Machine learning for beam correction study of the injection beamline at Wuhan Advanced Light Source

关键词: Beam correction; Injection transfer beamline; Machine learning; Beam dynamics; Invertible neural network;

DOI：10.12074/202503.00066

提交时间： 2025-03-10

摘要：        As a fourth-generation synchrotron radiation light source working at 1.5 GeV, Wuhan Advanced Light Source (WALS) is being designed, which uses a full-energy linear accelerator (LINAC) as its electron beam injector. The injection beamline adopts a three-stage scheme: firstly, the beam from the LINAC that is 6 m under the storage ring is horizontally deflected below the storage ring, then it gradually climbs from underground to the same altitude as the storage ring, and finally the beam is delivered horizontally into the injection straight section inside the storage ring. Meanwhile, the Twiss parameter matching between the LINAC and storage ring is completed. During the construction of the beamline, magnet manufacturing errors, installation errors and beam injection errors from the LINAC will cause beam deviations from predetermined ideal orbits, and even particle losses. As a result, the electron beam correction is required during beam commissioning. Different from the single-direction beam correction of general transfer lines, the horizontal and vertical directions of the beam are coupled in the WALS injection transfer line, which greatly increases the complexity and difficulty of beam correction. Machine learning technology has been developed extensively in recent years, and its powerful algorithm of invertible neural network model is expected to be able to solve the beam commissioning difficulty of the beam injection transfer line at the WALS. Therefore, an invertible neural network model has been designed and trained to simulate the beam transport and beam correction of the WALS injection beamline. By optimizing the number and location of beam profile diagnostics, the accuracy of bidirectional prediction and beam correction effect can be greatly improved. The method is of great practical significance for the commissioning and operation of similar complex beam transport systems.

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Exploring the synthesis of key superheavy nuclei using 40Ar as the projectile?

关键词: Keywords:; Superheavy; nuclei; ; Dinuclear; system; model; ; Heavy-ion; fusion;

DOI：10.12074/202503.00065

提交时间： 2025-03-08

摘要：This paper provides a comprehensive analysis of all stages of the heavy-ion fusion evaporation reaction,
aiming to enhance the understanding of the entire process and identify the influencing factors in calculating
the evaporation residue cross-section. By focusing on the synthesis of superheavy nuclei with Z = 114, we
discuss the capture cross-section, fusion probability, and survival probability of the 48Ca + 244 Pu reaction and
compare them with those of the 40Ar+ 248 Cm reaction. Moreover, a systematic study examined the evaporation
residue cross-sections for the synthesis of superheavy nuclei with Z = 112 − 116 using 40Ar as the projectile
nucleus. The results indicate that utilizing 40Ar as the projectile nucleus for synthesizing isotopes with Z = 114
offers advantages such as lower incident energy and reduced experimental costs. Furthermore, using 40Ar as
the projectile nucleus enables the synthesis of a new key isotope, 285115, thereby facilitating its identification.

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Comparison of displacement damage effects on the dark signal in CMOS image sensors induced by CSNS back-n and XAPR neutrons

关键词: Displacement damage effects; CMOS image sensor (CIS); CSNS back-n; XAPR neutrons; Geant4; dark signal non-uniformity (DSNU);

DOI：10.12074/202406.00266V1

提交时间： 2024-06-10

摘要：This study investigates the effects of displacement damage on the dark signal of a pinned photodiode CMOS image sensor (CIS) following irradiation with back-streaming white neutrons from white neutron sources at the China Spallation Neutron Source (CSNS) and Xi’an Pulsed Reactor (XAPR). The mean dark signal, dark signal non-uniformity (DSNU), dark signal distribution, and hot pixels of the CIS were compared between the CSNS back-n and XAPR neutron irradiations. The non-ionizing energy loss and energy distribution of primary knock on atoms in silicon, induced by neutrons, were calculated using the open-source package Geant4. An analysis combining experimental and simulation results showed a noticeable proportionality between the increase in the mean dark signal and the displacement damage dose (DDD). Additionally, neutron energies influence DSNU, dark signal distribution, and hot pixels. High neutron energies at the same DDD level may lead to pronounced dark signal non-uniformity and elevated hot pixel values.
 

