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The DsTau(NA65) experiment at CERN was proposed to measure an inclusive differential cross-section of D s production with decay to tau lepton and tau neutrino in p – A interactions. The DsTau detector is based on the nuclear emulsion technique, which provides excellent spatial resolution for detecting short-lived particles like charmed hadrons. This paper presents the first results of the analysis of the pilot-run (2018 run) data and reports the accuracy of the proton interaction vertex reconstruction. High precision in vertex reconstruction enables detailed measurement of proton interactions, even in environments with high track density. The measured data has been compared with several Monte Carlo event generators in terms of multiplicity and angular distribution of charged particles. The multiplicity distribution obtained in p–W interactions is tested for KNO-G scaling and is found to be nearly consistent. The interaction length of protons in tungsten is measured to be 93.7 ± 2.6 mm . The results presented in this study can be used to validate event generators of p – A interactions.

In this study, the plane contact problem for a rigid cylindrical punch and a functionally graded bilayer is considered. The layers have different thicknesses and elastic constants. The normal and tangential forces are applied to the upper layer with a rigid cylindrical punch, and the lower layer is fully bonded to a rigid substrate. Poisson’s ratios are taken as constant, and elasticity moduli are assumed to vary exponentially through the thickness of the layers. With the use of Fourier integral transform, the plane contact problem is reduced to a singular integral equation in which the unknowns are the contact pressure and the contact width. The singular integral equation is solved numerically using Gauss–Jacobi integration formula. The effect of several geometrical and physical parameters such as the material inhomogeneity, the friction coefficient, the layers’ height, the mismatch in the material properties at the interface, and the contact width on the contact stress and in-plane stress are investigated in detail.

Direct Dark Matter searches are nowadays one of the most exciting research topics. Several Experimental efforts are concentrated on the development, construction, and operation of detectors looking for the scattering of target nuclei with Weakly Interactive Massive Particles (WIMPs). In this field a new frontier can be opened by directional detectors able to reconstruct the direction of the WIMP-recoiled nucleus thus allowing to extend dark matter searches beyond the neutrino floor. Exploiting directionality would also give a proof of the galactic origin of dark matter making it possible to have a clear and unambiguous signal to background separation. The angular distribution of WIPM-scattered nuclei is indeed expected to be peaked in the direction of the motion of the Solar System in the Galaxy, i.e. toward the Cygnus constellation, while the background distribution is expected to be isotropic. Current directional experiments are based on the use of gas TPC whose sensitivity is limited by the small achievable detector mass. In this paper we show the potentiality in terms of exclusion limit of a directional experiment based on the use of a solid target made by newly developed nuclear emulsions and read-out systems reaching sub-micrometric resolution.

In this paper, the effects of various design options for improving the crashworthiness performance of a rectangular crash absorber with diaphragms are explored. These design options include (i) optimal tube and diaphragm dimensioning, (ii) optimal diaphragm placement, and (iii) tapering of the crash absorber. The wall thicknesses of the absorber and the diaphragms, the locations of the diaphragms, and the taper angle are taken as design variables to optimize the crashworthiness performance of the absorber. Before the optimization study, a finite element model is generated and validated with experimental results available in the literature. The effect of each design variable on crashworthiness performance is evaluated by solving a series of design optimization problems, and compared with the baseline design. A successive iterative approach is used in this study, where the optimum design variables obtained from a previous optimization problem are used as the initial design of the next optimization problem. Maximum specific energy absorption (SEA) is sought in these optimization problems. A surrogate-based optimization approach is used, where radial basis functions and response surface models are utilized. Optimal tube and diaphragm dimensioning resulted in 59.2% increase, optimum diaphragm placement led to 7.7% additional increase, and tapering resulted in 2.5% further increase in SEA. Overall, the design changes considered in this paper provided 69.4% increase in SEA.

A bstract The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km. The measurement is based on data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of was measured corresponding to a relative difference of the muon neutrino velocity with respect to the speed of light . The above result, obtained by comparing the time distributions of neutrino interactions and of protons hitting the CNGS target in 10.5  μ s long extractions, was confirmed by a test performed at the end of 2011 using a short bunch beam allowing to measure the neutrino time of flight at the single interaction level.

This study focuses on the thermo-elastic rolling contact problem of a graded coating/substrate system. The problem is formulated under the plane thermoelasticity framework. Assuming an exponential variation of the shear modulus within the coating, the governing singular integral equations are extracted by means of the Fourier transform. The solution to problem is provided via the Gauss-Chebyshev integration method. The sensitivity of the contact stresses as well as the surface temperature rise to the stiffness ratio, the coating thickness and the non-dimensional speed is investigated. The results indicate that the thermal expansion ratio substantially affects the contact stresses. Also, the softening coatings will result in maximum surface temperature rise. The coating thickness can alter the surface temperature rise such that an increase of the coating by a factor of 1.6 may result in 50% reduction of the maximum surface temperature.

A bstract The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the ν μ → ν τ channel, via the detection of the τ -leptons created in charged current ν τ interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first ν τ candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional ν τ candidate has been observed. The significance of the two events in terms of a ν μ → ν τ oscillation signal is of 2.40 σ .

Direct Dark Matter searches are nowadays one of the most fervid research topics with many experimental efforts devoted to the search for nuclear recoils induced by the scattering of Weakly Interactive Massive Particles (WIMPs). Detectors able to reconstruct the direction of the nucleus recoiling against the scattering WIMP are opening a new frontier to possibly extend Dark Matter searches beyond the neutrino background. Exploiting directionality would also prove the galactic origin of Dark Matter with an unambiguous signal-to-background separation. Indeed, the angular distribution of recoiled nuclei is centered around the direction of the Cygnus constellation, while the background distribution is expected to be isotropic. Current directional experiments are based on gas TPC whose sensitivity is limited by the small achievable detector mass. In this paper we present the discovery potential of a directional experiment based on the use of a solid target made of newly developed nuclear emulsions and of optical read-out systems reaching unprecedented nanometric resolution.

In this study, the contact problem for a graded elastic half-plane in frictional contact with a rigid stamp is considered. The plane contact problem is assumed to be linear elastic and the Poisson's ratio is assumed to be constant. Analytical formulation of the study includes Fourier transforms of the governing equations and boundary conditions. The resulting integral equation is solved numerically. Contact pressure, in-plane stress and the stress intensity factor at the sharp edges of the contact are evaluated and demonstrated for various stamp profiles. The results are compared with a closed form solution for homogeneous isotropic half-plane indented by rigid stamps. The effects of the nonhomogeneity parameter, coefficient of friction and stamp profiles on the contact and in-plane stresses are analyzed in detail.

After rapid approval and installation, the SND@LHC Collaboration was able to gather data successfully in 2022 and 2023. Neutrino interactions from νμs originating at the LHC IP1 were observed. Since muons constitute the major background for neutrino interactions, the muon flux entering the acceptance was also measured. To improve the rejection power of the detector and to increase the fiducial volume, a third Veto plane was recently installed. The energy resolution of the calorimeter system was measured in a test beam. This will help with the identification of νe interactions that can be used to probe charm production in the pseudo-rapidity range of SND@LHC (7.2 < η < 8.4). Events with three outgoing muons have been observed and are being studied. With no vertex in the target, these events are very likely from muon trident production in the rock before the detector. Events with a vertex in the detector could be from trident production, photon conversion, or positron annihilation. To enhance SND@LHC’s physics case, an upgrade is planned for HL-LHC that will increase the statistics and reduce the systematics. The installation of a magnet will allow the separation of νμ from ν¯μ