The elastoplastic state of thin cylindrical shells with two equal circular holes is analyzed with allowance made for finite deflections. The shells are made of an isotropic homogeneous material. The load is internal pressure of given intensity. The distribution of stresses along the hole boundary and in the stress concentration zone (when holes are closely spaced) is analyzed by solving doubly nonlinear boundary-value problems. The results obtained are compared with the solutions that allow either for physical nonlinearity (plastic strains) or geometrical nonlinearity (finite deflections) and with the numerical solution of the linearly elastic problem. The stresses near the holes are analyzed for different distances between the holes and nonlinear factors.Theoretical and experimental data on stress concentration in isotropic and anisotropic structural elements (plates and shells) with two or more curvilinear (circular, elliptic, or rectangular) holes have been obtained mainly based on the linear elastic theory of thin shells [1, 4, 6-9, 11, 12, 15, etc.].The distribution of stresses (strains or displacements) in multiply connected thin-walled shells of various shapes with physical (plastic strain or creep) or geometrical (finite or large deflections) nonlinearities was addressed in a few studies [1-3, 5-10, etc.]. Note that the unsteady creep of multiply connected shallow shells was studied in the publications [2,5], which analyzed the stress state of internally loaded spherical shells with two equal circular holes and with cyclically symmetrically located holes centered on a circle of given radius. Experimental data for a cylindrical shell with two longitudinally arranged nonreinforced circular holes are presented in the papers [3, 10], which analyzed the elastoplastic stability of shells and determined the critical axial compressive forces.An important task is to solve static and dynamic problems for cylindrical shells taking physical and geometrical nonlinearities into account. The paper [13] includes a generalized formulation of nonlinear stress-concentration problems for arbitrary thin shells with several holes, the governing equations, and a solution technique. Numerical data for spherical shells with two circular holes under a surface load are presented in the paper [14], which studies the influence of one and two nonlinearities on the stress distribution in shells for different distances between the holes.

During Run 3, the LHCb experiment will collect data at a higher luminosity with respect to the previous decade of data taking. The Radiation Monitoring System (RMS-R3), functionally designed for reliable long-run performance, will display the interaction rate of the LHC’s beams along with its background in LHCb. The RMS-R3 comprises 4 detector modules based on the Metal-Foil Detectors radiation hard technology that can withstand fluences up to 1020 MIPs/cm2 or radiation doses of up to a GGy, during its entire lifespan. The modules are placed symmetrically around the beam pipe remarkably close to the interaction point at LHCb at about 2.2 m, while covering a backward acceptance of 7-14 degrees. The readout electronics provide a continuous relative luminosity measurement for LHCb and observations of background evolutions during the various stages of the beam preparation towards collisions. The RMS-R3 detector’s performance has shown good response reproducibility of about 1% and excellent linearity, making it a robust and reliable complementary detector for beam induced background and luminosity measurement at LHCb.

An amplitude analysis of the D+→ π−π+π+ decay is performed with a sample corresponding to 1.5 fb−1 of integrated luminosity of pp collisions at a centre-of-mass energy $$ \sqrt{s} $$ s = 8 TeV collected by the LHCb detector in 2012. The sample contains approximately six hundred thousand candidates with a signal purity of 95%. The resonant structure is studied through a fit to the Dalitz plot where the π−π+ S-wave amplitude is extracted as a function of π−π+ mass, and spin-1 and spin-2 resonances are included coherently through an isobar model. The S-wave component is found to be dominant, followed by the ρ(770)0π+ and f2(1270)π+ components. A small contribution from the ω(782) → π−π+ decay is seen for the first time in the D+→ π−π+π+ decay.

A system for quality assessment of micropixel detectors is presented. The system includes a laser scanning microprobe and a setup for studying the response of micro detectors to minimum ionizing particles. The results of the validation of the developed system indicate its suitability for assessing the quality of the latest monolithic active pixel sensors (MAPS), promising elements of large-area tracking systems for future high-energy physics experiments. Comparison of MAPS with the double-sided microstrip detectors of the CBM experiment (FAIR, Darmstadt) indicates the feasibility of the upgrade of its Silicon Tracking System using MAPS.