分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2025-02-10
摘要： 7 over multiple past decades,leading to a deeper understanding8of theintrinsicinteractions constituting thefieldsofParticle9 and Astroparticle Physics.Although important results have10 been acquired by indirect (ground-based) experiments over11theyears,there is an imminentneed toexplore highly ener-12 getic CR particles from GeV up to PeV and gamma-rays via13 direct observations, carried out by space-borne instruments.14The High Energy cosmic Radiation Detector (HERD）is15 a prominent space-borne instrument to be installed on-board16 the Chinese Space Station (CSS) around 2027 [3,4].The17 main scientific objectives of HERD include the search for sig-18 nals of dark matter annihilation products, precise cosmic ray19 spectrum and composition measurements up to the knee en-20 ergy, and high energy gamma-ray monitoring and survey [5-217].ThedatagatheredfromtheHERDdetectorscanprovide22valuableinformationfor developingradiation shielding tech-23nologies andmitigating therisksposedbycosmicradiation24 during long-duration space missions.The HERD project also25holds significantimplications for fundamentalphysicsre26search.Bystudyingthepropertiesofcosmicrays,researchers27 can probe the boundaries of particle physics.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-02-03
摘要： components must operate in environments with high temper-atures,stresses,irradiation,andhydrogen concentrations[1-6]andmaydevelopnanocracks.Therefore,theirsafeopera-tionrequiresanunderstanding of thestabilizationbehaviorofthesenanocracks athigh temperatures.Alalloyshavea smallthermal neutron absorption cross-section,excellent plasticity,favorable thermal conductivity,and machinability,and arewidelyappliedinnuclearreactorcladdingshells andpressurevessels [1,2].The best candidate metal for the first wall isWowingtoitshighmeltingpoint,high-temperaturestrength.high thermal conductivity, and resistance to irradiation dam-age [3,4].However, the harsh,high-temperature,high-stress,and highly corrosive environment inside reactors requires Aland W alloys with exceptional stability and strength.Al-thoughTiis commonlyused tostore nuclearwaste,itis sus-ceptible to grain boundary (GB)embrittlement [5].In thisstudy, Al, W, and Ti alloys were investigated to understandTi with microstructures that resist deformation,cracking,andfailure (e.g., crack initiation,propagation, and extension)have been successfully developed [1-5]. However, few stud-ing.For example,stress-driven GB migration,which mayoriginate from inhomogeneous stresses,is widely observed innanocrystallinemetals;thisGBmigration canpromotecrackhealing [6].If localized compressive stresses drive crackhealing at the GBs, then concentrated tensile stresses near theGBs may damage the structure inthis vicinity;that is,crackhealing requires a stable structure that can store additionalenergy[4, 5]. The GB crack healing is closely related to GBmigration;therefore,the stability and characteristics of thismigration should be investigated.The complementary pro-cessofhigh-temperature-drivenmicrostructuralevolution canalso promote GB crack healing; the disappearance of GB mi-crocracksisdrivenbyatomicdiffusion after atomsbreakGBcrackbonds athigh temperatures[6-9].However,an accuratemechanical model of alloy crack migration at high tempera-tureshas notyetbeen developed.Todate.design strategiesfor self-healing materials have only been proposed for poly-mers and composites [10].
