Search

Abstract The search for neutrino events in correlation with gravitational wave (GW) events for three observing runs (O1, O2 and O3) from 09/2015 to 03/2020 has been performed using the Borexino data-set of the same period. We have searched for signals of neutrino-electron scattering and inverse beta-decay (IBD) within a time window of $$\pm \, 1000$$ ± 1000 s centered at the detection moment of a particular GW event. The search was done with three visible energy thresholds of 0.25, 0.8 and 3.0 MeV. Two types of incoming neutrino spectra were considered: the mono-energetic line and the supernova-like spectrum. GW candidates originated by merging binaries of black holes (BHBH), neutron stars (NSNS) and neutron star and black hole (NSBH) were analyzed separately. Additionally, the subset of most intensive BHBH mergers at closer distances and with larger radiative mass than the rest was considered. In total, follow-ups of 74 out of 93 gravitational waves reported in the GWTC-3 catalog were analyzed and no statistically significant excess over the background was observed. As a result, the strongest upper limits on GW-associated neutrino and antineutrino fluences for all flavors ( $$\nu _e, \nu _\mu , \nu _\tau $$ ν e , ν μ , ν τ ) at the level $$10^9{-}10^{15}~\textrm{cm}^{-2}\,\textrm{GW}^{-1}$$ 10 9 - 10 15 cm - 2 GW - 1 have been obtained in the 0.5–5 MeV neutrino energy range.

Abstract We present a novel approach for the search of dark matter in the DarkSide-50 experiment, relying on Bayesian Networks. This method incorporates the detector response model into the likelihood function, explicitly maintaining the connection with the quantity of interest. No assumptions about the linearity of the problem or the shape of the probability distribution functions are required, and there is no need to morph signal and background spectra as a function of nuisance parameters. By expressing the problem in terms of Bayesian Networks, we have developed an inference algorithm based on a Markov Chain Monte Carlo to calculate the posterior probability. A clever description of the detector response model in terms of parametric matrices allows us to study the impact of systematic variations of any parameter on the final results. Our approach not only provides the desired information on the parameter of interest, but also potential constraints on the response model. Our results are consistent with recent published analyses and further refine the parameters of the detector response model.

Abstract We present here a characterization of the low background NaI(Tl) crystal NaI-33 based on a period of almost one year of data taking (891 kg $$\times $$ × days exposure) in a detector configuration with no use of organic scintillator veto. This remarkably radio-pure crystal already showed a low background in the SABRE Proof-of-Principle (PoP) detector, in the low energy region of interest (1–6 keV) for the search of dark matter interaction via the annual modulation signature. As the vetoable background components, such as $$^{40}$$ 40 K, are here sub-dominant, we reassembled the PoP setup with a fully passive shielding. We upgraded the selection of events based on a Boosted Decision Tree algorithm that rejects most of the PMT-induced noise while retaining scintillation signals with > 90% efficiency in 1–6 keV. We find an average background of 1.39 ± 0.02 counts/day/kg/keV in the region of interest and a spectrum consistent with data previously acquired in the PoP setup, where the external veto background suppression was in place. Our background model indicates that the dominant background component is due to decays of $$^{210}$$ 210 Pb, only partly residing in the crystal itself. The other location of $$^{210}$$ 210 Pb is the reflector foil that wraps the crystal. We now proceed to design the experimental setup for the physics phase of the SABRE North detector, based on an array of similar crystals, using a low radioactivity PTFE reflector and further improving the passive shielding strategy, in compliance with the new safety and environmental requirements of Laboratori Nazionali del Gran Sasso.

Abstract The search for neutrino events in correlation with 42 most intense fast radio bursts (FRBs) has been performed using the Borexino dataset from 05/2007 to 06/2021. We have searched for signals with visible energies above 250 keV within a time window of $$\pm \, 1000$$ ± 1000 s corresponding to detection time of a particular FRB. We also applied an alternative approach based on searching for specific shapes of neutrino-electron scattering spectra in the full exposure data of the Borexino detector. In particular, two incoming neutrino spectra were considered: the monoenergetic line and the spectrum expected from supernovae. The same spectra were considered for electron antineutrinos detected through inverse beta-decay reaction. No statistically significant excess over the background was observed. As a result, the strongest upper limits on FRB-associated neutrino fluences of all flavors have been obtained in the 0.5–50 MeV neutrino energy range.

