In section‘Track decoding’of this article,one of the paragraphs was inadvertently missed out after the text'…shows the flow diagram of the Tr2-1121 track mode.'The missed paragraph is provided below.
A low-background γ spectrometer named the Gamma spectrometer for Nuclear Activation Studies(GNAS)was developed to detect scarce γ radioactivity,with a special focus on conducting activation experiments in nuclear as...A low-background γ spectrometer named the Gamma spectrometer for Nuclear Activation Studies(GNAS)was developed to detect scarce γ radioactivity,with a special focus on conducting activation experiments in nuclear astrophysics.It consisted of a well-type HPGe detector surrounded by optimized multi-layer shielding,which reduced the laboratory background counting rate by 99.5%and enabled a sensitivity edge as low as 0.044 Bq for the 477.6 KeV γ line of ^(7)Be.The near 4π geometry of the HPGe detector introduces a severe true coincidence summing(TCS)effect along with its high detection efficiency.To determine the intrinsic detection efficiency and correct for the TCS effect,a Monte Carlo simulation method was developed with the Geant4 toolkit.The detector model was optimized by matching the simulated full energy peak(FEP)statistics with those of a ^(137)Cs monoenergetic source and calibrated ^(55,57,58)Co sources produced by low-energy proton beam bombardment of natural iron.The intrinsic detection efficiency curve was obtained,and an algorithm for the correction of the TCS effect was programmed using decay data from the ENSDF library and Nuclear Wallet Cards.The GNAS fulfills the requirements of the ongoing activation measurement of proton-and alpha-induced reactions in nuclear astrophysics on the ground and at the Jinping Underground Nuclear Astrophysics(JUNA)facility.展开更多
The multiple nuclides identification algorithm with low consumption and strong robustness is crucial for rapid radioactive source searching.This study investigates the design of a low-consumption multiple nuclides ide...The multiple nuclides identification algorithm with low consumption and strong robustness is crucial for rapid radioactive source searching.This study investigates the design of a low-consumption multiple nuclides identification algorithm for portable gamma spectrometers.First,the gamma spectra of 12 target nuclides(including the background case)were measured to create training datasets.The characteristic energies,obtained through energy calibration and full-energy peak addresses,are utilized as input features for a neural network.A large number of single-and multiple-nuclide training datasets are generated using random combinations and small-range drifting.Subsequently,a multi-label classification neural network based on a binary cross-entropy loss function is applied to export the existence probability of certain nuclides.The designed algorithm effectively reduces the computation time and storage space required by the neural network and has been successfully implemented in a portable gamma spectrometer with a running time of t_(r)<2 s.Results show that,in both validation and actual tests,the identification accuracy of the designed algorithm reaches 94.8%,for gamma spectra with a dose rate of d≈0.5μSv∕h and a measurement time t_(m)=60 s.This improves the ability to perform rapid on-site nuclide identification at important sites.展开更多
The accumulation of^(222)Rn and^(220)Rn progeny in poorly ventilated environments poses the risk of natural radiation exposure to the public.A previous study indicated that satisfactory results in determining the^(222...The accumulation of^(222)Rn and^(220)Rn progeny in poorly ventilated environments poses the risk of natural radiation exposure to the public.A previous study indicated that satisfactory results in determining the^(222)Rn and^(220)Rn progeny concentrations by measuring the total alpha counts at five time intervals within 560 min should be expected only in the case of high progeny concentrations in air.To complete the measurement within a relatively short period and adapt it for simultaneous measurements at comparatively lower^(222)Rn and^(220)Rn progeny concentrations,a novel mathematical model was proposed based on the radioactive decay law.This model employs a nonlinear fitting method to distinguish nuclides with overlapping spectra by utilizing the alpha particle counts of non-overlapping spectra within consecutive measurement cycles to obtain the concentrations of^(222)Rn and^(220)Rn progeny in air.Several verification experiments were conducted using an alpha spectrometer.The experimental results demonstrate that the concentrations of^(222)Rn and^(220)Rn progeny calculated by the new method align more closely with the actual circumstances than those calculated by the total count method,and their relative uncertainties are all within±16%.Furthermore,the measurement time was reduced to 90 min,representing an acceleration of 84%.The improved capability of the new method in distinguishing alpha particles with similar energies emitted from ^(218)Po and^(212)Bi,both approximately 6 MeV,contributed to realizing more accurate results.The proposed method has the potential advantage of measuring relatively low concentrations of^(222)Rn and^(220)Rn progeny in air more quickly via air filtration.展开更多
In the field of deep space exploration,the rapid development of terahertz spectrometer has put forward higher requirements to the back-end chirp transform spectrometer(CTS)system.In order to simultaneously meet the me...In the field of deep space exploration,the rapid development of terahertz spectrometer has put forward higher requirements to the back-end chirp transform spectrometer(CTS)system.In order to simultaneously meet the measurement requirements of wide bandwidth and high accuracy spectral lines,we built a CTS system with an analysis bandwidth of 1 GHz and a frequency resolution of 100 kHz around the surface acoustic wave(SAW)chirp filter with a bandwidth of 1 GHz.In this paper,the relationship between the CTS nonlinear phase error shift model and the basic measurement parameters is studied,and the effect of CTS phase mismatch on the pulse compression waveform is analyzed by simulation.And the expander error optimization method is proposed for the problem that the large nonlinear error of the expander leads to the unbalanced response of the CTS system and the serious distortion of the compressed pulse waveform under large bandwidth.It is verified through simulation and experiment that the method is effective for reducing the root mean square error(RMSE)of the phase of the expander from 18.75°to 6.65°,reducing the in-band standard deviation of the CTS frequency resolution index from 8.43 kHz to 4.72 kHz,solving the problem of serious distortion of the compressed pulse waveform,and improving the uneven CTS response under large bandwidth.展开更多
