Spatial profiles of collimated laser Compton-scattering γ\gamma-ray beams

The intensity and energy spatial distributions of collimated laser Compton scattering (LCS) $\gamma$-ray beams and of the associated bremsstrahlung beams have been investigated as functions of the electron beam energy, electron beam phase space distribution, laser optics conditions and laser polarization. We show that the beam halo is affected to different extents by variations in the above listed parameters. In the present work, we have used laser Compton scattering simulations performed with the \texttt{eliLaBr} code (https://github.com/dan-mihai-filipescu/eliLaBr) and real LCS and bremsstrahlung $\gamma$-ray beams produced at the NewSUBARU synchrotron radiation facility. A 500~$\mu$m MiniPIX X-ray camera was used as beamspot monitor in a wide $\gamma$-ray beam energy range between 1.73~MeV and 38.1~MeV

Application of Scan-less Two-Dimensional Confocal Microscopy Based on a Combination of Confocal Slit With Wavelength/Space Conversion

Confocal laser microscope (CLM) has been widely used in the fields of the non-contact surface topography, biomedical imaging, and other applications, because the confocality gives two-dimensional (2D) optical-sectioning or three-dimensional (3D) imaging capability with the depth selectivity. Combination of line-focused CLM with one-dimensional (1D) spectral encoding CLM enables us to obtain the 2D confocal image without the need for the mechanical scanning. So-called scan-less 2D CLM is a unique imaging modality, however, there are no attempts to apply for practical application. In this paper, we constructed scan-less 2D CLM with the image acquisition time of 0.23 ms, the lateral resolution of 1.2 µm, the depth resolution of 2.4 µm, and apply it for different kinds of application to evaluate its practical potential

Scan-Less, Kilo-Pixel, Line-Field Confocal Phase Imaging with Spectrally Encoded Dual-Comb Microscopy

Confocal laser microscopy (CLM) is a powerful tool in life science research and industrial inspection, and its image acquisition rate is boosted by scan-less imaging techniques. However, the optical-intensity-based image contrast in CLM makes it difficult to visualize transparent non-fluorescent objects or reflective objects with nanometer unevenness. In this paper, we introduce an optical frequency comb (OFC) to scan-less CLM to give the optical-phase-based image contrast. One-dimensional (1D) image pixels of a sample are separately encoded onto OFC modes via 1D spectral encoding by using OFC as an optical carrier of amplitude and phase with a vast number of discrete frequency channels. Then, line-field confocal information of amplitude and phase are decoded from a mode-resolved OFC amplitude and phase spectra obtained by dual-comb spectroscopy. The proposed confocal phase imaging will further expand the application fields of CLM

Scan-Less, Kilo-Pixel, Line-Field Confocal Phase Imaging with Spectrally Encoded Dual-Comb Microscopy

Confocal laser microscopy (CLM) is a powerful tool in life science research and industrial inspection, and its image acquisition rate is boosted by scan-less imaging techniques. However, the optical-intensity-based image contrast in CLM makes it difficult to visualize transparent non-fluorescent objects or reflective objects with nanometer unevenness. In this paper, we introduce an optical frequency comb (OFC) to scan-less CLM to give the optical-phase-based image contrast. One-dimensional (1D) image pixels of a sample are separately encoded onto OFC modes via 1D spectral encoding by using OFC as an optical carrier of amplitude and phase with a vast number of discrete frequency channels. Then, line-field confocal information of amplitude and phase are decoded from a mode-resolved OFC amplitude and phase spectra obtained by dual-comb spectroscopy. The proposed confocal phase imaging will further expand the application fields of CLM

Production of positrons via pair creation from LCS gamma-rays and application to defect study in bulk materials

A new positron production and measurement apparatus has been developed at a synchrotron radia-tion facility. Highly energetic positrons were created via pair creation in a Pb target by implantation of 16.7 MeV photons generated via inverse Compton scattering of a Nd laser beam from a 1 GeV electron beam circulating in the storage ring at the NewSUBARU synchrotron radiation facility. These positrons, with an energy of around 8 MeV, are separated using a magnetic field and directly implanted into a thick sample to detect defects. By using laser Compton scattered (LCS) photon gen-erated positrons, we performed positron annihilation Doppler broadening measurement for fatigue stress applied iron with a thickness of 2 mm. Vacancy type defects in nondestructive fatigue stress applied iron specimens were successfully detected by this LCS-positron apparatus. 1

Dwarf Novae in the Shortest Orbital Period Regime: I. A New Short Period Dwarf Nova, OT J055717+683226

We report the observation of a new dwarf nova, OT J055717+683226, during its first-ever recorded superoutburst in December 2006. Our observation shows that this object is an SU UMa-type dwarf nova having a very short superhump period of 76.67+/- 0.03 min (0.05324+/-0.00002 d). The next superoutburst was observed in March 2008. The recurrence time of superoutbursts (supercycle) is, hence, estimated to be ~480 d. The supercycle is much shorter than those of WZ Sge-type dwarf novae having supercycles of >~ 10 yr, which are a major population of dwarf novae in the shortest orbital period regime (<~85 min). Using a hierarchical cluster analysis, we identified seven groups of dwarf novae in the shortest orbital period regime. We identified a small group of objects that have short supercycles, small outburst amplitudes, and large superhump period excesses, compared with those of WZ Sge stars. OT J055717+683226 probably belongs to this group.Comment: 14 pages, 11 figures, accepted for publication in PAS

Physical properties of the Dome Fuji deep ice core (review)

Recent results of physical analyses of the Dome Fuji ice core are summarized with special attention to new methods introduced in the present studies. Microphysical processes which affect the ice core records are reviewed to better understand the paleoclimatic and paleoenvironmental signals stored