Vol.35,

This study presents a new method for characterizing the thermal lattice deformation of a monochromator with high precision under service conditions and first reports the operando measurements of nanoscale thermal lattice deformation on a double-crystal monochromator at different incident powers. The nanoscale thermal lattice deformation of the monochromator first crystal was obtained by analyzing the intensity of the distorted DuMond diagrams. DuMond diagrams of the 333 diffraction index, sensitive to lattice deformation, were obtained directly using a 2D detector and an analyzer crystal orthogonal to the monochromator. With increasing incident power and power density, the maximum height of the lattice deformation increased from 3.2 nm to 18.5 nm, and the deformation coefficient of the maximum height increased from 1.1 nm/W to 3.2 nm/W. The maximum relative standard deviation was 4.2%, and the maximum standard deviation was 0.1 nm. Based on the measured thermal deformations, the flux saturation phenomenon and critical point for the linear operation of the monochromator were predicted with increasing incident power. This study provides a simple solution to the problem of the lower precision of synchrotron radiation monochromator characterizations compared to simulations.

684

The Shanghai Laser Electron Gamma Source (SLEGS, located in BL03SSID) beamline at the Shanghai Synchrotron Radiation Facility (SSRF) is a Laser Compton Scattering (LCS) gamma source used for the investigation of nuclear structure, which is in extensive demand in fields such as nuclear astrophysics, nuclear cluster structure, polarization physics, and nuclear energy. The beamline is based on the inverse Compton scattering of 10640 nm photons on 3.5 GeV electrons and a gamma source with variable energy by changing the scattering angle from 20° to 160°. γ-rays of 0.25–21.1 MeV can be extracted by the scheme consisting of the interaction chamber, coarse collimator, fine collimator, and attenuator. The maximum photon flux for 180° is approximately 10⁷ photons/s at the target at 21.7 MeV, with a 3-mm diameter beam. The beamline was equipped with four types of spectrometers for experiments in (γ,γ’), (γ,n), (γ,p), and (γ,α). At present, Nuclear Resonance Fluorescence (NRF) spectrometry, Flat Efficiency neutron Detector (FED) spectrometry, neutron time-of-flight (TOF) spectrometry, and light-charged particle (LCP) spectrometry methods have been developed.

658

The advantages of a flat-panel X-ray source (FPXS) make it a promising candidate for imaging applications. Accurate imaging-system modeling and projection simulation are critical for analyzing imaging performance and resolving overlapping projection issues in FPXS. The conventional analytical ray-tracing approach is limited by the number of patterns and is not applicable to FPXS-projection calculations. However, the computation time of Monte Carlo (MC) simulation is independent of the size of the patterned arrays in FPXS. This study proposes two high-efficiency MC projection simulators for FPXS: a graphics processing unit (GPU)-based phase-space sampling MC (gPSMC) simulator and GPU-based fluence sampling MC (gFSMC) simulator. The two simulators comprise three components: imaging-system modeling, photon initialization, and physical-interaction simulations in the phantom. Imaging-system modeling was performed by modeling the FPXS, imaging geometry, and detector. The gPSMC simulator samples the initial photons from the phase space, whereas the gFSMC simulator performs photon initialization from the calculated energy spectrum and fluence map. The entire process of photon interaction with the geometry and arrival at the detector was simulated in parallel using multiple GPU kernels, and projections based on the two simulators were calculated. The accuracies of the two simulators were evaluated by comparing them with the conventional analytical ray-tracing approach and acquired projections, and the efficiencies were evaluated by comparing the computation time. The results of simulated and realistic experiments illustrate the accuracy and efficiency of the proposed gPSMC and gFSMC simulators in the projection calculation of various phantoms.

526

BL02U2 of the Shanghai Synchrotron Radiation Facility (SSRF) is a surface diffraction beamline with a photon flux of 5.5 × 10¹² photons/s at 10 keV and a beam size of 160 µm ×80 µm at the sample site. It is dedicated to studying surfaces (solid–vacuum, solid–gas) and interfaces (solid–solid, solid–liquid, and liquid–liquid) in nanoscience, condensed matter, and soft matter systems using various surface scattering techniques over an energy range of 4.8–28 keV with transmission and reflection modes. Moreover, BL02U2 has a high energy resolution, high angular resolution, and low beam divergence, which can provide excellent properties for X-ray diffraction experiments, such as grazing incident X-ray diffraction, X-ray reflectivity, crystal truncation rods, and liquid X-ray scattering. Diversity of in-situ environments can also be provided for the samples studied. This paper describes the setup of the new beamline and its applications in various fields.