点击量 1629 下载量 380 评论 0

Improved mass relations of mirror nuclei

关键词: Nuclear mass; Mirror nuclei; Proton-rich nuclei;

提交时间： 2024-06-04

摘要：In this study, we revisit the previous mass relations of mirror nuclei by considering 1/N- and 1/Z-dependent terms and the shell effect across a shell. The root-mean-squared deviation is 66 keV for 116 nuclei with neutron number N ≥ 10, as compared with experimental data compiled in the AME2020 database. The predicted mass excesses of 173 proton-rich nuclei, including 98 unknown nuclei, are tabulated in the Supplemental Material herein with competitive accuracy.

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The medium temperature dependence of jet transport coefficient in high-energy nucleus-nucleus collisions

关键词: Jet quenching; jet transport parameter; hadron suppression; elliptic flow coefficient; energy loss asymmetry;

DOI：10.12074/202406.00097V1

提交时间： 2024-06-03

摘要：The medium temperature $T$ dependence of jet transport coefficient $ hat q$ is studied via nuclear modification factor $R_{AA}(p_{ rm T})$ and elliptical flow parameter $v_2(p_{ rm T})$ for large transverse momentum $p_{ rm T}$ 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 $ hat q$, we check the suppression as well as the azimuthal anisotropy for large $p_{ rm T}$ hadrons, and extract $ hat q$ by global fits to $R_{AA}(p_{ rm T})$ and $v_2(p_{ rm T})$ data in $A+A$ collisions at RHIC and the LHC, respectively. Numerical results from the best fits show that $ hat q/T^3$ goes down with the local medium temperature $T$ in the parton jet trajectory. Compared with the case of a constant $ hat{q}/T^3$, the going-down $T$ dependence of $ hat{q}/T^3$ makes a hard parton jet to lose more energy near $T_c$ and therefore strengthens the azimuthal anisotropy for large $p_{ rm T}$ hadrons. As a result, $v_2(p_{ rm T})$ for large $p_{ rm T}$ hadrons is enhanced by about 10 % to fit data better at RHIC/LHC. Considering the first-order phase transition from QGP to the hadron phase and additional energy loss in the hadron phase, $v_2(p_{ rm T})$ is again enhanced by 5-10 % at RHIC/LHC.

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Simulation and reconstruction of particle trajectories in the CEPC drift chamber

关键词: CEPC; Drift chamber; Detector simulation; Track reconstruction;

DOI：10.12074/202406.00031V1

提交时间： 2024-06-02

摘要：The Circular Electron Positron Collider (CEPC) is designed to precisely measure the properties of the Higgs boson, study electroweak interactions at the Z-boson peak, and search for new physics beyond the Standard Model. As a component of the 4^th Conceptual CEPC detector, the drift chamber facilitates the measurement of  charged particles. This study implemented a Geant4-based simulation and track reconstruction for the drift chamber. For the simulation, detector construction and response were implemented and added to the CEPC simulation chain. The development of track reconstruction involved track finding using the Combinatorial Kalman Filter method and track fitting using the tool of GenFit. Using the simulated data, the tracking performance was studied. The results showed that both the reconstruction resolution and tracking efficiency satisfied the requirements of the CEPC experiment.

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Cone-beam computed tomography noise reduction method based on U-Net with convolutional block attention module in proton therapy

关键词: proton therapy; cone beam CT; CBAM-U-Net; γ-index;

提交时间： 2024-05-30

摘要：Cone-beam computed tomography (CBCT) is mostly used for position verification during the treatment pro#2;
cess. 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 con#2;
volutional 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 can be used in dose calculation
and adaptive treatment planning in the future.

点击量 1967 下载量 586 评论 0

Impact of initial fluctuations and nuclear deformations in isobar collisions

关键词: Relativistic isobar collisions; multiplicity; eccentricity;

DOI：10.12074/202405.00334V1

提交时间： 2024-05-30

摘要：Relativistic isobar ($^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr) collisions have revealed intricate differences in their nuclear size and shape, inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions. In this study, we investigate the relative differences in the mean multiplicity ($R_{ langle N_{ rm ch} rangle}$) and the second- ($R_{ epsilon_{2}}$) and third-order eccentricity ($R_{ epsilon_{3}}$) between isobar collisions using Optical and Monte Carlo Glauber models. It is found that initial fluctuations and nuclear deformations have negligible effects on $R_{ langle N_{ rm ch} rangle}$ in most central collisions, while both are important for the $R_{ epsilon_{2}}$ and $R_{ epsilon_{3}}$, the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom. These features, compared to real data, may probe the particle production mechanism and the physics underlying nuclear structure.

