We present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e+e−→γa, a→γγ in the ...mass range 0.2<ma<9.7 GeV/c2 using data corresponding to an integrated luminosity of (445±3) pb−1. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength gaγγ of ALPs to photons at the level of 10−3 GeV−1. The limits are the most restrictive to date for 0.2<ma<1 GeV/c2.
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Innovative applications in light signal sensing require flexibility, lightweight, low-cost and low temperature processability, as well as high sensitivity and quantitative photoresponse. We report on ...flexible organic phototransistors (OPTs) with excellent reproducibility in the detection of outstandingly low light intensities of few nW cm−2. The optical response of the phototransistor was thoroughly characterized as a function of the wavelength, the incident optical intensity and the electrical polarizations. The photodetectors work reliably under bending and pulse cycling in different environmental conditions, at low polarizations down to the range 0.1–5 V. Based on these outcomes, arrays for broadband or multiple wavelength detection were implemented and successfully tested. The proposed device structure, derived from a layered p-p heterojunction, was developed to be easily implementable in each wavelength of interest. These results show a prospect of highly sensitive flexible OPT arrays for both experimental research and innovative optoelectronic systems.
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•Organic phototransistor for detection of weak light intensities of few nW/cm2•Full characterization and analysis of the optical response of the developed OPTs•Photodetector with high electrical stability and excellent reliability•OPTs with layered p-p heterojunction for broad/multiple wavelength detection arrays•Highly sensitive bendable photodetector array for innovative optoelectronics
Theories beyond the standard model often predict the existence of an additional neutral boson, the Z^{'}. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we ...perform the first searches for the invisible decay of a Z^{'} in the process e^{+}e^{-}→μ^{+}μ^{-}Z^{'} and of a lepton-flavor-violating Z^{'} in e^{+}e^{-}→e^{±}μ^{∓}Z^{'}. We do not find any excess of events and set 90% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an L_{μ}-L_{τ} theory, into upper limits on the Z^{'} coupling constant at the level of 5×10^{-2}-1 for M_{Z^{'}}≤6 GeV/c^{2}.
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A general purpose FPGA based DAQ module has been developed based on a Virtex-4 FPGA. It is able to acquire up to 1024 different channels distributed over 10 slave cards. The module has an optical ...interface a RS-232 a USB and a Gigabit Interface. The KLOE-2 experiment is going to use it to collect data from the Inner tracker and the QCALT. An embedded processor (power pc 604) is present on the FPGA and a telnet server has been developed and installed. A new general purpose data taking system has been based on this module to acquire the Inner Tracker. The system is at the moment working at LNF (Laboratori Nazionali di Frascati).
We present a global time fit to determine the reference time event-by-event in an array of drift cells. The method is applied to the monitored drift tube tracking chambers (MDT) of the muon ...spectrometer of the ATLAS experiment at the large hadron collider (LHC). During operation with proton-proton collisions, the muon trigger is based on dedicated fast detectors and the readout is clocked at the beam crossing frequency of 40 MHz. A method has been developed for tracking particles through the MDT chambers which works without a precisely timed external trigger. This study was conceived to exploit the MDT tracking capabilities in non standard operation of the ATLAS detector, e.g., during commissioning with cosmic rays when there is no time correlation with the LHC clock frequency. Results obtained using an asynchronous trigger, with a high energy muon beam from the CERN SPS, and with cosmic rays are reported.
Detectors for absolute luminosity measurement at DAFNE Valente, P.; Boscolo, M.; Bossi, F. ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
05/2010, Volume:
617, Issue:
1
Journal Article, Conference Proceeding
Peer reviewed
Open access
Since the second half of year 2007, the Frascati
Φ
- factory DAFNE has been running with an upgraded interaction region in order to test the crabbed waist collision scheme. The aim is to reach a ...large improvement of the specific luminosity of the accelerator. We describe the various detectors realized to have a reliable and fast absolute luminosity measurement, the on-line analysis in order to get rid of the machine background contribution, and the performances of the system.
We present a new limit on the production of a light dark-force mediator with the KLOE detector at DAΦNE. This boson, called U, has been searched for in the decay ϕ→ηU, U→e+e−, analyzing the decay ...η→π0π0π0 in a data sample of 1.7 fb−1. No structures are observed in the e+e− invariant mass distribution over the background. This search is combined with a previous result obtained from the decay η→π+π−π0, increasing the sensitivity. We set an upper limit at 90% C.L. on the ratio between the U boson coupling constant and the fine structure constant of α′/α<1.7×10−5 for 30<MU<400 MeV and α′/α⩽8×10−6 for the sub-region 50<MU<210 MeV. This result assumes the Vector Meson Dominance expectations for the ϕηγ⁎ transition form factor. The dependence of this limit on the transition form factor has also been studied.
We describe the realization and performance of a prototype high granularity calorimeter built with lead and scintillating fibers. We describe the calorimeter construction and show cosmic ray and ...electron test beam results obtained with a custom-designed trigger.
The trigger system of the ARGO-YBJ experiment Aloisio, A.; Branchini, P.; Catalanotti, S. ...
IEEE transactions on nuclear science,
2004-Aug., 2004-08-00, 20040801, Volume:
51, Issue:
4
Journal Article
Peer reviewed
Astrophysical radiation with ground-based observatory at YangBaJing (ARGO-YBJ) is a ground-based cosmic ray detector presently under construction at the Yangbajing High Altitude Cosmic Ray Laboratory ...(4300 m a.s.l.), Lhasa, Tibet. The apparatus has been designed to detect air showers with an energy threshold of a few hundred GeV and it has a total active area of 6400 m/sup 2/. The full-coverage central carpet of 5772 m/sup 2/ is equipped with an array of resistive plate counters. This array is surrounded by a partially instrumented guard ring to improve the reconstruction of showers with the core falling outside the carpet. The ARGO trigger logic implements simple yet robust algorithms, based on the timing distribution of the hits and their multiplicity on the central carpet. In this paper, we describe the hardware architecture and the main features of the trigger system.
The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured below the so-called ＂knee＂ by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive ...Plate Chamber （RPC） array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range （100-700 TeV）. The observed energy spectrum is compatible with a single power law with index γ=-2.63±0.06.
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