Four key reactions, 12C(, )13O, 13C(, n)16O, 25Mg(p, )26Al and 19F(p, )16O, will be studied for the first time within or near the astrophysical relevant energy regions (Gamow window) at Jinping Underground laboratory ...Four key reactions, 12C(, )13O, 13C(, n)16O, 25Mg(p, )26Al and 19F(p, )16O, will be studied for the first time within or near the astrophysical relevant energy regions (Gamow window) at Jinping Underground laboratory for Nuclear Astrophysics (JUNA)[1], which will take the advantage of the ultra-low background of China JinPing underground Laboratory (CJPL), high current accelerator based on ECR source and a highly sensitive detection system.展开更多
The temperature in the crust of an accreting neutron star is believed to have a signi cant impact on observable phenomena at the outer layer of a neutron star.This temperature is regulated by various factors,such as h...The temperature in the crust of an accreting neutron star is believed to have a signi cant impact on observable phenomena at the outer layer of a neutron star.This temperature is regulated by various factors,such as heating from nuclear reactions,neutrino cooling processes and heat transport from the interior^([1]).Among these,Urca process is considered to be the primary mechanism for neutrino cooling.展开更多
The presolar SiC grains[1]carry the original stellar nucleosynthesis signature.Their isotopic anomalies compared to the sun are the strong constrains in the supernovae(SN)model calculations.The 15N-excess in some SiC-...The presolar SiC grains[1]carry the original stellar nucleosynthesis signature.Their isotopic anomalies compared to the sun are the strong constrains in the supernovae(SN)model calculations.The 15N-excess in some SiC-AB grains(12C/13C<10 and 14N/15N<272)is one of the challenges of core-collapse supernovae(CCSNe)models[2].Recently,Pignatari pointed out that the entrainment of H-rich material into the He shell before the SN explosion allows the coproduction of 13C,15N and 26Al,which provides a new production scenario for SiC-AB grains[2].In the He shell nucleosynthesis,the 13C is produced through 12C(p,γ)13N(β+γ)13C reaction.The 14N is synthesized through 13N(n,γ)and 13C(p,γ)reactions.展开更多
134Cs a branching point in s-process path which is shown in Fig.1.The branching ratio is defined as fβ=λβ/(λβ+λn).It could be deduced from the abundance of 134Ba and 136Ba since 136Ba goes through both decay and...134Cs a branching point in s-process path which is shown in Fig.1.The branching ratio is defined as fβ=λβ/(λβ+λn).It could be deduced from the abundance of 134Ba and 136Ba since 136Ba goes through both decay and neutroncapture of 134Cs while 134Ba only experiences decay channel[1].Due to both 134Ba and 134Ba are pure s-process nuclei,this branching point is a good approach to determine the s-process parameters.With temperaturedependentβ-decay rate of 134Cs,the temperature of s-process could be deduced.展开更多
The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 k...The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 keV in the center of mass frame. Because of the Coulomb barrier, the cross sections drop exponentially asmeasurement approaches the Gamow window energies. Limited by cosmic ray background and the available beamintensity, the ground-based measurements are limited to energies above 280 keV. Therefore, the extrapolationbased on R-matrix calculation and/or in-direct measurement is the current method to estimate the cross sectionsfor astrophysical interest with limited precision. Moreover, due to the existence of sub-threshold resonances, thereare rather large uncertainties associated with the extrapolated cross sections which limit the precision of the currentreaction rate and thus prevent us from a complete understanding of the nucleosynthesis of heavy elements.展开更多
