Progress in high-energy physics has been closely tied to the development of high-performance electromagnetic calorimeters. Recent experiments have demonstrated the possibility to significantly ...accelerate the development of electromagnetic showers inside scintillating crystals typically used in homogeneous calorimeters based on scintillating crystals when the incident beam is aligned with a crystallographic axis to within a few mrad. In particular, a reduction of the radiation length has been measured when ultrarelativistic electron and photon beams were incident on a high-
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scintillator crystal along one of its main axes. Here, we propose the possibility to exploit this physical effect for the design of a new type of compact e.m. calorimeter, based on oriented ultra-fast lead tungstate (PWO-UF) crystals, with a significant reduction in the depth needed to contain electromagnetic showers produced by high-energy particles with respect to the state-of-the-art. We report results from tests of the crystallographic quality of PWO-UF samples via high-resolution X-ray diffraction and photoelastic analysis. We then describe a proof-of-concept calorimeter geometry defined with a Geant4 model including the shower development in oriented crystals. Finally, we discuss the experimental techniques needed for the realization of a matrix of scintillator crystals oriented along a specific crystallographic direction. Since the angular acceptance for e.m. shower acceleration depends little on the particle energy, while the decrease of the shower length remains pronounced at very high energy, an oriented crystal calorimeter will open the way for applications at the maximum energies achievable in current and future experiments. Such applications span from forward calorimeters, to compact beam dumps for the search for light dark matter, to source-pointing space-borne
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-ray telescopes, to decrease the size and the cost of the calorimeter needed to fully contain e.m. showers initiated by GeV to TeV particles.
Existing literature clearly documents the association between cybervictimization and psychological symptoms; less clear is the association between cybervictimization and somatic symptoms. This study ...aims to verify the association between cybervictimization and both psychological and somatic symptoms on a representative sample of Italian early adolescents.
This study used data from 24 099 students aged 13 years participating in the 2009/2010 Health Behaviour in School-aged Children Survey. Self-completed questionnaires, devised by the HBSC international group, were administered in classrooms. Multilevel models of logistic regression (controlling for traditional bullying victimization, computer use and demographics) were used to investigate the association between cybervictimization and psychological and somatic symptoms.
Overall, 3.1% of the students reported having been bullied frequently electronically and 8.7% occasionally (compared, respectively, to 4.0 and 9.2% victims of traditional forms of bullying). Overall, prevalence of students reporting psychological and somatic symptoms was 32.5 and 12.0%, respectively. Being victims of cyberbullying was positively associated to students' psychological and somatic symptoms, after controlling for traditional bullying victimization and computer use.
Cybervictimization has similar psychological and somatic consequences for boys and girls, thus suggesting that intervention and prevention efforts should focus on both gender groups.
The basal succession of the Lajas Formation at Trasandino section, Arroyo Covunco area, constitutes an excellent example of proximal prodelta facies cut by sediment-waves formed during a complete ...acceleration-deceleration hyperpycnal discharge cycle. The main outcome of this contribution was to present a new studied locality in which the Lajas Formation outcrops. Nine mudstones and fine-grained heterolites levels deposited during the waning stage, were sampled to palynological analysis. The recovered assemblages are dominated by sporomorphs, which are characterized by a great diversity of the trilete spores. Among them, is interesting to highlight the first mention of Manumia variverrucata and the extension of the last occurrence of Striatella seebergensis until to Callovian in Argentina. Based on selected key taxa a Late Bathonian–Callovian age is proposed for the Lajas Formation at the Trasandino section in this area. The Trasandino section spore assemblages show the greatest similarity with the Arroyo Covunco section spore associations when they are compared with the Lajas Formation of other studied localities. The endemic development of certain types of bryophyte (sensu lato) spores, e.g. Taurocusporites quattrocchiensis, was favored by locally humid conditions inferred at the Arroyo Covunco area. Large abundance of phytoclasts, sporomorphs and fresh-water algae characterize the recovered organic matter suggesting a high input of continental organic particles to the basin, as the result of fluvial-derived density discharges. Three palynofacies type (PT) had been identified which allow to evaluate the hydrodynamic characteristics of the flow, taking into account the differential buoyancy of the opaque particles. The large amount of equidimensional opaque particles recognized at the PT-B, characterizes the beginning of the deceleration phase of the flow and the abundance of blade-shape opaque particles, identified in the PT-A, point out a deposition from the final buoyant plume of hyperpycnal flow. The PT-C shows transitional features between these two conditions.