分类： 核科学技术 >> 核科学与技术 提交时间： 2025-03-31
摘要： metry energy, is essential in both nuclear physics and astro-physics [1-6]. In nuclear physics, the symmetry energy sig-nificantly affects the structure of finite nuclei, including theit influences the key properties of neutron stars, such as theirmasses and radi [3], as well as their cooling processes [8].Consequently, constraining the symmetry energy is an impor-tant challenge in nuclear physics.Many experimental attempts have been conducted to con-strain the symmetry energy around the saturation densityPo [9-22]. These include measurements of the dipole po-larizabilities of 208pb [13, 14], giant dipole resonance ener-gies [12], isospin diffusion in heavy-ion collisions [10], iso-baric analog states [18], and neutron skin thickness [11, 23].Because of the extensive research on determining the symme-try energy,the constraint on the symmetry energy at saturation density is relativelyprecise,with a commonly acceptedvalue of J =30±4MeV [9,10,12-21].In contrast, the symmetry energy at suprasaturation re-mains unclear.Many terrestrial experiments have beenperformed to extract information on symmetry energy atsuprasaturation. In studies on heavy-ion collisions, the con-straints on the suprasaturation density dependence of the sym-metry energy have been obtained from analyses of the π—/π+ratio [24-30] and n/p elliptic flows ratio [31, 32]. However,the symmetry energy at supurasaturation densities exhibit alarge model dependence. This is caused by the diffculties insolving the transport models and extrapolating the finite ex-The mass measurement of the pulsar PSR J0740+6620from the Neutron Star Interior Composition Explorer [34] re-vealedaasW190814from theLIGO/Virgo collaboration[35]observeda 2.5 - 2.67 Mo compact star because of the neutron s-tars impose tight constraints on the EoS [36-39]. For theobservations of the mass around the 1.4 Mo neutron star,the analysis of the tidal deformability fromGW170817byLIGO/Virgo[40.41] along with radius R1.4= 13.02123 k-1.06 m and mass-radius posterior distributions from millisecond-pulsar PSR J0030+0451 via the (NICER) mission[42]havesignificantly enhanced the ability to constrain the symmetryenergy of nuclear matter [43, 44]. Moreover, constraints onthe symmetry energy have been derived from multiple ob-servations of neutron stars in combination with nuclear the-ory [9, 43-46]. Among these studies, Skyme interaction-s [44, 47, 48], chiral effective field theory [9] and empiri-cal local density functional metamodels[49] were developedunder the non-relativistic framework.Relativistic mean-fieldmodels have been widely used to describe the properties of in-finite nuclear matter, finite nuclei, and stellar matter [5053].A systematically analysis of the influence of all relativisticmean-field (RMF) sets on the properties of neutron stars. Inthis paper, we utilize RMF models to describe the propertiesof neutron stars with a focus on exploring the constraints im-posed by these models on the EoS and symmetry energy atboth saturation and suprasaturation densities.The remainder of this paper is organized as follows. InSect. II, we review the theoretical aspects of RMF models, theEoS of a neutron star, and the Tolman-Oppenheimer-Volkov(TOV) equation. In Sect. III, we present the results of the con-
分类： 核科学技术 >> 核科学与技术 提交时间： 2025-01-10
摘要： developed toprobeunchartedfieldsofnuclear physics,de-livering a variety of heavy ions of elements from hydrogen touranium with energies up to1 GeV/u.The external-target ex-periment (CEE)[4] at the HIRFL-CSR,which is designed tostudy the nuclear matter phase structure at low temperaturesand high baryon densities [5], is currently under development.The design specifications of the CEE include a detectionbeam energy ranging from 0.3 GeV/u to 2.8 GeV/u, a max-imum collisionsystem ofuranium+uranium,andamaximumevent rate of104-s,correspondingtoamaximumbeampar-ticlerate of approximately106.s1[4].As shown inFig.1theCEEdetector consists of adipolemagnet,abeammoni-tor [6-10], a start time detector (T0) [11,12], a time projec-tion chamber(TPC)[13-16],aninner time-of-flightdetector（iTOF)[17,18],multi-wiredriftchambers(MWDCs)[1921],an external time-of-flight detector(eTOF)[22,23],and azero-degree calorimeter (ZDC) [24-26].The beam monitor of the CEE spectrometer is designed tomonitor the beam status and improve the reconstruction res-olutionof theprimaryvertex,whichisotherwisedeterminedby the TPC and MWDCs.The main specifications includea spatial resolution of less than 50μm and a time resolutionof less than 1μs.To achieve these specifications,custom-designed pixel chips named Topmetal-CEEv1[27],which cansimultaneously measure amplitude and time,are deployedin the detector. This approach combines the functions of achargesensor andreadoutapplication-specificintegratedcir-cuit (ASIC).
