Vol.31,

The proton beam with energy around 100 MeV has seen wide applications in modern scientific research and in various fields. However, proton sources in China fall short for meeting experimental needs owing to the vast size and expensive traditional proton accelerators. The Institute of Nuclear Science and Technology of Sichuan University proposed to build a 3 GHz side-coupled cavity linac (SCL) for re-accelerating a 26 MeV proton beam extracted from a CS-30 cyclotron to 120 MeV. We carried out investigations into several vital factors of S-band SCL for proton acceleration, such as optimization of SCL cavity geometry, end cell tuning, and bridge coupler design. Results demonstrated that the effective shunt impedance per unit length ranged from 22.5 to 59.8 MΩ/m throughout the acceleration process, and the acceleration gradient changed from 11.5 to 15.7 MV/m when the maximum surface electric field was equivalent to Kilpatrick electric field. We obtained equivalent circuit parameters of the biperiodic structures and applied them to the end cell tuning; results of the theoretical analysis agreed well with the 3D simulation. We designed and optimized a bridge coupler based on the previously obtained biperiodic structure parameters, and the field distribution un-uniformness was < 1.5% for a two-tank module. The radio frequency (RF) power distribution system of the linac was obtained based on the preliminary beam dynamics design.

848

An Fe-based nanocrystalline alloy powder is important for application in microwave absorption, and the particle size has a critical impact on the electromagnetic microwave parameters. Therefore, it is necessary to study further the effects of the particle size on such parameters and improve the microwave absorption performance of Fe-based nanocrystalline powers. In this study, Fe-B-P particles were prepared through a synthetic approach consisting of an aqueous chemical reduction and a ball milling treatment. We investigated the effects of ball milling on the microstructure and electromagnetic properties of Fe-B-P particles. The experimental results indicate that the Fe-B-P particles synthesized through an aqueous chemical reduction are amorphous spheres. Fe-B-P particles with an original particle size of 200–1,200 nm can be milled into an irregular shape with the size reduced to <500 nm after 0.5 h of ball milling, and subsequently, the particles become smaller with increases in the milling time, with traces of Fe₂O₃ generated on the particle surface. The results of the Mössbauer spectra show that a portion of the small particles demonstrate a superparamagnetic property. The volume proportions of the superparamagnetic component increase from 13.1% to 15.8% as the treatment time increases. We measured the permittivity and permeability spectra of Fe-B-P particles within the frequency range of 2–18 GHz. The reflection loss (R_L) is -10 dB for an absorber thickness of 1.7–5.0 mm. The R_L is -20 dB for an absorber thickness of 1.9–2.7 mm. The microwave absorption properties of samples with the same thickness are improved with an increase in the treatment time, and are shifted to a higher frequency, which will broaden the bandwidth of the absorption as well.

542

The China initiative Accelerator Driven System, CiADS, physics design adopts 162.5 MHz, 325 MHz, and 650 MHz cavities, which are driven by the corresponding radio frequency (RF) power system, requiring frequency translation front-end for the RF station. For that application, a general-purpose design front-end prototype has been developed to evaluate the multi-frequency point supported design feasibility. The difficult parts to achieve the requirements of the general-purpose design are reasonable device selection and balanced design. With a carefully selected low-noise wide-band RF mixer and amplifier to balance the performance of multi-frequency supported down-conversion, specially designed LO distribution net to increase isolation between adjacent channels, and external band-pass filter to realize expected up-conversion frequencies, high maintenance and modular front-end general-purpose design has been implemented. Results of standard parameters show an R² value of at least 99.991% in the range of -60-10 dBm for linearity, up to 18 dBm for P1dB, and up to 89 dBc for crosstalk between adjacent channels. The phase noise spectrum is lower than 80 dBc in the range of 0-1 MHz, and cumulative phase noise is 0.006°; amplitude and phase stability are 0.022

589

Ion bombardment analysis of perovskite materials is challenging owing to their peculiar structure. This shortcoming renders the reliability on the technique somewhat questionable. In this research, three structured modifications (i.e., scan angle, low energy, and large ion bombardment) were adopted to improve the ion bombardment analysis of 99,999 ions using Monte Carlo simulations. The modified technique was used to analyze the effects of a chemically pressurized "A" site in the perovskite lattice system. The LaCeTh_0.1Cu₂O_y compound was used in this experiment. Despite the low probing energy, it was observed that the high number of ions bombarding the material resulted in external pressure on the lattice structure of the material. Moreover, the chemically pressurized "A" site perovskite material was characterized by lattice mismatch, lattice fluctuations, grain boundary collapse, and oxygen displacement. The novel discovery of this research is the inter- and intra-extended lattice mismatches that are likely to connect. Hence, further investigation of the connection between inter- and intra-extended lattice mismatches is recommended as they may enable fabrication of room temperature superconductors.

645

Scintillation light from a liquid noble gas during a neutrino or dark matter experiment lies typically within the vacuum ultraviolet (VUV) region and might be strongly absorbed by surrounding materials such as light guides or photomultipliers. Tetraphenyl butadiene (TPB) is a fluorescent material and acts as a wavelength shifter (WLS), and can turn UV light into visible light at a peak wavelength of approximately 425 nm, enabling the light signals to be easily detected during physics studies. Compared with a traditional TPB coating method using vapor deposition, we propose an alternative technique applying a spin-coating procedure to facilitate the development of neutrino and dark matter detectors. This article introduces a method to fabricate a TPB film on an acrylic substrate by using a spin-coating method, reports the measurements of the sample film thickness and roughness, demonstrates the reemission spectrum, and quantifies the wavelength shifting efficiency.

