With the much-anticipated multi-petawatt(PW)laser facilities that are coming online,neutron sources with extreme fluxes could soon be in reach.Such sources would rely on spallation by protons accelerated by the high-i...With the much-anticipated multi-petawatt(PW)laser facilities that are coming online,neutron sources with extreme fluxes could soon be in reach.Such sources would rely on spallation by protons accelerated by the high-intensity lasers.These high neutron fluxes would make possible not only direct measurements of neutron capture andβ-decay rates related to the r-process of nucleosynthesis of heavy elements,but also such nuclear measurements in a hot plasma environment,which would be beneficial for s-process investigations in astrophysically relevant conditions.This could,in turn,finally allow possible reconciliation of the observed element abundances in stars and those derived from simulations,which at present show large discrepancies.Here,we review a possible pathway to reach unprecedented neutron fluxes using multi-PW lasers,as well as strategies to perform measurements to investigate the r-and s-processes of nucleosynthesis of heavy elements in cold matter,as well as in a hot plasma environment.展开更多
High sensitivity radio searches of unassociated γ-ray sources have proven to be an effective way of finding new pulsars. Using the Five-hundred-meter Aperture Spherical radio Telescope(FAST) during its commissioning ...High sensitivity radio searches of unassociated γ-ray sources have proven to be an effective way of finding new pulsars. Using the Five-hundred-meter Aperture Spherical radio Telescope(FAST) during its commissioning phase, we have carried out a number of targeted deep searches of Fermi Large Area Telescope(LAT) γ-ray sources. On February 27, 2018 we discovered an isolated millisecond pulsar(MSP), PSR J0318+0253, coincident with the unassociated γ-ray source 3 FGL J0318.1+0252. PSR J0318+0253 has a spin period of 5.19 ms, a dispersion measure(DM) of 26 pc cm-3 corresponding to a DM distance of about 1.3 kpc, and a period-averaged flux density of(~11±2) μJy at L-band(1.05-1.45 GHz). Among all high energy MSPs, PSR J0318+0253 is the faintest ever detected in radio bands, by a factor of at least ~4 in terms of L-band fluxes. With the aid of the radio ephemeris, an analysis of 9.6 years of Fermi-LAT data revealed that PSR J0318+0253 also displays strong γ-ray pulsations. Follow-up observations carried out by both Arecibo and FAST suggest a likely spectral turn-over around 350 MHz. This is the first result from the collaboration between FAST and the Fermi-LAT teams as well as the first confirmed new MSP discovery by FAST, raising hopes for the detection of many more MSPs. Such discoveries will make a significant contribution to our understanding of the neutron star zoo while potentially contributing to the future detection of gravitational waves, via pulsar timing array(PTA) experiments.展开更多
基金We acknowledge fruitful discussions with H.P´epin(INRS),V.M´eot,L.Gremillet,X.Davoine(CEA),S.Orlando(INAF),C.Guerrero(Universidad de Sevilla),and Y.Caristan(Universit´e Paris-Saclay).This project received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Programme(Grant Agreement No.787539),and was partly conducted within the LABEX Plas@Par project and supported by Grant Nos.11-IDEX-0004-02 and an ANR-17-CE30-0026 PiNNaCLE grant from Agence Nationale de la Recherche(France).I.P.acknowledges the support of ISF Grant No.1135/15.The research leading to these results is supported by Extreme Light Infrastructure Nuclear Physics(ELI-NP)Phase I,a project cofinanced by the Romanian Government and the European Union through the European Regional Development Fund.
文摘With the much-anticipated multi-petawatt(PW)laser facilities that are coming online,neutron sources with extreme fluxes could soon be in reach.Such sources would rely on spallation by protons accelerated by the high-intensity lasers.These high neutron fluxes would make possible not only direct measurements of neutron capture andβ-decay rates related to the r-process of nucleosynthesis of heavy elements,but also such nuclear measurements in a hot plasma environment,which would be beneficial for s-process investigations in astrophysically relevant conditions.This could,in turn,finally allow possible reconciliation of the observed element abundances in stars and those derived from simulations,which at present show large discrepancies.Here,we review a possible pathway to reach unprecedented neutron fluxes using multi-PW lasers,as well as strategies to perform measurements to investigate the r-and s-processes of nucleosynthesis of heavy elements in cold matter,as well as in a hot plasma environment.
基金supported by the National Natural Science Foundation of China (Grant Nos.11988101,11690024,11743002,11873067,U1631132,U1831131,U1731238,U1938103,11703047,11773041,and 11673060)the National Key R&D Program of China (Grant No.2017YFA0402600)+10 种基金the Chinese Academy of Sciences (CAS) Key Laboratory of FAST,NAOC,Chinese Academy of Sciences,the National Basic Research Program of China (Grant No.2015CB857100)the CAS Strategic Priority Research Program (Grant No.XDB23000000)the CAS International Partnership Program (Grant No.114A11KYSB20160008)the Open Project Program of the Key Laboratory of FAST,NAOC,Chinese Academy of Sciences and Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing,Guizhou Normal Universitysupport by the Youth Innovation Promotion Association CAS (Grant No.2021055)the CAS Project for Young Scientists in Basic Reasearch (Grant No.YSBR-006)the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CASpartially supported by the Fermi Guest Observer Program,administered by NASA (Grant No.80NSSC18K1731)support from the ERC under the European Union’s Horizon 2020 Research and Innovation Programme (Grant No.715051Spiders)NRL is supported by NASA。
文摘High sensitivity radio searches of unassociated γ-ray sources have proven to be an effective way of finding new pulsars. Using the Five-hundred-meter Aperture Spherical radio Telescope(FAST) during its commissioning phase, we have carried out a number of targeted deep searches of Fermi Large Area Telescope(LAT) γ-ray sources. On February 27, 2018 we discovered an isolated millisecond pulsar(MSP), PSR J0318+0253, coincident with the unassociated γ-ray source 3 FGL J0318.1+0252. PSR J0318+0253 has a spin period of 5.19 ms, a dispersion measure(DM) of 26 pc cm-3 corresponding to a DM distance of about 1.3 kpc, and a period-averaged flux density of(~11±2) μJy at L-band(1.05-1.45 GHz). Among all high energy MSPs, PSR J0318+0253 is the faintest ever detected in radio bands, by a factor of at least ~4 in terms of L-band fluxes. With the aid of the radio ephemeris, an analysis of 9.6 years of Fermi-LAT data revealed that PSR J0318+0253 also displays strong γ-ray pulsations. Follow-up observations carried out by both Arecibo and FAST suggest a likely spectral turn-over around 350 MHz. This is the first result from the collaboration between FAST and the Fermi-LAT teams as well as the first confirmed new MSP discovery by FAST, raising hopes for the detection of many more MSPs. Such discoveries will make a significant contribution to our understanding of the neutron star zoo while potentially contributing to the future detection of gravitational waves, via pulsar timing array(PTA) experiments.
