First Synchrotron Light of Taiwan Photon Source

On the last day of 2014, the newly completed second accelerator of the National Synchrotron Radiation Research Center (NSRRC), Taiwan Photon Source (TPS), delivered its first synchrotron light in the early afternoon. The electron beam energy of the TPS circulating in the storage ring has reached the design value of 3 GeV, and the stored beam current has achieved over 5 mA, marking a significant milestone for Taiwan's new synchrotron light source. After nearly five years of construction and development efforts in full scale, the successful commissioning of TPS will forever change the course of scientific research in Taiwan.     

NSRRC Holds Dedication Ceremony for the Taiwan Photon Source's New Experimental Facility

More than 300 participants, including nearly 50 invited guests, attended the dedication ceremony for the Taiwan Photon Source's (TPS) new experimental facility at the National Synchrotron Radiation Research Center (NSRRC) on September 19, 2016. The special ceremony marked an important milestone that will dramatically change the course of Taiwan's scientific advancement in the coming years. Since the successful commissioning of the synchrotron accelerator TPS on New Year's Eve in 2015, the NSRRC has constructed an additional seven beamlines during Phase I of the TPS Experimental Facility Construction Project in order to channel an electron beam of 3 billion electron volts (GeV) away from the circular TPS storage ring into the experimental target samples. The ceremony, inaugurated by President Ing-Wen Tsai, officially announced the availability of these beamlines to scientific users worldwide.     

Progress of the Injector Linac Upgrade for the BEPCⅡ Project

BEPCⅡ—an upgrade project of Beijing Electron Positron Collider (BEPC) is a factory type of e+e- collider. It requires its injector linac to have a higher beam energy (1.89 GeV) for on-energy injection and a higher beam current (40 mA e+ beam) for a higher injection rate ( 50 mA/min). The low beam emittance (1.6π mm·mrad for e+ beam, and 0.2πmm·mrad for 300 mA e- beam) and the low beam energy spread (±0.5%) are also required to meet the storage ring acceptance. Thus the original BEPC injector linac must be upgraded to have a new electron gun with its complete tuning system, a new positron source with a flux concentrator, a new RF power system with its phasing loops and a new beam tuning system with orbit correction and optics tuning devices. These new components have been designed, fabricated, tested and will be installed in their final positions in this spring and summer, which are described in this paper.     

BEPCⅡ:construction and commissioning

This is a status report of the project on befalf of the BEPC Ⅱ team.BEPC Ⅱ is a major upgrade radiation(SR)source with its outer ring,or SR ring.As a collider,BEPC Ⅱ operates in the beam energy region of 1-2.3 GeV with design luminosity of 1×1033 cm-2s-1 at 1.89 GeV.As a light source.the SR ring operates at 2.5 GeV and 250 mA.Construction of the project started in the beginning of 2004.Installation of the storage ring components was completed in October 2007.Commissioning is in progress.There are still many issues for further studies before reach to 3×1032 cm-2s-1.     

Twenty-First NSRRC Users' Meeting and Workshops

The Twenty-First NSRRC Users' Meeting was held at the Activity Center of the National Synchrotron Radiation Research Center (NSRRC) in Taiwan from September 9 to 10, 2015. At the same time, celebration of the first light of the Taiwan Photon Source (TPS), achieved at the end of 2014, highlighted the prospective scientific frontiers marked by the TPS storage ring. Jointly organized by the UEC Chair Ying-Hao Chu (National Chiao Tung Univ.) and Cheng-Maw Cheng (NSRRC), the meeting consisted of two plenary sessions and three featured workshops. Nearly 30 distinguished scholars, both domestic and international, were invited to present their research achievements. This highly anticipated event attracted an enthusiastic crowd of more than 370 synchrotron experts, users, and potential users.     

From NEXAFS spectroscopy to new flat panel displays: A story of basic science with technological impact

The Twentieth NSRRC Users' Meeting was held successfully at the National Synchrotron Radiation Research Center (NSRRC) in Taiwan from September 10th to 12th, 2014. The three-day meeting was the first such event to be held at the newly furnished Activity Center on the NSRRC campus, celebrating 20 years since the first NSRRC Users' Meeting and highlighting the prospective scientific frontiers marked by the newly established Taiwan Photon Source (TPS) storage ring.     

BEPCII Injector Linac Upgrade and Beam Instabilities

The upgrade project of the Beijing Electron Positron Collider （BEPCII） and its injector linac is working well. The linac upgrade aims at a higher injection rate of 5OmA/min into the storage ring, which requires an injected beam with low emittance, low energy spread and high beam orbit and energy stabilities. This goal is finally reached recently by upgrading the linac components and by dealing with rich and practical beam physics, which are described in this study.     

