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
Spectroscopic measurements and terahertz imaging of the cornea are carried out by using a rapid scanning terahertz time domain spectroscopy（THz-TDS） system.A voice coil motor stage based optical delay line（VCM-ODL...Spectroscopic measurements and terahertz imaging of the cornea are carried out by using a rapid scanning terahertz time domain spectroscopy（THz-TDS） system.A voice coil motor stage based optical delay line（VCM-ODL） is developed to provide a rather simple and robust structure with both the high scanning speed and the large delay length.The developed system is used for THz spectroscopic measurements and imaging of the corneal tissue with different amounts of water content,and the measurement results show the consistence with the reported results,in which the measurement time using VCM-ODL is a factor of 360 shorter than the traditional motorized optical delay line（MDL）.With reducing the water content a monotonic decrease of the complex permittivity of the cornea is observed.The two-term Debye relaxation model is employed to explain our experimental results,revealing that the fast relaxation time of a dehydrated cornea is much larger than that of a hydrated cornea and its dielectric behavior can be affected by the presence of the biological macromolecules.These results demonstrate that our THz spectrometer may be a promising candidate for tissue hydration sensing and practical application of THz technology.展开更多
A Neutron Time-of-Flight(NTOF) spectrometer, based at the Heavy Ion Research Facility in Lanzhou(HIRFL) was developed for studies of neutron production of proton induced spallation reactions related to the ADS project...A Neutron Time-of-Flight(NTOF) spectrometer, based at the Heavy Ion Research Facility in Lanzhou(HIRFL) was developed for studies of neutron production of proton induced spallation reactions related to the ADS project. After the presentation of comparisons between calculated spallation neutron production doubledifferential cross sections and the available experimental data, a detailed description of the NTOF spectrometer is given. Test beam results show that the spectrometer works well and data analysis procedures are established.The comparisons of the test beam neutron spectra with those of GEANT4 simulations are presented.展开更多
An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as o...An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wideband spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.展开更多
A digital three-detector positron lifetime spectrometer was developed.It consists of a DRS4 waveform digitizing board and three La Br3scintillation detectors coupled to XP2020Q photomultiplier tubes.DRS4 waveform digi...A digital three-detector positron lifetime spectrometer was developed.It consists of a DRS4 waveform digitizing board and three La Br3scintillation detectors coupled to XP2020Q photomultiplier tubes.DRS4 waveform digitizing allows data sampling at up to 5 GSPS with high amplitude resolution,with good time scale linearity and stability.In the triple-coincidence,the new system could reach a 195 ps time resolution,which is better than the conventional analog apparatus with the same detectors.This spectrometer can be applied to the other scintillation timing measurements with picoseconds accuracy.展开更多
The anionic products from the reactions between metal（M=Ag, Au, Pd, Pt, Pb and Bi） vapour produced by laser ablation and hexafluorobenzene seeded in carrier gas（Ar） were studied by means of a homemade reflectron t...The anionic products from the reactions between metal（M=Ag, Au, Pd, Pt, Pb and Bi） vapour produced by laser ablation and hexafluorobenzene seeded in carrier gas（Ar） were studied by means of a homemade reflectron time-of-flight mass spectrometry（RTOF-MS）. Experimental results show that the dominant products were [MmC6F6]^- complexes for the reactions ofAg, Au, Pd and Pt with C6F6, while the dominant products were [MmC6F5]^- complexes for the reactions of Pb and Bi with C6F6. The formation mechanisms of the products, including the adsorption of metal cluster anions on hexafluorobenzene and the C--F cleavage induced by metal cluster anions, were discussed.展开更多
Photooxidation of the aromatic hydrocarbon toluene and its subsequent reactions were carried out using UV-irradiation of toluene/CH3ONO/NO/air mixtures in a home-made smog chamber. The secondary organic aerosols could...Photooxidation of the aromatic hydrocarbon toluene and its subsequent reactions were carried out using UV-irradiation of toluene/CH3ONO/NO/air mixtures in a home-made smog chamber. The secondary organic aerosols could be formed after those oxidation products of semi-volatile or- ganic compounds were partitioned between gas phase and particle phase. The aerosol time of flight mass spectrometer (ATOFMS) was used to measure size and molecular composition of individual secondary organic aerosol particle. Size distribution and chemical composition of secondary organic aerosol were got in real time.展开更多
基金V. ACKNOWLEDGMENTS This work supported by the National Natural Science Foundation of China （No.20853001）. We thank Professor Qi-he Zhu and Professor Zhen Gao for valuable discussions.