•Trasandino section at the Arroyo Covunco locality (Neuquén Basin) is a new palynological record of the Lajas Formation.•Samples are dominated by phytoclasts, sporomorphs and fresh-water algae suggesting a high input of continental organic matter.•The ratio between the opaque equidimensional and blade-shaped fragments might be related to variations in flow velocity.•The studied spores may suggest a terrestrial locally humid and an endemic development of certain bryophyte spores.
Based on the notion that the local dark-matter field of axions or axionlike particles (ALPs) in our Galaxy induces oscillating couplings to the spins of nucleons and nuclei (via the electric dipole ...moment of the latter and/or the paramagnetic axion-wind effect), we establish the feasibility of a new method to search for ALPs in storage rings. Based on previous work that allows us to maintain the in-plane polarization of a stored deuteron beam for a few hundred seconds, we perform a first proof-of-principle experiment at the Cooler Synchrotron (COSY) to scan momenta near 970 MeV/c. This entails a scan of the spin-precession frequency. At resonance between the spin-precession frequency of deuterons and the ALP-induced electric dipole moment (EDM) oscillation frequency, there is an accumulation of the polarization component out of the ring plane. Since the axion frequency is unknown, the momentum of the beam and, consequently, the spin-precession frequency are ramped to search for a vertical polarization change that occurs when the resonance is crossed. At COSY, four beam bunches with different polarization directions are used to make sure that no resonance is missed because of the unknown relative phase between the polarization precession and the axion or ALP field. A frequency window of 1.5 kHz width around the spin-precession frequency of 121 kHz is scanned. We describe the experimental procedure and a test of the methodology with the help of a radio-frequency Wien filter located on the COSY ring. No ALP resonance is observed. As a consequence, an upper limit of the oscillating EDM component of the deuteron as well as its axion coupling constants are provided.
To examine the association between adolescent at-risk or problem gambling (ARPG) and medicine used to treat nervousness in a large-scale nationally representative sample of Italian adolescents.
Data ...from the 2013/2014 Health Behaviour in School-aged Children Survey was used for cross-sectional analyses (a sample of 20,791 15-year-old students). Self-administered questionnaires were completed by a representative sample of high-school students. Respondents' ARPG, use of medicine for nervousness and potential confounding factors were assessed. Multilevel logistic regression analyses were used to test the association between medicine use to treat nervousness and ARPG.
The overall prevalence of adolescents reporting medicine use for nervousness in the last month was 6.3%. The odds of ARPG were 3 times higher among adolescents who used medicine for nervousness compared to that among adolescents who did not take such medicine (OR 2.96, 95% CI 2.07-4.25). Importantly, the association between medicine used to treat nervousness and ARPG did not vary significantly when viewed in light of psychological symptoms.
Medicine use to treat nervousness is associated with increased risk of gambling-related harm.
