To observe gamma-ray sources precisely, a balloon-borne experiment with a new type of detector, the emulsion gamma-ray telescope, is planned. A multi-stage shifter mechanism based on the concept of ...an analog clock serves as a time stamper with subsecond time resolution and uses multiple moving stages mounted on the emulsion chambers. This new technique was employed in a test experiment using a small-scale model in a short-duration balloon flight. Tracks recorded in nuclear emulsion were read by a fully automated scanning system, were reconstructed, and time information were assigned by analysis of their position displacements in the shifter layers. The estimated time resolution was 0.06–0.15s. The number of tracks passing through the detector was counted every second, and hadron jets were detected as significant excesses observed in the counting rate. In future, the multi-stage shifter is greatly contributing to ongoing efforts to increase the effective area of emulsion gamma-ray telescopes.
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.
A gamma-ray telescope using nuclear emulsions allows observations of stellar objects in the 0.01–100 GeV energy region with high angular resolution, polarization sensitivity, and large aperture area. ...The Gamma-Ray Astro-Imager with Nuclear Emulsion (GRAINE) project is designed to enable high-precision observation of cosmic gamma rays through the use of balloon-borne emulsion telescopes. We have developed a balloon-style pressure vessel gondola for the GRAINE 2018 balloon-borne experiment. It enables us to maintain robust and vacuum-packed emulsion chambers even at balloon altitudes. The greater part of the vessel is made of membrane materials consisting of ultra-thin polyurethane-coated polyester fabric. It is lightweight and portable, and can be used to expand the mounting area of the detector, unlike mostly metal vessels. Moreover, the absorption of signal gamma rays and background gamma-ray production due to interactions between cosmic rays and the vessel can be minimized. The pressure vessel gondola, equipped with a 0.38-m2 emulsion telescope and other equipment, was launched on April 26, 2018. During the whole observation (17 h 21 m), the internal pressure was kept above 230 hPa. The GRAINE project will start scientific observation using enlarged telescopes and the pressure vessel gondola is planned to include an expansion of the mounting area of the detector to ∼10 m2 while following the design on the GRAINE 2018 model.
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.
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