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"Patrizii, L."
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Search for magnetic monopoles produced via the Schwinger mechanism
Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism
1
. By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles, if they exist
2
. Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model
3
–
7
but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size
8
,
9
and strong coupling to photons
2
,
10
. Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb–Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe
11
. It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 × 10
9
, of Pb–Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.
At the Large Hadron Collider, the MoEDAL experiment shows no evidence for magnetic monopoles generated via the Schwinger mechanism at integer Dirac charges below 3, and suggests a lower mass limit of 75 GeV/
c
2
.
Journal Article
Design and performance of the ENUBET monitored neutrino beam
The ENUBET project is aimed at designing and experimentally demonstrating the concept of monitored neutrino beams. These novel beams are enhanced by an instrumented decay tunnel, whose detectors reconstruct large-angle charged leptons produced in the tunnel and give a direct estimate of the neutrino flux at the source. These facilities are thus the ideal tool for high-precision neutrino cross-section measurements at the GeV scale because they offer superior control of beam systematics with respect to existing facilities. In this paper, we present the first end-to-end design of a monitored neutrino beam capable of monitoring lepton production at the single particle level. This goal is achieved by a new focusing system without magnetic horns, a 20 m normal-conducting transfer line for charge and momentum selection, and a 40 m tunnel instrumented with cost-effective particle detectors. Employing such a design, we show that percent precision in cross-section measurements can be achieved at the CERN SPS complex with existing neutrino detectors.
Journal Article
Coded masks for imaging of neutrino events
The capture of scintillation light emitted by liquid Argon and Xenon under molecular excitations by charged particles is still a challenging task. Here we present a first attempt to design a device able to have a sufficiently high photon detection efficiency, in order to reconstruct the path of ionizing particles. The study is based on the use of masks to encode the light signal combined with single-photon detectors, showing the capability to detect tracks over focal distances of about tens of centimeters. From numerical simulations it emerges that it is possible to successfully decode and recognize signals, even of rather complex topology, with a relatively limited number of acquisition channels. Thus, the main aim is to elucidate a proof of principle of a technology developed in very different contexts, but which has potential applications in liquid argon detectors that require a fast reading. The findings support us to think that such innovative technique could be very fruitful in a new generation of detectors devoted to neutrino physics.
Journal Article
The Euclid Near Infrared Spectro-Photometer (NISP) instrument and science
Euclid is an ESA mission designed to understand why the expansion of the Universe is accelerating and what is the nature of the dark energy responsible for this acceleration. By measuring two cosmological probes simultaneously, the Weak Gravitational Lensing and the Galaxy Clustering (BAO and Redshift-Space distorsions), Euclid will constrain dark energy, general relativity, dark matter and the initial conditions of the Universe with unprecedented accuracy. Euclid will be equipped with a 1.2 m diameter SiC mirror telescope feeding 2 instruments: the visible imager and the Near-Infrared Spectro-Photometer. Here the Euclid's observation probes and main aims are recalled, and the NISP instrument and expected performances are presented.
Journal Article
Magnetic monopole search at high altitude with the SLIM experiment
The SLIM experiment was a large array of nuclear track detectors located at the Chacaltaya high altitude Laboratory (5230 m a.s.l.). The detector was in particular sensitive to intermediate mass magnetic monopoles, with masses 10
5
GeV
Journal Article
The HEPD apparatus for the CSES mission
The High-Energy Particle Detector (HEPD) is one of the payloads of the CSES space mission. The HEPD is built by the Italian Limadou collaboration and has different goals. It will study the temporal stability of the inner Van Allen radiation belts, the precipitation of trapped particles in the atmosphere and the low energy component of the cosmic rays (5-100 MeV for electrons and 15 - 300 MeV for protons). It has been tested at the Beam Test Facility of the INFN National Laboratory of Frascati, for electrons, and at the Proton Cyclotron of Trento, for protons. Here is presented a study of the performance of the apparatus to separate electrons and protons and identify nuclei up to iron.
Journal Article
Results of the search for strange quark matter and Q-balls with the SLIM experiment
The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive to nuclearites and Q-balls which could be present in the cosmic radiation as possible Dark Matter components. It was sensitive also to strangelets, i.e. small lumps of Strange Quark Matter predicted at such altitudes by various phenomenological models. The analysis of 427 m
2
of Nuclear Track Detectors exposed for 4.22 years showed no candidate event. New upper limits on the flux of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null result also restricts models for strangelets propagation through the Earth atmosphere.
Journal Article
Cp violation and mass hierarchy at medium baselines in the large θ.sub.13 era
The large value of [θ.sub.13] recently measured by rector and accelerator experiments opens unprecedented opportunities for precision oscillation physics. In this paper, we reconsider the physics reach of medium baseline superbeams. For [θ.sub.13] [equivalent] 9° we show that facilities at medium baselines-- i.e. L [equivalent] O (1000 km)--remain optimal for the study of CP violation in the leptonic sector, although their ultimate precision strongly depends on experimental systematics. This is demonstrated in particular for facilities of practical interest in Europe: a CERN to Gran Sasso and CERN to Phyasalmi [v.sub.μ] beam based on the present SPS and on new high power 50 GeV proton driver. Due to the large value of [θ.sub.13], spectral information can be employed at medium baselines to resolve the sign ambiguity and determine the neutrino mass hierarchy. However, longer baselines, where matter effects dominate the [v.sub.μ] → [v.sub.e] transition, can achieve much stronger sensitivity to sign(Δ[m.sup.2]) even at moderate exposures.
Journal Article
Shashlik calorimeters for the ENUBET tagged neutrino beam
Shashlik calorimeters equipped with a compact readout based on Silicon PhotoMultipliers can be longitudinally segmented by directly coupling the WLS fibers with the photosensors thus embedding the readout in the bulk of the calorimeter. Results on energy resolution and particle identification for such calorimeters are presented. The SiPMs for the readout have also been characterized after being exposed to neutron fluences up to 2×1011 n/cm2 (1 MeV eq.). Alternative options for the active material were also investigated; we studied in particular polysiloxane as a substitute for plastic scintillator.
Journal Article
Neutrino Oscillations in the Atmospheric Parameter Region : From the Early Experiments to the Present
The aim of this paper is to provide a historical perspective on the main experimental steps which led to the current picture of neutrino oscillations in the “atmospheric parameter region.” In the 1980s a deficit of atmospheric muon neutrinos was observed with the first generation of underground experiments. In the following decade new experiments provided fundamental results which led to the discovery claims in 1998. At the beginning of the new century neutrino beams of medium and high energy became available and several long baseline experiments were performed and added new information to the atmospheric neutrino puzzle. The interpretation of the results of atmospheric and long baseline neutrino experiments was in terms of dominant νμ→ντ oscillations. Short recollections are made of the SNO solar neutrino measurements, of the results with neutrino telescopes, and of reactor neutrinos to measure sin2θ13. Over the years the phenomenological picture improved in completeness and increased in complexity. A short perspective concludes the paper.
Journal Article