点击量 1705 下载量 385 评论 0

Method for detector description conversion from DD4hep to Filmbox

关键词: Detector description; DD4hep; FBX; Geometry; Offline software;

DOI：10.12074/202405.00335V1

提交时间： 2024-05-30

摘要：DD4hep serves as a generic detector de Conversely, Filmbox~(FBX) stands out as a widely used 3D modeling file format within the 3D software industry.
In this paper, we introduce a novel method that can automatically convert complex HEP detector geometries from DD4hep de The feasibility of this method was demonstrated by its application to the DD4hep de The automatic DD4hep--FBX detector conversion interface provides convenience for further development of applications, such as detector design, simulation, visualization, data monitoring, and outreach, in HEP experiments. 
 

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Fast X-ray Imaging Beamline at SSRF

关键词: multiple time-scale X-ray imaging; single-pulse X-ray imaging; dynamic 2D imaging; dynamic micro-CT;

DOI：10.12074/202405.00336V1

提交时间： 2024-05-29

摘要：The fast X-ray imaging beamline (BL16U2) at Shanghai Synchrotron Radiation Facility (SSRF) is a new beamline that provides X-ray micro-imaging capabilities across a wide range of time scales, spanning from 100 ps to μs and ms. This beamline has been specifically designed to facilitate the investigation of a wide range of rapid phenomena, such as the deformation and failure of materials subjected to intense dynamic loads. In addition, it enables the study of high-pressure and high-speed fuel spray processes in automotive engines. The light source of this beamline is a cryogenic permanent magnet undulator (CPMU) that is cooled by liquid nitrogen. This CPMU can generate X-ray photons within an energy range of 8.7-30 keV. The beamline offers two modes of operation: monochromatic beam mode with a liquid nitrogen-cooled double-crystal monochromator (DCM) and pink beam mode with the first crystal of the DCM out of the beam path. Four X-ray imaging methods were implemented in BL16U2: single-pulse ultrafast X-ray imaging, microsecond-resolved X-ray dynamic imaging, millisecond-resolved X-ray dynamic micro-CT, and high-resolution quantitative micro-CT. Furthermore, BL16U2 is equipped with various in situ impact loading systems, such as a split Hopkinson bar system, light gas gun, and fuel spray chamber. Following the completion of the final commissioning in 2021 and subsequent trial operations in 2022, the beamline has been officially available to users from 2023.

点击量 2697 下载量 749 评论 0

Structure and 2p decay mechanism of $^{18}Mg$

关键词: Structure of 18Mg; Two-proton decay; Proton–proton correlation;

DOI：10.12074/202405.00317V1

提交时间： 2024-05-24

摘要：The recently discovered, extremely proton-rich nuclide ¹⁸Mg exhibits ground-state decay via two sequential two-proton (2p) emissions through the intermediate nucleus, ¹⁶Ne. This study investigates the structure and the initial 2p decay mechanism of ¹⁸Mg by examining the density and correlations of the valence protons using a three-body Gamow-coupled-channel method. The results show that the ground state of ¹⁸Mg is significantly influenced by the continuum, resulting in a significant s-wave component. However, based on the current frame- work, this does not lead to a significant deviation in mirror symmetry in either the structure or spectroscopy of the ¹⁸Mg-¹⁸C pair. Additionally, the time evolution analysis of the ¹⁸Mg ground state suggests a simultaneous 2p emission during the first step of decay. The observed nucleon–nucleon correlations align with those of the light–mass 2p emitters, indicating a consistent decay behavior within this nuclear region.

