We report the first direct observation of neutrino interactions at a particle collider experiment. Neutrino candidate events are identified in a 13.6 TeV center-of-mass energy $pp$ collision dataset of $35.4{\mathrm{fb}}^{-1}$ using the active electronic components of the FASER detector at the Large Hadron Collider. The candidates are required to have a track propagating through the entire length of the FASER detector and be consistent with a muon neutrino charged-current interaction. We infer ${153}_{-13}^{+12}$ neutrino interactions with a significance of 16 standard deviations above the background-only hypothesis. These events are consistent with the characteristics expected from neutrino interactions in terms of secondary particle production and spatial distribution, and they imply the observation of both neutrinos and anti-neutrinos with an incident neutrino energy of significantly above 200 GeV.

The first results of the study of high-energy electron neutrino (${\nu }_e$) and muon neutrino (${\nu }_{\mu }$) charged-current interactions in the $\mathrm{FASER}\nu$ emulsion-tungsten detector of the FASER experiment at the LHC are presented. A 128.8 kg subset of the $\mathrm{FASER}\nu$ volume was analyzed after exposure to $9.5{\mathrm{fb}}^{-1}$ of $\sqrt{s}=13.6\mathrm{TeV}$ $pp$ data. Four (eight) ${\nu }_e$ (${\nu }_{\mu }$) interaction candidate events are observed with a statistical significance of $5.2\sigma$ ($5.7\sigma$). This is the first direct observation of ${\nu }_e$ interactions at a particle collider and includes the highest-energy ${\nu }_e$ and ${\nu }_{\mu }$ ever detected from an artificial source. The interaction cross section per nucleon $\sigma /E_{\nu }$ is measured over an energy range of 560–1740 GeV (520–1760 GeV) for ${\nu }_e$ (${\nu }_{\mu }$) to be $({1.2}_{-0.7}^{+0.8})\times {10}^{-38}{\mathrm{cm}}^2{\mathrm{GeV}}^{-1}$ [$(0.5\pm 0.2)\times {10}^{-38}{\mathrm{cm}}^2{\mathrm{GeV}}^{-1}$], consistent with standard model predictions. These are the first measurements of neutrino interaction cross sections in those energy ranges.

We have demonstrated wave-particle duality of single positrons in a double-slit-like experiment.

The shape of the bedrock underneath alpine glaciers bears vital information on the erosional mechanism related to the flow of ice. So far, several geophysical exploration methods have been proposed to map the bedrock topography though with limited accuracy. Here we illustrate the first results from a technology, called cosmic ray muon radiography, newly applied in glacial geology to investigate the bedrock geometry beneath the Aletsch Glacier situated in the Central Swiss Alps. For this purpose we installed new cosmic muon detectors made of emulsion films at three sites along the Jungfrau railway tunnel and measured the shape of the bedrock under the uppermost part of Aletsch Glacier (Jungfraufirn). Our results constrain the continuation of the bedrock‐ice interface up to a depth of 50 m below the surface, where the bedrock underneath the glacier strikes NE‐SW and dips at 45° ± 5°. This documents the first successful application of this technology to a glaciated environment.

¹⁵⁵Tb [t_1/2 = 5.32 d, E_γ = 87 keV (32%); 105 keV (25%) (IAEA, 2021)] is a novel promising radionuclide for theranostic applications in nuclear medicine. Its physical properties make it suitable for single photon emission computed tomography (SPECT) imaging, while its chemistry allows it to be used as a diagnostic partner for therapeutic radiolanthanides or pseudo-radiolanthanides, such as ¹⁷⁷Lu and ⁹⁰Y. Moreover, ¹⁵⁵Tb could be used as a precise diagnostic match for the β^--emitter ¹⁶¹Tb, opening doors for the true theranostics concept. The availability of ¹⁵⁵Tb in quantity and quality suitable for medical applications is an open issue and its production with medical cyclotrons via the ¹⁵⁵Gd(p,n)¹⁵⁵Tb and ¹⁵⁶Gd(p,2n)¹⁵⁵Tb nuclear reactions represents a possible but challenging solution. For this purpose, an accurate knowledge of the production cross sections is mandatory. In this paper, we report on the measurement of the production cross sections of ¹⁵⁵Tb and other terbium radionuclides formed by proton irradiation of ^natGd₂O₃, ¹⁵⁵Gd₂O₃ and ¹⁵⁶Gd₂O₃ enriched targets, performed at the Bern University Hospital cyclotron laboratory. On the basis of the obtained results, the production yield and purity were calculated to assess the optimal irradiation conditions. The results of several production tests are also presented.