Effects of plasma equilibrium parameters on the alpha particle loss with the toroidal field ripple based on the CFETR steady-state scenario have been numerically investigated by the orbit-following code GYCAVA. It is ...Effects of plasma equilibrium parameters on the alpha particle loss with the toroidal field ripple based on the CFETR steady-state scenario have been numerically investigated by the orbit-following code GYCAVA. It is found that alpha particle losses decrease and loss regions become narrower with the plasma current increasing or with the magnetic field decreasing. It is because the ripple stochastic transport and the ripple well loss of alpha particle are reduced with the safety factor decreasing. Decrease of the plasma density and temperature can reduce alpha particle losses due to enhancement of the slowing-down effect. The direction of the toroidal magnetic field can significantly affect heat loads induced by lost alpha particle. The vertical asymmetry of heat loads induced by the clockwise and counter-clockwise toroidal magnetic fields are due to the fact that the ripple distribution is asymmetric about the mid-plane, which can be explained by the typical orbits of alpha particle. The maximal heat load of alpha particle for the clockwise toroidal magnetic field is much smaller than that for the counter-clockwise one.展开更多
Au/Ni/n-type 4H-SiC Schottky alpha particle detectors are fabricated and annealed at temperatures between 400℃ and 700 ℃ to investigate the effects of thermal stability of the Schottky contact on the structural and ...Au/Ni/n-type 4H-SiC Schottky alpha particle detectors are fabricated and annealed at temperatures between 400℃ and 700 ℃ to investigate the effects of thermal stability of the Schottky contact on the structural and electrical properties of the detectors. At the annealing temperature of 500 ℃, the two nickel silicides （i.e., Ni31Sil2 and Ni2Si） are formed at the interface and result in the formation of an inhomogeneous Schottky barrier. By increasing the annealing temperature, the Ni31Sil2 transforms into the more stable Ni2Si. The structural evolution of the Schottky contact directly affects the electrical properties and alpha particle energy resolutions of the detectors. A better energy resolution of 2.60% is obtained for 5.48-MeV alpha particles with the detector after being annealed at 600 ℃. As a result, the Au/Ni/n-type 4H-SiC Schottky detector shows a good performance after thermal treatment at temperatures up to 700℃.展开更多
Alpha particle radiation detectors with planar double Schottky contacts(DSC)are directly fabricated on 5-μm-thick epitaxial semi-insulating(SI)GaN:Fe film with resistivity higher than 1×10^(8)Ω·cm.Under 10...Alpha particle radiation detectors with planar double Schottky contacts(DSC)are directly fabricated on 5-μm-thick epitaxial semi-insulating(SI)GaN:Fe film with resistivity higher than 1×10^(8)Ω·cm.Under 10 V bias,the detector exhibits a low dark current of less than 5.0×10^(-11) A at room-temperature,which increases at higher temperatures.Linear behavior in the semi-log reverse current-voltage plot suggests that Poole-Frenkel emission is the dominant carrier leakage mechanism at high bias.Distinct double-peak characteristics are observed in the energy spectrum of alpha particles regardless of bias voltage.The energy resolution of the SI-GaN based detector is determined to be8.6%at the deposited energy of 1.209 MeV with a charge collection efficiency of81.7%.At a higher temperature of 90℃,the measured full width at half maximum(FWHM)rises to 235 keV with no shift of energy peak position,which proves that the GaN detector has potential to work stably in high temperature environment.This study provides a possible route to fabricate the low cost GaN-based alpha particle detector with reasonable performance.展开更多
Energetic alpha particle losses with the toroidal field ripple and the Coulomb collision in the CFETR tokamak have been simulated by using the orbit-following code GYCAVA for the steady-state and hybrid scenarios.The ...Energetic alpha particle losses with the toroidal field ripple and the Coulomb collision in the CFETR tokamak have been simulated by using the orbit-following code GYCAVA for the steady-state and hybrid scenarios.The effects of the outer boundary and the ripple amplitude on alpha particle losses have been investigated.The loss fractions and heat loads of alpha particles in the hybrid scenario are much smaller than those in the steady-state scenario for a significant ripple amplitude.Some alpha particles in the plasma core are lost due to the ripple stochastic transport for a large ripple amplitude parameter.The heat loads with the last closed flux surface boundary are different from those with the wall boundary for the CFETR tokamak,which can be explained by typical alpha particle orbits.Discrete heat load spots have been observed in alpha particle loss simulations,which is due to the ripple well loss.The transition of the lost alpha particle behavior from the ripple stochastic diffusion to the ripple well trapping has been identified in our CFETR simulations.The Coulomb collision effect is responsible for this transition.展开更多