普洱茶及其原料多糖分子组成及光谱学特性研究

研究了普洱茶发酵过程中多糖分子组成及光谱学特性的变化规律。结果显示,普洱茶及其原料多糖主要组分TPS1和TPS2的分子组成及光谱学特性差异显著。TPS2含有较高糖醛酸,而TPS1含有较高的中性糖和蛋白质。TPS1和TPS2均由半乳糖(Gal)、阿拉伯糖(Arb)、甘露糖(Man)、葡萄糖(Glu)、木糖(Xyl)、鼠李糖(Rha)六种单糖组成,其分子摩尔比分别为23.6∶5.9∶24.2∶1.1∶1.8∶3.2和26.9∶3.2∶19.3∶5.5∶1.3∶2.7。TPS2和TPS1的重均分子量分别为1.68×104和1.21×104道尔顿。TPS1和TPS2水溶液在200～400 nm之间无特征吸收峰。红外光谱图显示,TPS1和TPS2的信息基本相同,都是含有吡喃环的多糖。在三维AFM图中,TPS1形成的聚集体高度约为4 nm, 长宽约为0.2～0.4 μm,TPS2形成的聚集体高度约为40 nm,长宽约为0.5～0.8 μm。SEM图片显示,TPS1呈表面光滑的鳞片状聚集体,TPS2呈表面粗糙的片状聚集体。引起普洱茶及其原料多糖分子组成及光谱学性质发生变化的动力主要为微生物作用和湿热作用。     

半导体光纤环形激光器输出状态分析与分类

研究了不同注入电流、不同输出偏振度下,半导体光纤环形激光器输出光的混沌特性.分别采用时域观察法、C-C法、Wigner-ville分布时频分析法、最大Lyapunov指数法联合分析输出光的时域、频域统计特性.从而将激光器输出按偏振度划分为三类:偏振度在0%到20%,随着电流的增大,激光器输出偏振混沌激光,其类型发生阶跃性跳变;偏振度在30～80%,激光器输出仍以偏振混沌激光为主,其类型不随电流增大而发生跳变;偏振度趋于90～100%,激光器输出以强度混沌激光为主,偏振混沌光随着偏振度趋向100%而下降为零.利用虚假邻点法计算嵌入维数和回归图法重构吸引子,得到上述三种输出类型的复杂程度依次是:椭圆吸引子(6维)、方形吸引子(7维)、点形吸引子(5维).由此得出,半导体光纤环形激光器用于偏振混沌通信的最佳区域为:偏振度处于30%至80%,注入电流处于330 mA～550 mA.     

Twinning-plane superconductivity

A new phenomenon has been discovered recently: twinning-plane superconductivity (TPS). The present paper is a survey of experimental and theoretical work on TPS. TPS arises at temperatures higher than the bulk critical temperature of a single crystal, and has a localized character. This phenomenon is caused by Cooper-pairing enhancement near the twinning plane. TPS is characterized by anomalously strong diamagnetism above the critical point. The phase (H, T) diagram of TPS is very specific and differs noticeably for type-I and type-II superconductors (e.g. tin and niobium). The interaction of closely spaced twinning planes is discussed, as well as the case of TPS in microscopic particles. The proximity effect is shown to be reduced under these conditions, and the critical temperature noticeably increased (by a factor of two to three times for tin). The prospects for further investigations of TPS are considered.     

Novel internal target for electron scattering off unstable nuclei

A novel internal target has been developed, which will make electron scattering off short-lived radioactive nuclei possible in an electron storage ring. An "ion trapping" phenomenon in the electron storage ring was successfully utilized for the first time to form the target for electron scattering. Approximately 7 x 10(6) stable 133Cs ions were trapped along the electron beam axis for 85 ms at an electron beam current of 80 mA. The collision luminosity between the stored electrons and trapped Cs ions was determined to be 2.4(8) x 10(25) cm(-2) s(-1) by measuring elastically scattered electrons.     

Magnetoelectric effect from the direct coupling of the Lorentz force from a brass ring with transverse piezoelectricity in a lead zirconate titanate (PZT) disk

A novel composite of brass ring and PZT disk shows a high dc magnetic field (H_dc) response when using the product effect of the Lorentz force effect from a metal ring in a dc magnetic field applied with ac electrical current, and the piezoelectric effect of piezoelectric material. The output voltage between the two faces of PZT shows a good linear response to the dc magnetic field (<1 kOe) under different ac electrical current inputs (<300 mA). The magnetoelectric coefficient is about ∼33.2 mV/T A. Simultaneously, the magnitude of its magnetoelectric coefficient can be manually controlled by an applied electrical current. This composite has the potential for applications in magnetoelectric transducers and sensors that work without coils even for static magnetic fields. PACS 85.80.Jm; 77.84.-S; 75.80.+q; 77.84.Dy; 77.65.-j     

红外探测器TPS434低温、磁场性能研究

以商用高灵敏度红外探测器TPS434为研究对象,测量了其灵敏度随温度(280～10 K)、辐射的调制频率、磁场变化(0～6 T)的相关信息。从实验结果得到：TPS434的灵敏度随着温度降低而降低,随辐射的调制频率增加而衰减,但是低温下的衰减速率变缓,说明探测器的弛豫时间变短;热电堆的温差电动势在低温下会随磁场发生线性变化,可以通过线性拟合扣除磁场对测量结果的影响。由实验所得数据估算等效噪声功率NEP以及最小可检测功率Pmin,对TPS434作为THz探测器的可行性进行了分析。     