Abstract Cosmogenic radio-nuclei are an important source of background for low-energy neutrino experiments. In Borexino, cosmogenic $$^{11}$$ 11 C decays outnumber solar pep and CNO neutrino events by about ten to one. In order to extract the flux of these two neutrino species, a highly efficient identification of this background is mandatory. We present here the details of the most consolidated strategy, used throughout Borexino solar neutrino measurements. It hinges upon finding the space-time correlations between $$^{11}$$ 11 C decays, the preceding parent muons and the accompanying neutrons. This article describes the working principles and evaluates the performance of this Three-Fold Coincidence (TFC) technique in its two current implementations: a hard-cut and a likelihood-based approach. Both show stable performances throughout Borexino Phases II (2012–2016) and III (2016–2020) data sets, with a $$^{11}$$ 11 C tagging efficiency of $$\sim 90$$ ∼ 90 % and $$\sim $$ ∼ 63–66 % of the exposure surviving the tagging. We present also a novel technique that targets specifically $$^{11}$$ 11 C produced in high-multiplicity during major spallation events. Such $$^{11}$$ 11 C appear as a burst of events, whose space-time correlation can be exploited. Burst identification can be combined with the TFC to obtain about the same tagging efficiency of $$\sim 90\%$$ ∼ 90 % but with a higher fraction of the exposure surviving, in the range of $$\sim $$ ∼ 66–68 %.

Abstract Ultra-pure NaI(Tl) crystals are the key element for a model-independent verification of the long standing DAMA result and a powerful means to search for the annual modulation signature of dark matter interactions. The SABRE collaboration has been developing cutting-edge techniques for the reduction of intrinsic backgrounds over several years. In this paper we report the first characterization of a 3.4 kg crystal, named NaI-33, performed in an underground passive shielding setup at LNGS. NaI-33 has a record low $$^{39}$$ 39 K contamination of 4.3 ± 0.2 ppb as determined by mass spectrometry. We measured a light yield of 11.1 ± 0.2 photoelectrons/keV and an energy resolution of 13.2% (FWHM/E) at 59.5 keV. We evaluated the activities of $$^{226}$$ 226 Ra and $$^{228}$$ 228 Th inside the crystal to be $$5.9\pm 0.6~\upmu $$ 5.9 ± 0.6 μ Bq/kg and $$1.6\pm 0.3~\upmu $$ 1.6 ± 0.3 μ Bq/kg, respectively, which would indicate a contamination from $$^{238}$$ 238 U and $$^{232}$$ 232 Th at part-per-trillion level. We measured an activity of 0.51 ± 0.02 mBq/kg due to $$^{210}$$ 210 Pb out of equilibrium and a $$\alpha $$ α quenching factor of 0.63 ± 0.01 at 5304 keV. We illustrate the analyses techniques developed to reject electronic noise in the lower part of the energy spectrum. A cut-based strategy and a multivariate approach indicated a rate, attributed to the intrinsic radioactivity of the crystal, of $$\sim $$ ∼ 1 count/day/kg/keV in the [5–20] keV region.

Abstract The Borexino detector measures solar neutrino fluxes via neutrino-electron elastic scattering. Observed spectra are determined by the solar-ν e survival probability P ee (E), and the chiral couplings of the neutrino and electron. Some theories of physics beyond the Standard Model postulate the existence of Non-Standard Interactions (NSI’s) which modify the chiral couplings and P ee (E). In this paper, we search for such NSI’s, in particular, flavor-diagonal neutral current interactions that modify the ν e e and ν τ e couplings using Borexino Phase II data. Standard Solar Model predictions of the solar neutrino fluxes for both high- and low-metallicity assumptions are considered. No indication of new physics is found at the level of sensitivity of the detector and constraints on the parameters of the NSI’s are placed. In addition, with the same dataset the value of sin2 θ W is obtained with a precision comparable to that achieved in reactor antineutrino experiments .

