Abstract
THEIA is a proposed large-scale neutrino experiment based on advanced liquid scintillator and readout by high-quantum efficiency and fast photosensors. In order to combine the advantages of ...water Cherenkov detectors (i.e. large mass, direction reconstruction and low cost) with the ones of liquid scintillator (high light yield, low threshold) THEIA will deploy a Water-based Liquid Scintillator, which is currently at the center of an active R&D program. This detector concept has the potential to pursue a broad physics program that is summarized in this contribution. As a long baseline experiment installed at Homestake, THEIA will be complementary to the forthcoming DUNE experiment for the determination of the neutrino mass hierarchy and of the CP phase. At the same time, the low energy threshold and efficient neutron tagging makes THEIA an excellent detector for solar and supernova neutrinos measurements as well as for the search of neutrinoless
ββ
-decay and of other rare phenomena.
The goal of the FAMU experiment is the measurement of the proton Zemach radius using muonic hydrogen, a subject that has raised much interest in recent years due to its implications in the so-called ...proton radius puzzle. In order to extract the Zemach radius, the FAMU collaboration aims at measuring the hyperfine splitting of the µp ground state, since the effect of the proton finite size affects the HF transition energy. The proposed experimental method requires a detection system which is suited for time resolved X-ray spectroscopy: in this contribution the results of the first measurements performed at the RIKEN-RAL muon facility in order to verify the fitness of the detection system in the pulsed intense muon beam are presented. The characteristic X-rays from atomic transitions in muonic atoms formed in different targets have been detected using a HPGe detector and five scintillating counters based on LaBr3(Ce) crystals, whose output has been recorded for 5 ps using a 500 MHz digitizer to measure both the energy and the time spectrum of the detected events. With a detailed pulse analysis considering pile-up events, both the expected characteristic X-rays and lifetimes of various elements were measured, paving the way for future measurements to be carried out in early 2016.
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
±
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 (
ν
e
,
ν
μ
,
ν
τ
) at the level
10
9
-
10
15
cm
-
2
GW
-
1
have been obtained in the 0.5–5 MeV neutrino energy range.
Since the beginning of 2012, the Borexino collaboration has been reporting precision measurements of the solar neutrino fluxes, emitted in the proton–proton chain and in the Carbon–Nitrogen–Oxygen ...cycle. The experimental sensitivity achieved in Phase-II and Phase-III of the Borexino data taking made it possible to detect the annual modulation of the solar neutrino interaction rate due to the eccentricity of Earth’s orbit, with a statistical significance greater than 5σ. This is the first precise measurement of the Earth’s orbital parameters based solely on solar neutrinos and an additional signature of the solar origin of the Borexino signal. The complete periodogram of the time series of the Borexino solar neutrino detection rate is also reported, exploring frequencies between one cycle/year and one cycle/day. No other significant modulation frequencies are found. The present results were uniquely made possible by Borexino’s decade-long high-precision solar neutrino detection.
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 Formula omitted 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 ( Formula omitted) at the level Formula omitted have been obtained in the 0.5-5 MeV neutrino energy range.
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.
•Temperature dependence of the μ transfer rate from μp to oxygen is measured.•A strong monotonic rise by a factor three of the rate is observed between 104-300 K.•This effect will be exploited to ...measure the hyperfine splitting of the μp 1S state.•Experiment took place at the RIKEN muon facility, Rutherford Appleton Laboratory.•Fast scintillator counters based on LaBr3 crystals read by photomultipliers are used.
We report the first measurement of the temperature dependence of muon transfer rate from muonic hydrogen atoms to oxygen between 100 and 300 K. Data were obtained from the X-ray spectra of delayed events in a gaseous target, made of a H2/O2 mixture, exposed to a muon beam. This work sets constraints on theoretical models of muon transfer and is of fundamental importance for the measurement of the hyperfine splitting of muonic hydrogen ground state as proposed by the FAMU collaboration.
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
±
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 %.
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