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.     

Shangjr (Felix) Gwo Assumes NSRRC Directorship

Shangjr (Felix) Gwo, a professor of physics at National Tsing Hua University (NTHU), assumed directorship of the National Synchrotron Radiation Research Center (NSRRC), Taiwan, on August 1, 2014. The handover ceremony was hosted by the chairman of the NSRRC Board of Trustees, Lih J. Chen. Chen commented positively on Gwo's comprehensive administrative experience, outstanding scientific research, and superb talent in industrial cooperation and leadership.     

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.     

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.     

Taiwan Photon Source Delivers its Design Target with a Stored Current of 520 mA

After several months of upgrade work in the second phase of commissioning, the 3 GeV Taiwan Photon Source (TPS) of the National Synchrotron Radiation Research Center (NSRRC) successfully stored 520 mA of electron current, exceeding its design goal of 500 mA, in its storage ring on December 12, 2015. It is less than a year since the first light was achieved in the TPS store ring by using two room-temperature, five-cell PETRA radio frequency (RF) cavities.     

NSLS 2001 annual users' meeting workshops: Frontiers in structural biology at high-brightness X-ray sources

The Canadian Light Source (CLS) has made several significant strides since our official opening in October 2004. These have included the completion of the first seven beamlines, the arrival of users and their first scientific publications using CLS data, the commencement of design and initial construction of our second flight of seven beamlines, and proposals for up to another five experimental facilities. Canada's synchrotron has met or exceeded its performance targets projected for the first two years of operations and is poised to continue to make substantial progress as it grows into a mature, user-oriented facility.     

AOFSRR 2014 in Taiwan

The Asia-Oceania Forum for Synchrotron Radiation Research (AOFSRR) was formally established by Australia, China, Japan, South Korea, Singapore, Taiwan, and Thailand in 2006. Its objective is to strengthen the collaboration, as well as the inter-communication, among the synchrotron radiation facilities and to promote synchrotron radiation sciences and accelerator-based research in the Asia-Oceania region. Regular meetings have been organized to uphold its objective. The first scientific meeting of AOFSRR took place at KEK, Japan, in 2006. Member countries have been taking turns to organize meetings: Taiwan (NSRRC, 2007), Australia (Australian Synchrotron, 2008), China (SSRF, 2009), South Korea (POSTEC, 2010), Thailand (SLRI, 2012), and Japan (SPring-8, 2013). In 2014, the National Synchrotron Radiation Research Center (NSRRC) hosted the Eighth Asia-Oceania Forum for Synchrotron Radiation Research (AOFSRR 2014) from September 15th to 18th in Hsinchu, Taiwan. The NSRRC is located in the Hsinchu Science Park, within an hour's drive from Taipei, the largest city in Taiwan. Hsinchu is a city not only composed of historical landmarks but also the heartland of high-tech semiconductor industries in Taiwan.     

NSRRC Hosts the FEL Winter School

With continuous support from professors and scientists from the Stanford Linear Accelerator Center (SLAC), Indiana University, National Tsing Hua University, and National Chiao Tung University, the National Synchrotron Radiation Research Center (NSRRC) held the Free Electron Laser (FEL) Winter School on January 18–22, 2016, in Hsinchu, Taiwan for the fourth consecutive year. The five-day program was sponsored by the Physics Research Promotion Center (PRPC) under the Ministry of Science and Technology (MOST) and organized by the NSRRC. Thirty-four applicants were accepted, including 19 undergraduate students, 12 graduate students in master's programs, and three doctoral students.     

Status of the MAX IV Laboratory

On the day of the 2016 summer solstice, June 21, MAX IV, the new synchrotron radiation facility in Lund, Sweden, will be inaugurated. MAX IV is setting a new standard in terms of emittance, thereby providing beamlines with the best possible brilliance and coherence. At the same time, MAX IV continues a more than three-decades-long successful history of Swedish synchrotron-radiation-based research. The activities at the present MAX-lab, which officially started when the MAX I storage ring opened for users in 1986, have been concluded with a “last beamdump” ceremony for the MAX II and MAX III storage rings on December 13, 2015, Saint Lucy's Day. In Sweden, the winter solstice is celebrated with a festival of light.     

The impact of synchrotron radiation in protein crystallography

The Pohang Light Source (PLS) at the Pohang Accelerator Laboratory (PAL) is a third-generation light source, the only synchrotron radiation facility in Korea, and the fifth machine of its kind in the world (see Figure 1). In 1988, PAL was organized for the construction of the PLS. Ground-breaking was celebrated in 1991, and PLS construction was completed in 1994. In 1995, the PLS opened two beamlines to public users. The PLS was initially operated at 2.0 GeV in 1995. Since 2002, the energy of the electron beam has been upgraded to 2.5 GeV (see Table 1 for the principal parameters of PLS). Remarkable increases in the number of beamlines, users, and scientific results have been achieved since the opening of the PLS in 1995. Two or three beamlines have been added each year for the past 15 years, and as of February 2009 we have in total 27 beamlines in operation and 3 beamlines under construction, which will be completed by the end of 2009 (Figures 2 and 3).     

