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We investigate a possibility of precision measurements for parameters of the Littlest Higgs model with T-parity at the International Linear Collider (ILC).The model predicts new gauge bosons (A H , Z H , and W H ), among which the heavy photon (A H ) is a candidate for dark matter. The masses of these new gauge bosons strongly depend on the vacuum expectation value that breaks a global symmetry of the model. Through Monte Carlo simulations of the processes: e + e − → A H Z H and e + e − → W + H W − H , we show how precisely the masses can be determined at the ILC for a representative parameter point of the model. We also discuss the determination of the Little Higgs parameters and its impact on the future measurement of the thermal abundance of the dark matter relics in our universe.

Scintillators are key components in high-energy x-ray detectors for x-ray computed tomography, which are applied in medical diagnosis, nondestructive testing, and security inspection. Scintillators in x-ray imaging are required to have both high spatial resolution and sensitivity; however, a trade-off between spatial resolution and sensitivity exists. To improve the sensitivity of a scintillator, its thickness must be increased; however, spatial resolution deteriorates with increasing thickness. Here, we developed a well-aligned Tb-doped GdAlO3- αAl2O3 phase-separated scintillator fiber (PSSF) with a diameter of 1.25- μm by a micro-pulling-down method. The luminescence, scintillation, and imaging performances of a grown PSSF sample were evaluated. X-ray-induced radioluminescence measurements of the sample showed Tb3+ 4f–4f emissions in the wavelength range of 470–700 nm, and the maximum emission peak was at 550 nm. The contrast transfer function at 10 lp/mm was 82% for both 270 and 500 μm-thick PSSF samples. We calculated the luminescence index, which is the product of the scintillator’s light yield and sensitivity, of the samples and compared their values with commercially available conventional CsI:Tl columnar scintillators. The Tb-doped GdAlO3- αAl2O3 PSSF exhibits higher contrast transfer function and luminescence index values at above 60 keV x-ray region compared with the tested conventional scintillators.

In recent years, thermal neutron detection using scintillators has been used in a wide range of fields. Thus, the development of scintillators with a higher light yield, faster decay, and higher sensitivity for thermal neutrons is required. In this study, K2CeCl5/6LiCl and CeCl3/SrCl2/6LiCl were developed as novel eutectic scintillators for thermal neutron detection. LiCl was selected as the neutron capture phase and K2CeCl5 and CeCl3 were used as the scintillator phases. The eutectics of K2CeCl5/6LiCl and CeCl3/SrCl2/6LiCl were prepared using the Vertical Bridgman method and the phases were identified by scanning electron microscopy and powder X-ray diffraction measurements. The results of radioluminescence measurements under Ag source X-ray tube irradiation confirmed that the 5d-4f emission derived from Ce3+. The cathodoluminescence spectra and thermal neutron responses of the prepared eutectics were measured to evaluate their optical properties.