the SARS-CoV-2 pandemic started in December 2019 and still remains a major global health issue. Every country in the world has adopted drastic measures to contain the virus, although their stringency ...varies among countries, ranging from increased surveillance and focused interventions to strict lockdown (1). Italy was the second country where the disease had a major impact early in the pandemic, such that a strict nationwide lockdown was declared from March 9 to May 3, 2020. Nonetheless, between January and May 2020, there were 210,000 COVID-19 cases in Italy and 29,000 deaths were recorded (2). Due to the lockdown, universities (and in general all educational services) shifted to online classes, with students attending lessons and taking their exams from home. On-site activities were reduced to those considered indispensable. Research activities also had to be modified, such as by the adoption of a smart-working model (3). Between May and August 2020, the number of SARS-CoV-2 infections in Italy decreased. In response, the lockdown was loosened and some activities were restarted, albeit with specific safety protocols (social distancing, use of masks, temperature checks at the workplace entry, environmental disinfection, mixed models of smart and in-office work). These actions were accompanied by periodic serological and PCR screening tests (4).
The J/ψ meson has negative G parity so that, in the limit of isospin conservation, its decay into π+π− should be purely electromagnetic. However, the measured branching fraction B(J/ψ→π+π−) exceeds ...by more than 4.5 standard deviations the expectation computed according to BABAR data on the e+e−→π+π− cross section. The possibility that the two-gluon plus one-photon decay mechanism is not suppressed by G-parity conservation is discussed, even by considering other multipion decay channels. As also obtained by phenomenological computation, such a decay mechanism could be responsible for the observed discrepancy. Finally, we notice that the BESIII experiment, having the potential to perform an accurate measurement of the e+e−→π+π− cross section in the J/ψ mass energy region, can definitely prove or disprove this strong G-parity-violating mechanism by confirming or confuting the BABAR data.
The experiment BESIII, running at the accelerator BEPCII in Beijing (P.R.C.), is going to be updated with the replacement of the Inner Drift Chamber with a Cylindrical triple-GEM Inner Tracker ...(CGEM-IT). In the R&D stage, two standalone C++ codes were implemented: GTS (Garfield-based Triple-GEM Simulator), for digitization and tuning of simulated data to the experimental ones, and GRAAL (GEM Reconstruction And Analysis Library), for the reconstruction and analysis of the experimental events collected in testbeams. GTS simulates the triple-GEM response to the particle passage, treating each stage separately: ionization, GEM properties, gas mixture, magnetic field and finally the induction of the signal on the anode. The necessary information was extracted by GARFIELD++ simulations, parametrized and used as input in GTS. This speeds up the simulation, since GTS performs only samplings instead of the full digitization chain. The simulated events were reconstructed with the same procedure used for experimental data and tuning factors were evaluated to obtain a satisfactory match. GRAAL is used in the analysis of the testbeam experimental data. It provides several levels of reconstruction: from the cluster formation, gathering contiguous firing strips, to the spatial position and the signal time reconstruciton. Two algorithms are used: the charge centroid and the micro-TPC, which exploit the charge deposition on the strips and the time information. Also a merging of the two algorithms is available to efficiently weight the two outcomes and obtain the best estimate of the spatial coordinate. Moreover, GRAAL performs tracking and alignment. Both codes are going to be made available also for other MPGDs simulation and reconstruction.
The zero degree detector at BESIII Anelli, M.; Baldini Ferroli, R.; Bertani, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
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A small-size calorimeter has been built in the Frascati National Laboratory of INFN for BESIII detector based on the BEPCII storage ring of the Institute of High Energy Physics in Beijing. It has ...been installed in one of the two small-theta angle regions of BEPCII to measure the energy of photons from Initial State Radiation events and is currently taking data together with BESIII. The detector is a sandwich of Pb and scintillating fibers, the same technique employed for the KLOE calorimeter at the DAΦNE accelerator, but the readout is actuated by way of bundles of clear plastic fibers. We describe here the fabrication, present results from tests with cosmic rays and at the Frascati Beam Test Facility, the installation in BESIII, and preliminary luminosity measurements.
This paper examines individuals’ reactions to the prospect of gaining or losing status in groups. The results of three experiments provide evidence that individuals attach greater value to status ...when recalling the risk of status loss than when recalling the potential for status gain (Experiment 1), are willing to pay more to avoid a status loss than to achieve a status gain (Experiment 1), and put forth greater effort when striving to prevent status loss than when striving to gain status (Experiment 2). Finally, individuals who risk losing status allocate more resources toward personal status concerns (and away from group interests and potential monetary gain) than do individuals who have a chance of gaining status (Experiment 3). We discuss the implications of this research both in terms of individuals’ psychological experience of their status, as well as status attainment and maintenance concerns in groups.
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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