A mid-infrared free electron laser (MIR-FEL) (5 – 20 µm) facility (KU-FEL: Kyoto University Free Electron Laser) was constructed to aid various energy science researchers at the Institute of Advanced Energy, Kyoto University. In May 2008, the first power saturation at 13.2 µm was achieved. A pilot application to evaluate selective phonon excitation processes in solid materials by irradiating with MIR-FEL was implemented, and a preliminary experiment without FEL irradiation was conducted. N-doped silicon carbide (SiC) was selected as a sample material due to its unique electrical property where the lattice vibration and the electronic structure are coupled. Two peaks, 1.8 – 2.2 eV and 2.4 – 2.8 eV, which showed strong temperature dependences in both their intensities and peak energies, were observed. These tendencies could be explained by using a donor-acceptor pair luminescence (DAP) model with impurity and defects in the SiC sample. The results imply that we can verify selective phonon excitation by investigating the change in the PL spectrum introduced by MIR-FEL irradiation.

A use of bulk high-temperature superconductors (HTSs) for an undulator is attractive since a high magnetic field can be generated at low-temperatures. While potential for generation of the high magnetic field is high, in-situ magnetization of the bulk HTSs for periodic field generation is challenging issue. Recently, we proposed a new type of undulator using bulk high-Tc superconductors (HTS) and a solenoid magnet. The undulator, named Bulk HTSC staggered array undulator (Bulk HTSC SAU), consists of a stacked array of bulk HTSs and copper insulators and a solenoid magnet. A proof of principle experiment at 77 K using liquid nitrogen has been carried out. The estimated performance at about 30 K was estimated using results of property measurements for the HTS used for the Bulk HTSC SAU. The expected undulator peak field reaches to 1.08 T for undulator period length of 9.9 mm for the undulator gap of 4.0 mm. This performance is about 2 times higher than that of existing technologies.

A use of bulk high-temperature superconductors (HTSs) for an undulator is attractive since a high magnetic field can be generated at low-temperatures. While potential for generation of the high magnetic field is high, in-situ magnetization of the bulk HTSs for periodic field generation is challenging issue. Recently, we proposed a new type of undulator using bulk high-Tc superconductors (HTS) and a solenoid magnet. The undulator, named Bulk HTSC staggered array undulator (Bulk HTSC SAU), consists of a stacked array of bulk HTSs and copper insulators and a solenoid magnet. A proof of principle experiment at 77 K using liquid nitrogen has been carried out. The estimated performance at about 30 K was estimated using results of property measurements for the HTS used for the Bulk HTSC SAU. The expected undulator peak field reaches to 1.08 T for undulator period length of 9.9 mm for the undulator gap of 4.0 mm. This performance is about 2 times higher than that of existing technologies.

We have designed a relatively simple, compact and powerful THz-FEL (terahertz free electron laser) amplifier in Kyoto University. The target wavelength range of the amplifier is 150–340 m, corresponding to 0.5-1.1 THz. The system consists of 1.6 cell photocathode radio frequency (RF) gun, THz wave parametric generator, focusing solenoid, transport line, and 120 cm long undulator with 30 periods. A start-to-end simulation in the institute of advanced energy Kyoto University has been conducted to estimate the performance of the designed system. Tracking of the electron beam from the photocathode RF gun up to the undulator entrance has been done using Parmela code while Genesis 1.3 code has been used to estimate the FEL interaction in the undulator. For feasibility study the FEL temporal distribution at resonance wavelength 186 m was determined. The results show that 1250% amplification could be achieved in the resonance wavelength in the present design compared with the seed THz power. Details of the design and calculation conditions together with the performance test are presented in this paper.

The performance of LaBr3(Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussed in terms of limits of detection and in comparison with high-purity germanium (HPGe) detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity γ-ray Source (HIγS) facility. The incident γ-rays, of 2.12 MeV energy, hit a B4C target to excite the 11B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate the background and enhance the limits of detection for the spectra measured with LaBr3(Ce). Both detection and determination limits were deduced from the experimental data.

The performance of LaBr3(Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussed in terms of limits of detection and in comparison with high-purity germanium (HPGe) detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity γ-ray Source (HIγS) facility. The incident γ-rays, of 2.12 MeV energy, hit a B4C target to excite the 11B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate the background and enhance the limits of detection for the spectra measured with LaBr3(Ce). Both detection and determination limits were deduced from the experimental data.

The performance of LaBr3(Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussed in terms of limits of detection and in comparison with high-purity germanium (HPGe) detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity γ-ray Source (HIγS) facility. The incident γ-rays, of 2.12 MeV energy, hit a B4C target to excite the 11B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate the background and enhance the limits of detection for the spectra measured with LaBr3(Ce). Both detection and determination limits were deduced from the experimental data.

High brightness photoinjectors for superconducting linac-based FELs are developed, optimized and characterized at the Photo Injector Test facility at DESY in Zeuthen (PITZ). Last year the facility was significantly upgraded with a new prototype photocathode laser system capable of producing homogeneous ellipsoidal pulses. Previous simulations have shown that the corresponding pulses allow the production of high brightness electron bunches with minimized emittance. Furthermore, a new normal conducting RF gun cavity was installed with a modified two-window waveguide RF feed layout for stability and reliability tests, as required for the European XFEL. Other relevant additions to the facility include beamline modifications for improved electron beam transport through the PITZ accelerator, refinement of both the cooling and RF systems for improved parameter stability, and preparations for the installation of a plasma cell. This paper describes the facility upgrades and reports on the operational experience with the new components.

Production of electron bunches with extremely small transverse emittance is the focus of the PITZ (Photo Injector Test facility at DESY in Zeuthen) scientific program. PITZ is one of the leading laboratories on generation and optimization of high brightness electron bunches with different charges for free electron laser (FEL) machines such as FLASH and the European XFEL. In 2011 using a photocathode laser with a flattop temporal profile, PITZ has revealed record low transverse properties emittance values at different bunch charges. However, further improvement of beam quality with smaller emittance is foreseen using a cathode laser system, capable of producing 3D ellipsoidal bunches. Numerical simulations were performed to study and compare the beam dynamics of electron beams produced with 3D ellipsoidal and flattop laser profiles. Different bunch charges from 20 pC up to 4 nC are considered in the simulation, in order to find an optimum PITZ machine setup which yields the lowest transverse emittance. In the present paper, the simulation setup, conditions, and results of the comparison are presented and discussed.

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