A sealed high gas pressure detector working in pure argon is assembled.It consists of a 5 cm × 5 cm PCB THGEM（THick Gaseous Electron Multiplier）.The detector structure and experimental setup are described.The p...A sealed high gas pressure detector working in pure argon is assembled.It consists of a 5 cm × 5 cm PCB THGEM（THick Gaseous Electron Multiplier）.The detector structure and experimental setup are described.The performance under high pressure（2 atm） is examined,selecting optimal voltages for the ionization region and induction region.The dependence of the shape of alpha particle spectra measured with relative gas gain on gas pressure（1.3-2.0 atm） has been studied.Eight data sets of relative gas gain versus working voltage of THGEM,expressed by weighting field E/P,are normalized,consistent with theory.The results show that the air tightness of the chamber is good,measured by a sensitive barometer and checked with gas gain.The experimental results are compared with Monte Carlo simulation of energy deposition without gas gain involved.展开更多
The results of experiments on measuring the energy spectra of alpha particles in reactions with heavy ions are presented.The measurements were performed using the high-resolution magnetic analyzer MAVR with beams of ^...The results of experiments on measuring the energy spectra of alpha particles in reactions with heavy ions are presented.The measurements were performed using the high-resolution magnetic analyzer MAVR with beams of ^(48)Ca(280 MeV)and ^(56)Fe(320 and 400 MeV)on ^(181)Ta and ^(238)U targets at an angle of 0°.A strong dependence of the double differential cross sections for production of alpha particles on the atomic number of the target nucleus was observed,which indicates that fast alpha particles are mainly emitted from the target nucleus;this conclusion was also confirmed by calculations within the time-dependent Schrödinger equation approach.An analysis of the obtained experimental data was carried out within the model of moving sources modified to consider the kinematic limits for two-body and three-body exit channels.展开更多
This study analyzes fast ion losses in the EHL-2 fusion device,focusing on both beam ions and alpha particles as p-11B fusion reaction products.Using the Monte Carlo orbit-following code TGCO,we evaluate particle conf...This study analyzes fast ion losses in the EHL-2 fusion device,focusing on both beam ions and alpha particles as p-11B fusion reaction products.Using the Monte Carlo orbit-following code TGCO,we evaluate particle confinement under various operational scenarios,including co-injected tangential neutral beam injection at beam energies of 60 keV,80 keV,and 200 keV.Our simulations estimate the heat load driven by lost beam ions and find it to be within acceptable material limits for a plasma current on the order of mega-amperes.Additionally,we simulate the distribution of fusion products and observe a higher particle loss fraction for alpha particles compared to beam ions.However,due to the relatively low fusion power,these lost alpha particles are unlikely to significantly impact the plasma-facing materials.To assess the impact of the magnetic ripple,we compute the ripple field distribution by modelling the toroidal field(TF)coils as current filaments.The results indicate that the ripple field effect on particle confinement is minimal,primarily due to the large distance of over 1 m between the TF coils and the plasma on the low-field side.The analysis based on the test particle model is a foundational step in ensuring the basic safety aspects of the new device,which is essential for developing a robust design,optimizing performance,and maintaining safe operation.展开更多
Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential a...Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.展开更多
Radiopharmaceuticals operate by combining radionuclides with carriers.The radiation energy emitted by radionuclides is utilized to selectively irradiate diseased tissues while minimizing damage to healthy tissues.In c...Radiopharmaceuticals operate by combining radionuclides with carriers.The radiation energy emitted by radionuclides is utilized to selectively irradiate diseased tissues while minimizing damage to healthy tissues.In comparison to external beam radiation therapy,radionuclide drugs demonstrate research potential due to their biological targeting capabilities and reduced normal tissue toxicity.This article reviews the applications and research progress of radiopharmaceuticals in cancer treatment.Several key radionuclides are examined,including^(223)Ra,^(90)Y,Lutetium-177(^(177)Lu),212 Pb,and Actinium-225(^(225)Ac).It also explores the current development trends of radiopharmaceuticals,encompassing the introduction of novel radionuclides,advancements in imaging technologies,integrated diagnosis and treatment approaches,and equipment-medication combinations.We review the progress in the development of new treatments,such as neutron capture therapy,proton therapy,and heavy ion therapy.Furthermore,we examine the challenges and breakthroughs associated with the clinical translation of radiopharmaceuticals and provide recommendations for the research and development of novel radionuclide drugs.展开更多