450

Heat shock proteins (Hsp) are a family of abundantly expressed ATP-dependent chaperone proteins. Hsp90 is an eminent member of Hsp family. Thus far, two primary functions have been described for Hsp90: first, as a regulator of conformation change of some protein kinases and nuclear hormone receptors, and the other as an indispensable factor in cellular stress response. Hsp90 has an essential number of interaction proteins since it participates in almost every biological process and its importance is self-evident. Hsp90 has an inextricable relationship in the pathogenesis of cancer, especially in the proliferation and irradiation of cancer cells, thus, being a notable cancer target. Since the discovery of geldanamycin, the first inhibitor of Hsp90, from the bacterial species Streptomyces hygroscopicus, even more attention has been focused towards Hsp90. Many structure-based inhibitors of Hsp90 have been designed to develop an innovative method to defeat cancer. However, already designed inhibitors have various deficiencies, such as hepatotoxicity, poor aqueous solubility, instability, and non-ideal oral bioavailability. Based on the aforementioned reasons and to achieve an optimal performance and fewer side effects, we designed a novel inhibitor of Hsp90, called FS5, and resolved the crystal structure of the Hsp90^N-FS5 complex (1.65Å, PDB code 5XRB). Furthermore, we compared the complexes Hsp90^N, Hsp90^N-GDM, and Hsp90^N-ATP and suggest that the inhibitor FS5 may compete with ATP for binding to Hsp90, which can be regarded as a potential strategy for the development of novel cancer drugs in the future.

499

Accident-tolerant fuel (ATF) has attracted considerable research attention since the 2011 Fukushima nuclear disaster. To improve the accident tolerance of the fuel-cladding systems in the current light-water reactors (LWRs), it is proposed to develop and deploy (1) an enhanced Zr-based alloy or coated zircaloy for the fuel cladding, (2) alternative cladding materials with better accident tolerance, and (3) alternative fuels with enhanced accident tolerance and/or a higher U density. This review presents the features of the current UO₂-zircaloy system. Different techniques and characters to develop coating materials and enhanced Zr-based alloys are summarized. The features of several selected alternative fuels and cladding materials are reviewed and discussed. The neutronic evaluations of alternative fuel-cladding systems are analyzed. It is expected that one or more types of accident-tolerant fuel-cladding systems discussed in the present review will be implemented in commercial reactors.

833

The thin layer activation technique (TLA) is very effective in wear analysis for tribological systems where disassembly is costly or impractical. Since its development in the 1970s, TLA has been applied through direct irradiation of solid targets using ionizing particle beams to obtain an activation with a specific profile. This profile is then used to measure wear in a variety of experiments. These experiments rely heavily on how deep the normalized activation occurs. Depths of 30 μm to 50 μm are obtained for constant activation by the standard method, which for many experiments is sufficient. However, many others would benefit greatly from a 300 μm constant activation layer, such as high-performance engines, softer alloys (brakes), and oil transport systems. Achieving this aim was the goal of this paper. First, we needed to find an adequate irradiation line for the TLA technique. Then, another technique/system was developed (the Attenuation Wheel), which would bring the depth of constant activation from 50 μm to 300 μm.

469

A 1.5 GHz passive third harmonic superconducting cavity was proposed to improve the beam quality and lifetime in the Shanghai Synchrotron Radiation Facility Phase-II beamline project. Lifetime improvement highly depends on the resonant frequency of the passive third harmonic superconducting cavity. It is important that the operating frequency of the cavity is within the design range and the cavity has reasonable mechanical stability. A simulation method for the multiphysics coupled analysis has been developed based on the ANSYS code. Multiphysics coupled simulations have been performed under different conditions, such as etching, evacuation, cooling, and pre-loading. Analyses of mechanical modes and structural stress have been executed. A possible stiffening ring method for the two-cell superconducting niobium cavity has been investigated. In this paper, we present a multiphysics coupled analysis of the third harmonic cavity using a finite element analysis code. The results of the analysis show that a reliable frequency for the cavity after electron beam welding is 1498.033 MHz, and the corresponding frequency of the pre-tuning goal is 1496.163 MHz. A naked cavity is a reasonable option based on structural stress and mechanical modal analyses. A frequency range of ±500 kHz and limiting tolerable displacement of ±0.35 mm are proposed for the design of the frequency tuner.

503

A molten chloride salt fast reactor (MCFR) is well suited to fuel breeding and the transmutation of transuranium (TRU) elements owing to its advantageous features of fast neutron spectrum and high TRU solubility. However, the neutron absorption cross section of ³⁵Cl is approximately 1000 times greater than for ³⁷Cl, which has a significant impact on the neutron physical characteristics of a MCFR. Based on an automatic online refueling and reprocessing procedure, the influences of ³⁷Cl enrichment on neutron economy, breeding performance, and the production of harmful nuclides were analyzed. Results show that ³⁷Cl enrichment strongly influences the neutron properties of a MCFR. With natural chlorine, ²³³U breeding cannot be achieved and the yields of S and ³⁶Cl are very high. Increasing the ³⁷Cl enrichment to 97% brings a clear improvement in its neutronics property, making it almost equal to that corresponding to 100% enrichment. Moreover, when ³⁷Cl is enriched to 99%, its neutronics parameters are almost the same as for 100% enrichment. Considering the enrichment cost and the neutron properties, a ³⁷Cl enrichment of 97% is recommended. Achieving an optimal neutronics performance requires 99% ³⁷Cl enrichment.

469