Gas detectors are one of the pillars of the research in fundamental physics. Since several years, a new concept of detectors, called Micro Pattern Gas Detectors (MPGD), allows to overcome many of the ...problems of other types of commonly used detectors, like drift chambers and microstrip detectors, reducing the discharge rate and increasing the radiation tolerance. Among these, one of the most commonly used is the Gas Electron Multiplier (GEM). GEMs have become an important reality for fundamental physics detectors. Commonly deployed as fast timing detectors and triggers, due to their fast response, high rate capability and high radiation hardness, they can also be used as trackers. The readout scheme is one of the most important features in tracking technology. The center of gravity technique allows to overcome the limit of the digital pads, whose spatial resolution is constrained by the pitch dimension. The presence of a high external magnetic field can distort the electronic cloud and affect the spatial resolution. The micro-TPC (μ-TPC) reconstruction method allows to reconstruct the three dimensional particle position as in a traditional Time Projection Chamber, but within a drift gap of a few millimeters. This method brings these detectors into a new perspective for what concerns the spatial resolution in strong magnetic field. In this report, the basis of this new technique will be shown and it will be compared to the traditional center of gravity. The results of a series of test beam performed with 10 × 10 cm 2 planar prototypes in magnetic field will also be presented. This is one of the first implementations of this technique for GEM detectors in magnetic field and allows to reach unprecedented performance for gas detectors, up to a limit of 120 \mu~{\mathrm {m}} at 1 T, one of the world's best results for MPGDs in strong magnetic field. The μ-TPC reconstruction has been recently tested at very high rates in a test beam at the MAMI facility; preliminary results of the test will be presented.
Gas detector development is one of the pillars of the research in fundamental physics. Since several years, a new concept of detectors, called Micro Pattern Gas Detector (MPGD), allowed to overcome ...several problems related to other types of commonly used detectors, like drift chamber and micro strips detectors, reducing the rate of discharges and providing better radiation tolerance. Among the most used MPGDs are the Gas Electron Multipliers (GEMs). Invented by Sauli in 1997, nowadays GEMs have become an important reality for particle detectors in high energy physics. Commonly deployed as fast timing detectors and triggers, their fast response, high rate capability and high radiation hardness make them also suitable as tracking detectors. The readout scheme is one of the most important features in tracking technology. Analog readout based on the calculation of the center of gravity technique allows to overcome the limit imposed by digital pads, whose spatial resolution is limited by the pitch dimensions. However, the presence of high external magnetic fields can distort the electronic cloud and affect the performance. The development of the micro-TPC reconstruction method brings GEM detectors into a new prospective, improving significantly the spatial resolutionin presence of high magnetic fields. This innovative technique allows to reconstruct the 3-dimensional particle position, as Time Projection Chamber, but within a drift gap of a few millimeters. In these report, the charge centroid and micro-TPC methods are described in details. We discuss the results of several test beams performed with planar chambers in magnetic field. These results are one of the first developments of micro-TPC technique for GEM detectors, which allows to reach unprecedented performance in a high magnetic field of 1 T.
Performance of triple GEM prototypes has been evaluated by means of a muon beam at the H4 line of the SPS test area at CERN. The data from two planar prototypes have been reconstructed and analyzed ...offline with two clusterization methods: the center of gravity of the charge distribution and the micro Time Projection Chamber (μTPC). GEM prototype performance evaluation, performed with the analysis of data from a TB, showed that two-dimensional cluster efficiency is above 95% for a wide range of operational settings. Concerning the spatial resolution, the charge centroid cluster reconstruction performs extremely well with no magnetic field: the resolution is well below 100 μm. Increasing the magnetic field intensity, the resolution degrades almost linearly as effect of the Lorentz force that displaces, broadens and asymmetrizes the electron avalanche. Tuning the electric fields of the GEM prototype we could achieve the unprecedented spatial resolution of 190 μm at 1 Tesla. In order to boost the spatial resolution with strong magnetic field and inclined tracks a μTPC cluster reconstruction has been investigated. Such a readout mode exploits the good time resolution of the GEM detector and electronics to reconstruct the trajectory of the particle inside the conversion gap. Beside the improvement of the spatial resolution, information on the track angle can be also extracted. The new clustering algorithm has been tested with diagonal tracks with no magnetic field showing a resolution between 100 μm and 150 μm for the incident angle ranging from 10° to 45°. Studies show similar performance with 1 Tesla magnetic field. This is the first use of a μTPC readout with a triple GEM detector in magnetic field. This study has shown that a combined readout is capable to guarantee stable performance over a broad spectrum of particle momenta and incident angles, up to a 1 Tesla magnetic field.
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