SND@LHC is a compact and stand-alone experiment designed to perform measurements with neutrinos produced at the LHC in the pseudo-rapidity region of 7.2 < η < 8.4. The experiment is located 480 m downstream of the ATLAS interaction point, in the TI18 tunnel. The detector is composed of a hybrid system based on an 830 kg target made of tungsten plates, interleaved with emulsion and electronic trackers, also acting as an electromagnetic calorimeter, and followed by a hadronic calorimeter and a muon identification system. The detector is able to distinguish interactions of all three neutrino flavours, which allows probing the physics of heavy flavour production at the LHC in the very forward region. This region is of particular interest for future circular colliders and for very high energy astrophysical neutrino experiments. The detector is also able to search for the scattering of Feebly Interacting Particles. In its first phase, the detector is ready to operate throughout LHC Run 3 and collect a total of 250 fb^-1.

We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at $\sqrt{s}=13.6\mathrm{TeV}$ collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of $36.8{\mathrm{fb}}^{-1}$. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of $7.2<\eta <8.4$, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 ${\nu }_{\mu }$ interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed ${\nu }_{\mu }$ signal.

The Scattering and Neutrino Detector at the LHC (SND@LHC) started taking data at the beginning of Run 3 of the LHC. The experiment is designed to perform measurements with neutrinos produced in proton-proton collisions at the LHC in an energy range between 100 GeV and 1 TeV. It covers a previously unexplored pseudo-rapidity range of $$7.2<\eta <8.4$$7.2 < η < 8.4 . The detector is located 480 m downstream of the ATLAS interaction point in the TI18 tunnel. It comprises a veto system, a target consisting of tungsten plates interleaved with nuclear emulsion and scintillating fiber (SciFi) trackers, followed by a muon detector (UpStream, US and DownStream, DS). In this article we report the measurement of the muon flux in three subdetectors: the emulsion, the SciFi trackers and the DownStream Muon detector. The muon flux per integrated luminosity through an 18 $$\times $$× 18 cm $$^{2}$$2 area in the emulsion is: $$\begin{aligned} 1.5 \pm 0.1(\text {stat}) \times 10^4\,\text {fb/cm}^{2}. \end{aligned}$$1.5 ± 0.1 ( stat ) × 10 4 fb/cm 2 . The muon flux per integrated luminosity through a 31 $$\times $$× 31 cm $$^{2}$$2 area in the centre of the SciFi is: $$\begin{aligned} 2.06\pm 0.01(\text {stat})\pm 0.12(\text {sys}) \times 10^{4} \text {fb/cm}^{2} \end{aligned}$$2.06 ± 0.01 ( stat ) ± 0.12 ( sys ) × 10 4 fb/cm 2 The muon flux per integrated luminosity through a 52 $$\times $$× 52 cm $$^{2}$$2 area in the centre of the downstream muon system is: $$\begin{aligned} 2.35\pm 0.01(\text {stat})\pm 0.10(\text {sys}) \times 10^{4}\,\text {fb/cm}^{2} \end{aligned}$$2.35 ± 0.01 ( stat ) ± 0.10 ( sys ) × 10 4 fb/cm 2 The total relative uncertainty of the measurements by the electronic detectors is 6 $$\%$$% for the SciFi and 4 $$\%$$% for the DS measurement. The Monte Carlo simulation prediction of these fluxes is 20–25 $$\%$$% lower than the measured values.