ENN is planning the next generation experimental device EHL-2 with the goal to verify the thermal reaction rates of p-^(11)B fusion,establish spherical torus/tokamak experimental scaling laws at 10’s keV ion temperat...ENN is planning the next generation experimental device EHL-2 with the goal to verify the thermal reaction rates of p-^(11)B fusion,establish spherical torus/tokamak experimental scaling laws at 10’s keV ion temperature,and provide a design basis for subsequent experiments to test and realize the p-^(11)B fusion burning plasma.Based on 0-dimensional(0-D)system design and 1.5-dimensional transport modelling analyses,the main target parameters of EHL-2 have been basically determined,including the plasma major radius,R0,of 1.05 m,the aspect ratio,A,of 1.85,the maximum central toroidal magnetic field strength,B0,of 3 T,and the plasma toroidal current,Ip,of 3 MA.The main heating system will be the neutral beam injection at a total power of 17 MW.In addition,6 MW of electron cyclotron resonance heating will serve as the main means of local current drive and MHD instabilities control.The physics design of EHL-2 is focused on addressing three main operating scenarios,i.e.,(1)high ion temperature scenario,(2)high-performance steady-state scenario and(3)high triple product scenario.Each scenario will integrate solutions to different important issues,including equilibrium configuration,heating and current drive,confinement and transport,MHD instability,p-^(11)B fusion reaction,plasma-wall interactions,etc.Beyond that,there are several unique and significant challenges to address,including●establish a plasma with extremely high core ion temperature(T_(i,0)>30 keV),and ensure a large ion-to-electron tempera-ture ratio(T_(i,0)/Te,0>2),and a boron concentration of 10%‒15%at the plasma core;●realize the start-up by non-inductive current drive and the rise of MA-level plasma toroidal current.This is because the volt-seconds that the central solenoid of the ST can provide are very limited;●achieve divertor heat and particle fluxes control including complete detachment under high P/R(>20 MW/m)at rela-tively low electron densities.This overview will introduce the advanced progress in the physics design of EHL-2.展开更多
The response of a silicon alpha detector to beta particles, electrons and photons was investigated using measurements and Monte Carlo simulations. This information is of relevance for in situ alpha spectrometry from d...The response of a silicon alpha detector to beta particles, electrons and photons was investigated using measurements and Monte Carlo simulations. This information is of relevance for in situ alpha spectrometry from different surfaces at ambient air pressure. According to the simulations, photon detection efficiencies were more than two orders of magnitude smaller than those of electrons. Photons generate signals mainly by Compton electrons. Counts originating from beta particles, electrons and photons were usually below 1 MeV in energy and no clear peaks could be identified from the measured spectra. Unequivocal identification of radionuclides emitting beta particles, electrons and photons is not possible when a mixture of different radionuclides is present in the source. However, radionuclide classification according to their emission energies appears to be possible. Surface contamination measurements will benefit from this capability.展开更多
A model for fast electron-driven high-density plasma is proposed to describe the effect of injected fast electrons on the temperature and inner pressure of the plasma in the fast heating process of the double-cone ign...A model for fast electron-driven high-density plasma is proposed to describe the effect of injected fast electrons on the temperature and inner pressure of the plasma in the fast heating process of the double-cone ignition(DCI)scheme.Due to the collision of the two low-density plasmas,the density and volume of the high-density plasma vary.Therefore,the ignition temperature and energy requirement of the high-density plasma vary at different moments,and the required energy for hot electrons to heat the plasma also changes.In practical experiments,the energy input of hot electrons needs to be considered.To reduce the energy input of hot electrons,the optimal moment and the shortest time for injecting hot electrons with minimum energy are analyzed.In this paper,it is proposed to inject hot electrons for a short time to heat the high-density plasma to a relatively high temperature.Then,the alpha particles with the high heating rate and PdV work heat the plasma to the ignition temperature,further reducing the energy required to inject hot electrons.The study of the injection time of fast electrons can reduce the energy requirement of fast electrons for the high-density plasma and increase the probability of successful ignition of the high-density plasma.展开更多
Convolutional neural networks(CNNs) exhibit excellent performance in the areas of image recognition and object detection, which can enhance the intelligence level of spacecraft. However, in aerospace, energetic partic...Convolutional neural networks(CNNs) exhibit excellent performance in the areas of image recognition and object detection, which can enhance the intelligence level of spacecraft. However, in aerospace, energetic particles, such as heavy ions, protons, and alpha particles, can induce single event effects(SEEs) that lead CNNs to malfunction and can significantly impact the reliability of a CNN system. In this paper, the MNIST CNN system was constructed based on a 28 nm systemon-chip(SoC), and then an alpha particle irradiation experiment and fault injection were applied to evaluate the SEE of the CNN system. Various types of soft errors in the CNN system have been detected, and the SEE cross sections have been calculated. Furthermore, the mechanisms behind some soft errors have been explained. This research will provide technical support for the design of radiation-resistant artificial intelligence chips.展开更多