The neutron total cross-section spectrometer(NTOX)applied on the Back-n beamline at the China Spallation Neutron Source(CSNS)is based on a multicell fission chamber and utilizes ^(235,238)U for neutron detection.To re...The neutron total cross-section spectrometer(NTOX)applied on the Back-n beamline at the China Spallation Neutron Source(CSNS)is based on a multicell fission chamber and utilizes ^(235,238)U for neutron detection.To reduce the experimental uncertainty in the resonance energy region of ^(235,238)U and improve the neutron detection efficiency,a fast scintillator-based neutron total cross-section(FAST)spectrometer was designed.A prototype based on a large-area square ^(6)Li-enriched Cs_(2)LiLaBr_(6)(CLLB)scintillator was constructed and beam-tested.The size of the CLLB scintillator was 50.8 mm×50.8 mm×6 mm,and its side was coupled to an array of 1×8 S14160 MPPC to avoid the irradiation from the high-intensity neutrons and rays.The beam test was performed using a broad-energy pulsed neutron and the time-of-flight(TOF)technique on the Back-n beamline.The results demonstrate that the prototype exhibits good neutron/ γ discrimination capability under strong flash irradiation.The prototype was applied to measure the neutron total cross-section of ^(nat)Pb and the result was compared with that obtained using the NTOX.The two results were consistent in the energy region of 0.3 eV to 1 keV,and the prototype showed a higher detection efficiency and did not exhibit fission resonance effect.This type of spectrometer can be used as a complement to the NTOX in the low-energy range and provides a technical reference and framework for developing the FAST spectrometer on the Back-n beamline.展开更多
A combination of high-field asymmetric waveform ion mobility spectrometry （FAIMS） with mass spectrometer （MS） was analyzed. FAIMS separates ions from the volatile organic compounds in the gas-phase as an ion-filte...A combination of high-field asymmetric waveform ion mobility spectrometry （FAIMS） with mass spectrometer （MS） was analyzed. FAIMS separates ions from the volatile organic compounds in the gas-phase as an ion-filter for MS. The sample ions were created at ambient pressure by ion source, which was equipped with a 10.6 eV UV discharge lamp （A=116.5 nm）. The drift tube of FAIMS is composed of two parallel planar electrodes and the dimension is 10 mm×8 mm×0.5 mm. FAIMS was investigated when driven by the high-filed rectangular asymmetric waveform with the peak-to-peak voltage of 1.36 kV at the frequency of 1 MHz and the duty cycle of 30%. The acetone, the butanone, and their mixture were adopted to characterize the FAIMS-MS. The mass spectra obtained from MS illustrate that there are ion-molecular reactions between the ions and the sample neutral molecular. And the proton transfer behavior in the mixture of the acetone and the butanone is also observed. With the compensation voltage tuned from -30 V to 10 V with a step size of 0.1 V, the ion pre-separation before MS is realized.展开更多
A wide-range and phase-locked Michelson interferometer technique is described. This technique combined with femtosecond laser is used to measure the spectrum of the rare-earth ion Nd：YVO4, which presents very high si...A wide-range and phase-locked Michelson interferometer technique is described. This technique combined with femtosecond laser is used to measure the spectrum of the rare-earth ion Nd：YVO4, which presents very high signal to noise ratio of interferometric intensity output and higher spectral resolution than traditional grating spectrophotometer.展开更多
An experiment facility has been set up for the study of metal cluster compounds in our laboratory, which consists of a nano-electrospray ionization source, an ion transmission and focus system, and a reflectron time-o...An experiment facility has been set up for the study of metal cluster compounds in our laboratory, which consists of a nano-electrospray ionization source, an ion transmission and focus system, and a reflectron time-of-fight mass spectrometer. Taking advantage of the nano-electrospray ionization source, polyvalent ions are usually produced in the ＂ionization＂ process and the obtained mass resolution of the equipment is over 8000. The molecular ion peaks of metal cluster compounds [Au20（PPhpy2）10Cl2]（SbF6）4, where PPhpy2=bis（2- pyridyl）phenylphosphine, and [AuaAg2（C）L6]（BF4）4, where L=2-（diphenylphosphino）-5- methylpyridine, are distinguished in the respective mass spectrum, accompanied by some fragment ion peaks. In addition, the mass-to-charge ratios of the parent ions are determi- nated. Preliminary results suggest that the device is a powerful tool for the study of metal cluster compounds. It turns out that the information obtained by the instrumentation serves as an essential supplement to single crystal X-ray diffraction for structure characterization of metal cluster compounds.展开更多
Background:Pine wilt disease(PWD)is a major ecological concern in China that has caused severe damage to millions of Chinese pines(Pinus tabulaeformis).To control the spread of PWD,it is necessary to develop an effect...Background:Pine wilt disease(PWD)is a major ecological concern in China that has caused severe damage to millions of Chinese pines(Pinus tabulaeformis).To control the spread of PWD,it is necessary to develop an effective approach to detect its presence in the early stage of infection.One potential solution is the use of Unmanned Airborne Vehicle(UAV)based hyperspectral images(HIs).UAV-based HIs have high spatial and spectral resolution and can gather data rapidly,potentially enabling the effective monitoring of large forests.Despite this,few studies examine the feasibility of HI data use in assessing the stage and severity of PWD infection in Chinese pine.Method:To fill this gap,we used a Random Forest(RF)algorithm to estimate the stage of PWD infection of trees sampled using UAV-based HI data and ground-based data(data directly collected from trees in the field).We compared relative accuracy of each of these data collection methods.We built our RF model using vegetation indices(VIs),red edge parameters(REPs),moisture indices(MIs),and their combination.Results:We report several key results.For ground data,the model that combined all parameters(OA:80.17%,Kappa:0.73)performed better than VIs(OA:75.21%,Kappa:0.66),REPs(OA:79.34%,Kappa:0.67),and MIs(OA:74.38%,Kappa:0.65)in predicting the PWD stage of individual pine tree infection.REPs had the highest accuracy(OA:80.33%,Kappa:0.58)in distinguishing trees at the early stage of PWD from healthy trees.UAV-based HI data yielded similar results:the model combined VIs,REPs and MIs(OA:74.38%,Kappa:0.66)exhibited the highest accuracy in estimating the PWD stage of sampled trees,and REPs performed best in distinguishing healthy trees from trees at early stage of PWD(OA:71.67%,Kappa:0.40).Conclusion:Overall,our results confirm the validity of using HI data to identify pine trees infected with PWD in its early stage,although its accuracy must be improved before widespread use is practical.We also show UAV-based data PWD classifications are less accurate but comparable to those of ground-based data.We believe that these results can be used to improve preventative measures in the control of PWD.展开更多