(1) Background: COVID-19 is a novel cause of acute respiratory distress syndrome (ARDS). Indeed, with the increase of ARDS cases due to the COVID-19 pandemic, there has also been an increase in the incidence of cases with pneumothorax (PNX) and pneumomediastinum (PNM). However, the incidence and the predictors of PNX/PMN in these patients are currently unclear and even conflicting. (2) Methods: The present observational study analyzed the incidence of barotrauma (PNX/PNM) in COVID-19 patients with moderate–severe ARDS hospitalized in a year of the pandemic, also focusing on the three waves occurring during the year, and treated with positive-pressure ventilation (PPV). We collected demographic and clinical data. (3) Results: During this period, 40 patients developed PNX/PNM. The overall incidence of barotrauma in all COVID-19 patients hospitalized in a year was 1.6%, and in those with moderate–severe ARDS in PPV was 7.2% and 3.8 events per 1000 positive-pressure ventilator days. The incidence of barotrauma in moderate–severe ARDS COVID-19 patients during the three waves was 7.8%, 7.4%, and 8.7%, respectively. Treatment with noninvasive respiratory support alone was associated with an incidence of barotrauma of 9.1% and 2.6 events per 1000 noninvasive ventilator days, of which 95% were admitted to the ICU after the event, due to a worsening of respiratory parameters. The incidence of barotrauma of ICU COVID-19 patients in invasive ventilation over a year was 5.8% and 2.7 events per 1000 invasive ventilator days. There was no significant difference in demographics and clinical features between the barotrauma and non-barotrauma group. The mortality was higher in the barotrauma group (17 patients died, 47.2%) than in the non-barotrauma group (170 patients died, 37%), although this difference was not statistically significant (p = 0.429). (4) Conclusions: The incidence of PNX/PNM in moderate–severe ARDS COVID-19 patients did not differ significantly between the three waves over a year, and does not appear to be very different from that in ARDS patients in the pre-COVID era. The barotrauma does not appear to significantly increase mortality in COVID-19 patients with moderate–severe ARDS if protective ventilation strategies are applied. Attention should be paid to the risk of barotrauma in COVID-19 patients in noninvasive ventilation because the event increases the probability of admission to the intensive care unit (ICU) and intubation.

Background: The benefits and timing of percutaneous dilatational tracheostomy (PDT) in Intensive Care Unit (ICU) COVID-19 patients are still controversial. PDT is considered a high-risk procedure for the transmission of SARS-CoV-2 to healthcare workers (HCWs). The present study analyzed the optimal timing of PDT, the clinical outcomes of patients undergoing PDT, and the safety of HCWs performing PDT. Methods: Of the 133 COVID-19 patients who underwent PDT in our ICU from 1 April 2020 to 31 March 2021, 13 patients were excluded, and 120 patients were enrolled. A trained medical team was dedicated to the PDT procedure. Demographic, clinical history, and outcome data were collected. Patients who underwent PDT were stratified into two groups: an early group (PDT ≤ 12 days after orotracheal intubation (OTI) and a late group (>12 days after OTI). An HCW surveillance program was also performed. Results: The early group included 61 patients and the late group included 59 patients. The early group patients had a shorter ICU length of stay and fewer days of mechanical ventilation than the late group (p < 0.001). On day 7 after tracheostomy, early group patients required fewer intravenous anesthetic drugs and experienced an improvement of the ventilation parameters PaO₂/FiO₂ ratio, PEEP, and FiO₂ (p < 0.001). No difference in the case fatality ratio between the two groups was observed. No SARS-CoV-2 infections were reported in the HCWs performing the PDTs. Conclusions: PDT was safe and effective for COVID-19 patients since it improved respiratory support parameters, reduced ICU length of stay and duration of mechanical ventilation, and optimized the weaning process. The procedure was safe for all HCWs involved in the dedicated medical team. The development of standardized early PDT protocols should be implemented, and PDT could be considered a first-line approach in ICU COVID-19 patients requiring prolonged mechanical ventilation.

We report the observation of neutrino interactions without final state muons at the LHC, with a significance of 6.4 σ . A dataset of proton-proton collisions at s = 13.6 TeV collected by SND@LHC in 2022 and 2023 is used, corresponding to an integrated luminosity of 68.6 fb − 1 . Neutrino interactions without a reconstructed muon are selected, resulting in an event sample consisting mainly of neutral-current and electron neutrino charged-current interactions in the detector. After selection cuts, 9 neutrino interaction candidate events are observed with an estimated background of 0.32 events.