分类： 计算机科学 >> 计算机应用技术 提交时间： 2025-04-06
摘要： Object detection in Unmanned Aerial Vehicle (UAV) images poses significant challenges due to complex scale variations and class imbalance among objects.Existing methods often address these challenges separately, overlooking the intricate nature of UAV images and the potential synergy between them. In response, this paper proposes AD-Det, a novel framework employing a coherent coarse-to-fine strategy that seamlessly integrates two pivotal components: Adaptive Small Object Enhancement (ASOE) and Dynamic Class-balanced Copy-paste (DCC).ASOE utilizes a high-resolution feature map to identify and cluster regions containing small objects. These regions are subsequently enlarged and processed by a fine-grained detector. On the other hand, DCC conducts object-level resampling by dynamically pasting tail classes around the cluster centers obtained by ASOE, maintaining a dynamic memory bank for each tail class. This approach enables AD-Det to not only extract regions with small objects for precise detection but also dynamically perform reasonable resampling for tail-class objects. Consequently, AD-Det enhances the overall detection performance by addressing the challenges of scale variations and class imbalance in UAV images through a synergistic and adaptive framework.We extensively evaluate our approach on two public datasets, i.e., VisDrone and UAVDT, and demonstrate that AD-Det significantly outperforms existing competitive alternatives.Notably, AD-Det achieves a 37.5% Average Precision (AP) on the VisDrone dataset, surpassing its counterparts by at least 3.1%.
分类： 核科学技术 >> 辐射物理与技术 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 calculatingthe evaporation residue cross-section. By focusing on the synthesis of superheavy nuclei with Z = 114, wediscuss the capture cross-section, fusion probability, and survival probability of the 48Ca + 244 Pu reaction andcompare them with those of the 40Ar+ 248 Cm reaction. Moreover, a systematic study examined the evaporationresidue cross-sections for the synthesis of superheavy nuclei with Z = 112 − 116 using 40Ar as the projectilenucleus. The results indicate that utilizing 40Ar as the projectile nucleus for synthesizing isotopes with Z = 114offers advantages such as lower incident energy and reduced experimental costs. Furthermore, using 40Ar asthe projectile nucleus enables the synthesis of a new key isotope, 285115, thereby facilitating its identification.
分类： 核科学技术 >> 核安全 提交时间： 2025-02-19
摘要： Molten salt reactors (MSRs) are a promising candidatefor Generation IV reactor technologies, and the small modular molten salt reactor (SM-MSR), which utilizes low-enriched uranium and thorium fuels, is regarded as a wise development path to accelerate deployment time. Uncertainty and sensitivity analyses of accidents guide nuclear reactor design and safety analyses. Uncertainty analysis can ascertain the safety margin, and sensitivity analysis can reveal the correlation between accident consequences and input parameters. Loss of forced cooling (LOFC) represents an accident scenario of the SM-MSR, and the study of LOFCcould offer useful information to improve physical thermohydraulicand structural designs. Therefore, this study investigates the uncertainty of LOFCconsequences and the sensitivity of related parameters. The uncertainty of the LOFCconsequences was analyzedusing the Monte Carlo method, and multiple linear regression was employed to analyzethe sensitivity of the input parameters. The uncertainty and sensitivity analyses showed that the maximum reactor outlet fuel salt temperature was 725.5℃, which is lower than the acceptable criterion, and five important parameters influencing LOFCconsequences were identified.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-02-17
摘要： Reduced activation ferritic-martensitic (RAFM) steels have been considered as the candidate structure material for fusion reactor. Temperature effects on strain distribution of RAFM steel CLF-1 during deformation have been explored within the operating temperature range by using uniaxial tensile test combined with in-situ DIC analysis. The yield strength, ultimate tensile strength, and uniform elongation decrease while total elongation decreases and then increases with increasing test temperature. The form of the plateau in the variation of strength and the minimum value of total elongation with increasing test temperature could be attributed to dynamic strain aging (DSA) induced hardening and DSA induced embrittlement, respectively. Strain concentrated region was alternately distributed ±45° along the tensile direction could be attributed to the shear stress takes the maximum value at ±45° along the tensile direction and the coordinated deformation of microstructure. The total strain distribution changes from a normal distribution to a lognormal distribution with increasing deformation at all test temperatures due to the competition between elastic strain and plastic strain. Strain localisation has a strong relationship with temperature at same engineering strain due to the effect of DSA is affected by temperature. The stronger the effect of DSA, the stronger the strain localization. The relevant conclusions would be helpful for establishing the finite element model by using crystal plasticity finite element method(CPFEM).
