Atsushi Iyono

Coordinate measurement system supported by image processor for emulsion plates

Abstract Central collisions of 32S and 16O with Pb at 200 GeV amu have been studied by the emulsion spectrometer in the CERN-EMU05 experiment. The emission angles, momenta and charge signs of the secondary particles are measured. The position of a track in an emulsion plate should be measured by using a microscope to determine the momenta of more than 500 charged secondaries in an event. A new coordinate measurement system has been developed by using a video image processor connected to the microscope. In this system, the position, direction and length of a track in a coated emulsion are expressed as a vector which is linked with the motion of micro X-Y stage and is superimposed on an emulsion image on a TV monitor. By using this system, the data acquisition rate has become about ten times faster than that by using only an emulsion image and the momentum resolution has become higher than that. Moreover, this system is effective for identifying tracks emitted in more than 45°.

Development of newly designed VHF interferometer system for observing earthquake-related atmospheric anomalies

Temporal correlation between atmospheric anomalies and earthquakes has recently been verified statistically through measuring VHF FM radio waves transmitted beyond the line-of-sight. In order to locate the sources of such atmospheric anomalies, we developed a VHF interferometer system (bistatic-radar type) capable of finding the arrival direction of FM radio waves scattered possibly by earthquake-related atmospheric anomalies. In general, frequency modulation of FM radio waves produces ambiguity of arrival direction. However, our system, employing high-sampling rates of the order of kHz, can precisely measure the arrival direction of FM radio waves by stacking received signals.

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

Survival probability of charged particles dissipating their energies by radiation and ionization

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Update of the observation system for the primary energy spectrum with compact EAS arrays in LAAS experiment

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.

Measurement of Cosmic Ray Nuclei with GRAINE2015

The survival probabilities of charged particle traversing through matters are evaluated by solving the diffusion equation, taking account of radiation and ionization losses. The solutions corresponding to high and low incident energies are proposed respectively, and inaccuracies of the saddle point method appearing in case of large probabilities are removed by deriving the results via the complementary probabilities. The enough-accurate results will be valuable to improve the resolution of radiographic analyses with atmospheric muons, and others.

The primary energy spectrum with the Linsley method correcting heavy primary effects in the LAAS experiments

The relation between the core distance and the time structure of extensive air shower (EAS) particles shown by Linsley provided to determine the primary energy by using compact EAS arrays. In an apparatus for restricting the zenith angle of EAS event, relocation and update of the apparatus was carried out. And the simulation for this upgrading was performed. We report the simulation results and comparisons of old and new apparatus.

The primary energy spectrum derived from Linsley method with simulations of heavy compositions in the LAAS mini array observation

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

Simulation of electron trajectories in nuclear emulsion and its application

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Simultaneous, parallel and multiple EAS events due to Gerasimova‐Zatsepin effect in LAAS experiments

sr and 14 hours at 37 km above sea level, respectively. The main scientific goals of GRAINE2015 are the precise measurement of sub GeV gamma-rays from Vela pulsar, the measurement of charm particle production cross section at high altitude in the air and the study of cosmic ray nuclei compositions. The nuclear emulsion films used in GRAINE2015 will be able to measure cosmic ray nuclei from hydrogen nuclei to more than iron nuclei. The measurement of the chemical composition of cosmic ray nuclei in the MeV-TeV energy range will reveal new insights about the cosmic ray nuclei life in the our galaxy, from their origin to the propagation in the interstellar medium. The Cosmic ray nuclei absolute charge Z is measured along the trajectory in the GRAINE2015 emulsion films by using high speed emulsion track selector (HTS). This allows to scan the entire emulsion film within the zenith angle less than 63 degree. The charge measurement methods in HTS scan data are here explained, and their performance presented.