A new fully automatic ^40Ar/^39Ar laboratory with a Thermo Scientific ARGUS VI mass spectrometer has been established in China University of Geosciences （Wuhan）. We designed and developed a mini efficient preparatio...A new fully automatic ^40Ar/^39Ar laboratory with a Thermo Scientific ARGUS VI mass spectrometer has been established in China University of Geosciences （Wuhan）. We designed and developed a mini efficient preparation system （80 mL）, a CO2 laser for heating samples, a crusher for extracting fluid inclusions within K-poor minerals and an air reservoir （31 L） and pipette （0.1 mL） system. The ARGUS VI mass spectrometer is operated by the Qtegra Noble Gas software, which can control the peripheral accessories, such as pneumatic valves, CO2 laser and crusher through a PeriCon （peripheral controller）. The experimental procedures of atmospheric argon ana- lyses, ^40Ar/^39Ar dating by laser stepwise heating and by progressive crushing in vacuo, can be fully automatically performed. The weighted mean of atmospheric ^40Ar/^36Ar ratios is 302.22＋0.03 （1σ, MSWD=0.74, n=200）, indicating that air reservoir and pipette system and the whole instrument sys- tem are very stable. This laboratory is a successful pioneer example in China to establish a new no- ble gas laboratory with self-made peripheral accessories expect for the mass spectrometer.展开更多
A newly developed Deep Ocean Compact Autonomous Raman Spectrometer （DOCARS） system is introduced and used for in-situ detection of acid radical ions in this paper. To evaluate the feasibility and capability of DOCAR...A newly developed Deep Ocean Compact Autonomous Raman Spectrometer （DOCARS） system is introduced and used for in-situ detection of acid radical ions in this paper. To evaluate the feasibility and capability of DOCARS for quantitative analysis of the acid radical ions in the deep ocean, extensive investigations have been carried out both in laboratory and sea trials during the development phase. In the laboratory investigations, Raman spectra of the prepared samples （acid radical ions solutions） were obtained, and analyzed using the method of internal standard normalization in data processing. The Raman signal of acid radical ions was normalized by that of water molecules. The calibration curve showed that the normalized Raman signal intensity of SO4^2-, NO3^-, and HCO^-3 increases linearly as the concentration rises with correlation coefficient R^2 of 0.99, 0.99, and 0.98 respectively. The linear function obtained from the calibration curve was then used for the analysis of the spectra ,data acquired in the sea trial under a simulating chemical field in the deep-sea environment. It was found that the detected concentration of NO3 according to the linear function can reflect the concentration changes of NO~ after the sample was released, and the detection accuracy of the DOCARS system for SO^2-_4 is 8%. All the results showed that the DOCARS system has great potential in quantitative detection of acid radical ions under the deep-sea environment, while the sensitivity of the DOCARS system is expected to be improved.展开更多
With outstanding analytical performance and portability, miniature mass spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass spectrometers has lasted for more than ten years...With outstanding analytical performance and portability, miniature mass spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass spectrometers has lasted for more than ten years, during which a number of miniature mass spectrometers employing different techniques have been developed. Small-in-size, working at relatively high pressure region and capable of performing tandem mass spectrometry, ion trap is the most widely used mass analyzer in miniature mass spectrometer systems. The recent development of miniature ion trap mass spectrometer systems in the last ten years was reviewed in this paper. These instruments adopt different atmospheric pressure interfaces （APIs）, which are membrane inlets （MIs）, discontinuous atmospheric pressure interface （DAPI） and continuous atmospheric pressure interface （CAPI）. This review emphasizes on the mini mass spectrometry （MS） system that can be handheld by one person, but not the field-able ones that are too large to be hand-portable.展开更多
Fine particle of organic aerosol （OA）, mostly arising from pollution, are abundant in Beijing. To achieve a better un- derstanding of the difference in OA in summer and autumn, a high-resolution time-of-flight aeros...Fine particle of organic aerosol （OA）, mostly arising from pollution, are abundant in Beijing. To achieve a better un- derstanding of the difference in OA in summer and autumn, a high-resolution time-of-flight aerosol mass spectrometer （HR- ToF-AMS, Aerodyne Research Inc., USA） was deployed in urban Beijing in August and October 2012. The mean OA mass concentration in autumn was 30 4-30 μg m-3, which was higher than in summer （13 4-6.9 μg m-3）. The elemental anal- ysis found that OA was more aged in summer （oxygen-to-carbon （O/C） ratios were 0.41 and 0.32 for summer and autumn, respectively）. Positive matrix factorization （PMF） analysis identified three and five components in summer and autumn, re- spectively. In summer, an oxygenated OA （OOA）, a cooking-emission-related OA （COA）, and a hydrocarbon-like OA （HOA） were indentified. Meanwhile, the OOA was separated into LV-OOA （low-volatility OOA） and SV-OOA （semi-volatile OOA）; and in autumn, a nitrogen-containing OA （NOA） was also found. The SOA （secondary OA） was always the most important OA component, accounting for 55% of the OA in the two seasons. Back trajectory clustering analysis found that the origin of the air masses was more complex in summer. Southerly air masses in both seasons were associated with the highest OA loading, while northerly air masses were associated with the lowest OA loading. A preliminary study of OA components, especially the POA （primary OA）, in different periods found that the HOA and COA all decreased during the National Day holiday period, and HOA decreased at weekends compared with weekdays.展开更多
