N. Naganawa

Measurements of Total and Partial Charge-changing Cross Sections for 200-400 MeV/nucleon 12C in Water and Polycarbonate

We have studied charged nuclear fragments produced by 200 - 400 MeV/nucleon carbon ions, interacting with water and polycarbonate, using a newly developed emulsion detector. Total and partial charge-changing cross sections for the production of B, Be, and Li fragments were measured and compared with both previously published measurements, and model predictions. This study is of importance for validating and improving carbon ion therapy treatment planning systems, and for estimating the radiological risks for personnel on space missions, since carbon is a significant component of the Galactic Cosmic Rays.

Measurement of low-energy neutrino cross-sections with the PEANUT experiment

The PEANUT experiment was designed to study the NuMi neutrino beam at Fermilab. The detector uses a hybrid technique, being made of nuclear emulsions and scintillator trackers. Emulsion films act as a micrometric tracking device and are interleaved with lead plates used as passive material. The detector is designed to precisely reconstruct the topology of neutrino interactions and hence to measure the different contributions to the cross section. We present here the full reconstruction and analysis of 147 neutrino interactions and the measurement of the quasi-elastic, resonance and deep-inelastic contributions to the total charged current cross section at the energies of the NuMi neutrino beam. This technique could be applied for beam monitoring in future neutrino facilities, and this paper shows its proof-of-principle.

Development and utilization of ``Plate Changer'' system for neutrino interaction locations in OPERA emulsion target

In the OPERA experiment, so-called Scan Back method is used to locate neutrino interaction vertices in the emulsion target named ECC (Emulsion Cloud Chamber). In Scan Back method, tracks detected in the most downstream emulsion plate in ECCs are followed to upstream plate by plate until it reaches to the interaction points. In order to treat a number of neutrino interactions recorded in OPERA, dedicated systems called Plate Changer has been developed and utilized to neutrino event location in Japan. The details of the system have been described in this report. Until the end of November 2012, 6223 Scan Back trials have been performed using this system, and strongly contributed to the detection of tau neutrino appearance.

Development of high spatial resolution cold/ultra- cold neutron detector using fine-grained nuclear emulsion

We have been developing neutron detectors with spatial resolution of submicron to several tens of nanometers using fine-grained nuclear emulsion with nuclides with large neutron absorption cross sections such as 6Li and 10B. Those detectors were demonstrated their ability to detect cold and ultra-cold neutrons.

A Test Experiment to Develop a Neutrino Detector with Emulsions for Neutrino-Nucleus Cross Section Measurements at J-PARC

We would like to perform a test experiment to develop a new neutrino detector with nuclear emulsions at the near detector hall of the J-PARC neutrino beam line. The physics aim is to detect neutrino interactions with high efficiency and measure the cross sections of neutrino (νμ/νμ, νe/νe)-nucleus charged/neutral current interactions in around 1 GeV energy region. First, we will perform a preliminary run to study environmental background inside the near detector hall. Then, we will perform a test run to study performance of the new detector and establish the analysis method to study neutrino interactions in the low energy region. Finally, we will perform data taking of physics runs to measure cross sections of neutrino-nucleus interactions with high efficiency.

First demonstration of gamma-ray imaging using a balloon-borne emulsion telescope

We promote the precise gamma-ray observation project Gamma-Ray Astro-Imager with Nuclear Emulsion (GRAINE), which uses balloon-borne emulsion gamma-ray telescopes. The emulsion telescope realizes observations with high angular resolution, polarization sensitivity, and large aperture area in the 0.01--100 GeV energy region. Herein, we report the data analysis of emulsion tracks and the first demonstration of gamma-ray imaging via an emulsion telescope by using the flight data from the balloon experiment performed in 2015 (GRAINE 2015). The emulsion films were scanned by the latest read-out system for a total area of 41 m

Measurement of Cosmic Ray Nuclei with GRAINE2015

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Long-term characteristics of nuclear emulsion

in three months, and then the gamma-ray event selection was automatically processed. Millions of electron-pair events are accumulated in the balloon-borne emulsion telescope. The emulsion telescope detected signals from a calibration source (gamma rays from the interaction of cosmic rays with an aluminum plate) with a high significance during the balloon observation and created a gamma-ray image consistent with the source size and the expected angular resolution in the energy range of 100--300 MeV. The flight performance obtained in the GRAINE 2015 experiment proves that balloon-borne emulsion telescope experiments with larger area are feasible while maintaining expected imaging performance.

Measurements of projectile-like {sup 8}Be and {sup 9}B production in 200-400 MeV/nucleon {sup 12}C on water

GRAINE(Gamma Ray Astro-Imager with Nuclear Emulsion) experiment consists of a balloon borne emulsion chamber and emulsion film shifting system launched on May 6, 2015 in Australia and its acceptance and flight duration is 3780m

The OPERA film: New nuclear emulsion for large-scale, high-precision experiments

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