Hefei National Synchrotron Radiation Laboratory Research Articles

Design and experiment of conduction cooling HTS current leads suited for superconducting Wiggler magnets

The cryogenic system of the 6T superconducting Wiggler magnets at the Hefei National Synchrotron Radiation Laboratory was upgraded. During the upgrade process, the original copper leads of the superconducting Wiggler magnets are replaced with two 460A high-temperature superconducting current leads and three 20A high-temperature superconducting current leads, reducing the heat load of the cryogenic system. Five HTS current leads can be cooled using a GM cryocooler based on the optimal design and experimental verification of their current-carrying capability and heat load. According to the loading current experimental data, the running voltage and operating temperature are stable. The results of the overcurrent capacity experiments demonstrate that the maximum loading current of the 20A high-temperature superconducting current lead can reach 142A and that of the 460A high-temperature superconducting current lead can reach 780A.

Super Tau-Charm Facility of China

The tau-charm region is one of the most important energy regions in the research of particle physics due to its unique properties, rich frontier topics and great potential for scientific discovery. In order to maintain our country's pioneering position in the tau-charm research field, we propose to build a new generation electron-positron collider—the Super Tau-Charm Facility (STCF), based on the Hefei National Synchrotron Radiation Laboratory, the State Key Laboratory of Particle Detection and Electronics, and other research platforms. The STCF would have a luminosity greater than 0.5×1035 cm-2 s-1, and a center-of-mass energy region of 2 to 7 GeV. Its performance is expected to be significantly better than the currently running BEPCII, and will provide a key platform for exploring the asymmetry of matter-antimatter (charge parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as the quest for exotic particles and physics beyond the standard model. The construction of STCF poses a great challenge to the existing accelerator and detector technologies in China, but is very important scientifically and strategically not only for fundamental scientific research but also for the development of new technology and the cultivation of comprehensive expertise.

A threshold photoelectron-photoion coincidence spectrometer with double velocity imaging using synchrotron radiation

A novel threshold photoelectron-photoion coincidence (TPEPICO) imaging spectrometer at the U14-A beamline of the Hefei National Synchrotron Radiation Laboratory is presented. A set of open electron and ion lenses are utilized to map velocity imaging of photoelectrons and photoions simultaneously, in which a repelling electric field using an extra lens is applied to magnify images of photoelectrons instead of traditional accelerating electric field in order to suppress the contribution of energetic electrons in the threshold photoelectron spectroscopy (TPES) and the mass-selected TPEPICO spectroscopy. The typical energy resolution of TPES is measured to be 9 meV (full width at half maximum), as shown on the (2)P(1/2) ionization of argon. The measured mass resolving power for the present TPEPICO imaging spectrometer is above 900 of M/DeltaM. Subsequently as a benchmark, oxygen molecule is photoionized by monochromatic synchrotron radiation at 20.298 eV and dissociates to an oxygen atomic ion and a neutral oxygen atom, and the translation energy distribution of oxygen atomic ion is measured by the time-sliced imaging based on mass-selected TPEPICO experiment. The kinetic energy resolution of the present ion velocity imaging is better than 3% of DeltaE/E.

Soft X-ray holographic microscopy with 300 nm resolution

x--ray in-line holograms are recorded in photoresist at Hefei National Synchrotron Radiation Laboratory. An Atomic Force Microscope(AFM) is used to read the X-ray holograms recorded on photoresist PMMA. Digitized hologram is reconstructed by numerical method. The granules with a size less than 300 nm can be resolved in the reconstructed image. So,the estimated resolution reaches the level of 300 nm.

The design of the beamline for magnetic circular dichroism study at HNSRL

A synchrotron radiation beamline for MCD study is being developed at Hefei National Synchrotron Radiation Laboratory (HNSRL) in the P. R. China. As a key component on the beamline, the varied line-spacing plane grating (VLSPG) monochromator is designed to cover a broad photon energy range from 100 to 1000 eV with a medium energy resolving power of 2000. The design is analyzed and optimized to meet the high requirements of MCD studying.

The first x-ray lithography beamline at Hefei National Synchrotron Radiation Laboratory

An x‐ray lithography beamline, the first of six planned at Hefei National Synchrotron Radiation Laboratory (HESYRL), was completed and installed in the summer of 1989. A scanning mirror, the key optical component of the beamline, is used to cut off shorter wavelength light and to expand the vertical dimension of the exposure beam. It is oscillated by a stepping motor, while an in situ Moire fringe grating system measures the uniformity of the motor speed. Downstream after the front end section of the beamline, a Be window is used to block longer wavelength light. A laser alignment system is used to align the beamline with a He‐Ne laser. A special exposure shutter controlled by a second stepping motor can define the exposure time. An exposure chamber in which the vacuum can reach 5×10−7 Torr is located 7 m downstream from the synchrotron radiation source. Since the chamber does not include a vacuum window, a differential pumping system has been installed upstream from the exposure chamber. Test results of ...

Optics on a synchrotron radiation soft X-ray microscopy beamline and its dispersing components in Hefei

A modified optical design for a synchrotron radiation (SR) soft X-ray scanning microscopy beamline at Hefei National Synchrotron Radiation laboratory (HESYRL) has been done. On the beamline the main component is a linear monochromator which consists of a diaphragm with a diameter of 7 µm and a condenser zone plate (CZP). The CZP is selected from among three condenser zone plates with different parameters for the following three overlapping wavelength ranges: 1.97-2.78 nm, 2.74-3.87 nm, and 3.84-5.44 nm. Estimating the flux losses from the pinhole source to the end spot for 2.3 nm, for example, a photon flux of 3.1 × 105 photons/s can be achieved at the end spot from a 150 mA current and a high brightness configuration at HESYRL.Parameters of three kinds of CZPs are presented as a compromise to a variety of requirements from the experimenters. In addition, the thickness of some CZP layers, such as polyimide and gold, are calculated to be optimal. Finally, the processing steps for CZP fabrication at HESYRL are described briefly.

Lithography beamline design and exposure uniformity controlling and measuring

The lithography beamline design of Hefei National Synchrotron Radiation Laboratory is presented. A scanning mirror is used to cut off short wavelength radiation and to expand the vertical exposure dimension to 50 mm. A thin beryllium window is installed before the scanning mirror to prevent the longer wavelength radiation from going through. An exposure chamber with a vacuum of 5×10E−7 Torr is located at 7 m downstream from the source point. Because there is no window at the entrance of the chamber, a differential pumping system is used. The scanning mirror is driven by a stepping motor which oscillates through a 1° angle. The required driving speed curve is determined by a computer in order to obtain a uniform exposure area. An in situ moiré fringe grating system is used to measure the uniformity of the motor speed.

200-MeV LINAC—injector of storage ring for HESYRL

The 200-MeV electron linac at the Hefei National Synchrotron Radiation Laboratory (HESYRL) is described. It is not only an injector of the 800-MeV storage ring, but an electron accelerator used for nuclear physics experiments and some other applications as well. The main design parameters and measuring results of the LINAC are given. The linac is a travelling wave structure, operating at a frequency of 2856 MHz, constant impedance, in a 2/3π mode. Its total length is about 35 m. Five klystrons are used as rf power; each klystron will provide 15 MW. In November 1987, the machine was successfully commissioned and typical operating parameters are 220 MeV, and 50 mA with an energy spread of ±0.8%.

Hefei National Synchrotron Radiation Laboratory

The Hefei Synchrotron Radiation Laboratory attached to the University of Science and Technology of China is a dedicated VUV and soft X-ray synchrotron radiation light source. In the present work the design of the machine is presented and the main parameters listed.