A simple negative ion mobility spectrometer （IMS） is designed and used to investi- gate the factors that influence the number and efficiency of electrons generated by the needle-ring pulsed corona discharge electron...A simple negative ion mobility spectrometer （IMS） is designed and used to investi- gate the factors that influence the number and efficiency of electrons generated by the needle-ring pulsed corona discharge electron source. Simulation with Ansoft Maxwell 12 is carried out to analyze the electric field distribution within the IMS, and to offer the basis and foundation for analyzing the measurement results. The measurement results of the quantities of electrons show that when the drift electric field strength and the ring inner diameter rise, both the number of ef- fective electrons and the effective electron rate are increased. When the discharge voltage becomes stronger, the number of effective electrons goes up while the effective electron rate goes down. In light of the simulation results, mechanisms underlying the effects of drift electric field strength, ring inner diameter, and discharge voltage on the effective electron number and effective electron rate are discussed. These will make great sense for designing negative ion mode IMS using the needle-ring pulsed corona discharge as the electron source.展开更多
A real-time Bonner sphere spectrometer(BSS)has been developed for spectral neutron measurements with the HL-2A Tokamak.To correct and verify the accuracy of the neutron spectrum from the BSS,the BSS system was calibra...A real-time Bonner sphere spectrometer(BSS)has been developed for spectral neutron measurements with the HL-2A Tokamak.To correct and verify the accuracy of the neutron spectrum from the BSS,the BSS system was calibrated using monoenergetic neutron beams in the energy range of 100 keV–5 MeV.The response function of the BSS was corrected based on the calibration results,and the corrected BSS system was verified by unfolding monoenergetic neutron spectra.Fusion neutron spectra on the HL-2A have been obtained from the calibrated BSS system for the first time.展开更多
A self-adaptive differential evolution neutron spectrum unfolding algorithm(SDENUA)is established in this study to unfold the neutron spectra obtained from a water-pumping-injection multilayered concentric sphere neut...A self-adaptive differential evolution neutron spectrum unfolding algorithm(SDENUA)is established in this study to unfold the neutron spectra obtained from a water-pumping-injection multilayered concentric sphere neutron spectrometer(WMNS).Specifically,the neutron fluence bounds are estimated to accelerate the algorithm convergence,and the minimum error between the optimal solution and input neutron counts with relative uncertainties is limited to 10^(-6)to avoid unnecessary calculations.Furthermore,the crossover probability and scaling factor are self-adaptively controlled.FLUKA Monte Carlo is used to simulate the readings of the WMNS under(1)a spectrum of Cf-252 and(2)its spectrum after being moderated,(3)a spectrum used for boron neutron capture therapy,and(4)a reactor spectrum.Subsequently,the measured neutron counts are unfolded using the SDENUA.The uncertainties of the measured neutron count and the response matrix are considered in the SDENUA,which does not require complex parameter tuning or an a priori default spectrum.The results indicate that the solutions of the SDENUA agree better with the IAEA spectra than those of MAXED and GRAVEL in UMG 3.1,and the errors of the final results calculated using the SDENUA are less than 12%.The established SDENUA can be used to unfold spectra from the WMNS.展开更多
For a characteristic c-ray with interlaced overlap peak, and the case where its reliable and credible net count cannot be obtained using the current high-purity germanium(HPGe) multichannel γ-ray spectrum software, t...For a characteristic c-ray with interlaced overlap peak, and the case where its reliable and credible net count cannot be obtained using the current high-purity germanium(HPGe) multichannel γ-ray spectrum software, two new methods are proposed herein to obtain the γ-ray net peak count from the interlaced overlap peak in the HPGe cray spectrometer system, of which one is the symmetric conversion method based on Gaussian distribution and the other is where the energy average value of two close γ-rays is regarded as the γ-ray energy. The experimental results indicate that the two methods mentioned above are reliable and credible. This study is significant for the development of better γ-ray spectrum processing software for measuring complex γ-ray spectra concerning the nuclear reaction cross section, neutron activation analysis, and analysis of transuranium elements, using an HPGe detector.展开更多
A real-time double-ring neutron time-of-flight(TOFII) spectrometer system has been proposed to achieve plasma diagnosis on HL-2M tokamak with a relatively high count rate and sufficient energy resolution.The TOFII sys...A real-time double-ring neutron time-of-flight(TOFII) spectrometer system has been proposed to achieve plasma diagnosis on HL-2M tokamak with a relatively high count rate and sufficient energy resolution.The TOFII system is in its development stage,and this work describes its characteristics in terms of design principle,system structure,electronic system design,preliminary tests,and neutron transport simulation.The preliminary test results illustrate that the TOFII system can demonstrate the realtime dynamic spectrum every 10 ms.The results also show that based on the support vector machine method,the n-γ discrimination algorithm achieves the discrimination accuracy of 99.1%with a figure of merit of 1.30,and the intrinsic timing resolution of the system is within 0.3%.The simulated flight time spectrums from 1 to 5 MeV are obtained through the Monte Carlo tool Geant4,which also provide the reasonable results.The TOFII system will then be calibrated on mono-energetic neutron sources for further verification.展开更多
A compact spectrometer on silicon is proposed and demonstrated with an ultrahigh resolution.It consists of a thermally-tunable ultra-high-Q resonator aiming at ultrahigh resolution and an array of wideband resonators ...A compact spectrometer on silicon is proposed and demonstrated with an ultrahigh resolution.It consists of a thermally-tunable ultra-high-Q resonator aiming at ultrahigh resolution and an array of wideband resonators for achieving a broadened working window.The present on-chip spectrometer has a footprint as compact as 0.35 mm^(2),and is realized with standard multi-project-wafer foundry processes.The measurement results show that the on-chip spectrometer has an ultra-high resolution Δλ of 5 pm and a wide working window of 10 nm.The dynamic range defined as the ratio of the working window and the wavelength resolution is as large as 1940,which is the largest for on-chip dispersive spectro-meters to the best of our knowledge.The present high-performance on-chip spectrometer has great potential for high-resolution spectrum measurement in the applications of gas sensing,food monitoring,health analysis,etc.展开更多
文摘In section‘Track decoding’of this article,one of the paragraphs was inadvertently missed out after the text'…shows the flow diagram of the Tr2-1121 track mode.'The missed paragraph is provided below.
