Properties of the CsI(Tl) detector elements of the CALIFA detector

In the R3B experiment at FAIR, charged particles with energies up to 600 MeV and forward boosted γ-rays with energies up to 20 MeV need to be detected in scattering experiments. Calorimeters for nuclear physics experiments of this kind, using relativistic radioactive ion beams, require high energy resolution and high efficiency for simultaneous detection of strongly Doppler shifted γ-rays and high-energy charged particles. A calorimeter design that can meet these requirements, using CsI(Tl) scintillators, results in detector elements that may exhibit light output variations with crystal depth, which can limit the attainable resolution. In this paper we present results from a systematic study of 478 detector modules of CALIFA, the R3B calorimeter, in order to determine and minimize such variations. To facilitate further systematic studies we also present results for the total absorption length of the scintillation light, using spectrophotometry, light crosstalk between adjacent detector modules, and surface topography of the CsI(Tl) crystals from atomic force microscopy.Swedish research council | Ref. 2017-03986Swedish research council | Ref. 2014-06644Swedish research council | Ref. 2013-04178Swedish research council | Ref. 2012-04550BMBF, Alemania | Ref. 05P15WOFNABMBF, Alemania | Ref. 05P19WOFN1BMBF, Alemania | Ref. 05P15RDFN1BMBF, Alemania | Ref. 05P19RDFN

β-Delayed and isomer spectroscopy of neutron-rich Ta and W isotopes

Decays of neutron-rich A ~ 190 nuclei have been studied following projectile fragmentation of a 208Pb beam on a 9Be target at the GSI Fragment Separator. Gamma-ray decays from previously reported isomeric states in 188Ta, 190W and 192, 193Re were used as internal calibrations for the particle identification analysis, together with the identification of previously unreported isomeric decays in 189Ta and 191W. The current work also identifies β-delayed γ rays following the decay of 188Ta to 188W for the first time.Algora, Alejandro, [email protected] ; Molina Palacios, Francisco Manuel, [email protected]; Rubio Barroso, Berta, [email protected]

Angular momentum population in fragmentation reactions

Neutron-deficient nuclei with N = 126 have been populated following projectile fragmentation of a 238U beam with energy 1 GeV/A. The decay of several previously reported isomers has been measured. This will allow us to calculate high-spin isomeric ratios and compare them with model calculations to allow a better understanding of the reaction mechanism.Algora, Alejandro, [email protected] ; Molina Palacios, Francisco Manuel, [email protected] ; Rubio Barroso, Berta, [email protected]

Quasi-free neutron and proton knockout reactions from light nuclei in a wide neutron-to-proton asymmetry range

The quasi-free scattering reactions 11C(p,2p) and 10,11,12C(p,pn) have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the R3B-LAND setup. The outgoing proton-proton and proton-neutron pairs were detected in coincidence with the reaction fragments in kinematically complete measurements. The efficiency to detect these pairs has been obtained from GEANT4 simulations which were tested using the 12C(p,2p) and 12C(p,pn) reactions. Experimental cross sections and momentum distributions have been obtained and compared to DWIA calculations based on eikonal theory. The new results reported here are combined with previously published cross sections for quasi-free scattering from oxygen and nitrogen isotopes and together they enable a systematic study of the reduction of single-particle strength compared to predictions of the shell model over a wide neutron-to-proton asymmetry range. The combined reduction factors show a weak or no dependence on isospin asymmetry, in contrast to the strong dependency reported in nucleon-removal reactions induced by nuclear targets at lower energies. However, the reduction factors for (p,2p) are found to be 'significantly smaller than for (p,pn) reactions for all investigated nuclei.German Federal Ministry of Education and Research | Ref. BMBF 05P2015RDFN1German Federal Ministry of Education and Research | Ref. 05P15WOFNAEuropean Commission | Ref. FP7, ENSAR, n. 262010Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2012-32443Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2015-64969-07387Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2015-69640-C2-1-PSwedish Research Council | Ref. 621-2011-5324National Science Foundation, EE. UU. | Ref. n. 1415656Department of Energy, EE. UU. | Ref. n. DE-FG02-08ER41533Fundação para a Ciência e a Tecnologia | Ref. PTDC/FIS/ 103902/200

Structural Potting of Large Aeronautic Honeycomb Panels: End-Effector Design and Test for Automated Manufacturing

Structural potting is used to prepare honeycomb panels to fix metallic elements, typical in aircraft doors. In this paper, a full procedure for structural potting using robotic arms is presented for the first time. Automating this procedure requires the integration of, first, machining operations to remove the skin layers and prepare the potting points and, then, resin injection into the honeycomb cells. The paper describes the design, prototyping, and testing of specific end-effectors. Different end-effectors were explored to ensure efficient injection. The results obtained with the prototypes show that the potting quality is adequate to accomplish the required process checks for industrial manufacturing. The injection process time can be reduced by a factor greater than 3.5, together with the extra assets associated with the automation of complex tasks. Therefore, structural potting automation is demonstrated to be feasible with the end-effectors proposed for milling and injection, which are ready for use with conventional robotic arms in manufacturing lines.Ministerio de Ciencia e Innovacion | Ref. PGC2018-099746-B-C2

Finite element validation of an energy attenuator for the design of a formula student car

Passive safety systems of cars include parts on the structure that, in the event of an impact, can absorb a large amount of the kinetic energy by deforming and crushing in a design-controlled way. One such energy absorber part, located in the front structure of a Formula Student car, was measured under impact in a test bench. The test is modeled within the Finite Element (FE) framework including the weld characteristics and weld failure description. The continuous welding feature is almost always disregarded in parts included in impact test models. In this work, the FE model is fully defined to reproduce the observed results. The test is used for the qualitative and quantitative validation of the crushing model. On the one hand, the acceleration against time curve is reproduced, and on the other hand, the plying shapes and welding failure observed in the test are also correctly described. Finally, a model that includes additional elements of the car structure is also simulated to verify that the energy absorption system is adequate according to the safety regulations.Ministerio de Ciencia, Innovación y Universidades | Ref. PGC2018-096696-B-I00Xunta de Galicia | Ref. beca ED431C 2019/21Xunta de Galicia | Ref. ED481A-2019/23

Optimization of the auxiliary-beam system in railway bridge vibration mitigation using FEM simulation and genetic algorithms

In this paper, we present the optimization of a vibration mitigation system for railway bridges. These structures are subjected to significant moving loads, whose dynamic characteristics may produce resonance effects, compromising the integrity of the bridge and the security of the passengers if the speed or the load of the train is not controlled. The study focuses on the Auxiliary Beam system. It consists of a beam located under the bridge and connected to the slab by viscous dampers. The symmetry of the problem allowed for the use of a 2D Finite Element model of the system. This model was used together with a genetic algorithm in order to evaluate the behaviour of different candidates and to optimize the design parameters: the inertia of the beam and the damper coefficient. The goal of the optimization process is to minimize the acceleration of the bridge while adding the lightest mitigation system possible. The combination of a Finite Element Model and Genetic Algorithm helps to address the complex problem and to find an optimized set of structural parameters. The system finally shows good behaviour for optimal parameters.Ministerio de Ciencia, Innovación y Universidades (España) | Ref. PGC2018-096696-B-I00Xunta de Galicia | Ref. ED481A-2019/23