Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to dire...Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of^(25)Mg(p,γ)^(26)Al,^(19)F(p,α)^(16)O,^(13)C(α,n)^(16)O and ^(12)C(α,γ)^(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given.展开更多
In this work,two approaches,based on the certified Reduced Basis method,have been developed for simulating the movement of nuclear reactor control rods,in time-dependent non-coercive settings featuring a 3D geometrica...In this work,two approaches,based on the certified Reduced Basis method,have been developed for simulating the movement of nuclear reactor control rods,in time-dependent non-coercive settings featuring a 3D geometrical framework.In particular,in a first approach,a piece-wise affine transformation based on subdomains division has been implemented for modelling the movement of one control rod.In the second approach,a“staircase”strategy has been adopted for simulating themovement of all the three rods featured by the nuclear reactor chosen as case study.The neutron kinetics has been modelled according to the so-called multi-group neutron diffusion,which,in the present case,is a set of ten coupled parametrized parabolic equations(two energy groups for the neutron flux,and eight for the precursors).Both the reduced order models,developed according to the two approaches,provided a very good accuracy comparedwith high-fidelity results,assumed as“truth”solutions.At the same time,the computational speed-up in the Online phase,with respect to the fine“truth”finite element discretization,achievable by both the proposed approaches is at least of three orders of magnitude,allowing a real-time simulation of the rod movement and control.展开更多
We report on the first observation of the neutron-rich nucleus^(131)Ag.This isotope was produced via fragmentation reactions of intense secondary radioactive ion beams,including 134,135Sn.The secondary beams were prod...We report on the first observation of the neutron-rich nucleus^(131)Ag.This isotope was produced via fragmentation reactions of intense secondary radioactive ion beams,including 134,135Sn.The secondary beams were produced from induced fission reactions from a stable 238U beam at 345 MeV/nucleon.Secondary reaction residues were selected by the ZeroDegree spectrometer and identified by measuring their magnetic rigidity,time of flight,energy loss,and total kinetic energy.展开更多
Proton resonant states in 22Mg have been investigated by the resonant elastic scattering of 21Na+p. The 21Na beam with a mean energy of 4.00 MeV/u was separated by the CNS radioactive ion beam separator(CRIB) and bomb...Proton resonant states in 22Mg have been investigated by the resonant elastic scattering of 21Na+p. The 21Na beam with a mean energy of 4.00 MeV/u was separated by the CNS radioactive ion beam separator(CRIB) and bombarded a thick(CH2)n target. The energy spectra of recoiled protons were measured at scattering angles of θcm ≈172° and 146°,respectively. A new state at 7.06 MeV has been observed clearly and another new one at 7.28 MeV is tentatively identified due to its low statistics. The proton resonant parameters were deduced from an R-matrix analysis of the differential cross section data. The astrophysical resonant reaction rate for the 18Ne(α,p)21Na reaction has been estimated,and it is about five times larger than that assumed before.展开更多
The upgrade of the MAX-lab injector and the construction of MAX Ⅲ, provided the opportunity for upgrading the tagged-photon facility and thus lead to the possibility of more extensive program in nuclear physics resea...The upgrade of the MAX-lab injector and the construction of MAX Ⅲ, provided the opportunity for upgrading the tagged-photon facility and thus lead to the possibility of more extensive program in nuclear physics research. This upgrade increased the injected electron energy to an eventual maximum of 250 MeV and allows for the extraction of electrons from the MAX Ⅰ ring operated in the stretcher mode. The first stretched beam was delivered in September 2005. The tagged-photon facility was commissioned in parallel with the commissioning of new experimental equipment. The PAC approved experimental program is current in progress, including measurements of pion photoproduction below the △（1232）. The efforts at the tagged photon-facility are pursued within an international collaboration with around fifty members.展开更多
