The neutron-induced total cross sections of natural lead have been measured in a wide energy range(0.3 eV-20 MeV)on the back-streaming white neutron beamline(Back-n)at the China Spallation Neutron Source.Neutron energ...The neutron-induced total cross sections of natural lead have been measured in a wide energy range(0.3 eV-20 MeV)on the back-streaming white neutron beamline(Back-n)at the China Spallation Neutron Source.Neutron energy was determined by the neutron total cross-section spectrometer using the time-of-flight technique.A fast multi-cell fission chamber was used as the neutron detector,and a 10-mm-thick high-purity natural lead sample was employed for the neutron transmission measurements.The on-beam background was determined using Co,In,Ag,and Cd filters.The excitation function of ^(nat)Pb(n,tot)reaction below 20 MeV was calculated using the TALYS-1.96 nuclear-reaction modeling program.The present results were compared with previous results,the evaluated data available in the five major evaluated nuclear data libraries(i.e.,ENDF/B-VIII.0,JEFF-3.3,JENDL-5,CENDL-3.2,and BROND-3.1),and the theoretical calculation curve.Good agreement was found between the new results and those of previous experiments and with the theoretical curves in the corresponding region.This measurement obtained the neutron total cross section of natural lead with good accuracy over a wide energy range and added experimental data in the resonance energy range.This provides more reliable experimental data for nuclear engineering design and nuclear data evaluation of lead.展开更多
Extreme rainfall associated with landfalling typhoon(ERLTC)can cause severe disasters and economic impacts throughout China.Improving the accuracy of ERLTC forecasts is therefore crucial in disaster prevention and mit...Extreme rainfall associated with landfalling typhoon(ERLTC)can cause severe disasters and economic impacts throughout China.Improving the accuracy of ERLTC forecasts is therefore crucial in disaster prevention and mitigation.The top 26 ERLTC events in China during 1960–2020 are investigated based on multi-source datasets.These ERLTC events are categorized into five main types according to the geographical location of the extreme precipitation and its position relative to the tropical cyclone(TC)center,namely:the typhoon inner-core rainfall in Taiwan(TWIC),typhoon inverted trough rainfall in Taiwan(TWIT),weak typhoon rainfall in Hainan(HNWK),strong typhoon rainfall in Zhejiang(ZJST)and inland typhoon remnant rainfall(ILRM).All the ERLTC events occurred in the weakening stage of TC after reaching its lifetime maximum intensity in convective cloud(TBB≤−32℃)regions over complex local terrain.The translational speeds of 20 TCs(76.9%of the total)were smaller than the climatological average(20.6 km h^(−1))during the extreme precipitation events.The differences are as follows:the TWIC and TWIT types are featured with different season,track and water vapor channel although both occurred in Taiwan.The other three types are distinguished by spinning track and strong convective cloud for HNWK type,strong TC intensity and binary TC interactions for ZJST type;and stagnation and strong westerly trough activity for ILRM type,respectively.These results are expected to provide useful clues for an in-depth understanding of ERLTC events over China.展开更多
基金This work is supported by the National Natural Science Foundation of China(No.12375296)the Key Laboratory of Nuclear Data Foundation(No.JCKY2022201C153)+2 种基金the Natural Science Foundation of Hunan Province of China(Nos.2021JJ40444,2020RC3054)the Youth Innovation Promotion Association CAS(No.2023014)the National Key Research and Development Plan(No.2022YFA1603303).
文摘The neutron-induced total cross sections of natural lead have been measured in a wide energy range(0.3 eV-20 MeV)on the back-streaming white neutron beamline(Back-n)at the China Spallation Neutron Source.Neutron energy was determined by the neutron total cross-section spectrometer using the time-of-flight technique.A fast multi-cell fission chamber was used as the neutron detector,and a 10-mm-thick high-purity natural lead sample was employed for the neutron transmission measurements.The on-beam background was determined using Co,In,Ag,and Cd filters.The excitation function of ^(nat)Pb(n,tot)reaction below 20 MeV was calculated using the TALYS-1.96 nuclear-reaction modeling program.The present results were compared with previous results,the evaluated data available in the five major evaluated nuclear data libraries(i.e.,ENDF/B-VIII.0,JEFF-3.3,JENDL-5,CENDL-3.2,and BROND-3.1),and the theoretical calculation curve.Good agreement was found between the new results and those of previous experiments and with the theoretical curves in the corresponding region.This measurement obtained the neutron total cross section of natural lead with good accuracy over a wide energy range and added experimental data in the resonance energy range.This provides more reliable experimental data for nuclear engineering design and nuclear data evaluation of lead.
基金supported by the National Natural Science Foundation of China(42192554,42175008,41905095,41930972)the S&T Development Fund of CAMS(2021KJ031)+2 种基金the National Basic Research Program of China(2015CB452804)the Open Grants of the State KeyLaboratory of SevereWeather(2021LASW-A12)the Basic Research Fund of CAMS(2020Y015).
文摘Extreme rainfall associated with landfalling typhoon(ERLTC)can cause severe disasters and economic impacts throughout China.Improving the accuracy of ERLTC forecasts is therefore crucial in disaster prevention and mitigation.The top 26 ERLTC events in China during 1960–2020 are investigated based on multi-source datasets.These ERLTC events are categorized into five main types according to the geographical location of the extreme precipitation and its position relative to the tropical cyclone(TC)center,namely:the typhoon inner-core rainfall in Taiwan(TWIC),typhoon inverted trough rainfall in Taiwan(TWIT),weak typhoon rainfall in Hainan(HNWK),strong typhoon rainfall in Zhejiang(ZJST)and inland typhoon remnant rainfall(ILRM).All the ERLTC events occurred in the weakening stage of TC after reaching its lifetime maximum intensity in convective cloud(TBB≤−32℃)regions over complex local terrain.The translational speeds of 20 TCs(76.9%of the total)were smaller than the climatological average(20.6 km h^(−1))during the extreme precipitation events.The differences are as follows:the TWIC and TWIT types are featured with different season,track and water vapor channel although both occurred in Taiwan.The other three types are distinguished by spinning track and strong convective cloud for HNWK type,strong TC intensity and binary TC interactions for ZJST type;and stagnation and strong westerly trough activity for ILRM type,respectively.These results are expected to provide useful clues for an in-depth understanding of ERLTC events over China.