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-02-10
摘要： actor.Additionally,by connecting the reactor to a foatingplatform,FNPPs offer the advantage of adaptable site selec-tion with fewer restrictions.These plants can explore in-dependentlyunder difficultconditions or canbepulledintosafe waters to avoid potential dangers.FNPPs have becomea prominentresearch topicinrecentyears[4,5].VariousFNPPreactors arebeing designed indifferentnations,suchas ACP100s and ACPR50s in China,OFNP-300/OFNP1100in the USA,Flexblue in France,and KLT-4Os.RITM-200VBER-300,ABV-6E,and SHELFinRussia(WNA,2020).mobility and deployment to accommodate various ma-rineconditionsandoperationalrequirements.Russia’s"Akademik Lomonosov"foating nuclear power station hasbeeneffectivelydeployed andoperated[6].Chinaiscurrentlydeveloping FNPPs by placing ACP100 reactors on barge-typeplatforms.Bargeplatforms[7]haveasignificantlyreducedstabilitycomparedtocolumn-stabilizedplatforms,tensionleg platforms,and other center-basedplatforms because oftheirnon-isotropicrotationalinertia,which affects theirper-formance in winds,waves,and currents.When exposed tocrosswindsandwaves,yawandswaycanleadtodangerouslateral movements, ranging from slight structural deforma-tions toputtingthereactor’ssafety atrisk[8].Variousloadssuch as tilting, rocking, swaying, and impact can affect theperformance of steam delivery systems in reactors. Duringnaturalcirculation,theseeffectsmayalsobe affectedby thepressure caused by variations in elevation and fluctuations[9].Jie[10]andYan[11]performedadvantageousevaluationsbyusingsystematicanalyticalprogramsfordistinctreactortypes or specialized circuits under rolling,heaving,and sway-ing circumstances. The FNPP was unable to maintain stableoperation under significant rolling and pitching movements.Strother[12]andLiuet al.[13]studied thedynamicresponseandmooringcharacteristicsofmulti-point-mooredcolumn-stabilized FNPPs.Few studies have examined the hydrody-namic response of barge-type FNPPs to waves. To evaluateandreduce therisks posed by wind andwaves,it is crucialto study the factors affecting barge-type FNPPs and their dy-namic reactions when exposed to wind, waves, and currents.
分类： 管理学 >> 管理学其他学科 提交时间： 2024-06-13
摘要： Abstract:Public toilets reflect human civilization, embodying not only social efficiency but also gender equality. However, the current widespread issue of insufficient and mismatched toilet spaces persists. The demand for toilet facilities by men and women is not simply a matter of population ratios. Due to differences in wait times, arrival time distributions, and the ability for men to switch to urinals, the traditional queuing theory is not precise enough for this issue. This study investigates the usage of public toilets and constructs a simulation system based on agent-based modeling. Using this system, the toilet space requirements for gender-segregated and non-segregated toilets are measured under different satisfaction rates, foot traffic volumes, and toilet usage frequencies. Additionally, the consistency between the real distribution of time spent entering and exiting toilets and the simulation system is verified, demonstrating the robustness of the conclusions drawn. The study concludes that under a fixed satisfaction rate, the number of toilet stalls satisfies a specific function of foot traffic volume. The agent-based modeling approach demonstrated in this study can be extended to address other complex real-world optimization problems.
