In the last years Friction Stir Welding has produced a big impact on several industries due to its advantages. Particularly, automotive industry has developed a variant of the original process named ...Friction Stir Spot Welding (FSSW), having a strong influence on welding of thin sheets of aluminum alloys and dissimilar materials. Nevertheless, the knowledge about the influence of welding procedure on joint characteristics is scarce, mainly for dissimilar materials. The aim of this work was to study the effect of the tool penetration depth during welding, as well as, the relative position of the materials used in the superimposed joints, when AA5052-AA6063 sheets samples were welded. Tool penetration depths between 0.05 and 1.25mm were analyzed, for both materials positions. Macrostructural and dimension characterization, microhardness profiles and Peel tests (PT) were done for different conditions. The fracture loads in PT increased with the tool penetration depth for both material positions, being higher when AA6063 was the upper material. However, the tool penetration depth has a limit in the increasing of fracture load, for which the fracture mechanism changes from interfacial to circumferential.
The NA62 experiment at the European Organization for Nuclear Research (CERN) Super Proton Synchrotron (SPS) aims to measure the Branching Ratio of the very rare kaon decay K + → π + νν, collecting O ...(100) events with a 10% background to make a stringent test of the Standard Model. One of the main backgrounds to the proposed measurement is represented by the K + → π + π 0 , decay. To suppress this background an efficient photo veto system is foreseen with the Liquid Krypton (LKr) Electromagnetic Calorimeter Level 0 (L0) trigger. The development of a high-performance as well as reliable digital data system addresses this issue providing a mean to have the right bandwidth and efficiency to transmit experimental data to and from the counting room. This paper describes the LKr L0 trigger system, with particular emphasis for what concerns a LVDS digital data link used inside the system. Some aspects relative to the test set-up implementation as well as protocol test used to evaluate and qualify the digital data system are also part of the paper.
Particle identification with the NA62 RICH detector Duk, V.; Anzivino, G.; Bizzeti, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
December 2023, 2023-12-00, Volume:
1057
Journal Article
Peer reviewed
NA62 is a new generation kaon experiment at the CERN SPS aiming at studying rare and forbidden decays. One of main challenges of the experiment is the suppression of background decay channels with ...branching ratios up to 10 orders of magnitude higher than the signal and with similar experimental signatures. To provide such suppression, a powerful particle identification (PID) is needed.
A key element of PID in NA62 is the Ring Imaging Cherenkov (RICH) detector. The RICH has successfully operated during the 2016–2018 data taking periods, being essential in the measurement of the branching ratio of the K+→π+νν̄ decay. The detector was also used for searches for lepton number violation in 3-track kaon decays. The results on the π/μ and π/e separation directly measured with the data for the aforementioned decays are presented.
Performance of the NA62 RICH detector Pepe, M.; Aisa, D.; Anzivino, G. ...
2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC),
2015-Oct.
Conference Proceeding
NA62 is the last generation kaon experiment at CERN SPS aiming to study the decay K + _ π + νν̅. The goal of the experiment is to measure the decay branching ratio (O(10 -10 )) with 10% accuracy, ...collecting about 100 K + → π + νν̅ events in three years of data taking and assuming a 10% signal acceptance. The NA62 detector must be able to reject background events from decay channels with branching ratios up to 10 orders of magnitude higher than the signal and with similar experimental signature. To this purpose, good Particle Identification (PID) and kinematic rejection are required. Precise timing is also needed to correctly associate the π + with the parent K + in a high rate environment. The key element of the PID in NA62 is the Ring Imaging CHerenkov detector (RICH) to identify π and μ in the momentum range between 15 and 35 GeV/c with a muon rejection factor better than 1%; it is also required to measure the pion arrival time with a precision better than 100 ps and the Cherenkov angle with a resolution better than 80 μ rad. Finally, it must provide a fast L0 trigger signal for charged particles. At the beginning of the NA62 pilot run, from mid October to mid December 2014, the RICH detector was completely installed and ready to take data. The installation details and the results on the detector performance will be presented together with preliminary results from the first NA62 physics run in 2015.
A commercial Graphics Processing Unit (GPU) is used to build a fast Level 0 (L0) trigger system for the NA62 experiment at CERN. In particular, the parallel computing power of the GPU is exploited to ...perform real-time fitting in the Ring Imaging CHerenkov (RICH) detector for the L0 trigger of the NA62 experiment. Direct GPU communication using a FPGA-based board has been used to reduce the data transmission latency. The first result of multi-ring Cherenkov reconstrunction obtained during the NA62 physics run will be presented.
The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003–2004. A new upper limit on the rate of the lepton number ...violating decay K±→π∓μ±μ± is reported: B(K±→π∓μ±μ±)<8.6×10−11 at 90% CL. Searches for two-body resonances X in K±→πμμ decays (such as heavy neutral leptons N4 and inflatons χ) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K±→μ±N4)B(N4→πμ) and B(K±→π±X)B(X→μ+μ−) for ranges of assumed resonance masses and lifetimes. The limits are in the (10−11,10−9) range for resonance lifetimes below 100 ps.
A precision measurement of the ratio RK of the rates of kaon leptonic decays K±→e±ν and K±→μ±ν with the full data sample collected by the NA62 experiment at CERN in 2007–2008 is reported. The result, ...obtained by analysing ∼150000 reconstructed K±→e±ν candidates with 11% background contamination, is RK=(2.488±0.010)×10−5, in agreement with the Standard Model expectation.
The design of control systems and human–machine interfaces in the field of complex and safety-critical environments remains today an open issue, in spite of the high technological evolution of the ...last decades. The increasing use of automation has improved efficiency, safety and ease of operations but, at the same time, it has complicated operators’ situation awareness and has changed the nature of their possible errors. The research activity described in this paper is an attempt to develop a methodological framework to support designers of control systems and human–machine interfaces. In particular, it focuses on the need for a deeply recursive approach related to the implementation of the systemic and human aspects of the design process of a human–machine system, intended as a Joint Cognitive System. A validating case study has been performed, based on the full application of the framework on the control of the turbine/alternator system of a thermoelectric power plant in northern Italy.
Workshop summary: Kaons@CERN 2023 Anzivino, G.; Cuendis, Sergio Arguedas; Bernard, V. ...
The European physical journal. C, Particles and fields,
04/2024, Volume:
84, Issue:
4
Journal Article
Peer reviewed
Open access
Kaon physics is at a turning point – while the rare-kaon experiments NA62 and KOTO are in full swing, the end of their lifetime is approaching and the future experimental landscape needs to be ...defined. With HIKE, KOTO-II and LHCb-Phase-II on the table and under scrutiny, it is a very good moment in time to take stock and contemplate about the opportunities these experiments and theoretical developments provide for particle physics in the coming decade and beyond. This paper provides a compact summary of talks and discussions from the Kaons@CERN 2023 workshop, held in September 2023 at CERN.
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