647

This paper details the development and testing of the first working prototype of the S-band high-power klystron, accomplished at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences (BINP SB RAS). Upon testing, the klystron demonstrated the following parameters: an operating frequency of 2856 MHz and a peak power output of 50 MW. The paper presents the klystron's design, its constituent units, and pertinent processing procedures, along with discussions on the measurement of its parameters.

819

A Laue microdiffraction beamline (BL03HB) was constructed at the Shanghai Synchrotron Radiation Facility (SSRF). This beamline features two consecutive focusing points in two different sectors within its end station, the first dedicated to protein crystallography and the other tailored to materials science applications. Based on a superbend dipole magnet with a magnetic field of 2.29 T, a two-stage focusing design was implemented with two sets of Kirkpatrick–Baez mirrors to achieve a micro white beam as small as 4.2 μm×4.3 μm at the first sector and 0.9 μm×1.3 μm at the second sector in the standard beamline operation mode at SSRF. The X-ray microbeam in the two sectors can be easily switched between monochromatic and white beams by moving a four-bounce monochromator in or out of the light path, respectively. In the protein crystallography sector, white-beam Laue microdiffraction was demonstrated to successfully determine the structure of protein crystals from only a few images of diffraction data collected by a Pilatus 2M area detector. In the materials science sector, the white-beam Laue diffraction was collected in a reflection geometry using another Pilatus 2M area detector, which could map the microstructural distribution on the sample surface by scanning the samples. In general, the BL03HB beamline promotes the application of Laue microdiffraction in both protein crystallography and materials science. This paper presents a comprehensive overview of the BL03HB beamline, end station, and the first commission results.

495

The hard X-ray nanoprobe beamline BL13U is a phase II beamline project at the Shanghai Synchrotron Radiation Facility. The beamline aims to enable comprehensive experiments at high spatial resolutions ranging from 50 to 10 nm. The X-ray energy range of the beamline, 5–25 keV, can detect most elements in the periodic table. Two operating modes were designed to accommodate the experimental requirements of high energy resolution or high photon flux, respectively. X-ray nanofluorescence, nanodiffraction, and coherent diffraction imaging are developed as the main experimental techniques for BL13U. This paper describes the beamline optics, end-station configurations, experimental methods under development, and preliminary test results. This comprehensive overview aims to provide a clear understanding of the beamline capabilities and potential applications.

697

Cone-beam computed tomography (CBCT) is mostly used for position verification during the treatment process. However, severe image artifacts in CBCT hinder its direct use in dose calculation and adaptive radiation therapy re-planning for proton therapy. In this study, an improved U-Net neural network named CBAM-U-Net was proposed for CBCT noise reduction in proton therapy, which is a CBCT denoised U-Net network with convolutional block attention modules. The datasets contained 20 groups of head and neck images. The CT images were registered to CBCT images as ground truth. The original CBCT denoised U-Net network, sCTU-Net, was trained for model performance comparison. The synthetic CT(SCT) images generated by CBAM-U-Net and the original sCTU-Net are called CBAM-SCT and U-Net-SCT images, respectively. The HU accuracies of the CT, CBCT, and SCT images were compared using four metrics: mean absolute error (MAE), root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structure similarity index measure (SSIM). The mean values of the MAE, RMSE, PSNR, and SSIM of CBAM-SCT images were 23.80 HU, 64.63 HU, 52.27 dB, and 0.9919, respectively, which were superior to those of the U-Net-SCT images. To evaluate dosimetric accuracy, the range accuracy was compared for a single-energy proton beam. The γ-index pass rates of a 4 cm × 4 cm scanned field and simple plan were calculated to compare the effects of the noise reduction capabilities of the original U-Net and CBAM-U-Net on the dose calculation results. CBAM-U-Net reduced noise more effectively than sCTU-Net, particularly in high-density tissues. We proposed a CBAM-U-Net model for CBCT noise reduction in proton therapy. Owing to the excellent noise reduction capabilities of CBAM-U-Net, the proposed model provided relatively explicit information regarding patient tissues. Moreover, it maybe be used in dose calculation and adaptive treatment planning in the future.