The efficiency of energetic ion confinement is reduced in a tokamak plasma by the non-axisymmetric field, namely the ripple field. The ripple field is produced by a finite number of toroidal field coils. It is affecte...The efficiency of energetic ion confinement is reduced in a tokamak plasma by the non-axisymmetric field, namely the ripple field. The ripple field is produced by a finite number of toroidal field coils. It is affected by the non-axisymmetric finite beta effect. The three-dimensional MHD equilibrium calculation code VMEC is used to analyze the non-axisymmetric finite beta effect in a ripple tokamak. In the VMEC code, the flux coordinates are used, so the calculation region is limited to the area of plasma. To calculate the orbit outside the plasma, we develop a field calculation code, which is based on the Biot-Savart law. The details of the method and results are described in this paper.展开更多
In the large helical device （LHD） having three dimensional configuration, Alfven eigenmodes （AEs） destabilized by energetic ions are widely investigated using neutral beam heated plasmas with monotonic and non-mon...In the large helical device （LHD） having three dimensional configuration, Alfven eigenmodes （AEs） destabilized by energetic ions are widely investigated using neutral beam heated plasmas with monotonic and non-monotonic rotational transform （l/2π） profiles. In a plasma with monotonic l/2π-profile, core-localized toroidicity-induced Alfven eigenmode （TAE） as well as global one are often observed. With the increase in the averaged toroidal beta value, defined as the ratio of total plasma pressure to toroidal magnetic pressure, core-localized TAE with low toroidal mode number becomes global. In a relatively high beta plasma with monotonic l/2π-profile, two TAEs with different toroidal mode number often interact nonlinearly and generate another modes through three wave coupling. In a plasma with non-monotonic l/2π-profile generated by intense counter neutral beam current drive, reversed shear Alfven eigenmode （RSAE） and geodesic acoustic mode （CAM） excited by energetic ions were observed for the first time in a helical plasma. Nonlinear coupling was also observed between RSAE and GAM.展开更多
A simple method employing a pair of pancake-style Geiger-Mueller (GM) counters for quantitative measurement of radon activity concentration (activity per unit volume) is described and demonstrated. The use of two GM c...A simple method employing a pair of pancake-style Geiger-Mueller (GM) counters for quantitative measurement of radon activity concentration (activity per unit volume) is described and demonstrated. The use of two GM counters, together with the basic theory derived in this paper, permit the detection of alpha particles from decay of and progeny ( <sup>218</sup>Po, <sup>214</sup>Po) and the conversion of the alpha count rate into a radon concentration. A unique feature of this method, in comparison with standard methodologies to measure radon concentration, is the absence of a fixed control volume. Advantages afforded by the reported GM method include: 1) it provides a direct in-situ value of radon level, thereby eliminating the need to send samples to an external testing laboratory;2) it can be applied to monitoring radon levels exhibiting wide short-term variability;3) it can yield short-term measurements of comparable accuracy and equivalent or higher precision than a commercial radon monitor sampling by passive diffusion;4) it yields long-term measurements statistically equivalent to commercial radon monitors;5) it uses the most commonly employed, overall least expensive, and most easily operated type of nuclear instrumentation. As such, the method is par-ticularly suitable for use by researchers, public health personnel, and home dwellers who prefer to monitor indoor radon levels themselves. The results of a consecutive 30-day sequence of 24 hour mean radon measurements by the proposed GM method and a commercial state-of-the-art radon monitor certified for radon testing are compared.展开更多
After one century of nuclear physics, its underlying fundamental laws remain a puzzle. Rutherford scattering is well known to be electric at low kinetic energy. Nobody noticed that the Rutherford scattering formula wo...After one century of nuclear physics, its underlying fundamental laws remain a puzzle. Rutherford scattering is well known to be electric at low kinetic energy. Nobody noticed that the Rutherford scattering formula works also at high kinetic energy, needing only to replace the repulsive electric -2 exponent by the also repulsive magnetic -6 exponent. A proton attracts a not so neutral neutron as amber attracts dust. The nucleons have magnetic moments that interact as magnets, equilibrating statically the electric attraction between a proton and a not so neutral neutron. In this paper, the electromagnetic potential energies of the deuteron 2H and the α particle 4He have been calculated statically, using only electromagnetic fundamental laws and constants. Nuclear scattering and binding energy are both electromagnetic.展开更多
The linear-chain structure in which three alpha particles are arranged in a straight line was initially proposed by H.Morinaga[1]as the structure of the Hoyle state of carbon-12[2].This unique idea attracted much atte...The linear-chain structure in which three alpha particles are arranged in a straight line was initially proposed by H.Morinaga[1]as the structure of the Hoyle state of carbon-12[2].This unique idea attracted much attention,but it was rejected because it could not explain the lifetime of the Hoyle state.Half a century later,the concept of the linear chain structure was revived in the physics of unstable nuclei,and experimental and theoretical research have demonstrated that this structure exists in carbon-14 and 16.The authors have conducted internationally recognized experimental research on the linear-chain structure of carbon-14 and carbon-16.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12175034 and 12005063)the National Key Research and Development Program of China (Grant No.2019YFE03030001)the Fundamental Research Funds for the Central Universities (Grant No.2232022G-10)。