分类： 计算机科学 >> 计算机科学的集成理论 提交时间： 2022-11-28 合作期刊: 《数据智能（英文）》
摘要： Relational extraction plays an important role in the field of natural language processing to predict semantic relationships between entities in a sentence. Currently, most models have typically utilized the natural language processing tools to capture high-level features with an attention mechanism to mitigate the adverse effects of noise in sentences for the prediction results. However, in the task of relational classification, these attention mechanisms do not take full advantage of the semantic information of some keywords which have information on relational expressions in the sentences. Therefore, we propose a novel relation extraction model based on the attention mechanism with keywords, named Relation Extraction Based on Keywords Attention (REKA). In particular, the proposed model makes use of bi-directional GRU (Bi-GRU) to reduce computation, obtain the representation of sentences , and extracts prior knowledge of entity pair without any NLP tools. Besides the calculation of the entity-pair similarity, Keywords attention in the REKA model also utilizes a linear-chain conditional random field (CRF) combining entity-pair features, similarity features between entity-pair features, and its hidden vectors, to obtain the attention weight resulting from the marginal distribution of each word. Experiments demonstrate that the proposed approach can utilize keywords incorporating relational expression semantics in sentences without the assistance of any high-level features and achieve better performance than traditional methods.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2025-02-25
Yin, Ziang
Zhang, Yaru
Kang, Zhe
Zhang, Xianggang
Liu, Jinbo
Liu, Kejin
Sun, Zhengyi
Jie, Wangqi
Zhao, Qinhua
Wang, Tao
摘要： Cadmium telluride (CdTe), which has a high average atomic number and a unique band structure, is a leadingmaterial for room-temperature X/γ-ray detectors. Resistivity and mobility are the two most importantproperties of detector-grade CdTe single crystals. However, despite decades of research, the fabrication ofhigh-resistivity and high-mobility CdTe single crystals faces persistent challenges, primarily because the stoichiometriccomposition cannot be well controlled owing to the high volatility of Cd under high-temperatureconditions. This volatility introduces Te inclusions and cadmium vacancies (VCd) into the as-grown CdTe ingot,which significantly degrades the device performance. In this study, we successfully obtained detector-gradeCdTe single crystals by simultaneously employing a Cd reservoir and chlorine (Cl) dopants via a vertical gradientfreeze (VGF) method. By installing a Cd reservoir, we can maintain the Cd pressure under the crystalgrowth conditions, thereby preventing the accumulation of Te in the CdTe ingot. Additionally, the existenceof the Cl dopant helps improve the CdTe resistivity by minimizing VCd density through the formation of anacceptor complex (ClTe-VCd)−1. The crystalline quality of the obtained CdTe(Cl) was evidenced by a reductionin large Te inclusions, high optical transmission (60%), and a sharp absorption edge (1.456 eV). Thepresence of substitutional Cl dopants, known as Cl+ Te, simultaneously supports the record high resistivity of1.5 × 1010 Ω · c meter and remarkable electron mobility of 1075±88 cm2 V−1 s−1 simultaneously, has beenconfirmed by photoluminescence spectroscopy. Moreover, using our crystals, we fabricated a planar detectorwith μτe of (1.11 ± 0.04) × 10−4 cm2/V, which performed with a decent radiation-detection feature. Thisstudy demonstrates that the vapor-pressure-controlled VGF method is a viable technical route for fabricatingdetector-grade CdTe crystals.
分类： 物理学 >> 核物理学 提交时间： 2025-02-17
摘要： ously around the synchronous electrons. Using a higher har-ductioninthevoltageslopeeffectivelyminimizestheimpactness [2, 3]. Additionally, the introduction of more nonlin-of the coupled beam bunch [4, 5]
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-02-04
Wang, Cheng
Tan, Jianhao
Nie,Yuancun
Su, Dinghui
Gao, Zihe
Guo, Yusen
Zhang, Yuxin
He, Jianhua
Fang, Wencheng
Zhao, Zhentang
摘要： Radio frequency (RF) cavities for advanced storage rings, also known as diffraction-limited storage rings, are under development. To this end, a competitive and promising approach involves normal-conducting continuous wave technology. The design and preliminary test of a 499.654MHz RF cavity for the Wuhan Advanced Light Source (WALS) based on specific beam parameters were conducted at the SSRF. Multi-objective evolutionary algorithms have been utilized to optimize RF properties, such as the power loss and power density, resulting in better performance in the continuous wave mode. Further improvements were made to suppress multipacting effects in the working area. To operate stably with the beam, higher-order mode dampers were applied to better address the coupling bunch instability than in previous designs, along with thermal analysis to achieve the desired RF performance. Comprehensive simulation studies demonstrated the stable operation of the RF cavity at the defined beam parameters in the WALS design. A prototype RF cavity was then developed, and the RF performance results in a low-power test showed good agreement with the design and simulation, exhibiting readiness for high-power experiments and operation.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-04-07
Xiang-Fei Wang
Kai-Jie Chen
Hang-Hua Xu
Gong-Tao Fan
Zi-Rui Hao
Zhen-Wei Wang
Long-Xiang Liu
Yue Zhang
Sheng Jin
Qian-kun Sun
Zhi-Cai Li
Pu Jiao
Meng-Die Zhou
Yu-Long Shen
Meng-Ke Xu
Hong-Wei Wang
