and combination of knowledge is a challenge. A new documentation method, the Matrix Flow Chart, MFC, turned out to be a promising solution for large scale documentation.
39.	Keskitalo, M., et al. (författare) The Influence of Shielding Gas and Heat Input on the Mechanical Properties of Laser Welds in Ferritic Stainless Steel 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 78, s. 222-229 Tidskriftsartikel (refereegranskat)abstract Laser welding of ferritic steel in normal atmosphere gives rise to weld embrittlement and poor formability. This paper demonstrates that the addition of an argon gas shield to the welding process results in tough, formable welds. Post weld heat treatment and microscopic analysis has suggested that the poor ductility of welds produced without a gas shield is, to some extent, the result of the presence of oxides in the weld metal.
40.	Kong, Choon Yen, et al. (författare) Single-pulse Conduction Limited Laser Welding Using A Diffractive Optical Element 2016 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 83, s. 1217-1222 Tidskriftsartikel (refereegranskat)abstract Conduction limited laser welding is commonly used in electronic and battery applications, where a high width-to-depth ratio weld is desirable. A laser beam with Gaussian or top-hat distributions is often used to produce conduction limited spot welds. Both these energy distributions result in a higher proportion of the laser beam energy being introduced towards the centre of the welded spot and consequently, a reduced penetration weld towards the circumference of the beam spot. The use of diffractive optical elements to tailor the energy distribution of the laser beam has been evaluated. An incident laser beam with an energy distribution in the shape of a ring or C-shape was projected onto the material, which results in heat propagating towards the centre, producing a shallow weld with a consistent depth of penetration across the entire overlapped joint. The results confirmed a corresponding thermal model which predicted an even distribution of heat at the joint interface.
41.	Kowalski, B. J., et al. (författare) Angle-resolved photoemission study and pseudopotential calculations of GeTe and Ge1-xMnxTe band structure 2010 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 3:2, s. 1357-1362 Tidskriftsartikel (refereegranskat)abstract The valence band structure along the Γ-T and T-W-L directions in the Brillouin zone of GeTe is studied by means of angle-resolved photoemission and compared with the results of ab initio pseudopotential calculations. For Ge1-xMnxTe surface alloy, changes in the valence band induced by presence of Mn atoms are revealed.
42.	Krakhmalev, Pavel, 1973-, et al. (författare) Deformation Behavior and Microstructure of Ti6Al4V Manufactured by SLM 2016 Ingår i: Physics Procedia. - : Elsevier. - 1875-3892. ; 83, s. 778-788 Tidskriftsartikel (refereegranskat)
43.	Löveborn, D., et al. (författare) Weldability of Aluminium Alloys for Automotive Applications 2017 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. - 9781510848900 ; , s. 89-99 Konferensbidrag (refereegranskat)abstract Restrictions in CO2-emissions have caused increased demands on decreased weight and increased use of lightweight materials in the automotive industry. Aluminium has shown to be of great interest due to its beneficial weight to strength ratio, and are suitable for hang-on parts such as roof, doors etc. However, the use of aluminium requires reliable joining techniques. This project has been focusing on laser welding of aluminium. It have been reported earlier that hot cracks and porosity are common defects while joining aluminium with laser welding. The aim with this project has been to produce crack free laser welds while joining thin aluminium sheets. Two different optics have been used in this project, oscillating-and triple-spot optics. The results from the experiments show that both the oscillating optics and the triple-spot optics can produce crack free welds. The amount of pores is shown to be low for both cases. The results do also show that the amount of pores in the welds increases with the weld length while the flange length is of minor impact. The mechanical properties are similar for the both optics. The oscillation specimens receive a higher tensile strength while the triple-spot specimens receive a larger elongation at break value. © 2017 The Authors.
44.	Matti, Ramiz, et al. (författare) Analyzing and Post-modelling the High Speed Images of a Wavy Laser Induced Boiling Front 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 78, s. 192-201 Tidskriftsartikel (refereegranskat)abstract The boiling front in laser materials processing like remote fusion cutting, keyhole welding or drilling can nowadays be recorded by high speed imaging. It was recently observed that bright waves flow down the front. Several complex physical mechanisms are associated with a stable laser-induced boiling front, like beam absorption, shadowing, heating, ablation pressure, fluid flow, etc. The evidence of dynamic phenomena from high speed imaging is closely linked to these phenomena. As a first step, the directly visible phenomena were classified and analyzed. This has led to the insight that the appearance of steady flow of the bright front peaks is a composition of many short flashing events of 20-50 μs duration, though composing a rather constant melt film flow downwards. Five geometrical front shapes of bright and dark domains were categorized, for example long inclined dark valleys. In addition, the special top and bottom regions of the front are distinguished. As a second step, a new method of post-modelling based on the greyscale variation of the images was applied, to approximately reconstruct the topology of the wavy front and subsequently to calculate the absorption across the front. Despite certain simplifications this kind of analysis provides a variety of additional information, including statistical analysis. In particular, the model could show the sensitivity of front waves to the formation of shadow domains and the robustness of fiber lasers to keep most of an irradiated steel surface in an absorptivity window between 35 to 43%.
45.	Mohanty, Sandipan, et al. (författare) Protein folding, aggregation and unfolding in Monte Carlo Simulations 2010 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 7, s. 68-71 Konferensbidrag (refereegranskat)abstract An implicit water all-atom model is used to study folding, aggregation and mechanical unfolding of small proteins. Physically reasonable results obtained for a variety of applications indicate healthy global properties of the interaction potential.