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Design and high power testing of offline conditioning cavity for CiADS RFQ high power coupler

关键词: RFQ 腔体; 功率耦合器; 离线锻炼; 谐振腔;

DOI：10.12074/202405.00318V1

提交时间： 2024-05-23

摘要：为验证RFQ腔体功率输入耦合器设计的合理性和减少腔体污染，设计了低损耗离线锻炼腔体，并进行了高功率试验。离线锻炼腔由两个耦合口和两个调谐器口组成。此外，耦合环的安装角度和调谐器的插入深度可以用来低腔体的功率损耗。对该离线锻炼腔体进行了电磁结构和多物理场模拟，结果表明该腔体的最小理论功率损耗为4.3%。当腔体频率变化为110kHz时，理论功率损耗增加到10%。因此，调谐器在调节过程中始终处于运动状态。多物理场模拟表明，腔体温度的升高对频率变化没有影响。当离线高功率锻炼平台建成后，测量了该系统的传输性能，功率损耗为6.3%，大于理论计算值。高功率离线锻炼采用了高效的自动扫福和驻波谐振锻炼方法。为了充分锻炼高功率输入耦合器，选择了13个驻波点。最大连续波功率大于20kW，优于预期目标。

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Development of a MWDC prototype of the CSR external-target experiment

关键词: CEE ; MWDC ; Garfield++ ; 55Fe source ; Position resolution;

DOI：10.12074/202405.00254V1

提交时间： 2024-05-21

摘要：The cooling storage ring (CSR) external-target experiment (CEE) is a spectrometer used in construction to study the properties of nuclear matter in high-baryon density regions at the Heavy-Ion Research Facility in Lanzhou (HIRFL). This study presents the design, simulation, manufacturing, and testing of a half-size prototype of a multi-wire drift chamber (MWDC) for the CEE. First, the performance of the MWDC connected to home-made electronics was simulated. The results demonstrated that an energy resolution of 18.5% for 5.9-keV X-rays and a position resolution of 194 um for protons can be achieved by the current design. Because the size of the largest MWDC reached 176 × 314 cm, a set of 98 × 98 cm prototypes was built using the new techniques. The positioning accuracy of the anode wires in this prototype exceeded 20 um. After optimization using commercially available electronic devices, the prototype achieved an energy resolution of 19.7% for a 55Fe X-ray source. The CEE-MWDC detector and electronics were simultaneously tested. An energy resolution of 22% was achieved for the 55Fe source; the track residuals were approximately 330 um for the cosmic rays. The results demonstrate that the current design and techniques meet the requirements of the CEE-MWDC array.

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Development of an enhanced online tritium monitoring system using plastic scintillation fiber array

关键词: Tritium; Plastic scintillating fiber array; Detector;

DOI：10.12074/202405.00255V1

提交时间： 2024-05-20

摘要：Tritium, a radioactive nuclide discharged by nuclear power plants, poses challenges for removal. Continuous online monitoring of tritium in water is crucial for real-time radiation data, given its predominant existence in the environment as water. This paper presents the design, simulation, and development of a tritium monitoring device utilizing a plastic scintillation fiber (PSF) array. Experimental validation confirmed the device’s detection efficiency and minimum detectable activity. The recorded detection efficiency of the device is 1.6 × 10−3 , which exceeds the theoretically simulated value of 4 × 10−4 by four times. Without shielding, the device can achieve a minimum detectable activity of 3165 Bq L−1 over a 1600-second measurement duration. According to simulation and experimental results, enhancing detection efficiency is possible by increasing the number and length of PSFs and implementing rigorous shielding measures. Additionally, reducing the diameter of PSFs can also improve detection efficiency. The minimum detectable activity of the device can be further reduced using the aforementioned methods.

点击量 2576 下载量 623 评论 0

Sustainability-oriented prioritization of nuclear fuel cycle transitions in China: A holistic MCDM framework under uncertainties

关键词: Nuclear energy systems; Nuclear fuel cycle; Fuzzy AHP; PROMETHEE-GAIA;