文摘Effects of plasma equilibrium parameters on the alpha particle loss with the toroidal field ripple based on the CFETR steady-state scenario have been numerically investigated by the orbit-following code GYCAVA. It is found that alpha particle losses decrease and loss regions become narrower with the plasma current increasing or with the magnetic field decreasing. It is because the ripple stochastic transport and the ripple well loss of alpha particle are reduced with the safety factor decreasing. Decrease of the plasma density and temperature can reduce alpha particle losses due to enhancement of the slowing-down effect. The direction of the toroidal magnetic field can significantly affect heat loads induced by lost alpha particle. The vertical asymmetry of heat loads induced by the clockwise and counter-clockwise toroidal magnetic fields are due to the fact that the ripple distribution is asymmetric about the mid-plane, which can be explained by the typical orbits of alpha particle. The maximal heat load of alpha particle for the clockwise toroidal magnetic field is much smaller than that for the counter-clockwise one.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11675198,61574026,and 11405017)the National Key Research and Development Program of China(Grant Nos.2016YFB0400600 and 2016YFB0400601)+1 种基金the Natural Science Foundation of Liaoning Province of China(Grant Nos.201602453 and 201602176)the China Postdoctoral Science Foundation(Grant No.2016M591434)
文摘Au/Ni/n-type 4H-SiC Schottky alpha particle detectors are fabricated and annealed at temperatures between 400℃ and 700 ℃ to investigate the effects of thermal stability of the Schottky contact on the structural and electrical properties of the detectors. At the annealing temperature of 500 ℃, the two nickel silicides （i.e., Ni31Sil2 and Ni2Si） are formed at the interface and result in the formation of an inhomogeneous Schottky barrier. By increasing the annealing temperature, the Ni31Sil2 transforms into the more stable Ni2Si. The structural evolution of the Schottky contact directly affects the electrical properties and alpha particle energy resolutions of the detectors. A better energy resolution of 2.60% is obtained for 5.48-MeV alpha particles with the detector after being annealed at 600 ℃. As a result, the Au/Ni/n-type 4H-SiC Schottky detector shows a good performance after thermal treatment at temperatures up to 700℃.
基金Project supported by the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20190302 and BK20201253).
文摘Alpha particle radiation detectors with planar double Schottky contacts(DSC)are directly fabricated on 5-μm-thick epitaxial semi-insulating(SI)GaN:Fe film with resistivity higher than 1×10^(8)Ω·cm.Under 10 V bias,the detector exhibits a low dark current of less than 5.0×10^(-11) A at room-temperature,which increases at higher temperatures.Linear behavior in the semi-log reverse current-voltage plot suggests that Poole-Frenkel emission is the dominant carrier leakage mechanism at high bias.Distinct double-peak characteristics are observed in the energy spectrum of alpha particles regardless of bias voltage.The energy resolution of the SI-GaN based detector is determined to be8.6%at the deposited energy of 1.209 MeV with a charge collection efficiency of81.7%.At a higher temperature of 90℃,the measured full width at half maximum(FWHM)rises to 235 keV with no shift of energy peak position,which proves that the GaN detector has potential to work stably in high temperature environment.This study provides a possible route to fabricate the low cost GaN-based alpha particle detector with reasonable performance.
基金the support from the CFETR teamjointly supported by National Natural Science Foundation of China(Nos.12175034,12005063)+1 种基金the National Key R&D Program of China(No.2019YFE03030001)the Fundamental Research Funds for the Central Universities(No.2232022G-10)。
文摘Energetic alpha particle losses with the toroidal field ripple and the Coulomb collision in the CFETR tokamak have been simulated by using the orbit-following code GYCAVA for the steady-state and hybrid scenarios.The effects of the outer boundary and the ripple amplitude on alpha particle losses have been investigated.The loss fractions and heat loads of alpha particles in the hybrid scenario are much smaller than those in the steady-state scenario for a significant ripple amplitude.Some alpha particles in the plasma core are lost due to the ripple stochastic transport for a large ripple amplitude parameter.The heat loads with the last closed flux surface boundary are different from those with the wall boundary for the CFETR tokamak,which can be explained by typical alpha particle orbits.Discrete heat load spots have been observed in alpha particle loss simulations,which is due to the ripple well loss.The transition of the lost alpha particle behavior from the ripple stochastic diffusion to the ripple well trapping has been identified in our CFETR simulations.The Coulomb collision effect is responsible for this transition.
