793 research outputs found
A deep neural network to search for new long-lived particles decaying to jets
No full textA tagging algorithm to identify jets that are significantly displaced from the proton-proton (pp) collision region in the CMS detector at the LHC is presented. Displaced jets can arise from the decays of long-lived particles (LLPs), which are predicted by several theoretical extensions of the standard model. The tagger is a multiclass classifier based on a deep neural network, which is parameterised according to the proper decay length c tau(0) of the LLP. A novel scheme is defined to reliably label jets from LLP decays for supervised learning. Samples of pp collision data, recorded by the CMS detector at a centre-of-mass energy of 13 TeV, and simulated events are used to train the neural network. Domain adaptation by backward propagation is performed to improve the simulation modelling of the jet class probability distributions observed in pp collision data. The potential performance of the tagger is demonstrated with a search for long-lived gluinos, a manifestation of split supersymmetric models. The tagger provides a rejection factor of 10 000 for jets from standard model processes, while maintaining an LLP jet tagging efficiency of 30%-80% for gluinos with 1 mm <= c tau(0)<= 10 m. The expected coverage of the parameter space for split supersymmetry is presented
Implementing Circular Economy in Universities. Successful Practices at Politecnico di Torino (Italy)
No full textThe circular economy (CE) concept reported a growing interest as an operationalizing framework, able to support the implementation of sustainable production and consumption, resource use and waste prevention broader concepts. Even if CE is different from waste management, it has traditionally been associated with waste reduction, recycling improvement, and minimization of environmental impacts in cities and territories. Additionally, CE could be a driver for the achievement of multiple Sustainable Development Goals (SDGs). On the other side, universities are recognized as key actors in the transition towards sustainable development at the territorial level. Given the use of CE as a possible change paradigm to decouple economic growth from associated environmental impacts, this paper aims at highlighting some of the main successful practices put forwards by an Italian university, Politecnico di Torino, in implementing CE principles.Keyword: Circular Economy, University Sustainability, waste managemen
Local and global performance of double-gap resistive plate chambers operated in avalanche mode
No full textTwo large double-gap resistive plate chambers, with 2 and 3 mm gap widths, were tested to study their response uniformity when operated in avalanche mode. The effects of mechanical tolerances and the presence of the spacers is thoroughly examined. Results on efficiency and time resolution are presented. We find that average performance and response uniformity over the whole chamber surface are fully adequate to the requirements of future collider experiments. (author
Recent results and developments on double-gap RPCs for CMS
No full textA 3 mm wide-gap Resistive Plate Chamber, as proposed for CMS, has been tested in the H2 Cern beam line. Results on efficiency, rate capability, time resolution and cluster size are reported
Properties of C2H2F4-based gas mixture for avalanche mode operation of resistive plate chambers
No full textSome properties of a 90% C2H2F4 gas mixture, used to operate resistive plate chambers in the avalanche mode, are determined by comparing the experimental results with the prediction of simple analytical calculations. The fast charge distribution of the signal induced on pick-up electrodes is reproduced by means of a Monte Carlo simulation of the avalanche development. In addition, predictions for a gas mixture with poor content of C2H2F4 are given for comparison
{Search for at a Multi-TeV Muon Collider}
No full textA muon collider represents the ideal machine to reach very high center-of-mass energies (√s=1.5−10 TeV) and luminosities O(0.5−10/ab). A large number of Higgs bosons will be produced mainly through the Vector Boson Fusion (VBF) processes. The VBF through Z bosons (ZZH) production process could be difficult to disentangle from the dominant WWZ, since the final state VBF muons, produced in the very forward region, could escape the detector. As a consequence, at a multi-TeV muon collider, the H→ZZ decay process turns out to be favoured to probe exclusively the Higgs boson coupling to Z bosons. In this paper, for the first time, a feasibility study of the search for H→ZZ∗→4μ at a 1.5 and 3 TeV muon collider is presented. The study of the four muons final state, performed on fully simulated Monte Carlo samples, allows to optimize the muon reconstruction, thus providing feedback for the detector design. Irreducible backgrounds from Standard Model are studied. A first estimate of the senistivity of the Higgs boson coupling to Z bosons in the 4μ channel is provided, along with a preliminary evaluation of the impact of the machine background in the 1.5-TeV scenario
{Search for at a Multi-TeV Muon Collider}
No full textA Multi-TeV (ss
= 1.5 - 10 TeV) Muon Collider providing O(ab−1)O(ab−1) integrated luminosity will be a great opportunity to probe the most intimate nature of the Standard Model (SM) and the Electroweak Symmetry Breaking mechanism, allowing the precise measurement of the Higgs couplings to several SM particles. The study of the Higgs boson couplings to the second generations of fermions is of particular interest due to sensitivity to a whole class of new physics models. It is also true that this measurement is extremely challenging, because of the small branching ratio. Indeed, it is currently not accessible at LHC, where the quantum chromodynamics processes are overwhelming. In this paper it is explored, for the first time, the search for H→ccˉH→ccˉ at a Multi-TeV Muon Collider. The μ+μ−→Hννˉ→ccˉννˉμ+μ−→Hννˉ→ccˉννˉ signal process has been fully simulated and reconstructed at s=1.5 TeVs
=1.5TeV with a preliminary detector design, along with the main physics backgrounds. The machine background originated from the decay of beam muons, the so-called Beam Induced Background (BIB), is not included in this preliminary study. A c quark-tagging algorithm has been developed, combining several observables in a single discriminator using Machine Learning techniques, with the goal to improve the rejection of jets coming from b-quark and u-d-s-g hadronization. A first estimate of the precision on the Higgs coupling with c-quark reachable with a Muon Collider machine is presented. The relative uncertainty on the coupling at s=1.5 TeVs
=1.5TeV is estimated to be 5.5 %%. A projection to s=3 TeVs
=3TeV shows that the precision improves with increasing energy, reaching the value of 2.6%2.6%
Performances of Resistive Plate chamber Operated in Avalanche Mode under 137Cs Irradiation
No full textA 2 mm gas RPC with bakelite plates has been operated in avalanche mode under 137Cs source irradiation. We report on measurements of the efficiency in cosmic rays detection and of the charge developed in the gap, performed for different gas mixtures. We show that C2H2F4 based mixtures exhibit a wide full efficiency plateau with low streamer probability, while the argon based mixtures allow to reduce the detector power consumptio
Local and global performance of double-gap resistive plate chambers operated in avalanche mode
No full textTwo large double-gap resistive plate chambers, with 2 and 3 mm gap widths, were tested to study their response uniformity when operated in avalanche mode. The effects of mechanical tolerances and the presence of the spacers is thoroughly examined. Results on efficiency and time resolution are presented. We find that average performance and response uniformity over the whole chamber surface are fully adequate to the requirements of future collider experiments
Modified POF Sensor for Gaseous Hydrogen Fluoride Monitoring in the Presence of Ionizing Radiations
No full textThis paper describes the development of a sensor designed to detect low concentrations of hydrogen fluoride (HF) in gas mixtures. The sensor employs a plastic optical fiber (POF) covered with a thin layer of glass- like material. HF attacks the glass and alters the fiber transmission capability so that the detection simply requires a LED and a photodiode. The coated POF is obtained by means of low-pressure plasma-enhanced chemical vapor deposition that allows the glass-like film to be deposited at low temperature without damaging the fiber core. The developed sensor will be installed in the recirculation gas system of the resistive plate chamber muon detector of the Compact Muon Solenoid experiment at the Large Hadron Collider accelerator of the European Organization for Nuclear Research (CERN
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