We discuss the analysis of data from πN elastic scattering and single pion photo- and electroproduction. The main focus is a study of low-lying non-strange baryon resonances. Here we concentrate on some difficulties ...We discuss the analysis of data from πN elastic scattering and single pion photo- and electroproduction. The main focus is a study of low-lying non-strange baryon resonances. Here we concentrate on some difficulties associated with resonance identification, in particular the Roper and higher P11 states.展开更多
Two-proton relative momentum distributions from the break-up channels 23Al→p+p+21Na and 22Mg→p+p+20Ne at an energy of 60-70 A MeV have been measured together with two-proton opening angles at the projectile fragment...Two-proton relative momentum distributions from the break-up channels 23Al→p+p+21Na and 22Mg→p+p+20Ne at an energy of 60-70 A MeV have been measured together with two-proton opening angles at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility. The results demonstrate the existence of diproton emission component from single-step 2He for highly excited 23Al and 22Mg.展开更多
The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning condi...The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning conditions. The νp-process, which is supposed to take place at the very early epoch of type II supernovae, has considerable neutrons and alphas together with protons. The alpha-induced reactions on proton-rich unstable nuclei in the light mass regions is expected to play a crucial role, but very few of them were investigated well yet because of the experimental difficulties. Specifically, I report our recent experimental effort for the breakout process from the pp-chain region,~7Be(α, γ)^(11)C(α,p)^(14)N under the νp-process. The neutron-induced reactions on proton-rich nuclei, which is even more a challenging subject, were investigated previously for very few nuclei. One possible experimental method is the Trojan Horse Method(THM). We successfully have applied THM to the ^(18)F(n,α)^(14)N reaction study with an unstable beam of ^(18)F.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11490560 and 11321064)the National Basic Research Program of China(Grant No.2013CB834406)
文摘Jinping Underground laboratory for Nuclear Astrophysics(JUNA) will take the advantage of the ultra-low background of CJPL lab and high current accelerator based on an ECR source and a highly sensitive detector to directly study for the first time a number of crucial reactions occurring at their relevant stellar energies during the evolution of hydrostatic stars. In its first phase, JUNA aims at the direct measurements of^(25)Mg(p,γ)^(26)Al,^(19)F(p,α)^(16)O,^(13)C(α,n)^(16)O and ^(12)C(α,γ)^(16)O reactions. The experimental setup,which includes an accelerator system with high stability and high intensity, a detector system, and a shielding material with low background, will be established during the above research. The current progress of JUNA will be given.
基金We acknowledge CINECA and Regione Lombardia LISA computational initiative,for the availability of high performance computing resources and support.G.Rozza acknowledges INDAM-GNCS national activity group and NOFYSAS program of SISSA.
文摘In this work,two approaches,based on the certified Reduced Basis method,have been developed for simulating the movement of nuclear reactor control rods,in time-dependent non-coercive settings featuring a 3D geometrical framework.In particular,in a first approach,a piece-wise affine transformation based on subdomains division has been implemented for modelling the movement of one control rod.In the second approach,a“staircase”strategy has been adopted for simulating themovement of all the three rods featured by the nuclear reactor chosen as case study.The neutron kinetics has been modelled according to the so-called multi-group neutron diffusion,which,in the present case,is a set of ten coupled parametrized parabolic equations(two energy groups for the neutron flux,and eight for the precursors).Both the reduced order models,developed according to the two approaches,provided a very good accuracy comparedwith high-fidelity results,assumed as“truth”solutions.At the same time,the computational speed-up in the Online phase,with respect to the fine“truth”finite element discretization,achievable by both the proposed approaches is at least of three orders of magnitude,allowing a real-time simulation of the rod movement and control.
基金the National Basic Research Program of China under Grant No 2013CB834402the National Natural Science Foundation of China under Grant Nos 11035001 and 11275011.