基金supported by the National Key Research and Development Project(No.2022YFA1602301)the National Natural Science Foundation of China(Nos.U2267205 and 12275361)the Continuous-Support Basic Scientific Research Project.
文摘A low-background γ spectrometer named the Gamma spectrometer for Nuclear Activation Studies(GNAS)was developed to detect scarce γ radioactivity,with a special focus on conducting activation experiments in nuclear astrophysics.It consisted of a well-type HPGe detector surrounded by optimized multi-layer shielding,which reduced the laboratory background counting rate by 99.5%and enabled a sensitivity edge as low as 0.044 Bq for the 477.6 KeV γ line of ^(7)Be.The near 4π geometry of the HPGe detector introduces a severe true coincidence summing(TCS)effect along with its high detection efficiency.To determine the intrinsic detection efficiency and correct for the TCS effect,a Monte Carlo simulation method was developed with the Geant4 toolkit.The detector model was optimized by matching the simulated full energy peak(FEP)statistics with those of a ^(137)Cs monoenergetic source and calibrated ^(55,57,58)Co sources produced by low-energy proton beam bombardment of natural iron.The intrinsic detection efficiency curve was obtained,and an algorithm for the correction of the TCS effect was programmed using decay data from the ENSDF library and Nuclear Wallet Cards.The GNAS fulfills the requirements of the ongoing activation measurement of proton-and alpha-induced reactions in nuclear astrophysics on the ground and at the Jinping Underground Nuclear Astrophysics(JUNA)facility.
文摘The multiple nuclides identification algorithm with low consumption and strong robustness is crucial for rapid radioactive source searching.This study investigates the design of a low-consumption multiple nuclides identification algorithm for portable gamma spectrometers.First,the gamma spectra of 12 target nuclides(including the background case)were measured to create training datasets.The characteristic energies,obtained through energy calibration and full-energy peak addresses,are utilized as input features for a neural network.A large number of single-and multiple-nuclide training datasets are generated using random combinations and small-range drifting.Subsequently,a multi-label classification neural network based on a binary cross-entropy loss function is applied to export the existence probability of certain nuclides.The designed algorithm effectively reduces the computation time and storage space required by the neural network and has been successfully implemented in a portable gamma spectrometer with a running time of t_(r)<2 s.Results show that,in both validation and actual tests,the identification accuracy of the designed algorithm reaches 94.8%,for gamma spectra with a dose rate of d≈0.5μSv∕h and a measurement time t_(m)=60 s.This improves the ability to perform rapid on-site nuclide identification at important sites.
基金supported by the National Natural Science Foundation of China(No.12075112)Natural Science Foundation of Hunan(No.2023JJ50121),Natural Science Foundation of Hunan Province(No.2023JJ50091)Key Projects of Hunan Provincial Department of Education(No.23A0516).
文摘The accumulation of^(222)Rn and^(220)Rn progeny in poorly ventilated environments poses the risk of natural radiation exposure to the public.A previous study indicated that satisfactory results in determining the^(222)Rn and^(220)Rn progeny concentrations by measuring the total alpha counts at five time intervals within 560 min should be expected only in the case of high progeny concentrations in air.To complete the measurement within a relatively short period and adapt it for simultaneous measurements at comparatively lower^(222)Rn and^(220)Rn progeny concentrations,a novel mathematical model was proposed based on the radioactive decay law.This model employs a nonlinear fitting method to distinguish nuclides with overlapping spectra by utilizing the alpha particle counts of non-overlapping spectra within consecutive measurement cycles to obtain the concentrations of^(222)Rn and^(220)Rn progeny in air.Several verification experiments were conducted using an alpha spectrometer.The experimental results demonstrate that the concentrations of^(222)Rn and^(220)Rn progeny calculated by the new method align more closely with the actual circumstances than those calculated by the total count method,and their relative uncertainties are all within±16%.Furthermore,the measurement time was reduced to 90 min,representing an acceleration of 84%.The improved capability of the new method in distinguishing alpha particles with similar energies emitted from ^(218)Po and^(212)Bi,both approximately 6 MeV,contributed to realizing more accurate results.The proposed method has the potential advantage of measuring relatively low concentrations of^(222)Rn and^(220)Rn progeny in air more quickly via air filtration.
文摘In the field of deep space exploration,the rapid development of terahertz spectrometer has put forward higher requirements to the back-end chirp transform spectrometer(CTS)system.In order to simultaneously meet the measurement requirements of wide bandwidth and high accuracy spectral lines,we built a CTS system with an analysis bandwidth of 1 GHz and a frequency resolution of 100 kHz around the surface acoustic wave(SAW)chirp filter with a bandwidth of 1 GHz.In this paper,the relationship between the CTS nonlinear phase error shift model and the basic measurement parameters is studied,and the effect of CTS phase mismatch on the pulse compression waveform is analyzed by simulation.And the expander error optimization method is proposed for the problem that the large nonlinear error of the expander leads to the unbalanced response of the CTS system and the serious distortion of the compressed pulse waveform under large bandwidth.It is verified through simulation and experiment that the method is effective for reducing the root mean square error(RMSE)of the phase of the expander from 18.75°to 6.65°,reducing the in-band standard deviation of the CTS frequency resolution index from 8.43 kHz to 4.72 kHz,solving the problem of serious distortion of the compressed pulse waveform,and improving the uneven CTS response under large bandwidth.
