We have designed and tested an automated simple setup for measuring the profile and spot size of a Gaussian laser beam, which exhibits a similar performance to ready-made optical devices, using three ...light sensors. We use a light dependent resistor as a novel instrument in this approach with good accuracy. We provide the setup in detail in order to be reproduced with the current technology at a standard laboratory. Two profiling techniques were implemented: the imaging technique for the CMOS 2D array (webcam) and scanning knife-edge-like technique using a single photodiode and a light dependent resistor. We apply up-to-date devices, such as a Raspberry Pi, for automation. The methods and sensors were compared to determine their accuracy using lasers of two different wavelengths and technologies. We verify that it is possible to use a webcam to determine the profile of a laser with 1% uncertainty on the beam waist, 1.5% error on the waistline position, and less than 3% error in determining the minimum spot radius. We show that it is possible to use a light dependent resistor to estimate the laser spot size with an 11% error. The photodiode measurement is the most stable since it is not affected by the change in laser intensity.
The silicon microstrip Tracker is a key subdetector of the AMS-02 instrument, designed to measure the momentum and charge of cosmic rays. The subdetector is composed of 9 layers of silicons sensors ...inside a permanent 0.15 T magnetic field. The detector has been installed on board of the International Space Station, at an altitude of 400 km, and is taking data since May 19th 2011. AMS-02 aims to provide a precise measurement of the cosmic-ray spectrum and perform antimatter searches in the GeV-TeV energy range. This review presents the Tracker performances during the first year of operation in space, covering all the most relevant aspects of detector stability, efficiency and capabilities in charge and track reconstruction.
Neutrino charged-current quasielastic-like scattering, a reaction category extensively used in neutrino oscillation measurements, probes nuclear effects that govern neutrino-nucleus interactions. ...This Letter reports the first measurement of the triple-differential cross section for νμ quasielastic-like reactions using the hydrocarbon medium of the MINERvA detector exposed to a wide-band beam spanning 2 ≤ Eν≤ 20 GeV. The measurement maps the correlations among transverse and longitudinal muon momenta and summed proton kinetic energies, and compares them to predictions from a state-of-art simulation. Discrepancies are observed that likely reflect shortfalls with modeling of pion and nucleon intranuclear scattering and/or spectator nucleon ejection from struck nuclei. The separate determination of leptonic and hadronic variables can inform experimental approaches to neutrino-energy estimation.
DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6
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liquid argon ...time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019–2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties.
The ALICE Collaboration reports three measurements in ultraperipheral proton-lead collisions at forward rapidity. The exclusive two-photon process γγ → μ+μ- and the exclusive photoproduction of J/ψ ...are studied. J/ψ photoproduction with proton dissociation is measured for the first time at a hadron collider. The cross section for the two-photon process of dimuons in the invariant mass range from 1 to 2.5 GeV/c2 agrees with leading-order quantum electrodynamics calculations. The exclusive and dissociative cross sections for J/ψ photoproductions are measured for photon-proton center-of-mass energies from 27 to 57 GeV. They are in good agreement with HERA results.
Between 2009 May and 2010 May, the IceCube neutrino detector at the South Pole recorded 32 billion muons generated in air showers produced by cosmic rays with a median energy of 20 TeV. With a data ...set of this size, it is possible to probe the southern sky for per-mil anisotropy on all angular scales in the arrival direction distribution of cosmic rays. Applying a power spectrum analysis to the relative intensity map of the cosmic ray flux in the southern hemisphere, we show that the arrival direction distribution is not isotropic, but shows significant structure on several angular scales. In addition to previously reported large-scale structure in the form of a strong dipole and quadrupole, the data show small-scale structure on scales between 15{sup 0} and 30{sup 0}. The skymap exhibits several localized regions of significant excess and deficit in cosmic ray intensity. The relative intensity of the smaller-scale structures is about a factor of five weaker than that of the dipole and quadrupole structure. The most significant structure, an excess localized at (right ascension {alpha} = 122.{sup 0}4 and declination {delta} = -47.{sup 0}4), extends over at least 20{sup 0} in right ascension and has a post-trials significance of 5.3{sigma}. The origin of this anisotropy is still unknown.
DUNE is a dual-site experiment for long-baseline neutrino oscillation studies, neutrino astrophysics and nucleon decay searches. ProtoDUNE Dual Phase (DP) is a 6x6x6m3 liquid argon ...time-projection-chamber (LArTPC) that recorded cosmic-muon data at the CERN Neutrino Platform in 2019-2020 as a prototype of the DUNE Far Detector. Charged particles propagating through the LArTPC produce ionization and scintillation light. The scintillation light signal in these detectors can provide the trigger for non-beam events. In addition, it adds precise timing capabilities and improves the calorimetry measurements. In ProtoDUNE-DP, scintillation and electroluminescence light produced by cosmic muons in the LArTPC is collected by photomultiplier tubes placed up to 7 m away from the ionizing track. In this paper, the ProtoDUNE-DP photon detection system performance is evaluated with a particular focus on the different wavelength shifters, such as PEN and TPB, and the use of Xe-doped LAr, considering its future use in giant LArTPCs. The scintillation light production and propagation processes are analyzed and a comparison of simulation to data is performed, improving understanding of the liquid argon properties
We report on a search with the IceCube detector for high-energy muon neutrinos from GRB 080319B, one of the brightest gamma-ray bursts (GRBs) ever observed. The fireball model predicts that a mean of ...0.1 events should be detected by IceCube for a bulk Lorentz boost of the jet of 300. In both the direct on-time window of 66 s and an extended window of about 300 s around the GRB, no excess was found above background. The 90% CL upper limit on the number of track-like events from the GRB is 2.7, corresponding to a muon neutrino fluence limit of 9.5 x 10{sup -3} erg cm{sup -2} in the energy range between 120 TeV and 2.2 PeV, which contains 90% of the expected events.
The IceCube detector took data in its 22-string configuration in 2007–2008. This data has been analyzed to search for extraterrestrial point sources of neutrinos using several methods. Two main ...methods are discussed and compared here: the binned and the unbinned maximum likelihood method. The best sky-averaged sensitivity (90% C.L.) is
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over the energy range from 3 TeV to 3 PeV. No neutrino point sources are found from the individual directions of a pre-selected catalogue nor in a search extended to the northern sky. Limits are improved by a factor of two compared to the total statistics collected with the AMANDA-II detector and represent the best results to date.
A time-dependent search for neutrino flares from pre-defined directions in the whole sky is presented. The analysis uses a time clustering algorithm combined with an unbinned likelihood method. This ...algorithm provides a search for significant neutrino flares over time-scales that are not fixed a-priori and that are not triggered by multiwavelength observations. The event selection is optimized to maximize the discovery potential, taking into account different time-scales of source activity and background rates. The method is applied to a pre-defined list of bright and variable astrophysical sources using 22-string IceCube data. No significant excess is found.
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