摘要： A Monte Carlo simulation code and an analytical calculation code for polarization study were developed at Shanghai Laser Gamma Source (SLEGS), employing the unique laser Compton slant scattering (LCSS) mode. The intensity of spatial distributions and its Stokes parameters are simulated for LCSS of linearly/circularly polarized laser photons and unpolarized relativistic electrons. The polarization degree of the incident photon is almost completely transferred to the scattered gamma rays for any incident angle. For a linearly polarized laser incident in a fixed direction, the direction of polarization of the scattered gamma-ray changes with the scattering angle. The measured polarization direction and size of the scattered gamma spatial distribution are in general agreement with the simulation in the linearly polarized laser case.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-02-19
摘要： Industrial linear accelerators often contain many bunches when their pulse widths are extended to microsec onds. As they typically operate at low electron energies and high currents, the interactions among bunches cannot be neglected. In this study, an algorithm is introduced for calculating the space charge force of a train with infinite bunches. By utilizing the ring charge model and the particle-in-cell (PIC) method and combin ing analytical and numerical methods, the proposed algorithm efficiently calculates the space charge force of infinite bunches, enabling the accurate design of accelerator parameters and a comprehensive understanding of the space charge force. This is a significant improvement on existing simulation software such as ASTRA and PARMELA that can only handle a single-bunch or a small number of bunches. The PIC algorithm is val idated in long-drift space transport by comparing it with existing models, such as the infinite-bunch, ASTRA single-bunch, and PARMELA several-bunch algorithms. The space charge force calculation results for the ex ternal acceleration field are also verified. The reliability of the proposed algorithm provides a foundation for the design and optimization of industrial accelerators.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-01-19
Li, Zhixue
Wu, Junxia
Gu, Kewei
Ni, Fafu
Tian, Ruixia
Zhu, Guangyu
Zhang, Yong
Lu, Shangshang
Li, Lili
Xie, Hongming
Du, Ze
Qiu, Xiaoxuan
Wei, Yuan
Jing, Long
Yin, Jia
He, Peilin
Li, Wenhhui
Zhang, Hongfei
摘要： The heavy-ion accelerator facility (HIAF) under construction in China will produce various stable and intense radioactive beams with energies ranging from MeV/u to GeV/u. The ion-linac (iLinac) accelerator, which will serve as the injector for the HIAF, is a superconducting heavy-ion accelerator containing 13 cryomodules. It will operate in either continuous wave mode or pulsed mode, with a beam current ranging from 0.01 emA to 1 emA. The beam position monitor (BPM) is crucial for this high-beam-power machine, which requires precise beam control and a very small beam loss of less than 1W/m, especially inside the cryomodules of this unique beam instrument. Nearly 70 BPMs will be installed on the iLinac. New digital beam position and phase measurement (DBPPM) electronics based on a heterogeneous multiprocessing platform system-on-chip (MPSoC) has been developed to provide accurate beam trajectory and phase measurements as well as beam interlocking signals for a fast machine protection system (MPS). The DBPPM comprises an analog front-end (AFE) board in field programmable gate array (FPGA) mezzanine-connector (FMC) form factor, along with a digital signal processing board housed within a 2U 19” chassis. To mitigate radio frequency (RF) leakage effects from highpower RF systems in certain scenarios, beam signals undergo simultaneous processing at both fundamental and second-harmonic frequencies. A dynamic range from −65 dBm to 0 dBm was established to accommodate both weak beam commissioning and high-intensity operational demands. Laboratory tests demonstrated that at input power levels exceeding −45 dBm, the phase resolution surpasses 0.05◦ , and the position resolution exceeds 5 µm. These results align well with the stipulated measurement requirements. Moreover, the newly developed DBPPM has self-testing and self-calibration functions that are highly helpful for the systematic evaluation of numerous electronic components and fault diagnosis equipment. In addition, the DBPPM electronics implements a 2D non-linear polynomial correction on the FPGA and can collect accurate real-time position measurements at large beam offsets. This newly developed DBPPM electronics has been applied to several Linac machines, and the results from beam measurements show high performance, good long-term stability, and high reliability. In this paper, a detailed overview of the architecture, performance, and proof-of-principle measurement of the beams is presented
分类： 物理学 >> 核物理学 提交时间： 2025-01-18
摘要： A machine learning approach utilizing the Bayesian neural networks has been developed to predict the complete fusion cross sections of weakly bound nuclei.This method was trained and validated using 475 experimental data points from 39 reaction systems all induced by $^{6,7}$Li, $^9$Be and $^{10}$B.The constructed Bayesian neural network demonstrated a high degree of accuracy in evaluating the complete fusion cross sections.By comparing the predicted cross sections with those obtained from the single barrier penetration model, the suppression effect of $^{6,7}$Li and $^9$Be with stable nucleus was made a systematic analysis.In the cases of $^{6}$Li and $^{7}$Li, a less suppression was predicted at the relatively light mass targets than that found in heavy mass targets and a notably distinct dependence relationship was identified, suggesting that the predominant breakup mechanisms might change in different mass target regions.In addition, the minimum suppression factors are predicted to occur near the neutron magic number nuclei.