合肥电子储存环束流不稳定性的抑制

合肥光源二期工程改造的电子储存环调试过程中,发现多束团存储和运行时存在耦合束团不稳定性,严重地限制了注入的最高流强,并且影响了光源运行的质量。通过过正地增大正色品以及在储存环上插入八极磁铁,基本上抑制了横向的耦合束团不稳定性,保证了稳定注入束流300 mA的技术指标。     

合肥光源储存环上八极磁铁的动力学效应分析

 为达到合肥光源二期工程通用模式的设计流强，在储存环上选择垂直方向β函数比较大的位置增加一组八极磁铁。该组八极磁铁对水平方向动力学孔径影响很小，虽然垂直方向动力学孔径明显减小，但仍然大于物理孔径，不会影响束流的注入积累过程。该组八极磁铁产生的垂直方向振荡频率分散可以提供ms量级的Landau阻尼时间，将明显增强抑制垂直方向束流集体不稳定性的能力。该组八极磁铁投入运行后，合肥光源注入积累过程明显改善，注入流强从无八极磁铁时的约100 mA提高到330 mA左右。     

合肥电子储存环束流不稳定性的抑制

 合肥光源二期工程改造的电子储存环调试过程中,发现多束团存储和运行时存在耦合束团不稳定性,严重地限制了注入的最高流强,并且影响了光源运行的质量。通过过正地增大正色品以及在储存环上插入八极磁铁,基本上抑制了横向的耦合束团不稳定性,保证了稳定注入束流300 mA的技术指标。     

Selective ablation-assisted two-photon stereolithography for effective nano- and microfabrication

The two-photon stereolithography (TPS) process has strong merits for the direct fabrication of 2-D and 3-D microstructures with sub-100-nm resolution. In this paper, we report an effective fabrication process in which selective ablation-assisted TPS (SA-TPS) was used to ameliorate some of the limitations of the TPS process. In SA-TPS, two processes (namely, an additive process of two-photon induced photocuring and a subtractive process of selective laser ablation) were performed sequentially using a single femtosecond laser optical scanning system. The effectiveness of the proposed process was demonstrated in several applications, including precise high-resolution patterning at resolution levels higher than those achievable using the TPS process, and the fabrication of structures with high mechanical sensitivity.     

Wavelength tunability of L-band fiber ring lasers using mechanically induced long-period fiber gratings

We report on oscillation wavelength control in erbium-doped fiber ring lasers by adjusting the period of a mechanically induced long-period fiber grating (LPFG) inserted into the fiber ring resonator. Pump light is provided by a 974 nm laser diode (LD), the emission of which is coupled into the fiber ring resonator through a wavelength-division multiplexing coupler. Laser oscillation occurs with a threshold pump LD current of 40 mA, corresponding to a threshold pump power of 5 mW. When a periodic pressure of 0.81 N/mm is applied to form the LPFG, the fiber ring laser exhibits the tunable range of 40.9 nm, i.e., from 1563.1 to 1604 nm, by changing the grating period.     

Discussions about FFT-based two-step phase-shifting algorithm

An FFT-based two-step phase-shifting (TPS) algorithm is described in detail and implemented by use of experimental interferograms. This algorithm has been proposed to solve the TPS problem with random phase shift except π. By comparison with the visibility-function-based TPS algorithm, it proves that the FFT-based algorithm has obvious advantages in phase extracting. Meanwhile, we present a π-phase-shift supplement to the TPS algorithm, which combines the two interferograms and demodulates the phase map by locating the extrema of the combined fringes after removing the respective backgrounds. So combining this method and FFT-based one, one could really implement the TPS with random phase shift. Whereafter, we systematically compare the TPS with single-interferogram analysis algorithm and conventional three-step phase-shifting one. The results demonstrate that the FFT-based TPS algorithm has a satisfactory accuracy. At last, based on the polarizing interferometry, a schematic setup of two-channel TPS interferometer with random phase shift is suggested to implement the simultaneous collection of interferograms.     

The exploration of magnetic photo-excited states using organometallic spin couplers based on the silole ring

The photoexcited states of the 1,1-dimethyl-2,3,4,5-tetraphenylsilole (TPS) and of the bis(tertiobutylnitroxide)-substituted TPS (TPS-TNO) have been studied using optical and time-resolved electron spin resonance (TRESR) spectroscopic methods. The TPS-TNO was designed and synthesized with in mind to achieve the photo-induced spin alignment which has been observed with anthracene-based radicals [3] and [4]. Although a photoexcited triplet state has been characterized for the TPS coupler, TPS-TNO did not show any signal arising from photoexcited states. This result may come from a very short lifetime of the photoexcited high spin states as a result of the attachment of radicals to TPS or from the very low efficiency of the intersystem crossing.