The LHCb upgrade I

The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software

Thermal behavior of indium nanoclusters in ion-implanted silica

Fused silica substrates were implanted with 2x10(17) In(2+)/cm(2) ions at 320 keV. Indium crystalline nanoclusters with an average size of about 15-20 nm were found in the as-implanted samples. The thermal behavior of the nanoclusters was studied by performing heating-cooling cycles in vacuum and by using in-situ techniques based on glancing-incidence x-ray diffraction and transmission electron microscopy. The precipitates showed both superheating and supercooling. Moreover, no evidence of clusters growth or reorientation during the thermal cycle was found. A detailed study of the heating sequence showed that the melting temperature of the Indium precipitates depended on their size, i.e., the smallest particles melt first and at a temperature which is about 7 K below the bulk melting point, while the largest ones were superheated until about 13 K above it. Moreover, a remarkable stability of the In cluster well above their melting temperature (up to about 980 K) was evidenced by in-situ transmission electron microscopy analysis. From a thermodynamic point of view, the experimental results were explained by considering two effects acting on the clusters: the thermodynamic size effect and the pressure of the silica matrix

SnO2 nanoparticles embedded in silica by ion implantation followed by thermal oxidation

Nanoparticles of tin dioxide embedded in silica matrix were synthesized by ion implanting a Sn(+) ion beam in a silica slide and by annealing, in oxidizing atmosphere at 800 degrees C. A detailed structural and optical characterization was performed by using glancing incidence x-ray diffraction, transmission electron microscopy, optical absorption, and photoluminescence spectroscopies. Metallic tetragonal, beta-tin crystalline nanoparticles were formed in the as-irnplanted sample. The annealing in oxidizing atmosphere promotes the total oxidation of the tin nanoparticles with a preferential migration of the nanoparticles toward the surface of the matrix. A broad blue-violet emission band peaked at 388 nm was observed in the photoluminescence spectra of both the as-implanted and annealed samples, which was attributed to the Sn-related oxygen deficiency center defects and the SnO(2) nanoparticles, respectively

Size-dependent oxidation in ZnO nanoparticles embedded in ion-implanted silica

ZnO-SiO(2) nanocomposites were synthesized by ion implanting a Zn(+) beam in a silica slide and by annealing in oxidizing atmosphere at 800 C. A detailed structural and optical characterization was performed by using glancing incidence x-ray diffraction, transmission electron microscopy combined with selected area electron diffraction and energy dispersive spectrometry, optical absorption, and photoluminescence spectroscopies. Samples obtained with three different Zn+ fluences in the range 1-2 x 10(17) ions/cm(2) have been investigated. According to the results, Zn crystalline nanoparticles were found in the as-implanted Zn-SiO(2) samples. The size of the Zn nanoparticles was proportional to the implantation fluence. The annealing in oxidizing atmosphere promotes the total oxidation of the Zn nanoparticles with a preferential migration of the nanoparticles toward the surface of the sample along with an opposite and less pronounced diffusion toward the bulk of the matrix. A relatively strong excitonic peak from the ZnO nanoparticles was observed both in the optical absorption and photoluminescence spectra. We found that the oxidation of the Zn nanoparticles is size-dependent because the time necessary for the total oxidation of the nanoparticles increases with the decreasing in the size of the nanoparticles. This size-oxidation correlation has been explained in terms of arguments related to the stress of the Zn nanoparticles

Synthesis and characterization of SnO(2) nanoparticles embedded in silica by ion implantation

Tin dioxide nanoparticles embedded in silica matrix were fabricated by ion implantation combined with thermal oxidation. Silica substrate was implanted with a 150 keV Sn(+) ions beam with a fluence of 1.0 x 10(17) ions/cm(2). The sample was annealed for 1 h in a conventional furnace at a temperature of 800 C under flowing O(2) gas. According to the structural characterization performed by X-ray diffraction and transmission electron microscopy techniques, metallic tetragonal tin nanoparticles with a volume average size of 12.8 nm were formed in the as-implanted sample. The annealing in oxidizing atmosphere promotes the total oxidation of the tin nanoparticles into tin dioxide nanoparticles with a preferential migration toward the surface of the matrix, where large and coalesced nanoparticles were observed, and a small diffusion toward the bulk, where smaller nanoparticles were found

Synthesis of wide band gap nanocrystals by ion implantation

Nanocrystals of wide band gap materials (GaN and In2O3) were synthesized by sequential ion implantation in dielectric substrates, followed by thermal annealing of the samples. Transmission electron microscopy, extended X-ray absorption fine structure spectroscopy and grazing incidence X-ray diffraction analyses confirmed the formation of GaN and In2O3 crystalline nanoparticles. Blue shift of the near-edge photoluminescence (PL) band (quantum con-finement effect) was observed for GaN nanocrystals. A strong PL band peaked at 3.35 eV was detected upon excitation of In2O3 nanocrystals at 5.20 eV