分类： 物理学 >> 核物理学 提交时间： 2025-03-22
Jian-Wu Chen
Yong-Qiang Shi
Fuchang Zuo
Zhiwu Mei
Weichun Fu
Fangqin Gai
Ye Chang
Ying Yang
Shujuan Yang
Zhijun Tu
Xuli Liu
Jianfu Zhang
Ran Zheng
Li Wang
Chunhui Zhao
Di Zhang
Xiaoping Zhang
摘要： The main scientific payload of Macau Science Satellite-1B is a solar soft X-ray detection unit. To obtain an accurate solar X-ray spectrum, we have designed low-noise, high-throughput electronics. Solar radiation is detected using a low-leakage silicon drift detector (SDD), which is cooled to −30 ◦C. The SDD output is processed using two parallel shaping amplifiers with peaking times of 315 ns and 65 ns. The amplifiers are designed using two-pole multiple-feedback active low-pass filters optimized to achieve a Bessel response. The differential output of the shaping amplifier generates a bipolar signal. The phase of the differential stage is tuned to ensure zero crossing corresponding to the peak of the shaping amplifier. A high-speed switch is inserted between the shaping amplifier and the peak-hold capacitor, and the peak value is maintained by turning off the switch. Fast and slow peak-hold circuits share a common ADC via time-division multiplexing. Both peak values are sampled for space-background rejection. Traditional pile-up detection methods cannot distinguish pulses that overlap in a fast channel. In this study, the differential of the “fast shaping” is selected, enabling the distinction of events separated by as little as 65 ns, which is crucial for solar flare detection. The energy resolution is measured to be 138 eV at 5.90 keV. The centroid drift is less than 3.6 eV between −5 ◦C and 20 ◦C. Compared with other solar X-ray instruments, this study demonstrates improved energy resolution with a lower peaking time, indicating a higher solar flare detection capability.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2025-03-11
摘要： With the increasing demand for controllable source logging, research on data-processing algorithms that meet accuracy requirements has become key to the development of controllable-source-logging tools. This study theoretically derives the relationship between the formation density and inelastic gamma count rate to investigate the data-processing methods for deuterium-tritium (D-T) source neutron-gamma density logging while drilling. Then, algorithms for the net inelastic gamma count-rate extraction and neutron transport correction are studied using Monte Carlo simulations. A new method for fast-neutron effect identification and additional correction is proposed to improve the density-calculation accuracy of gas-filled and heavy-mineral formations. Finally, the effectiveness and accuracy of the proposed data-processing methods are verified based on simulated and measured data. The results show that the density-calculation accuracy of water-bearing conventional formations in simulated data is ±0.02g/cm3. The accuracy of gas-filled and heavy-mineral formations after the additional fast-neutron effect correction is ±0.025g/cm3. For the measured data from the actual tool, the algorithms per form well in the density calculation. The density results obtained using the processing algorithms are consistent with the density data provided by NeoScope. Therefore, the D-T source neutron-gamma density-logging algo rithms proposed in this study can obtain relatively accurate data-processing results for a variety of formations. This study provides technical support for engineering applications and the development of logging tools for controllable-source neutron-density logging.
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