基金Supported by National Natural Science Foundation of China(11575193,11205240,11265003,U1431109)
文摘A sealed high gas pressure detector working in pure argon is assembled.It consists of a 5 cm × 5 cm PCB THGEM（THick Gaseous Electron Multiplier）.The detector structure and experimental setup are described.The performance under high pressure（2 atm） is examined,selecting optimal voltages for the ionization region and induction region.The dependence of the shape of alpha particle spectra measured with relative gas gain on gas pressure（1.3-2.0 atm） has been studied.Eight data sets of relative gas gain versus working voltage of THGEM,expressed by weighting field E/P,are normalized,consistent with theory.The results show that the air tightness of the chamber is good,measured by a sensitive barometer and checked with gas gain.The experimental results are compared with Monte Carlo simulation of energy deposition without gas gain involved.
文摘The results of experiments on measuring the energy spectra of alpha particles in reactions with heavy ions are presented.The measurements were performed using the high-resolution magnetic analyzer MAVR with beams of ^(48)Ca(280 MeV)and ^(56)Fe(320 and 400 MeV)on ^(181)Ta and ^(238)U targets at an angle of 0°.A strong dependence of the double differential cross sections for production of alpha particles on the atomic number of the target nucleus was observed,which indicates that fast alpha particles are mainly emitted from the target nucleus;this conclusion was also confirmed by calculations within the time-dependent Schrödinger equation approach.An analysis of the obtained experimental data was carried out within the model of moving sources modified to consider the kinematic limits for two-body and three-body exit channels.
基金supported by ENN Group and ENN Energy Research Institute.
文摘This study analyzes fast ion losses in the EHL-2 fusion device,focusing on both beam ions and alpha particles as p-11B fusion reaction products.Using the Monte Carlo orbit-following code TGCO,we evaluate particle confinement under various operational scenarios,including co-injected tangential neutral beam injection at beam energies of 60 keV,80 keV,and 200 keV.Our simulations estimate the heat load driven by lost beam ions and find it to be within acceptable material limits for a plasma current on the order of mega-amperes.Additionally,we simulate the distribution of fusion products and observe a higher particle loss fraction for alpha particles compared to beam ions.However,due to the relatively low fusion power,these lost alpha particles are unlikely to significantly impact the plasma-facing materials.To assess the impact of the magnetic ripple,we compute the ripple field distribution by modelling the toroidal field(TF)coils as current filaments.The results indicate that the ripple field effect on particle confinement is minimal,primarily due to the large distance of over 1 m between the TF coils and the plasma on the low-field side.The analysis based on the test particle model is a foundational step in ensuring the basic safety aspects of the new device,which is essential for developing a robust design,optimizing performance,and maintaining safe operation.
基金funded by the European Union via the Euratom Research and Training Program(Grant Agreement No.101052200-EUROfusion)funding from LASERLAB-EUROPE(Grant Agreement No.871124,European Union’s Horizon 2020 Research and Innovation Program)+5 种基金supported in part by the United States Department of Energy under Grant No.DE-FG02-93ER40773We also acknowledge support from Grant No.PID2021-125389OA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,UEby“ERDF A Way of Making Europe”by the European Union and Unidad de Investigación Consolidada of Junta de Castilla y León UIC 167supported in part by the National Natural Science Foundation of China under Grant No.12375125the Fundamental Research Funds for the Central Universitiesthe support of the Czech Science Foundation through Grant No.GACR24-11398S.
文摘Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.
基金the National Key R&D Program of China(No.2023YFE0197700)the Fundamental Research Funds for the Central Universities(No.2632023TD04).
文摘Radiopharmaceuticals operate by combining radionuclides with carriers.The radiation energy emitted by radionuclides is utilized to selectively irradiate diseased tissues while minimizing damage to healthy tissues.In comparison to external beam radiation therapy,radionuclide drugs demonstrate research potential due to their biological targeting capabilities and reduced normal tissue toxicity.This article reviews the applications and research progress of radiopharmaceuticals in cancer treatment.Several key radionuclides are examined,including^(223)Ra,^(90)Y,Lutetium-177(^(177)Lu),212 Pb,and Actinium-225(^(225)Ac).It also explores the current development trends of radiopharmaceuticals,encompassing the introduction of novel radionuclides,advancements in imaging technologies,integrated diagnosis and treatment approaches,and equipment-medication combinations.We review the progress in the development of new treatments,such as neutron capture therapy,proton therapy,and heavy ion therapy.Furthermore,we examine the challenges and breakthroughs associated with the clinical translation of radiopharmaceuticals and provide recommendations for the research and development of novel radionuclide drugs.