DOI：10.12074/202405.00246V1

提交时间： 2024-05-17

摘要：A sustainability-oriented assessment of the nuclear energy system can provide informative and convincing decision-making support for nuclear development strategies in China. In our previous study, four authentic nuclear fuel cycle (NFC) transition scenarios were proposed, featuring different development stages and exhibiting distinct environmental, economic, and technical characteristics. However, because of the multiple and often conflicting criteria embedded therein, determining the top-priority NFC alternative for a sustainability orientation remains challenging. To address this issue, this study proposed a novel hybrid multi-criteria decision-making framework comprising fuzzy Analytic Hierarchy Process (AHP), Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE)-Geometrical Analysis for Interactive Aid (GAIA), and MOORA. Initially, an improved fuzzy AHP weighting model was developed to determine criteria weights under uncertainty and investigate the influence of various weight aggregation and defuzzification approaches. Subsequently, PROMETHEE-GAIA was used to address conflicts among the criteria and prioritize alternatives on a visualized k-dimensional GAIA plane. As a result, the alternative for direct recycling pressurized water reactor spent fuel in fast reactors is considered the most sustainable. Furthermore, a sensitivity analysis was conducted to examine the influence of criteria weight variation and validate the screening results. Finally, using MOORA, some significant optimization ideas and valuable insights were provided to support decision-makers in shaping nuclear development strategies.

点击量 2254 下载量 467 评论 0

Passive Neutron Multiplicity Device for 240Pu Measurement Based on FPGA

关键词: Spent fuel; Non-destructive assay; Neutron multiplicity; 240Pu; FPGA;

DOI：10.12074/202405.00248V1

提交时间： 2024-05-17

摘要：A passive neutron multiplicity measurement device, FH-NCM/S1, based on field-programmable gate arrays
(FPGAs), is developed specifically for measuring the mass of plutonium-240 (240Pu) in mixed oxide fuel. FHNCM/
S1 adopts an integrated approach, combining the shift-register analysis mode with the pulse-position
timestamp mode using an FPGA. The optimal effective length of the 3He neutron detector was determined to
be 30 cm, and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations.
After fabricating the device, calibration measurements were performed using a 252Cf neutron source; a detection
efficiency of 43.07% and detector die-away time of 55.79 μs were observed. Nine samples of plutonium
oxide were measured under identical conditions using the FH-NCM/S1 in shift-register analysis mode and a
plutonium-waste multiplicity counter. The obtained double rates underwent corrections for detection efficiency
(ε) and double gate fraction (f d), resulting in corrected double rates (Dc), which were used to validate the accuracy
of the shift-register analysis mode. Furthermore, the device exhibited fluctuations in the measurement
results, and within a single 20-s measurement, these fluctuations remained below 10%. After 30 cycles, the
relative error in the mass of 240Pu was less than 5%. Finally, correlation calculations confirmed the robust
consistency of both measurement modes. This study holds specific significance for the subsequent design and
development of neutron multiplicity devices.

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The Dynamics Beamline at SSRF

关键词: ED-XAS; SR-IR; Time-Resolved; D-Line; SSRF;

DOI：10.12074/202405.00118V1

提交时间： 2024-05-11

摘要：The Dynamics beamline (D-Line), which combines synchrotron radiation infrared spectroscopy (SR-IR) and energy-dispersive X-ray absorption spectroscopy (ED-XAS), is the first beamline in the world to realize concurrent ED-XAS and SR-IR measurements at the same sample position on a millisecond time-resolved scale. This combined technique is effective for investigating rapid structural changes in atoms, electrons, and molecules in complicated disorder systems, such as those used in physics, chemistry, materials science, and extreme conditions. Moreover, ED-XAS and SR-IR can be used independently in the two branches of the D-Line. The ED-XAS branch is the first ED-XAS beamline in China, which uses a tapered undulator light source and can achieve approximately 2.5 × 1012 photons/s•300 eV BW@7.2 keV at the sample position. An exchangeable polychromator operating in the Bragg-reflection or Laue-transmission configuration is used in different energy ranges to satisfy the requirements for beam size and energy resolution. The focused beam size is approximately 3.5 μm (H) × 21.5 μm (V), and the X-ray energy range is 5–25 keV. Using one- and two-dimensional position-sensitive detectors with frame rates of up to 400 kHz enables time resolutions of tens of microseconds to be realized. Several distinctive techniques, such as the concurrent measurement of in-situ ED-XAS and infrared spectroscopy, time-resolved ED-XAS, high-pressure ED-XAS, XMCD, and pump–probe ED-XAS, can be applied to achieve different scientific goals.