784

An ultrafast framing camera with a pulse-dilation device, a microchannel plate (MCP) imager, and an electronic imaging system were reported. The camera achieved a temporal resolution of 10 ps by using a pulse-dilation device and gated MCP imager, and a spatial resolution of 100 μm by using an electronic imaging system comprising combined magnetic lenses. The spatial resolution characteristics of the camera were studied both theoretically and experimentally. The results showed that the camera with combined magnetic lenses reduced the field curvature and acquired a larger working area. A working area with a diameter of 53 mm was created by applying four magnetic lenses to the camera. Furthermore, the camera was used to detect the X-rays produced by the laser-targeting device. The diagnostic results indicated that the width of the X-ray pulse was approximately 18 ps.

449

A resonant cavity based on the TM₀₁₀ mode is an effective tool for noninvasive beam characterization. This technique has the advantages of a high signal-to-noise ratio, compact structure, and is related to multiple parameters compared with other beam monitors. In this study, high-precision measurements of the bunch charge, arrival time, bunch length, and energy parameters based on the TM₀₁₀ mode are discussed. A cavity beam arrival time monitor (BAM) utilizing a phase cavity has been widely used in many facilities. Regarding bunch-length measurements, the influence of the beam energy, beam offset, and longitudinal spectrum on the TM₀₁₀ mode are carefully considered to reduce errors, and the theoretical resolution of two cavities with different frequencies is analyzed. Owing to the dependence of the beam velocity of the beam loss factor, this method can also be used for the detection low beam energy using two cavities with the same frequency but different cavity lengths. A set of three cavities with different lengths and frequencies of 1.902 GHz and 11.424 GHz is presented for measuring the four aforementioned parameters.

637

Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods. An abnormal radon exhalation behavior was observed, leading to computational fluid dynamics (CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered. Based on the in-situ experimental and numerical simulation results, variations in the radon exhalation rate subject to permeability, flow rate, and insertion depth were quantified and analyzed. The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method, which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements. The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium–air interface. The synergistic effects of the three factors (insertion depth, flow rate, and permeability) on the negative pressure difference and measured exhalation rate were quantified, and multivariate regression models were established, with positive correlations in most cases; the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^-11 m². CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.

758

We present a theoretical study of the medium modifications of the p_T balance (x_J) of dijets in Xe+Xe collisions at sNN=5.44 TeV. The initial production of dijets was carried out using the POWHEG+PYTHIA8 prescription, which matches the next-to-leading-order (NLO) QCD matrix elements with the parton shower (PS) effect. The SHELL model described the in-medium evolution of nucleus-nucleus collisions using a transport approach. The theoretical results of the dijet x_J in the Xe+Xe collisions exhibit more imbalanced distributions than those in the p+p collisions, consistent with recently reported ATLAS data. By utilizing the Interleaved Flavor Neutralisation, an infrared-and-collinear-safe jet flavor algorithm, to identify the flavor of the reconstructed jets, we classify dijets processes into three categories: gluon-gluon (gg), quark-gluon (qg), and quark-quark (qq), and investigated the respective medium modification patterns and fraction changes of the gg, qg, and qq components of the dijet sample in Xe+Xe collisions. It is shown that the increased fraction of qg component at a small x_J contributes to the imbalance of the dijet; in particular, the q₁g₂ (quark-jet-leading) dijets experience more significant asymmetric energy loss than the g₁q₂ (gluon-jet-leading) dijets traversing the QGP. By comparing the Δ〈xJ〉=〈xJ〉pp−〈xJ〉AA of inclusive, cc¯ and bb¯ dijets in Xe+Xe collisions, we observe Δ〈 xJ 〉incl.>Δ〈 xJ 〉cc¯>Δ〈 xJ 〉bb¯. Moreover, ρ_{Xe, Pb}, the ratios of the nuclear modification factors of dijets in Xe+Xe to those in Pb+Pb, were calculated, which indicates that the yield suppression of dijets in Pb+Pb is more pronounced than that in Xe+Xe owing to the larger radius of the lead nucleus.

482

900

In nuclear collisions at RHIC energies, an excess of Ω hyperons over Ω¯ is observed, indicating that Ω has a net baryon number despite s and s¯ quarks being produced in pairs. The baryon number in Ω may have been transported from the incident nuclei and/or produced in the baryon-pair production of Ω with other types of anti-hyperons such as Ξ¯. To investigate these two scenarios, we propose to measure the correlations between Ω and K and between Ω and anti-hyperons. We use two versions, the default and string-melting, of a multiphase transport (AMPT) model to illustrate the method for measuring the correlation and to demonstrate the general shape of the correlation. We present the Ω-hadron correlations from simulated Au+Au collisions at sNN=7.7 and 14.6 GeV and discuss the dependence on the collision energy and on the hadronization scheme in these two AMPT versions. These correlations can be used to explore the mechanism of baryon number transport and the effects of baryon number and strangeness conservation on nuclear collisions.