文摘We report on the first observation of the neutron-rich nucleus^(131)Ag.This isotope was produced via fragmentation reactions of intense secondary radioactive ion beams,including 134,135Sn.The secondary beams were produced from induced fission reactions from a stable 238U beam at 345 MeV/nucleon.Secondary reaction residues were selected by the ZeroDegree spectrometer and identified by measuring their magnetic rigidity,time of flight,energy loss,and total kinetic energy.
基金Japanese Ministry of Education, Culture,Sports,and Technology,Japan(13440071,14740156)Grants-in-Aids for JSPS,Japan(1604055)
文摘Proton resonant states in 22Mg have been investigated by the resonant elastic scattering of 21Na+p. The 21Na beam with a mean energy of 4.00 MeV/u was separated by the CNS radioactive ion beam separator(CRIB) and bombarded a thick(CH2)n target. The energy spectra of recoiled protons were measured at scattering angles of θcm ≈172° and 146°,respectively. A new state at 7.06 MeV has been observed clearly and another new one at 7.28 MeV is tentatively identified due to its low statistics. The proton resonant parameters were deduced from an R-matrix analysis of the differential cross section data. The astrophysical resonant reaction rate for the 18Ne(α,p)21Na reaction has been estimated,and it is about five times larger than that assumed before.
基金We thank the US National Science Foundation, the Swedish Research Council, and Lund University for their support of the Nuclear Physics Program at Lund.
文摘The upgrade of the MAX-lab injector and the construction of MAX Ⅲ, provided the opportunity for upgrading the tagged-photon facility and thus lead to the possibility of more extensive program in nuclear physics research. This upgrade increased the injected electron energy to an eventual maximum of 250 MeV and allows for the extraction of electrons from the MAX Ⅰ ring operated in the stretcher mode. The first stretched beam was delivered in September 2005. The tagged-photon facility was commissioned in parallel with the commissioning of new experimental equipment. The PAC approved experimental program is current in progress, including measurements of pion photoproduction below the △（1232）. The efforts at the tagged photon-facility are pursued within an international collaboration with around fifty members.
基金Supported by U. S. Department of Energy (DE–FG02–99ER41110 and DE–AC05–84ER40150)
文摘We discuss the analysis of data from πN elastic scattering and single pion photo- and electroproduction. The main focus is a study of low-lying non-strange baryon resonances. Here we concentrate on some difficulties associated with resonance identification, in particular the Roper and higher P11 states.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10775167, 10775168, 10979074, 10405032, 10747163, 10805067 and 10605036)the Major State Basic Research Development Program of China (Grant No. 2007CB815004)the Shanghai Development Foundation for Science and Technology (Grant No. 09JC1416800)
文摘Two-proton relative momentum distributions from the break-up channels 23Al→p+p+21Na and 22Mg→p+p+20Ne at an energy of 60-70 A MeV have been measured together with two-proton opening angles at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility. The results demonstrate the existence of diproton emission component from single-step 2He for highly excited 23Al and 22Mg.
基金Japan Society for the Promotion of Science(JSPS)Research(KAKENHI)(26287058)
文摘The paper includes discussions on the important role of neutron and alpha configurations in proton-rich nuclei in nuclear astrophysics in terms of nucleosynthesis under extremely high-temperature hydrogenburning conditions. The νp-process, which is supposed to take place at the very early epoch of type II supernovae, has considerable neutrons and alphas together with protons. The alpha-induced reactions on proton-rich unstable nuclei in the light mass regions is expected to play a crucial role, but very few of them were investigated well yet because of the experimental difficulties. Specifically, I report our recent experimental effort for the breakout process from the pp-chain region,~7Be(α, γ)^(11)C(α,p)^(14)N under the νp-process. The neutron-induced reactions on proton-rich nuclei, which is even more a challenging subject, were investigated previously for very few nuclei. One possible experimental method is the Trojan Horse Method(THM). We successfully have applied THM to the ^(18)F(n,α)^(14)N reaction study with an unstable beam of ^(18)F.