文摘ENN is planning the next generation experimental device EHL-2 with the goal to verify the thermal reaction rates of p-^(11)B fusion,establish spherical torus/tokamak experimental scaling laws at 10’s keV ion temperature,and provide a design basis for subsequent experiments to test and realize the p-^(11)B fusion burning plasma.Based on 0-dimensional(0-D)system design and 1.5-dimensional transport modelling analyses,the main target parameters of EHL-2 have been basically determined,including the plasma major radius,R0,of 1.05 m,the aspect ratio,A,of 1.85,the maximum central toroidal magnetic field strength,B0,of 3 T,and the plasma toroidal current,Ip,of 3 MA.The main heating system will be the neutral beam injection at a total power of 17 MW.In addition,6 MW of electron cyclotron resonance heating will serve as the main means of local current drive and MHD instabilities control.The physics design of EHL-2 is focused on addressing three main operating scenarios,i.e.,(1)high ion temperature scenario,(2)high-performance steady-state scenario and(3)high triple product scenario.Each scenario will integrate solutions to different important issues,including equilibrium configuration,heating and current drive,confinement and transport,MHD instability,p-^(11)B fusion reaction,plasma-wall interactions,etc.Beyond that,there are several unique and significant challenges to address,including●establish a plasma with extremely high core ion temperature(T_(i,0)>30 keV),and ensure a large ion-to-electron tempera-ture ratio(T_(i,0)/Te,0>2),and a boron concentration of 10%‒15%at the plasma core;●realize the start-up by non-inductive current drive and the rise of MA-level plasma toroidal current.This is because the volt-seconds that the central solenoid of the ST can provide are very limited;●achieve divertor heat and particle fluxes control including complete detachment under high P/R(>20 MW/m)at rela-tively low electron densities.This overview will introduce the advanced progress in the physics design of EHL-2.
文摘The response of a silicon alpha detector to beta particles, electrons and photons was investigated using measurements and Monte Carlo simulations. This information is of relevance for in situ alpha spectrometry from different surfaces at ambient air pressure. According to the simulations, photon detection efficiencies were more than two orders of magnitude smaller than those of electrons. Photons generate signals mainly by Compton electrons. Counts originating from beta particles, electrons and photons were usually below 1 MeV in energy and no clear peaks could be identified from the measured spectra. Unequivocal identification of radionuclides emitting beta particles, electrons and photons is not possible when a mixture of different radionuclides is present in the source. However, radionuclide classification according to their emission energies appears to be possible. Surface contamination measurements will benefit from this capability.
基金Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA_(2)5051000)the National Key R&D Program of China(Grant No.2023YFA1608400)+1 种基金the National Natural Science Foundation of China(Grant No.12005008)the Natural Science Foundation of Top Talent of SZTU(Grant No.GDRC202209).
文摘A model for fast electron-driven high-density plasma is proposed to describe the effect of injected fast electrons on the temperature and inner pressure of the plasma in the fast heating process of the double-cone ignition(DCI)scheme.Due to the collision of the two low-density plasmas,the density and volume of the high-density plasma vary.Therefore,the ignition temperature and energy requirement of the high-density plasma vary at different moments,and the required energy for hot electrons to heat the plasma also changes.In practical experiments,the energy input of hot electrons needs to be considered.To reduce the energy input of hot electrons,the optimal moment and the shortest time for injecting hot electrons with minimum energy are analyzed.In this paper,it is proposed to inject hot electrons for a short time to heat the high-density plasma to a relatively high temperature.Then,the alpha particles with the high heating rate and PdV work heat the plasma to the ignition temperature,further reducing the energy required to inject hot electrons.The study of the injection time of fast electrons can reduce the energy requirement of fast electrons for the high-density plasma and increase the probability of successful ignition of the high-density plasma.
基金Project supported by the National Natural Science Foundation of China(Grant No.12305303)the Natural Science Foundation of Hunan Province of China(Grant Nos.2023JJ40520,2021JJ40444,and 2019JJ30019)+3 种基金the Research Foundation of Education Bureau of Hunan Province of China(Grant No.20A430)the Science and Technology Innovation Program of Hunan Province(Grant No.2020RC3054)the Natural Science Basic Research Plan in the Shaanxi Province of China(Grant No.2023-JC-QN-0015)the Doctoral Research Fund of University of South China。
文摘Convolutional neural networks(CNNs) exhibit excellent performance in the areas of image recognition and object detection, which can enhance the intelligence level of spacecraft. However, in aerospace, energetic particles, such as heavy ions, protons, and alpha particles, can induce single event effects(SEEs) that lead CNNs to malfunction and can significantly impact the reliability of a CNN system. In this paper, the MNIST CNN system was constructed based on a 28 nm systemon-chip(SoC), and then an alpha particle irradiation experiment and fault injection were applied to evaluate the SEE of the CNN system. Various types of soft errors in the CNN system have been detected, and the SEE cross sections have been calculated. Furthermore, the mechanisms behind some soft errors have been explained. This research will provide technical support for the design of radiation-resistant artificial intelligence chips.