Commissioning of a multi‐beamline femtoslicing facility at SOLEIL

The investigation of ultrafast dynamics, taking place on the few to sub‐picosecond time scale, is today a very active research area pursued in a variety of scientific domains. With the recent advent of X‐ray free‐electron lasers (XFELs), providing very intense X‐ray pulses of duration as short as a few femtoseconds, this research field has gained further momentum. As a consequence, the demand for access strongly exceeds the capacity of the very few XFEL facilities existing worldwide. This situation motivates the development of alternative sub‐picosecond pulsed X‐ray sources among which femtoslicing facilities at synchrotron radiation storage rings are standing out due to their tunability over an extended photon energy range and their high stability. Following the success of the femtoslicing installations at ALS, BESSY‐II, SLS and UVSOR, SOLEIL decided to implement a femtoslicing facility. Several challenges were faced, including operation at the highest electron beam energy ever, and achievement of slice separation exclusively with the natural dispersion function of the storage ring. SOLEIL's setup also enables, for the first time, delivering sub‐picosecond pulses simultaneously to several beamlines. This last feature enlarges the experimental capabilities of the facility, which covers the soft and hard X‐ray photon energy range. In this paper, the commissioning of this original femtoslicing facility is reported. Furthermore, it is shown that the slicing‐induced THz signal can be used to derive a quantitative estimate for the degree of energy exchange between the femtosecond infrared laser pulse and the circulating electron bunch.     

Synchrotron radiation in archaeometry

January 2008 was the time of the official opening of SOLEIL's beamlines and guest house. This transition from construction to operational phase was made possible after commissioning of the 17°C water circuits of the beamlines. Users have access to eleven beamlines, from infrared to hard X-ray (AILES, SMIS, DESIRS, CASSIOPEE, TEMPO, DIFFABS, ODE, CRISTAL, SAMBA, PROXIMA1 and SWING). The LUCIA beamline, which has been operational on SLS since June 2004, will be installed at SOLEIL from mid-2008, and the XPEEM station of the future “soft X-ray microscopy” beamline is already producing fascinating XMCD and XMLD results at ELETTRA. Five beamlines are under construction.     

View from HAXPES 2015

As the complexity of scientific research methods and applications deepens, collaboration among accelerator laboratories on hard X-ray technology is focused on the realization of broader scientific applications. The International Conference on Hard X-ray Photoelectron Spectroscopy (HAXPES) held its first gathering at ESRF in France in 2003. In 2015, the NSRRC hosted the Sixth HAXPES in Taiwan on March 30–April 3.     

X‐ray position‐sensitive duo‐lateral diamond detectors at SOLEIL

The performance of a diamond X‐ray beam position monitor is reported. This detector consists of an ionization solid‐state chamber based on a thin single‐crystal chemical‐vapour‐deposition diamond with position‐sensitive resistive electrodes in a duo‐lateral configuration. The detector's linearity, homogeneity and responsivity were studied on beamlines at Synchrotron SOLEIL with various beam sizes, intensities and energies. These measurements demonstrate the large and homogeneous (absorption variation of less than 0.7% over 500 µm × 500 µm) active area of the detector, with linear responses independent of the X‐ray beam spatial distribution. Due to the excellent charge collection efficiency (approaching 100%) and intensity sensitivity (0.05%), the detector allows monitoring of the incident beam flux precisely. In addition, the in‐beam position resolution was compared with a theoretical analysis providing an estimation of the detector's beam position resolution capability depending on the experimental conditions (X‐ray flux, energy and readout acquisition time).     

Elettra Update

Elettra is an international multidisciplinary research center, specializing in synchrotron and free-electron laser radiation and their application in material science. The center (see Figure 1) is located on the outskirts of Trieste (Basovizza), Italy. Two advanced light sources are in operation: Elettra, the 12-cell, double-bend achromat, 259.2-m-circumference electron storage ring operating since 1993; and FERMI, the new seeded free electron laser (FEL) operating since 2010 and open to the users' community with three beamlines covering the spectral range from 100 to 4 nm. The presence of the two complementary facilities, both open to the international community, is a unique asset of the research center.     

Technical Report: Absolute Radiometric Calibration at NSLS

For nearly 20 years the U3c and X8a beamlines at the National Synchrotron Light Source (NSLS) have been used for absolute calibration and X-ray characterization of detectors and optics. The motivation behind this capability has been the need of the U.S. Department of Energy's National Nuclear Security Agency (DOE-NNSA) programs at other U.S. national laboratories (Livermore, Sandia, and Los Alamos) to provide diagnostics capabilities for high-temperature plasma physics experiments. For example, specific applications of regularly NSLS-calibrated diagnostics are found at Livermore's National Ignition Facility (NIF) and Sandia's Z machine.     

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.     

Partial widths and branching ratios for the emitted electron resulting from interatomic Coulombic decay in quantum wells heterostructure

Interatomic coulomb decay (ICD) is a decay process relying on the Coulombic interaction between neighbouring atoms, molecules or nanostructures. Due to this process, an electron is emitted into the continuum. We study the ICD process in a system of the double quantum well heterostructure and investigate how we can manipulate the structure's parameters such that a better detection of the ICD's emitted electron is achieved. For this purpose, we calculated the partial widths (PWs) and branching ratios (BRs) of the ICD's emitted electron to the left and right asymptotes of the heterostructure; these will give an estimation of the detection current. We manipulated the structure's parameters and took into account the repulsion from the electron in the ground state located in the left well. By introducing two small barriers in the vicinity of the right QW, we observed a BR three times larger than in the structure without the barriers. We also investigate the effect of repulsion due to the second electron. This work gives a better understanding of the dynamics of the scattered ICD's electron, and realisation of better design rules for future experimental observation of ICD in nanostructures.