423

Chirality (Greek "handiness") is a property of many complex molecules. Chiral molecules exist in two forms, one being the mirror image of the other. Like for our hands, it is impossible to make the images identical by a suitable rotation. The two forms are called left-handed and right-handed. They have the same binding energy, because the electromagnetic interaction, which holds the molecule together, does not change under a reflection. Other properties that are insensitive to the geometry are also the same. The different geometry is the reason why the left-handed form turns the polarization plane of transmitted light in one direction by some angle while the right-handed form turns it in the opposite direction by the same angle. However, the geometrical differences between the two species may have other consequences. The two species of the carvon molecule shown in Fig. 1 taste quite differently.

636

We systematically studied the evaporation residue cross sections of ⁴⁸Ca-induced reactions on lanthanide and actinide target nuclei under the Dinuclear System (DNS) model framework to check the reliability and applicability of the model. To produce new proton-rich Fl and Lv isotopes through hot fusion reactions in the superheavy element region with Z≥104, we utilized the reactions ⁴⁸Ca+^236,238,239Pu and ⁴⁸Ca+^{242,243,244,250}Cm. However, owing to the detection limit of available equipment (0.1 pb), only ²⁸³Fl and ^287-289Lv, which have the maximum evaporation residue cross section values of 0.149, 0.130, 9.522, and 0.309 pb, respectively, can be produced. Furthermore, to produce neutron-deficient isotopes of actinides near the proton drip line with Z=93-100, we attempted to generate the new isotopes (^224-227Pu, ^228-232,237Cm) using the reactions ⁴⁸Ca+^{180, 182, 183}W and ⁴⁸Ca+^{184, 186, 187, 192}Os. The maximum evaporation residue cross section values are 0.07, 0.06, 0.26, and 0.30 nb for the former set of reactions, and 1.96 pb, 5.73 pb, 12.16 pb, 19.39 pb, 54.79 pb, and 6.45 nb for the latter, respectively. These results are expected to provide new information for the future synthesis of unknown neutron-deficient isotopes.

599

The medium-temperature T dependence of the jet transport coefficient q^ was studied via the nuclear modification factor R_AA(p_T) and elliptical flow parameter v₂(p_T) for large transverse momentum p_T hadrons in high-energy nucleus-nucleus collisions. Within a next-to-leading-order perturbative QCD parton model for hard scatterings with modified fragmentation functions due to jet quenching controlled by q^, we check the suppression and azimuthal anisotropy for large p_T hadrons, and extract q^ by global fits to R_AA(p_T) and v₂(p_T) data in A + A collisions at RHIC and LHC, respectively. The numerical results from the best fits show that q^/T3 goes down with local medium temperature T in the parton jet trajectory. Compared with the case of a constant q^/T3, the going-down T dependence of q^/T3 makes a hard parton jet to lose more energy near T_c and therefore strengthens the azimuthal anisotropy for large p_T hadrons. As a result, v₂(p_T) for large p_T hadrons was enhanced by approximately 10% to better fit the data at RHIC/LHC. Considering the first-order phase transition from QGP to the hadron phase and the additional energy loss in the hadron phase, v₂(p_T) is again enhanced by 5%-10% at RHIC/LHC.

784

The aim of this study is to evaluate the uncertainty of 2πα and 2πβ surface emission rates using the windowless multiwire proportional counter method. This study used the Monte Carlo method (MCM) to validate the conventional Guide to the Expression of Uncertainty in Measurement (GUM) method. A dead-time measurement model for the two-source method was established based on the characteristics of a single-channel measurement system, and the voltage threshold correction factor measurement function was indirectly obtained by fitting the threshold correction curve. The uncertainty in the surface emission rate was calculated using the GUM method and the law of propagation of uncertainty. The MCM provided clear definitions for each input quantity and its uncertainty distribution, and the simulation training was realized with a complete and complex mathematical model. The results of the surface emission rate uncertainty evaluation for four radioactive plane sources using both methods showed the uncertainty’s consistency E_n < 0.070 for the comparison of each source, and the uncertainty results of the GUM were all lower than those of the MCM. However, the MCM has a more objective evaluation process and can serve as a validation tool for GUM results.

505