ATLAS Collaboration(Abat, E. et al), Bernabeu Verdu, J., Castillo Gimenez, V., Costa, M. J., Escobar, C., Ferrer, A., et al. (2011). A layer correlation technique for pion energy calibration at the 2004 ATLAS Combined Beam Test. J. Instrum., 6, P06001–35pp.
Abstract: A new method for calibrating the hadron response of a segmented calorimeter is developed and successfully applied to beam test data. It is based on a principal component analysis of energy deposits in the calorimeter layers, exploiting longitudinal shower development information to improve the measured energy resolution. Corrections for invisible hadronic energy and energy lost in dead material in front of and between the calorimeters of the ATLAS experiment were calculated with simulated Geant4 Monte Carlo events and used to reconstruct the energy of pions impinging on the calorimeters during the 2004 Barrel Combined Beam Test at the CERN H8 area. For pion beams with energies between 20 GeV and 180 GeV, the particle energy is reconstructed within 3% and the energy resolution is improved by between 11% and 25% compared to the resolution at the electromagnetic scale.
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ANTARES Collaboration(Aguilar, J. A. et al), Bigongiari, C., Emanuele, U., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., Mangano, S., et al. (2010). Measurement of the atmospheric muon flux with a 4 GeV threshold in the ANTARES neutrino telescope. Astropart Phys., 33(2), 86–90.
Abstract: A new method for the measurement of the muon flux in the deep-sea ANTARES neutrino telescope and its dependence on the depth is presented. The method is based oil the observation of coincidence signals in adjacent storeys of the detector. This yields an energy threshold of about 4 GeV. The main sources of optical background are the decay of K-40 and the bioluminescence in the sea water. The K-40 background is used to calibrate the efficiency of the photo-multiplier tubes.
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NEXT Collaboration(McDonald, A. D. et al), Alvarez, V., Benlloch-Rodriguez, J. M., Botas, A., Carcel, S., Carrion, J. V., et al. (2018). Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging. Phys. Rev. Lett., 120(13), 132504–6pp.
Abstract: A new method to tag the barium daughter in the double-beta decay of Xe-136 is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba++) resolution at a transparent scanning surface is demonstrated. A single-step photobleach confirms the single ion interpretation. Individual ions are localized with superresolution (similar to 2 nm), and detected with a statistical significance of 12.9 sigma over backgrounds. This lays the foundation for a new and potentially background-free neutrinoless double-beta decay technology, based on SMFI coupled to high pressure xenon gas time projection chambers.
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Yao, D. L., Fernandez-Soler, P., Guo, F. K., & Nieves, J. (2020). New parametrization of the form factors in (B)over-bar -> Dl(nu)over-bar(l) decays. Phys. Rev. D, 101(3), 034014–7pp.
Abstract: A new model-independent parametrization is proposed for the hadronic form factors in the semileptonic (B) over bar -> Dl (nu) over bar (l) decay. By a combined consideration of the recent experimental and lattice QCD data, we determine precisely the Cabibbo-Kobayashi-Maskawa matrix element vertical bar V-cb vertical bar = 41.01(75) x 10(-3) and the ratio R-D = BR((B) over bar -> D tau(nu) over bar (tau))/BR((B) over bar -> Dl (nu) over bar (l)) = 0.301(5). The coefficients in this parametrization, related to phase shifts by sumrulelike dispersion relations and hence called phase moments, encode important scattering information of the (B) over bar (D) over bar interactions which are poorly known so far. Thus, we give strong hints about the existence of at least one bound and one virtual (B) over bar (D) over bar S-wave 0(+) states, subject to uncertainties produced by potentially sizable inelastic effects. This formalism is also applicable for any other semileptonic processes induced by the weak b -> c transition.
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Kasieczka, G. et al, & Sanz, V. (2021). The LHC Olympics 2020: a community challenge for anomaly detection in high energy physics. Rep. Prog. Phys., 84(12), 124201–64pp.
Abstract: A new paradigm for data-driven, model-agnostic new physics searches at colliders is emerging, and aims to leverage recent breakthroughs in anomaly detection and machine learning. In order to develop and benchmark new anomaly detection methods within this framework, it is essential to have standard datasets. To this end, we have created the LHC Olympics 2020, a community challenge accompanied by a set of simulated collider events. Participants in these Olympics have developed their methods using an R&D dataset and then tested them on black boxes: datasets with an unknown anomaly (or not). Methods made use of modern machine learning tools and were based on unsupervised learning (autoencoders, generative adversarial networks, normalizing flows), weakly supervised learning, and semi-supervised learning. This paper will review the LHC Olympics 2020 challenge, including an overview of the competition, a description of methods deployed in the competition, lessons learned from the experience, and implications for data analyses with future datasets as well as future colliders.
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Estienne, M., Fallot, M., Algora, A., Briz-Monago, J., Bui, V. M., Cormon, S., et al. (2019). Updated Summation Model: An Improved Agreement with the Daya Bay Antineutrino Fluxes. Phys. Rev. Lett., 123(2), 022502–6pp.