基金supported by the National Natural Science Foundation of China(No.12375296)the Key Laboratory of Nuclear Data Foundation(No.JCKY2022201C153)+1 种基金the Science and Technology Innovation Program of Hunan Province(No.2024RC3205)the Natural Science Foundation of Hunan Province,China(No.2024JJ2044).
文摘The neutron total cross-section spectrometer(NTOX)applied on the Back-n beamline at the China Spallation Neutron Source(CSNS)is based on a multicell fission chamber and utilizes ^(235,238)U for neutron detection.To reduce the experimental uncertainty in the resonance energy region of ^(235,238)U and improve the neutron detection efficiency,a fast scintillator-based neutron total cross-section(FAST)spectrometer was designed.A prototype based on a large-area square ^(6)Li-enriched Cs_(2)LiLaBr_(6)(CLLB)scintillator was constructed and beam-tested.The size of the CLLB scintillator was 50.8 mm×50.8 mm×6 mm,and its side was coupled to an array of 1×8 S14160 MPPC to avoid the irradiation from the high-intensity neutrons and rays.The beam test was performed using a broad-energy pulsed neutron and the time-of-flight(TOF)technique on the Back-n beamline.The results demonstrate that the prototype exhibits good neutron/ γ discrimination capability under strong flash irradiation.The prototype was applied to measure the neutron total cross-section of ^(nat)Pb and the result was compared with that obtained using the NTOX.The two results were consistent in the energy region of 0.3 eV to 1 keV,and the prototype showed a higher detection efficiency and did not exhibit fission resonance effect.This type of spectrometer can be used as a complement to the NTOX in the low-energy range and provides a technical reference and framework for developing the FAST spectrometer on the Back-n beamline.
文摘A combination of high-field asymmetric waveform ion mobility spectrometry （FAIMS） with mass spectrometer （MS） was analyzed. FAIMS separates ions from the volatile organic compounds in the gas-phase as an ion-filter for MS. The sample ions were created at ambient pressure by ion source, which was equipped with a 10.6 eV UV discharge lamp （A=116.5 nm）. The drift tube of FAIMS is composed of two parallel planar electrodes and the dimension is 10 mm×8 mm×0.5 mm. FAIMS was investigated when driven by the high-filed rectangular asymmetric waveform with the peak-to-peak voltage of 1.36 kV at the frequency of 1 MHz and the duty cycle of 30%. The acetone, the butanone, and their mixture were adopted to characterize the FAIMS-MS. The mass spectra obtained from MS illustrate that there are ion-molecular reactions between the ions and the sample neutral molecular. And the proton transfer behavior in the mixture of the acetone and the butanone is also observed. With the compensation voltage tuned from -30 V to 10 V with a step size of 0.1 V, the ion pre-separation before MS is realized.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.60677051 and No.10774193） and the National Key Basic Research Special Foundation （No.G2010CB923204）.
文摘A wide-range and phase-locked Michelson interferometer technique is described. This technique combined with femtosecond laser is used to measure the spectrum of the rare-earth ion Nd：YVO4, which presents very high signal to noise ratio of interferometric intensity output and higher spectral resolution than traditional grating spectrophotometer.
文摘An experiment facility has been set up for the study of metal cluster compounds in our laboratory, which consists of a nano-electrospray ionization source, an ion transmission and focus system, and a reflectron time-of-fight mass spectrometer. Taking advantage of the nano-electrospray ionization source, polyvalent ions are usually produced in the ＂ionization＂ process and the obtained mass resolution of the equipment is over 8000. The molecular ion peaks of metal cluster compounds [Au20（PPhpy2）10Cl2]（SbF6）4, where PPhpy2=bis（2- pyridyl）phenylphosphine, and [AuaAg2（C）L6]（BF4）4, where L=2-（diphenylphosphino）-5- methylpyridine, are distinguished in the respective mass spectrum, accompanied by some fragment ion peaks. In addition, the mass-to-charge ratios of the parent ions are determi- nated. Preliminary results suggest that the device is a powerful tool for the study of metal cluster compounds. It turns out that the information obtained by the instrumentation serves as an essential supplement to single crystal X-ray diffraction for structure characterization of metal cluster compounds.
基金funded by the National Key Research&Development Program of China(2018YFD0600200)Beijing’s Science and Technology Planning Project(Z191100008519004)Major emergency science and technology projects of National Forestry and Grassland Administration(ZD202001–05).
文摘Background:Pine wilt disease(PWD)is a major ecological concern in China that has caused severe damage to millions of Chinese pines(Pinus tabulaeformis).To control the spread of PWD,it is necessary to develop an effective approach to detect its presence in the early stage of infection.One potential solution is the use of Unmanned Airborne Vehicle(UAV)based hyperspectral images(HIs).UAV-based HIs have high spatial and spectral resolution and can gather data rapidly,potentially enabling the effective monitoring of large forests.Despite this,few studies examine the feasibility of HI data use in assessing the stage and severity of PWD infection in Chinese pine.Method:To fill this gap,we used a Random Forest(RF)algorithm to estimate the stage of PWD infection of trees sampled using UAV-based HI data and ground-based data(data directly collected from trees in the field).We compared relative accuracy of each of these data collection methods.We built our RF model using vegetation indices(VIs),red edge parameters(REPs),moisture indices(MIs),and their combination.Results:We report several key results.For ground data,the model that combined all parameters(OA:80.17%,Kappa:0.73)performed better than VIs(OA:75.21%,Kappa:0.66),REPs(OA:79.34%,Kappa:0.67),and MIs(OA:74.38%,Kappa:0.65)in predicting the PWD stage of individual pine tree infection.REPs had the highest accuracy(OA:80.33%,Kappa:0.58)in distinguishing trees at the early stage of PWD from healthy trees.UAV-based HI data yielded similar results:the model combined VIs,REPs and MIs(OA:74.38%,Kappa:0.66)exhibited the highest accuracy in estimating the PWD stage of sampled trees,and REPs performed best in distinguishing healthy trees from trees at early stage of PWD(OA:71.67%,Kappa:0.40).Conclusion:Overall,our results confirm the validity of using HI data to identify pine trees infected with PWD in its early stage,although its accuracy must be improved before widespread use is practical.We also show UAV-based data PWD classifications are less accurate but comparable to those of ground-based data.We believe that these results can be used to improve preventative measures in the control of PWD.