60Fe is a long-lived nucleus (T1=2=2.62×106 a) which is mainly synthesized in the Carbon-shell burning ofmassive stars. It still could be observed nowadays after being ejected to the space after massive star ends...60Fe is a long-lived nucleus (T1=2=2.62×106 a) which is mainly synthesized in the Carbon-shell burning ofmassive stars. It still could be observed nowadays after being ejected to the space after massive star ends its life assupernova. Along with another long-lived nucleus 26Al (T1=2=7.17×105 a) which is synthesized in the similar stars,the observation of their decay could provide the information of stellar evolution. From 2002-2005 the INTEGRALsatellite with detector obtained 60Fe/26Al flux ratio in our Galaxy to be 0.148(60)[1]. It's significantly smallerthan the theoretical prediction 0.45[2], and indicated that the theory need to be improved to increase the 60Fe yieldor decrease 26Al yield. 60Fe is produced by neutron capture reactions: 58Fe(n, )59Fe and 59Fe(n, )60Fe. Thecompetition between -decay of 59Fe and its neutron capture plays an important role in 60Fe synthesis path. In thepresent work, the impact on the 60Fe synthesis of the -decay process in stellar environment is studied.展开更多
Fusion reactions play a very important role for the creation of heavier elements in the quiescent and explosive burning phases in stars.Fusion processes also generate the energy in the Sun that created and maintain li...Fusion reactions play a very important role for the creation of heavier elements in the quiescent and explosive burning phases in stars.Fusion processes also generate the energy in the Sun that created and maintain life in our earth[1].展开更多
The understanding of open quantum systems in unbound nuclei is a challenge to the nuclear structure research[1].The continuum coupling effect may lead to a reordering of the shells in such systems[2].A way to study th...The understanding of open quantum systems in unbound nuclei is a challenge to the nuclear structure research[1].The continuum coupling effect may lead to a reordering of the shells in such systems[2].A way to study this effect is to compare the level schemes of two mirror nuclei involving an unbound and a bound nucleus such as 16F and 16N[3].Here we report an experiment of studying the level properties of 16F using the resonant elastic scattering with an 15O radioactive beam delivered by the Radioactive Ion Beam Line at Lanzhou(RIBLL)[4].展开更多
The carbon burning is predicted to be responsible for the phenomenon of X-ray super-burst.Stellar model calculations show that the temperature of neutron star crush is not high enough to trigger ignition^([1]).It has ...The carbon burning is predicted to be responsible for the phenomenon of X-ray super-burst.Stellar model calculations show that the temperature of neutron star crush is not high enough to trigger ignition^([1]).It has been suggested that the fusion reaction between light neutron-rich nuclei may provide an additional source of heat^([2]).展开更多
Stars with initial mass■8M_(sun)burn the carbon element after consuming most of its helium materials.The^(12)C+^(12)C fusion reaction is the primary reaction of the carbon burning process,producing magnesium and othe...Stars with initial mass■8M_(sun)burn the carbon element after consuming most of its helium materials.The^(12)C+^(12)C fusion reaction is the primary reaction of the carbon burning process,producing magnesium and other elements including neon,sodium and oxygen^([1]).展开更多
At a certain high temperature,this cycle will be dominant and end the rp-process to heavier region[2].It provides an upper temperature limit for rp-process along the proton drip line to produce nuclides beyond A=84,in...At a certain high temperature,this cycle will be dominant and end the rp-process to heavier region[2].It provides an upper temperature limit for rp-process along the proton drip line to produce nuclides beyond A=84,including the light p nuclides of 92;94Mo,96;94Ru.The existence of Zr-Nb cycle is an important question in rp-process[2].α-separation energy(Sα)of 84Mo plays an important role in the formation of this cycle.A strong enhancement of 83Nb(p,α)reaction rate is due to a very low Sαof 84Mo[1].展开更多
