A new type of cold/ultracold neutron detector that can realize a spatial resolution of less than 100 nm was developed using nuclear emulsion. The detector consists of a fine-grained nuclear emulsion ...coating and a 50-nm thick
10
B
4
C
layer for the neutron conversion. The detector was exposed to cold and ultracold neutrons (UCNs) at the J-PARC. Detection efficiencies were measured as (0.163 ± 0.015 (stat) ± 0.013 (sys))% and (10.3 ± 1.3 (stat) ± 1.1 (sys))% for cold and ultracold neutrons consistently with the
10
B content in the converter. Positions of individual neutrons can be determined by observing secondary particle tracks recorded in the nuclear emulsion. The spatial resolution of incident neutrons were found to be in the range of 11–99 nm in the angle region of tan
θ
≤
1.9
, where
θ
is the angle between a recorded track and the normal direction of the converter layer. The achieved spatial resolution corresponds to the improvement of one or two orders of magnitude compared with conventional techniques and it is comparable with the wavelength of UCNs.
Industrial mass production of nuclear emulsion film has been realized by the introduction of new photographic technologies.
In addition, emulsion-refreshing capability (erasing unwanted tracks before ...its use) was implemented by controlling the fading characteristics of the gel. The gel properties were optimized in order to satisfy this requirement; rapid track erasing at the erasing condition and minimum fading during the running of experiments.
Emulsion films with this capability are crucial for large-scale applications like the long base-line neutrino experiment, OPERA, which intend to detect Tau neutrino appearance at 732
km from the beam source.
OPERA is a unique experiment aimed at the first detection of ντ appearance in a flux of νμ due to the neutrino oscillation from νμ to ντ. The CERN CNGS beam is the source of νμ. The detector is ...hybrid; it is composed of nuclear emulsion films and electronic detectors. It is located in the LNGS underground laboratory. The target consists of 150,000 Emulsion Cloud Chambers (ECC) bricks, which are stacks of interleaved emulsion films and lead plates. The ντ charged current interactions will be detected by identifying the decay topology of the τ in the ECC bricks. The first run started in 2008. The experiment is currently in the phase of data taking and analysis. The experimental methods, the status and the summary of the results from the 2008 run are presented in this paper.
This paper reports the track multiplicity and kinematics of muons, charged pions, and protons from charged-current inclusive νμ and νμ interactions on a water target, measured using a nuclear ...emulsion detector in the NINJA experiment. A 3-kg water target was exposed to the T2K antineutrino-enhanced beam corresponding to 7.1 × 1020 protons on target with a mean energy of 1.3 GeV. Owing to the high granularity of the nuclear emulsion, protons with momenta down to 200 MeV=c from the neutrino-water interactions were detected. We find good agreement between the observed data and model predictions for all kinematic distributions other than the number of charged pions and the muon kinematics shapes. These results demonstrate the capability of measurements with nuclear emulsion to improve neutrino interaction models.
Abstract
Precise neutrino–nucleus interaction measurements in the sub-multi-GeV region are important to reduce the systematic uncertainty in future neutrino oscillation experiments. Furthermore, an ...excess of
${\nu_e}$
interactions, as a possible interpretation of the existence of a sterile neutrino, has been observed in such an energy region. The nuclear emulsion technique can measure all the final state particles with low energy threshold for a variety of targets (Fe, C, H
${_2}$
O, and so on). Its sub-
$\mu$
m position resolution allows measurements of the
${\nu_e}$
cross-section with good electron/gamma separation capability. We started a new experiment at J-PARC to study sub-multi-GeV neutrino interactions by introducing the nuclear emulsion technique. The J-PARC T60 experiment has been implemented as a first step in such a project. Systematic neutrino event analysis with full scanning data in the nuclear emulsion detector was performed for the first time. The first neutrino event detection and its analysis are described in this paper.
Abstract
We have carried out $\nu_{\mu}$ charged-current interaction measurement on iron using an emulsion detector exposed to the T2K neutrino beam in the J-PARC neutrino facility. The data samples ...correspond to $4.0 \times 10^{19}$ protons on target, and the neutrino mean energy is 1.49 GeV. The emulsion detector is suitable for precision measurements of charged particles produced in neutrino–iron interactions with a low momentum threshold thanks to a thin-layered structure and sub-$\mu$m spatial resolution. The charged particles are successfully detected, and their multiplicities are measured using the emulsion detector. The cross section was measured to be $\sigma^{\mathrm{Fe}}_{\mathrm{CC}} = (1.28 \pm 0.11({\mathrm{stat.}})^{+0.12}_{-0.11}({\mathrm{syst.}})) \times 10^{-38} \, {\mathrm{cm}}^{2}/{\mathrm{nucleon}}$. The cross section in a limited kinematic phase space of induced muons, $\theta_{\mu} < 45^{\circ}$ and $p_{\mu} > 400 \, {\rm MeV}/c$, on iron was $\sigma^{\mathrm{Fe}}_{\mathrm{CC \hspace{1mm} phase \hspace{0.5mm} space}} = (0.84 \pm 0.07({\mathrm{stat.}})^{+0.07}_{-0.06}({\mathrm{syst.}})) \times 10^{-38} \, {\mathrm{cm}}^{2}/{\mathrm{nucleon}}$. The cross-section results are consistent with previous values obtained via different techniques using the same beamline, and they are reproduced well by current neutrino interaction models. These results demonstrate the capability of the detector in the detailed measurement of neutrino–nucleus interactions around the 1 GeV energy region.
Abstract
We describe the first ever implementation of a clock-based, multi-stage emulsion shifter in an accelerator neutrino experiment. The system was installed in the neutrino monitoring building ...at the Japan Proton Accelerator Research Complex as part of a test experiment, T60, and stable operation was maintained for a total of 126.6 days. By applying time information to emulsion films, various results were obtained. Time resolutions of 5.3–14.7 s were evaluated in an operation spanning 46.9 days (yielding division numbers of 1.4–3.8
$\times10^{5}$
). By using timing and spatial information, reconstruction of coincident events consisting of high-multiplicity and vertex-contained events, including neutrino events, was performed. Emulsion events were matched to events observed by INGRID, one of the on-axis near detectors of the T2K experiment, with high reliability (98.5%), and hybrid analysis of the emulsion and INGRID events was established by means of the multi-stage shifter. The results demonstrate that the multi-stage shifter can feasibly be used in neutrino experiments.
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