Abstract SABRE aims to directly measure the annual modulation of the dark matter interaction rate with NaI(Tl) crystals. A modulation compatible with the standard hypothesis, in which our Galaxy is immersed in a dark matter halo, has been measured by the DAMA experiment in the same target material. Other direct detection experiments, using different target materials, seem to exclude the interpretation of such modulation in the simplest scenario of WIMP-nucleon elastic scattering. The SABRE experiment aims to carry out an independent search with sufficient sensitivity to confirm or refute the DAMA claim. The goal of the SABRE experiment is to achieve the lowest background rate for a NaI(Tl) experiment (order of 0.1 cpd/kg/keVee in the energy region of interest for dark matter). This challenging goal could be achievable by operating high-purity crystals inside a liquid scintillator veto for active background rejection. In addition, twin detectors will be located in the northern and southern hemispheres to identify possible contributions to the modulation from seasonal or site-related effects. The SABRE project includes an initial Proof-of-Principle phase at LNGS (Italy), to assess the radio-purity of the crystals and the efficiency of the liquid scintillator veto. This paper describes the general concept of SABRE and the expected sensitivity to WIMP annual modulation.

The deposition of organic functionalities on biomaterials to immobilize biomolecules is a research area of great interest in the medical field. The surface functionalization of a 3D porous scaffolds of PDLLA with carboxyl (-COOH) and amino (-NH2) groups by cold plasma treatment at atmospheric pressure is described in this paper. Two methods of continuous and pulsed plasma deposition were compared to assess the degree of functionalization of the internal porous 3D scaffold. In particular, the pulsed plasma treatment was found to functionalize uniformly not only the sample surface but also inside the open cavities thanks to its permeability and diffusion in the porous 3D scaffold. The species developed in the plasma were studied by optical emission spectroscopy (OES) technique, while the functionalization of the sponges was evaluated by the Diffuse Reflectance Fourier-Transform Infrared Spectroscopy (DR-FTIR) technique using also the adsorption of ammonia (NH3) and deuterated water (D2O) probe molecules. The functional groups were deposited only on the front of the sponge, then the structural characterization of both front and back of the sponge has demonstrated the uniform functionalization of the entire scaffold.

We report the first results of DarkSide-50, a direct search for dark matter operating in the underground Laboratori Nazionali del Gran Sasso (LNGS) and searching for the rare nuclear recoils possibly induced by weakly interacting massive particles (WIMPs). The dark matter detector is a Liquid Argon Time Projection Chamber with a (46.4±0.7) kg active mass, operated inside a 30 t organic liquid scintillator neutron veto, which is in turn installed at the center of a 1 kt water Cherenkov veto for the residual flux of cosmic rays. We report here the null results of a dark matter search for a (1422±67) kgd exposure with an atmospheric argon fill. This is the most sensitive dark matter search performed with an argon target, corresponding to a 90% CL upper limit on the WIMP-nucleon spin-independent cross section of 6.1×10−44 cm2 for a WIMP mass of 100 Gev/c2. Keywords: Dark matter, WIMP, Noble liquid detectors, Low-background detectors, Liquid scintillators

Although the existence of dark matter is supported by many evidences, based on astrophysical measurements, its nature is still completely unknown. One major candidate is represented by weakly interacting massive particles (WIMPs), which could in principle be detected through their collisions with ordinary nuclei in a sensitive target, producing observable low-energy (

The study examined the hypothesis that GSH is secreted into buffalo milk, and that some of the secreted GSH is degraded by the enzyme gamma-glutamyltransferase (GGT) within the milk space. The data confirmed such hypothesis and, together with previous studies concerning the presence of GSH synthetic and catabolic enzymes in mammary tissue, suggest that the buffalo mammary gland may have a functional gamma-glutamyl cycle. Such cycle probably contributes to the secretion of cysteine - a fundamental amino acid for neonatal growth and development- into buffalo milk.