基金performed with the support and backing of the NIFS Collaborative Research Program
文摘The efficiency of energetic ion confinement is reduced in a tokamak plasma by the non-axisymmetric field, namely the ripple field. The ripple field is produced by a finite number of toroidal field coils. It is affected by the non-axisymmetric finite beta effect. The three-dimensional MHD equilibrium calculation code VMEC is used to analyze the non-axisymmetric finite beta effect in a ripple tokamak. In the VMEC code, the flux coordinates are used, so the calculation region is limited to the area of plasma. To calculate the orbit outside the plasma, we develop a field calculation code, which is based on the Biot-Savart law. The details of the method and results are described in this paper.
基金LHD project budget of Japan (NIFS08ULHH508)the Grant-in-aid for Scientific Research from MEST of Japan (No.16082209)the JSPS-CAS Core-University Program in the field of Plasma and Nuclear Fusion
文摘In the large helical device （LHD） having three dimensional configuration, Alfven eigenmodes （AEs） destabilized by energetic ions are widely investigated using neutral beam heated plasmas with monotonic and non-monotonic rotational transform （l/2π） profiles. In a plasma with monotonic l/2π-profile, core-localized toroidicity-induced Alfven eigenmode （TAE） as well as global one are often observed. With the increase in the averaged toroidal beta value, defined as the ratio of total plasma pressure to toroidal magnetic pressure, core-localized TAE with low toroidal mode number becomes global. In a relatively high beta plasma with monotonic l/2π-profile, two TAEs with different toroidal mode number often interact nonlinearly and generate another modes through three wave coupling. In a plasma with non-monotonic l/2π-profile generated by intense counter neutral beam current drive, reversed shear Alfven eigenmode （RSAE） and geodesic acoustic mode （CAM） excited by energetic ions were observed for the first time in a helical plasma. Nonlinear coupling was also observed between RSAE and GAM.
文摘A simple method employing a pair of pancake-style Geiger-Mueller (GM) counters for quantitative measurement of radon activity concentration (activity per unit volume) is described and demonstrated. The use of two GM counters, together with the basic theory derived in this paper, permit the detection of alpha particles from decay of and progeny ( <sup>218</sup>Po, <sup>214</sup>Po) and the conversion of the alpha count rate into a radon concentration. A unique feature of this method, in comparison with standard methodologies to measure radon concentration, is the absence of a fixed control volume. Advantages afforded by the reported GM method include: 1) it provides a direct in-situ value of radon level, thereby eliminating the need to send samples to an external testing laboratory;2) it can be applied to monitoring radon levels exhibiting wide short-term variability;3) it can yield short-term measurements of comparable accuracy and equivalent or higher precision than a commercial radon monitor sampling by passive diffusion;4) it yields long-term measurements statistically equivalent to commercial radon monitors;5) it uses the most commonly employed, overall least expensive, and most easily operated type of nuclear instrumentation. As such, the method is par-ticularly suitable for use by researchers, public health personnel, and home dwellers who prefer to monitor indoor radon levels themselves. The results of a consecutive 30-day sequence of 24 hour mean radon measurements by the proposed GM method and a commercial state-of-the-art radon monitor certified for radon testing are compared.
文摘After one century of nuclear physics, its underlying fundamental laws remain a puzzle. Rutherford scattering is well known to be electric at low kinetic energy. Nobody noticed that the Rutherford scattering formula works also at high kinetic energy, needing only to replace the repulsive electric -2 exponent by the also repulsive magnetic -6 exponent. A proton attracts a not so neutral neutron as amber attracts dust. The nucleons have magnetic moments that interact as magnets, equilibrating statically the electric attraction between a proton and a not so neutral neutron. In this paper, the electromagnetic potential energies of the deuteron 2H and the α particle 4He have been calculated statically, using only electromagnetic fundamental laws and constants. Nuclear scattering and binding energy are both electromagnetic.
文摘The linear-chain structure in which three alpha particles are arranged in a straight line was initially proposed by H.Morinaga[1]as the structure of the Hoyle state of carbon-12[2].This unique idea attracted much attention,but it was rejected because it could not explain the lifetime of the Hoyle state.Half a century later,the concept of the linear chain structure was revived in the physics of unstable nuclei,and experimental and theoretical research have demonstrated that this structure exists in carbon-14 and 16.The authors have conducted internationally recognized experimental research on the linear-chain structure of carbon-14 and carbon-16.