点击量 2240 下载量 583 评论 0

Efficient and selective removal of Pb(II) from landfill leachate using L-serine-modified polyethylene/polypropylene nonwoven fabric synthesized via radiation grafting technique

关键词: Landfill leachate; Radiation grafting; Polyethylene/polypropylene nonwoven fabric; Pb(II) removal;

DOI：10.12074/202405.00059V1

提交时间： 2024-05-08

摘要：In this study, to efficiently remove Pb(II) from aqueous environments, a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent (NWF-serine) was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification. The effect of the absorbed dose was investigated in the range of 5–50 kGy. NWF-serine was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Batch adsorption tests were conducted to investigate the influences of pH, adsorption time, temperature, initial concentration, and sorbent dosage on the Pb(II) adsorption performance of NWF-serine. The results indicated that Pb(II) adsorption onto NWF-serine was an endothermic process, following the pseudo-second-order kinetic model and Langmuir isotherm model. The saturated adsorption capacity was 198.1 mg/g. NWF-serine exhibited Pb(II) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd, Cu, Ni, Mn, and Zn. Furthermore, NWF-serine maintained 86% of its Pb(II) uptake after five use cycles. The coordination of the carboxyl and amino groups with Pb(II) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.

点击量 2596 下载量 760 评论 0

One-neutron stripping process in the 209Bi(6Li, 5Li)210Bi* reaction

关键词: transfer reaction; weakly bound nuclei; cross section;

DOI：10.12074/202404.00320V1

提交时间： 2024-04-29

摘要：One-neutron stripping process between 6Li and 209Bi was studied at 28, 30, and 34 MeV using the in-beam γ-ray spectroscopy method. The γ-γ coincident analysis clearly identified two γ-rays feeding the ground and long-lived isomeric states, which were employed to determine the cross section. The one-neutron stripping cross sections were similar to the cross sections of complete fusion in the 6Li+209Bi system, but the one-neutron stripping cross sections decreased more gradually at the sub-barrier region. A coupled-reaction-channel calculation was performed to study the detailed reaction mechanism of the one-neutron stripping process in 6Li. The calculations indicated that the first excited state of 5Li is critical in the actual one-neutron transfer mechanism, and the valence proton of 209Bi can be excited to the low-lying excited state in (6Li, 5Li) reaction, unlike in the (d,p) reaction.

点击量 2157 下载量 483 评论 0

Ultrahard X-ray Multifunctional Application Beamline at the SSRF

关键词: Shanghai Synchrotron Radiation Facility; ultra-hard X-ray; high energy diffraction; high energy imaging; engineering materials; earth science;

提交时间： 2024-04-29

摘要：The Ultrahard X-ray Multifunctional Application Beamline (BL12SW) is one of the Phase-II Beamline Projects at the Shanghai Synchrotron Radiation Facility. The primary X-ray techniques used at the beamline are high-energy X-ray diffraction and imaging using white and monochromatic light. The main scientific objectives of ultrahard X-ray beamline are focused on two research areas. One is the study of the structural properties of Earth’s interior and new materials under extreme high-temperature and high-pressure conditions, and the other is the characterization of materials and processes in near-real service environments. The beamline utilizes a superconducting wiggler as the light source, with two diamond windows and SiC discs to filter out low-energy light (primarily below 30 keV) and a Cu filter assembly to control the thermal load entering the subsequent optical components. The beamline is equipped with dual monochromators. The first was a meridional bending Laue monochromator cooled by liquid nitrogen, achieving a full-energy coverage of 30–162 keV. The second was a sagittal bending Laue monochromator installed in an external building, providing a focused beam in the horizontal direction with an energy range of 60–120 keV. There were four experimental hutches: two large volume press (LVP) experimental hutches (LVP1 and LVP2) and two engineering material (ENG) experimental hutches (ENG1 and ENG2). Each hutch was equipped with various near-real service conditions to satisfy different requirements. For example, LVP1 and LVP2 were equipped with a 200-ton DDIA press and a 2000-ton dual-mode (DDIA and Kawai) press, respectively. ENG1 and ENG2 provide in-situ tensile, creep, and fatigue tests as well as high-temperature conditions. Since June 2023, the BL12SW has been in trial operation. It is expected to officially open to users by early 2024.

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