It has been proposed that fusion reactions between neutron-rich light nuclei,for example 24C,24O and 28Ne,may contribute to achieving the ignition temperature for explosive carbon burning process during superbusrsts[1...It has been proposed that fusion reactions between neutron-rich light nuclei,for example 24C,24O and 28Ne,may contribute to achieving the ignition temperature for explosive carbon burning process during superbusrsts[1,2].Studies of fusion reactions involving neutron-rich nuclei are beyond ordinary experimental techniques,since the intensity of radioactive beam become low for these measurements[3].The active target technique using TPC(Time Projection Chamber),with properties of multi-sampling,high efficiency and low background,is a suitable solution to the problem.展开更多
From an inelastic excitation and breakup experiment with a12Be beam at 29 MeV/u,a large4He+8He cluster decay width of 1.1(2)MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0...From an inelastic excitation and breakup experiment with a12Be beam at 29 MeV/u,a large4He+8He cluster decay width of 1.1(2)MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0+.By using the R-matrix analysis,a cluster spectroscopic factor of 0.53(10)is extracted from the cluster partial width,providing a strong support for the clustering structure in12Be.A specially designed zero-degree telescope played an essential role in the present experiment and has been demonstrated to be a promising tool in future studies of the molecular-like resonances near the cluster separation threshold.展开更多
文摘Four key reactions, 12C(, )13O, 13C(, n)16O, 25Mg(p, )26Al and 19F(p, )16O, will be studied for the first time within or near the astrophysical relevant energy regions (Gamow window) at Jinping Underground laboratory for Nuclear Astrophysics (JUNA)[1], which will take the advantage of the ultra-low background of China JinPing underground Laboratory (CJPL), high current accelerator based on ECR source and a highly sensitive detection system.
文摘The temperature in the crust of an accreting neutron star is believed to have a signi cant impact on observable phenomena at the outer layer of a neutron star.This temperature is regulated by various factors,such as heating from nuclear reactions,neutrino cooling processes and heat transport from the interior^([1]).Among these,Urca process is considered to be the primary mechanism for neutrino cooling.
基金National Key Research and Development program(MOST 2016YFA0400501),National Natural Science Foundation of China(11490564).
文摘The presolar SiC grains[1]carry the original stellar nucleosynthesis signature.Their isotopic anomalies compared to the sun are the strong constrains in the supernovae(SN)model calculations.The 15N-excess in some SiC-AB grains(12C/13C<10 and 14N/15N<272)is one of the challenges of core-collapse supernovae(CCSNe)models[2].Recently,Pignatari pointed out that the entrainment of H-rich material into the He shell before the SN explosion allows the coproduction of 13C,15N and 26Al,which provides a new production scenario for SiC-AB grains[2].In the He shell nucleosynthesis,the 13C is produced through 12C(p,γ)13N(β+γ)13C reaction.The 14N is synthesized through 13N(n,γ)and 13C(p,γ)reactions.
文摘134Cs a branching point in s-process path which is shown in Fig.1.The branching ratio is defined as fβ=λβ/(λβ+λn).It could be deduced from the abundance of 134Ba and 136Ba since 136Ba goes through both decay and neutroncapture of 134Cs while 134Ba only experiences decay channel[1].Due to both 134Ba and 134Ba are pure s-process nuclei,this branching point is a good approach to determine the s-process parameters.With temperaturedependentβ-decay rate of 134Cs,the temperature of s-process could be deduced.
文摘The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 keV in the center of mass frame. Because of the Coulomb barrier, the cross sections drop exponentially asmeasurement approaches the Gamow window energies. Limited by cosmic ray background and the available beamintensity, the ground-based measurements are limited to energies above 280 keV. Therefore, the extrapolationbased on R-matrix calculation and/or in-direct measurement is the current method to estimate the cross sectionsfor astrophysical interest with limited precision. Moreover, due to the existence of sub-threshold resonances, thereare rather large uncertainties associated with the extrapolated cross sections which limit the precision of the currentreaction rate and thus prevent us from a complete understanding of the nucleosynthesis of heavy elements.