: Introduction: Community‐based cohort studies of HIV seroconversion can identify important avenues for enhancing HIV prevention efforts in the era of pre‐exposure prophylaxis (PrEP). Within individuals, one can assess exposure and outcome variables repeatedly and with increased certainty regarding temporal ordering. This cohort study examined the association of several risk factors with subsequent HIV seroconversion. Methods: We report data from a 4‐year study (2017−2022) of 6059 HIV seronegative sexual and gender minority individuals who have sex with men who had indications for‐, but were not using‐, PrEP at enrolment. Participants completed repeat exposure assessments and self‐collection of biospecimens for HIV testing. We examined the roles of race and ethnicity, socio‐economic status, methamphetamine use and PrEP uptake over the course of follow‐up in relation to HIV seroconversion. Results: Over 4 years, 303 of the participants seroconverted across 18,421 person‐years (incidence rate = 1.64 [95% CI: 1.59−1.70] per 100 person‐years). In multivariable discrete‐time survival analysis, factors independently associated with elevated HIV seroconversion risk included being Black/African American (adjusted risk ratio [aRR]: 2.44, 1.79−3.28), Hispanic/Latinx (1.53, 1.19−1.96), housing instability (1.58, 1.22−2.05) and past year methamphetamine use (3.82, 2.74−5.33). Conversely, time since study enrolment (24 vs. 12 months, 0.67, 0.51−0.87; 36 months, 0.60, 0.45−0.80; 48 months, 0.48, 0.35−0.66) and higher education (master's degree or higher vs. less than or equal to high school, 0.36, 0.17−0.66) were associated with reduced seroconversion risk. Compared to non‐PrEP users in the past 2 years without a current clinical indication, those who started PrEP but then discontinued had higher seroconversion risk, irrespective of clinical indication (3.23, 1.74−6.46) or lack thereof (4.30, 1.85−9.88). However, those who initiated PrEP in the past year (0.14, 0.04−0.39) or persistently used PrEP in the past 2 years (0.33, 0.14−0.74) had a lower risk of seroconversion. Of all HIV seroconversions observed during follow‐up assessments (12, 24, 36 and 48 months), methamphetamine was reported in the 12 months prior 128 (42.2%) times (overall). Conclusions: Interventions that acknowledge race and ethnicity, economic variables such as education and housing instability, and methamphetamine use are critically needed. Not only are interventions to engage individuals in PrEP care needed, but those that retain them, and re‐engage those who may fall out of care are essential, given the exceptionally high risk of seroconversion in these groups., INTRODUCTION Sexual minority individuals represent 2−5% of the United States, yet account for more than two‐thirds of new HIV acquisitions [1−4]. Meanwhile, gender minority individuals (transgender [trans] men and trans [...]

Aim: Evidence suggests that translocation of oral pathogens through the oral–gut axis may induce intestinal dysbiosis. This study aimed to evaluate the impact of a highly leukotoxic Aggregatibacter actinomycetemcomitans (Aa) strain on the gut microbiota, intestinal mucosal integrity and immune system in healthy mice. Methods: Eight‐week‐old male C57BL6 mice were divided into control (n = 16) and JP2 groups (n = 19), which received intragastric gavage with PBS and with a suspension of Aa JP2 (HK921), respectively, twice a week for 4 weeks. Colonic lamina propria, fecal material, serum, gingival tissues, and mandibles were obtained for analyses of leukocyte populations, inflammatory mediators, mucosal integrity, alveolar bone loss, and gut microbiota. Differences between groups for these parameters were examined by non‐parametric tests. Results: The gut microbial richness and the number of colonic macrophages, neutrophils, and monocytes were significantly lower in Aa JP2‐infected mice than in controls (p <.05). In contrast, infected animals showed higher abundance of Clostridiaceae, Lactobacillus taiwanensis, Helicobacter rodentium, higher levels of IL‐6 expression in colonic tissues, and higher splenic MPO activity than controls (p <.05). No differences in tight junction expression, serum endotoxin levels, and colonic inflammatory cytokines were observed between groups. Infected animals presented also slightly more alveolar bone loss and gingival IL‐6 levels than controls (p <.05). Conclusion: Based on this model, intragastric administration of Aa JP2 is associated with changes in the gut ecosystem of healthy hosts, characterized by less live/recruited myeloid cells, enrichment of the gut microbiota with pathobionts and decrease in commensals. Negligible levels of colonic pro‐inflammatory cytokines, and no signs of mucosal barrier disruption were related to these changes. [ABSTRACT FROM AUTHOR]