基金financially supported by the National Natural Science Foundation of China (Nos. 41503053, 41630315, 41688103, and 91128203)
文摘A new fully automatic ^40Ar/^39Ar laboratory with a Thermo Scientific ARGUS VI mass spectrometer has been established in China University of Geosciences （Wuhan）. We designed and developed a mini efficient preparation system （80 mL）, a CO2 laser for heating samples, a crusher for extracting fluid inclusions within K-poor minerals and an air reservoir （31 L） and pipette （0.1 mL） system. The ARGUS VI mass spectrometer is operated by the Qtegra Noble Gas software, which can control the peripheral accessories, such as pneumatic valves, CO2 laser and crusher through a PeriCon （peripheral controller）. The experimental procedures of atmospheric argon ana- lyses, ^40Ar/^39Ar dating by laser stepwise heating and by progressive crushing in vacuo, can be fully automatically performed. The weighted mean of atmospheric ^40Ar/^36Ar ratios is 302.22＋0.03 （1σ, MSWD=0.74, n=200）, indicating that air reservoir and pipette system and the whole instrument sys- tem are very stable. This laboratory is a successful pioneer example in China to establish a new no- ble gas laboratory with self-made peripheral accessories expect for the mass spectrometer.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(Nos.2006AA09Z243,2012AA09A405)
文摘A newly developed Deep Ocean Compact Autonomous Raman Spectrometer （DOCARS） system is introduced and used for in-situ detection of acid radical ions in this paper. To evaluate the feasibility and capability of DOCARS for quantitative analysis of the acid radical ions in the deep ocean, extensive investigations have been carried out both in laboratory and sea trials during the development phase. In the laboratory investigations, Raman spectra of the prepared samples （acid radical ions solutions） were obtained, and analyzed using the method of internal standard normalization in data processing. The Raman signal of acid radical ions was normalized by that of water molecules. The calibration curve showed that the normalized Raman signal intensity of SO4^2-, NO3^-, and HCO^-3 increases linearly as the concentration rises with correlation coefficient R^2 of 0.99, 0.99, and 0.98 respectively. The linear function obtained from the calibration curve was then used for the analysis of the spectra ,data acquired in the sea trial under a simulating chemical field in the deep-sea environment. It was found that the detected concentration of NO3 according to the linear function can reflect the concentration changes of NO~ after the sample was released, and the detection accuracy of the DOCARS system for SO^2-_4 is 8%. All the results showed that the DOCARS system has great potential in quantitative detection of acid radical ions under the deep-sea environment, while the sensitivity of the DOCARS system is expected to be improved.
基金supported by the National Natural Science Foundation of China (Nos. 21475010, 61635003)Beijing Natural Science Foundation (No. 16L00065)State Key Laboratory Explosion Science and Technology (No. YBKT16-17)
文摘With outstanding analytical performance and portability, miniature mass spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass spectrometers has lasted for more than ten years, during which a number of miniature mass spectrometers employing different techniques have been developed. Small-in-size, working at relatively high pressure region and capable of performing tandem mass spectrometry, ion trap is the most widely used mass analyzer in miniature mass spectrometer systems. The recent development of miniature ion trap mass spectrometer systems in the last ten years was reviewed in this paper. These instruments adopt different atmospheric pressure interfaces （APIs）, which are membrane inlets （MIs）, discontinuous atmospheric pressure interface （DAPI） and continuous atmospheric pressure interface （CAPI）. This review emphasizes on the mini mass spectrometry （MS） system that can be handheld by one person, but not the field-able ones that are too large to be hand-portable.
基金supported by the "Strategic Priority Research Program" of the Chinese Academy of Sciences (Grant No. XDA05100100&XDB05020000)the National Natural Science Foundation of China (Grant Nos. 41230642 & 41275139)
文摘Fine particle of organic aerosol （OA）, mostly arising from pollution, are abundant in Beijing. To achieve a better un- derstanding of the difference in OA in summer and autumn, a high-resolution time-of-flight aerosol mass spectrometer （HR- ToF-AMS, Aerodyne Research Inc., USA） was deployed in urban Beijing in August and October 2012. The mean OA mass concentration in autumn was 30 4-30 μg m-3, which was higher than in summer （13 4-6.9 μg m-3）. The elemental anal- ysis found that OA was more aged in summer （oxygen-to-carbon （O/C） ratios were 0.41 and 0.32 for summer and autumn, respectively）. Positive matrix factorization （PMF） analysis identified three and five components in summer and autumn, re- spectively. In summer, an oxygenated OA （OOA）, a cooking-emission-related OA （COA）, and a hydrocarbon-like OA （HOA） were indentified. Meanwhile, the OOA was separated into LV-OOA （low-volatility OOA） and SV-OOA （semi-volatile OOA）; and in autumn, a nitrogen-containing OA （NOA） was also found. The SOA （secondary OA） was always the most important OA component, accounting for 55% of the OA in the two seasons. Back trajectory clustering analysis found that the origin of the air masses was more complex in summer. Southerly air masses in both seasons were associated with the highest OA loading, while northerly air masses were associated with the lowest OA loading. A preliminary study of OA components, especially the POA （primary OA）, in different periods found that the HOA and COA all decreased during the National Day holiday period, and HOA decreased at weekends compared with weekdays.
