This paper describes a new $\nu_e$ identification method specifically
designed to improve the low-energy ($< 30\,\mathrm{GeV}$) $\nu_e$
identification efficiency attained by enlarging the emulsion ...film scanning
volume with the next generation emulsion readout system. A relative increase of
25-70% in the $\nu_e$ low-energy region is expected, leading to improvements in
the OPERA sensitivity to neutrino oscillations in the framework of the 3 + 1
model. The method is applied to a subset of data where the detection efficiency
increase is expected to be more relevant, and one additional $\nu_e$ candidate
is found. The analysis combined with the $\nu_\tau$ appearance results improves
the upper limit on $\sin^2 2\theta_{\mu e}$ to 0.016 at 90% C.L. in the
MiniBooNE allowed region $\Delta m^2_{41} \sim 0.3\,\mathrm{eV}^2$.
This paper describes a new \(\nu_e\) identification method specifically designed to improve the low-energy (\(< 30\,\mathrm{GeV}\)) \(\nu_e\) identification efficiency attained by enlarging the ...emulsion film scanning volume with the next generation emulsion readout system. A relative increase of 25-70% in the \(\nu_e\) low-energy region is expected, leading to improvements in the OPERA sensitivity to neutrino oscillations in the framework of the 3 + 1 model. The method is applied to a subset of data where the detection efficiency increase is expected to be more relevant, and one additional \(\nu_e\) candidate is found. The analysis combined with the \(\nu_\tau\) appearance results improves the upper limit on \(\sin^2 2\theta_{\mu e}\) to 0.016 at 90% C.L. in the MiniBooNE allowed region \(\Delta m^2_{41} \sim 0.3\,\mathrm{eV}^2\).
Nowadays there is compelling evidence for the existence of dark matter in the Universe. A general consensus has been expressed on the need for a directional sensitive detector to confirm, with a ...complementary approach, the candidates found in conventional searches and to finally extend their sensitivity beyond the limit of neutrino-induced background. We propose here the use of a detector based on nuclear emulsions to measure the direction of WIMP-induced nuclear recoils. The production of nuclear emulsion films with nanometric grains is established. Several measurement campaigns have demonstrated the capability of detecting sub-micrometric tracks left by low energy ions in such emulsion films. Innovative analysis technologies with fully automated optical microscopes have made it possible to achieve the track reconstruction for path lengths down to one hundred nanometers and there are good prospects to further exceed this limit. The detector concept we propose foresees the use of a bulk of nuclear emulsion films surrounded by a shield from environmental radioactivity, to be placed on an equatorial telescope in order to cancel out the effect of the Earth rotation, thus keeping the detector at a fixed orientation toward the expected direction of galactic WIMPs. We report the schedule and cost estimate for a one-kilogram mass pilot experiment, aiming at delivering the first results on the time scale of six years.
The OPERA experiment has discovered the tau neutrino appearance in the CNGS muon neutrino beam, in agreement with the 3 neutrino flavour oscillation hypothesis. The OPERA neutrino interaction target, ...made of Emulsion Cloud Chamber, was particularly efficient in the reconstruction of electromagnetic showers. Moreover, thanks to the very high granularity of the emulsion films, showers induced by electrons can be distinguished from those induced by \(\pi^0\)s, thus allowing the detection of charged current interactions of electron neutrinos. In this paper the results of the search for electron neutrino events using the full dataset are reported. An improved method for the electron neutrino energy estimation is exploited. Data are compatible with the 3 neutrino flavour mixing model expectations and are used to set limits on the oscillation parameters of the 3+1 neutrino mixing model, in which an additional mass eigenstate \(m_{4}\) is introduced. At high \(\Delta m^{2}_{41}\) \(( \gtrsim 0.1~\textrm{eV}^{2})\), an upper limit on \(\sin^2 2\theta_{\mu e}\) is set to 0.021 at 90% C.L. and \(\Delta m^2_{41} \gtrsim 4 \times 10^{-3}~\textrm{eV}^{2}\) is excluded for maximal mixing in appearance mode.
The OPERA experiment is designed to search for $\nu_{\mu} \rightarrow \nu_{\tau}$ oscillations in appearance mode i.e. through the direct observation of the $\tau$ lepton in $\nu_{\tau}$ charged ...current interactions. The experiment has taken data for five years, since 2008, with the CERN Neutrino to Gran Sasso beam. Previously, two $\nu_{\tau}$ candidates with a $\tau$ decaying into hadrons were observed in a sub-sample of data of the 2008-2011 runs. Here we report the observation of a third $\nu_\tau$ candidate in the $\tau^-\to\mu^-$ decay channel coming from the analysis of a sub-sample of the 2012 run. Taking into account the estimated background, the absence of $\nu_{\mu} \rightarrow \nu_{\tau}$ oscillations is excluded at the 3.4 $\sigma$ level.
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
<
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
×
18 cm
2
area in the emulsion is:
1.5
±
0.1
(
stat
)
×
10
4
fb/cm
2
.
The muon flux per integrated luminosity through a 31
×
31 cm
2
area in the centre of the SciFi is:
2.06
±
0.01
(
stat
)
±
0.12
(
sys
)
×
10
4
fb/cm
2
The muon flux per integrated luminosity through a 52
×
52 cm
2
area in the centre of the downstream muon system is:
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.
After rapid approval and installation, the SND@LHC Collaboration was able to gather data successfully in 2022 and 2023. Neutrino interactions from νμs originating at the LHC IP1 were observed. Since ...muons constitute the major background for neutrino interactions, the muon flux entering the acceptance was also measured. To improve the rejection power of the detector and to increase the fiducial volume, a third Veto plane was recently installed. The energy resolution of the calorimeter system was measured in a test beam. This will help with the identification of νe interactions that can be used to probe charm production in the pseudo-rapidity range of SND@LHC (7.2 < η < 8.4). Events with three outgoing muons have been observed and are being studied. With no vertex in the target, these events are very likely from muon trident production in the rock before the detector. Events with a vertex in the detector could be from trident production, photon conversion, or positron annihilation. To enhance SND@LHC’s physics case, an upgrade is planned for HL-LHC that will increase the statistics and reduce the systematics. The installation of a magnet will allow the separation of νμ from ν¯μ
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