46.	Nilsen, Morgan, et al. (författare) Monitoring of Varying Joint Gap Width During Laser Beam Welding by a Dual Vision and Spectroscopic Sensing System 2017 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 89, s. 100-107 Tidskriftsartikel (refereegranskat)abstract A vision and spectroscopic system for estimation of the joint gap width in autogenous laser beam butt welding is presented. Variations in joint gap width can introduce imperfections in the butt joint seam, which in turn influence fatigue life and structural integrity. The aim of the monitoring approach explored here is to acquire sufficiently robust process data to be used to guide post inspection activities and/or to enable feedback control for a decreased process variability. The dual-sensing approach includes a calibrated CMOS camera and a miniature spectrometer integrated with a laser beam tool. The camera system includes LED illumination and matching optical filters and captures images of the area in front of the melt pool in order to estimate the joint gap width from the information in the image. The intensity of different spectral lines acquired by the spectrometer has been investigated and the correlation between the intensity of representative lines and the joint gap width has been studied. Welding experiments have been conducted using a 6 kW fiber laser. Results from both systems are promising, the camera system is able to give good estimations of the joint gap width, and good correlations between the signal from the spectrometer and the joint gap width have been found. However, developments of the camera setup and vision algorithm can further improve the joint gap estimations and more experimental work is needed in order to evaluate the robustness of the systems.
47.	Norman, Peter, et al. (författare) Classification and generalization of data from a fibre-laser hybrid welding case 2010 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 5:2, s. 69-76 Tidskriftsartikel (refereegranskat)abstract Compared to autonomous laser welding, the amount of parameters is higher for laser hybrid welding. Consequently, empirical optimisation of these parameters is a challenge. Handling and evaluation at a higher systematic level is desired in order to enhance the ability to build research on previous knowledge. Such new approach is studied on a case with 10 mm high strength steel sheets, fibre-laser hybrid welded. Aim of the paper is to provide a method of documenting and handling data, transferable to other disciplines, to continuously build knowledge, to simplify repetition of experiments and to facilitate the start-up phase of new trials. Starting from 30 experimental results depending on 23 parameters, by the Matrix Flow Chart a guideline has been developed that filters the information through combination, priorities and quality categorization. A chart resulted where five categories of poor quality are graphically related to a high quality category which can be achieved when following the guidelines for eight main arc- or laser-parameters. The chart is a guideline suitable for extension and for exploring the limits of its validity.
48.	Norman, Peter M., et al. (författare) Mechanisms forming undercuts during laser hybrid arc welding 2011 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 12:1, s. 201-207 Tidskriftsartikel (refereegranskat)abstract That the final quality of a welded joint, using a laser hybrid arc process, is sensitive not only to the geometrical joint conditions, but also to the content of elements in the surface itself, is already known. However the description of the mechanisms forming undercut defects is still vague. In the following study two kinds of undercuts were identified. It is shown how the mill scales affects the melt motion and what mechanisms actuate the creation of the defects. The conclusion that surface oxides affect the severity of weld undercuts is straight forward but here also the mechanism is explained.
49.	Näsström, Jonas, et al. (författare) Hot-wire Laser Welding of Deep and Wide Gaps 2015 Ingår i: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 78, s. 247-254 Tidskriftsartikel (refereegranskat)abstract Heavy section Gas Metal Arc Welding (GMAW) usually requires special edge preparation and several passes. One alternative for increased performance is Laser Arc Hybrid Welding (LAHW). For very thick sheets however, imperfections like root drops or solidification cracks can occur. In this study, other techniques are also studied, including multi-pass filling of deep gaps with wire deposition. A laser is then used to melt the filler and base material. The hot- and cold wire laser welding processes are highly sensitive to wire-laser positioning, where controlled melting of the wire is essential. Apart from a comprehensive literature survey, preliminary experiments were also performed in order to find a novel method variant that can successfully fill deep and wide gaps. The method applied uses a defocused laser that generates the melt pool. A resistance heated wire is fed into the melt pool front in a leading position. This is similar to additive manufacturing techniques such as laser direct metal deposition with wire. A layer height of several millimeters can be achieved and rather low laser power can be chosen. The preliminary experiments were observed using high speed imaging and briefly evaluated by visual examination of the resulting beads. Using a defocused laser beam turned out to have two major advantages; 1. It adds heat to the melt pool in a manner that properly fuses the bottom and walls of the base material. 2. It counteracts difficulties due to an irregularly oscillating filler wire. These early results show that this can be a promising technique for joining thick steels with wide gaps.
50.	Pocorni, Jetro Kenneth, et al. (författare) Measuring the Melt Flow on the Laser Cut Front 2015 Ingår i: 15th Nordic Laser Materials Processing Conference, Nolamp 15, 25-27 August 2015, Lappeenranta, Finland. - : Elsevier. ; 78, s. 99-109 Konferensbidrag (refereegranskat)abstract The flow characteristics on the laser cut front for 10 mm stainless steel AISI 304 (EN 1.4301) are studied in this paper using High Speed Imaging (HSI). The laser cut samples were produced with a 6 kW fiber laser with nitrogen gas assist. Previous work in this field has used unusual cutting parameters to make the experimentation easier. This work presents, for the first time, HSI results from standard commercially viable cutting parameters. This was made possible by the development of a new experimental technique. The results presented here suggest that the cut front produced when cutting stainless steel with a fiber laser and a nitrogen assist gas is covered in bumps which themselves are covered in a thin layer of liquid. Under the conditions shown here the bumps move down the cut front at an average speed of approximately 0.4m/s. The liquid flows at an average speed of approximately 1.1m/s. The average melt depth at the bottom of the cut zone under these conditions is approximately 0.17 mm.

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