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Hsinchu, Taiwan

Lau Wk.,NSRRC | Huang Ny.,NSRRC | Lee Ap.,NSRRC | Wei Zy.,NTHU
FEL 2013: Proceedings of the 35th International Free-Electron Laser Conference | Year: 2013

The NSRRC ultrashort beam facility is a few tens MeV linac system for generation of GHz-repetition-rate femtosecond electron pulses. The electron source for this linac system is a 2998 MHz, thermionic cathode rf gun with on-axis coupled rf structure in which the longitudinal electric field profile is trimmed to optimize the electron distribution in longitudinal phase space. Bunch compression will be done in the rf linac during the early stage of beam acceleration by velocity bunching. With this femtosecond electron beam, generation of broadband coherent THz synchrotron radiations from bending magnet and narrow-band coherent radiation from undulator are being studied. Copyright © 2013 CC-BY-3.0 and by the respective authors.

Huang C.W.,NTHU | Lee S.-Y.,IUCEEM | Hwang C.-S.,NSRRC
IPAC 2014: Proceedings of the 5th International Particle Accelerator Conference | Year: 2014

Robinson wiggler is a special insertion device that can be used to decrease natural emittance of the Taiwan Photon Source (TPS) storage ring. This Robinson wiggler can change damping partition number and then affect the emittance. This study will evaluate practicability of reducing the emittance of TPS storage ring by Multi-period Robinson Wiggler (MRW) in the 7 m long straight section. One period of the traditional Robinson Wiggler include four poles with different field polarity. In the same length, the multi-period Robinson Wiggler has been over four poles in one set of Robinson Wiggler that is different from the traditional Robinson wiggler. Due to the traditional Robinson wiggler cannot be effective to improve emittance in TPS storage ring (the efficiency is only 7% with 6 straight sections). So we adopt to use multi-period Robinson Wiggler, the efficiency can be up to 30% with 6 straight sections, and the linear matching result is better than traditional Robinson Wiggler. Copyright © 2014 CC-BY-3.0 and by the respective authors.

Yaseen M.T.,NTHU | Yaseen M.T.,Academia Sinica, Taiwan | Chen M.,Academia Sinica, Taiwan | Chang Y.-C.,Academia Sinica, Taiwan | Chang Y.-C.,National Cheng Kung University
RSC Advances | Year: 2014

We investigate the surface enhanced Raman scattering (SERS) of biomolecules attached to partially embedded gold nanoislands in a transparent substrate. In order to generate SERS hot spots in a large area, partially-embedded gold nanoislands were fabricated via thermal annealing of a thin gold layer. The partially embedded gold nanoislands have average sizes varying from 10 nm to 50 nm. The SERS performance has been investigated for samples made with various thicknesses of gold thin film. The SERS spectra showed that a gold thin film with 4.5 nm initial thickness can produce the highest SERS signal due to the high density of uniform partially embedded gold nanoislands with average size around 22 nm. Furthermore, we perform numerical simulations based on rigorous coupled-wave analysis (RCWA) and finite difference time domain (FDTD) to show that the SERS enhancement originates from enhanced electric fields surrounding the partially embedded gold nanoislands. Hence, we have demonstrated a simple, stable, large-area, and low cost preparation process for producing a SERS platform with excellent sensitivity for biosensing. © 2014 The Royal Society of Chemistry.

Hsu H.-L.,National Taiwan University | Teng L.-J.,National Chiao Tung University | Chen Y.-C.,Institute of Electronics Engineering | Hsu W.-L.,NTHU | And 6 more authors.
Advanced Materials | Year: 2010

Carbon nanotubes were grown on flexible polylmide substrates at temperatures below 400°C as electrodes for extracellularly neuronal recording. The electrical charge-transfer and electrochemical properties of such CNT electrodes were enhanced by UV-ozone exposure, which induced the formation of C-O, C=O, and O-C=O bonds and reduced the CNT/ electrolyte Interfacial Impedance while increasing the interfacial capacitance. Figure presented © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.

Hsu Y.C.,NTHU | Sheu R.J.,NTHU
11th International Topical Meeting on Nuclear Applications of Accelerators, AccApp 2013 | Year: 2013

This study intends to predict the scope of neutron production and induced radioactivity for two therapy accelerators in Taiwan: 235 MeV proton and 400 MeV/A carbon ion accelerators. For radiation safety concern, much effort has been put into associated benchmark calculations to ensure the quality of predictions. Two Monte Carlo codes FLUKA and MCNPX were applied to calculate the neutron yield from beam bombardment. In addition, FLUKA was used to study the target activation by examining isotope inventory, residual activity, remnant dose rate, and their time behaviour. The calculated results were compared with experimental data published in literature. For the proton-induced neutron yield, FLUKA and MCNPX both well reproduce the measured results over the entire neutron energy range and for various emission angles. For the carbon-induced neutron yield, there exist larger discrepancies between calculations and measurements. Regarding activation related calculations, a factor of two or larger differences between calculations and measurements were observed due to some limitations of underlying nuclear models and uncertainties involved in comparisons. For practical considerations in radiation safety, this study can give us guidance and confidence in using these codes for shielding design and activation analysis of particle therapy accelerators.

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