Abstract: A new summation method model of the reactor antineutrino energy spectrum is presented. It is updated with the most recent evaluated decay databases and with our total absorption gamma-ray spectroscopy measurements performed during the last decade. For the first time, the spectral measurements from the Daya Bay experiment are compared with the antineutrino energy spectrum computed with the updated summation method without any renormalization. The results exhibit a better agreement than is obtained with the Huber-Mueller model in the 2-5 MeV range, the region that dominates the detected flux. A systematic trend is found in which the antineutrino flux computed with the summation model decreases with the inclusion of more pandemonium-free data. The calculated flux obtained now lies only 1.9% above that detected in the Daya Bay experiment, a value that may be reduced with forthcoming new pandemonium-free data, leaving less room for a reactor anomaly. Eventually, the new predictions of individual antineutrino spectra for the U-235, Pu-239, Pu-241, and U-238 are used to compute the dependence of the reactor antineutrino spectral shape on the fission fractions.
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Yokoyama, R., Singh, M., Grzywacz, R., Keeler, A., King, T. T., Agramunt, J., et al. (2019). Segmented YSO scintillation detectors as a new beta-implant detection tool for decay spectroscopy in fragmentation facilities. Nucl. Instrum. Methods Phys. Res. A, 937, 93–97.
Abstract: A newly developed segmented YSO scintillator detector was implemented for the first time at the RI-beam Factory at RIKEN Nishina Center as an implantation-decay counter. The results from the experiment demonstrate that the detector is a viable alternative to conventional silicon-strip detectors with its good timing resolution and high detection efficiency for beta particles. A Position-Sensitive Photo-Multiplier Tube (PSPMT) is coupled with a 48 x 48 segmented YSO crystal. To demonstrate its capabilities, a known short-lived isomer in Ni-76 and the beta decay of Co-74 were measured by implanting those ions into the YSO detector. The half-lives and gamma-rays observed in this work are consistent with the known values. The beta-ray detection efficiency is more than 80 % for the decay of Co-74.
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Bernabeu, J., & Navarro-Salas, J. (2019). A Non-Local Action for Electrodynamics: Duality Symmetry and the Aharonov-Bohm Effect, Revisited. Symmetry-Basel, 11(10), 1191–13pp.
Abstract: A non-local action functional for electrodynamics depending on the electric and magnetic fields, instead of potentials, has been proposed in the literature. In this work we elaborate and improve this proposal. We also use this formalism to confront the electric-magnetic duality symmetry of the electromagnetic field and the Aharonov-Bohm effect, two subtle aspects of electrodynamics that we examine in a novel way. We show how the former can be derived from the simple harmonic oscillator character of vacuum electrodynamics, while also demonstrating how the magnetic version of the latter naturally arises in an explicitly non-local manner.
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Woolley, B., Burt, G., Dexter, A. C., Peacock, R., Millar, W. L., Catalan Lasheras, N., et al. (2020). High-gradient behavior of a dipole-mode rf structure. Phys. Rev. Accel. Beams, 23(12), 122002–11pp.
Abstract: A normal-conducting, X-band traveling wave structure operating in the dipole mode has been systematically high-gradient tested to gain insight into the maximum possible gradients in these types of structure. Measured structure conditioning, breakdown behavior, and achieved surface fields are reported as well as a postmortem analysis of the breakdown position and a scanning electron microscope analysis of the high-field surfaces. The results of these measurements are then compared to high-gradient results from monopole-mode cavities. Scaled to a breakdown rate of 10(-6), the cavities were found to operate at a peak electric field of 154 MV/m and a peak modified Poynting vector S-c of 5.48 MW/mm(2). The study provides important input for the further development of dipole-mode cavities for use in the Compact Linear Collider as a crab cavity and dipole-mode cavities for use in x-ray free-electron lasers as well as for studies of the fundamental processes in vacuum arcs. Of particular relevance are the unique field patterns in dipole cavities compared to monopole cavities, where the electric and magnetic fields peak in orthogonal planes, which allow the separation of the role of electric and magnetic fields in breakdown via postmortem damage observation. The azimuthal variation of breakdown crater density is measured and is fitted to sinusoidal functions. The best fit is a power law fit of exponent 6. This is significant, as it shows how breakdown probability varies over a surface area with a varying electric field after conditioning to a given peak field.
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ANTARES Collaboration(Albert, A. et al), Barrios-Marti, J., Coleiro, A., Hernandez-Rey, J. J., Illuminati, G., Lotze, M., et al. (2017). An algorithm for the reconstruction of high-energy neutrino-induced particle showers and its application to the ANTARES neutrino telescope. Eur. Phys. J. C, 77(6), 419–11pp.
Abstract: A novel algorithm to reconstruct neutrino-induced particle showers within the ANTARES neutrino telescope is presented. The method achieves a median angular resolution of 6. for shower energies below 100TeV. Applying this algorithm to 6 years of data taken with theANTARES detector, 8 events with reconstructed shower energies above 10TeV are observed. This is consistent with the expectation of about 5 events from atmospheric backgrounds, but also compatible with diffuse astrophysical flux measurements by the IceCube collaboration, from which 2-4 additional events are expected. A 90% C.L. upper limit on the diffuse astrophysical neutrino flux with a value per neutrino flavour of E-2.Phi(90%) = 4.9 . 10(-8) GeV.cm(-2).s(-1).sr(-1) is set, applicable to the energy range from 23TeV to 7.8PeV, assuming an unbroken E-2 spectrum and neutrino flavour equipartition at Earth.
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