文摘60Fe is a long-lived nucleus (T1=2=2.62×106 a) which is mainly synthesized in the Carbon-shell burning ofmassive stars. It still could be observed nowadays after being ejected to the space after massive star ends its life assupernova. Along with another long-lived nucleus 26Al (T1=2=7.17×105 a) which is synthesized in the similar stars,the observation of their decay could provide the information of stellar evolution. From 2002-2005 the INTEGRALsatellite with detector obtained 60Fe/26Al flux ratio in our Galaxy to be 0.148(60)[1]. It's significantly smallerthan the theoretical prediction 0.45[2], and indicated that the theory need to be improved to increase the 60Fe yieldor decrease 26Al yield. 60Fe is produced by neutron capture reactions: 58Fe(n, )59Fe and 59Fe(n, )60Fe. Thecompetition between -decay of 59Fe and its neutron capture plays an important role in 60Fe synthesis path. In thepresent work, the impact on the 60Fe synthesis of the -decay process in stellar environment is studied.
基金National Key Research and Development program(MOST 2016YFA0400501)from the Ministry of ScienceTechnology of China and National Natural Science Foundation of China(11021504,U1632142)。
文摘Fusion reactions play a very important role for the creation of heavier elements in the quiescent and explosive burning phases in stars.Fusion processes also generate the energy in the Sun that created and maintain life in our earth[1].
基金National Key Research and Development Program of China(2016YFA0400503).
文摘The understanding of open quantum systems in unbound nuclei is a challenge to the nuclear structure research[1].The continuum coupling effect may lead to a reordering of the shells in such systems[2].A way to study this effect is to compare the level schemes of two mirror nuclei involving an unbound and a bound nucleus such as 16F and 16N[3].Here we report an experiment of studying the level properties of 16F using the resonant elastic scattering with an 15O radioactive beam delivered by the Radioactive Ion Beam Line at Lanzhou(RIBLL)[4].
文摘The carbon burning is predicted to be responsible for the phenomenon of X-ray super-burst.Stellar model calculations show that the temperature of neutron star crush is not high enough to trigger ignition^([1]).It has been suggested that the fusion reaction between light neutron-rich nuclei may provide an additional source of heat^([2]).
基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB34020200)National Key Research and Development program(MOST 2016YFA0400501)from Ministry of Science and Technology of China。
文摘Stars with initial mass■8M_(sun)burn the carbon element after consuming most of its helium materials.The^(12)C+^(12)C fusion reaction is the primary reaction of the carbon burning process,producing magnesium and other elements including neon,sodium and oxygen^([1]).
文摘At a certain high temperature,this cycle will be dominant and end the rp-process to heavier region[2].It provides an upper temperature limit for rp-process along the proton drip line to produce nuclides beyond A=84,including the light p nuclides of 92;94Mo,96;94Ru.The existence of Zr-Nb cycle is an important question in rp-process[2].α-separation energy(Sα)of 84Mo plays an important role in the formation of this cycle.A strong enhancement of 83Nb(p,α)reaction rate is due to a very low Sαof 84Mo[1].
文摘It has been proposed that fusion reactions between neutron-rich light nuclei,for example 24C,24O and 28Ne,may contribute to achieving the ignition temperature for explosive carbon burning process during superbusrsts[1,2].Studies of fusion reactions involving neutron-rich nuclei are beyond ordinary experimental techniques,since the intensity of radioactive beam become low for these measurements[3].The active target technique using TPC(Time Projection Chamber),with properties of multi-sampling,high efficiency and low background,is a suitable solution to the problem.
基金supported by the National Basic Research Program of China(Grant No.2013CB834402)the National Natural Science Foundation of China(Grant Nos.11035001,11275011,11235001,11320101004 andJ1103206)
文摘From an inelastic excitation and breakup experiment with a12Be beam at 29 MeV/u,a large4He+8He cluster decay width of 1.1(2)MeV is determined for a state at an excitation energy of 10.3 MeV and with a spin parity of 0+.By using the R-matrix analysis,a cluster spectroscopic factor of 0.53(10)is extracted from the cluster partial width,providing a strong support for the clustering structure in12Be.A specially designed zero-degree telescope played an essential role in the present experiment and has been demonstrated to be a promising tool in future studies of the molecular-like resonances near the cluster separation threshold.