基金supported by National Natural Science Foundation of China(No.51077062)
文摘A simple negative ion mobility spectrometer （IMS） is designed and used to investi- gate the factors that influence the number and efficiency of electrons generated by the needle-ring pulsed corona discharge electron source. Simulation with Ansoft Maxwell 12 is carried out to analyze the electric field distribution within the IMS, and to offer the basis and foundation for analyzing the measurement results. The measurement results of the quantities of electrons show that when the drift electric field strength and the ring inner diameter rise, both the number of ef- fective electrons and the effective electron rate are increased. When the discharge voltage becomes stronger, the number of effective electrons goes up while the effective electron rate goes down. In light of the simulation results, mechanisms underlying the effects of drift electric field strength, ring inner diameter, and discharge voltage on the effective electron number and effective electron rate are discussed. These will make great sense for designing negative ion mode IMS using the needle-ring pulsed corona discharge as the electron source.
基金supported by the National Natural Science Foundation of China(Nos.11375195 and 11575184)
文摘A real-time Bonner sphere spectrometer(BSS)has been developed for spectral neutron measurements with the HL-2A Tokamak.To correct and verify the accuracy of the neutron spectrum from the BSS,the BSS system was calibrated using monoenergetic neutron beams in the energy range of 100 keV–5 MeV.The response function of the BSS was corrected based on the calibration results,and the corrected BSS system was verified by unfolding monoenergetic neutron spectra.Fusion neutron spectra on the HL-2A have been obtained from the calibrated BSS system for the first time.
基金supported by the National Key R&D Program of the MOST of China(No.2016YFA0300204)the National Natural Science Foundation of China(Nos.11227902)as part of the Si PáME2beamline project+1 种基金supported by the National Natural Science Foundation of China(No.41774120)the Sichuan Science and Technology Program(No.2021YJ0329)。
文摘A self-adaptive differential evolution neutron spectrum unfolding algorithm(SDENUA)is established in this study to unfold the neutron spectra obtained from a water-pumping-injection multilayered concentric sphere neutron spectrometer(WMNS).Specifically,the neutron fluence bounds are estimated to accelerate the algorithm convergence,and the minimum error between the optimal solution and input neutron counts with relative uncertainties is limited to 10^(-6)to avoid unnecessary calculations.Furthermore,the crossover probability and scaling factor are self-adaptively controlled.FLUKA Monte Carlo is used to simulate the readings of the WMNS under(1)a spectrum of Cf-252 and(2)its spectrum after being moderated,(3)a spectrum used for boron neutron capture therapy,and(4)a reactor spectrum.Subsequently,the measured neutron counts are unfolded using the SDENUA.The uncertainties of the measured neutron count and the response matrix are considered in the SDENUA,which does not require complex parameter tuning or an a priori default spectrum.The results indicate that the solutions of the SDENUA agree better with the IAEA spectra than those of MAXED and GRAVEL in UMG 3.1,and the errors of the final results calculated using the SDENUA are less than 12%.The established SDENUA can be used to unfold spectra from the WMNS.
基金supported by the National Natural Science Foundation of China(Nos.11575090,11605099)the Young Key Teachers Training Program of He’nan Higher Education in China(No.2015GGJS-258)
文摘For a characteristic c-ray with interlaced overlap peak, and the case where its reliable and credible net count cannot be obtained using the current high-purity germanium(HPGe) multichannel γ-ray spectrum software, two new methods are proposed herein to obtain the γ-ray net peak count from the interlaced overlap peak in the HPGe cray spectrometer system, of which one is the symmetric conversion method based on Gaussian distribution and the other is where the energy average value of two close γ-rays is regarded as the γ-ray energy. The experimental results indicate that the two methods mentioned above are reliable and credible. This study is significant for the development of better γ-ray spectrum processing software for measuring complex γ-ray spectra concerning the nuclear reaction cross section, neutron activation analysis, and analysis of transuranium elements, using an HPGe detector.
基金partially supported by the National Science and Technology Major Project of Ministry of Science and Technology of China(Nos.2014GB109003 and 2015GB111002)the National Natural Science Foundation of China(Nos.11375195,11575184,11375004,and 11775068)
文摘A real-time double-ring neutron time-of-flight(TOFII) spectrometer system has been proposed to achieve plasma diagnosis on HL-2M tokamak with a relatively high count rate and sufficient energy resolution.The TOFII system is in its development stage,and this work describes its characteristics in terms of design principle,system structure,electronic system design,preliminary tests,and neutron transport simulation.The preliminary test results illustrate that the TOFII system can demonstrate the realtime dynamic spectrum every 10 ms.The results also show that based on the support vector machine method,the n-γ discrimination algorithm achieves the discrimination accuracy of 99.1%with a figure of merit of 1.30,and the intrinsic timing resolution of the system is within 0.3%.The simulated flight time spectrums from 1 to 5 MeV are obtained through the Monte Carlo tool Geant4,which also provide the reasonable results.The TOFII system will then be calibrated on mono-energetic neutron sources for further verification.
基金financial supports from National Major Research and Development Program(No.2018YFB2200200)National Science Fund for Distinguished Young Scholars(61725503)+2 种基金National Natural Science Foundation of China(NSFC)(6191101294,91950205)Zhejiang Provincial Natural Science Foundation(LZ18F050001,LD19F050001)The Fundamental Research Funds for the Central Universities.Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001).
文摘A compact spectrometer on silicon is proposed and demonstrated with an ultrahigh resolution.It consists of a thermally-tunable ultra-high-Q resonator aiming at ultrahigh resolution and an array of wideband resonators for achieving a broadened working window.The present on-chip spectrometer has a footprint as compact as 0.35 mm^(2),and is realized with standard multi-project-wafer foundry processes.The measurement results show that the on-chip spectrometer has an ultra-high resolution Δλ of 5 pm and a wide working window of 10 nm.The dynamic range defined as the ratio of the working window and the wavelength resolution is as large as 1940,which is the largest for on-chip dispersive spectro-meters to the best of our knowledge.The present high-performance on-chip spectrometer has great potential for high-resolution spectrum measurement in the applications of gas sensing,food monitoring,health analysis,etc.