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Project supported by the National Natural Science Foundation of China(Grant No.61205101)the Shenzhen Municipal Research Foundation,China(Grant Nos.GJHZ201404171134305 and JCYJ20140417113130693)the Marie Curie Actions-International Research Staff Exchange Scheme(IRSES)(Grant No.FP7 PIRSES-2013-612267)
文摘Spectroscopic measurements and terahertz imaging of the cornea are carried out by using a rapid scanning terahertz time domain spectroscopy（THz-TDS） system.A voice coil motor stage based optical delay line（VCM-ODL） is developed to provide a rather simple and robust structure with both the high scanning speed and the large delay length.The developed system is used for THz spectroscopic measurements and imaging of the corneal tissue with different amounts of water content,and the measurement results show the consistence with the reported results,in which the measurement time using VCM-ODL is a factor of 360 shorter than the traditional motorized optical delay line（MDL）.With reducing the water content a monotonic decrease of the complex permittivity of the cornea is observed.The two-term Debye relaxation model is employed to explain our experimental results,revealing that the fast relaxation time of a dehydrated cornea is much larger than that of a hydrated cornea and its dielectric behavior can be affected by the presence of the biological macromolecules.These results demonstrate that our THz spectrometer may be a promising candidate for tissue hydration sensing and practical application of THz technology.
基金Supported by National Natural Science Foundation of China(No.11075189)100 Persons Project(Nos.0910020BR0 and Y010110BR0)ADS Project 302 of the Chinese Academy of Sciences(No.XDA03030200)
文摘A Neutron Time-of-Flight(NTOF) spectrometer, based at the Heavy Ion Research Facility in Lanzhou(HIRFL) was developed for studies of neutron production of proton induced spallation reactions related to the ADS project. After the presentation of comparisons between calculated spallation neutron production doubledifferential cross sections and the available experimental data, a detailed description of the NTOF spectrometer is given. Test beam results show that the spectrometer works well and data analysis procedures are established.The comparisons of the test beam neutron spectra with those of GEANT4 simulations are presented.
文摘An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wideband spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.
基金Supported by the National Natural Science Foundation of China(Nos.11175171,10835006,11105139 and 10975133)
文摘A digital three-detector positron lifetime spectrometer was developed.It consists of a DRS4 waveform digitizing board and three La Br3scintillation detectors coupled to XP2020Q photomultiplier tubes.DRS4 waveform digitizing allows data sampling at up to 5 GSPS with high amplitude resolution,with good time scale linearity and stability.In the triple-coincidence,the new system could reach a 195 ps time resolution,which is better than the conventional analog apparatus with the same detectors.This spectrometer can be applied to the other scintillation timing measurements with picoseconds accuracy.
基金This work was supported by the National Natural Science Foundation of China(No.22273065 and No.21673158)Science&Technology Commission of Shanghai Municipality(14DZ2261100).
基金Supported by the National Natural Science Foundation of China(No.20433080).
文摘The anionic products from the reactions between metal（M=Ag, Au, Pd, Pt, Pb and Bi） vapour produced by laser ablation and hexafluorobenzene seeded in carrier gas（Ar） were studied by means of a homemade reflectron time-of-flight mass spectrometry（RTOF-MS）. Experimental results show that the dominant products were [MmC6F6]^- complexes for the reactions ofAg, Au, Pd and Pt with C6F6, while the dominant products were [MmC6F5]^- complexes for the reactions of Pb and Bi with C6F6. The formation mechanisms of the products, including the adsorption of metal cluster anions on hexafluorobenzene and the C--F cleavage induced by metal cluster anions, were discussed.
基金This work was supported by the National Natural Science Foundation of China (Grant No.20477043) Knowledge Innovation Foundation of Chinese Academy of Sciences (KJCX2-SW-H08).
文摘Photooxidation of the aromatic hydrocarbon toluene and its subsequent reactions were carried out using UV-irradiation of toluene/CH3ONO/NO/air mixtures in a home-made smog chamber. The secondary organic aerosols could be formed after those oxidation products of semi-volatile or- ganic compounds were partitioned between gas phase and particle phase. The aerosol time of flight mass spectrometer (ATOFMS) was used to measure size and molecular composition of individual secondary organic aerosol particle. Size distribution and chemical composition of secondary organic aerosol were got in real time.
