Electron induced ionization-excitation (IE) of helium is a basic four-body Coulomb problem in which all thefour charged particles are actively involved. It is much more challenging to both experiment and theory in con...Electron induced ionization-excitation (IE) of helium is a basic four-body Coulomb problem in which all thefour charged particles are actively involved. It is much more challenging to both experiment and theory in contrastto direct ionization with the residual He+ ion in the ground state. The 2s or 2p separated TDCS data, especially atlow incident energy range where the high order effects are expected to play a significant role, would offer the moststringent test to theoretical models. However, only one experiment at high incident energy achieved the TDCSs for2p state till now due to the small cross section and the low detection efficiency for multi-coincidence events[1].展开更多
The momentum projecting techniques have been well applied so as to explore the mechanisms of electronemissions as well as the dynamical effects which influenced the momentum distribution of the electrons ionized inion...The momentum projecting techniques have been well applied so as to explore the mechanisms of electronemissions as well as the dynamical effects which influenced the momentum distribution of the electrons ionized inion-atom collisions[1??3]. Usually, the emitted electrons will be projected onto the scattering plane, which was definedas the plane containing the initial and the final momentum vectors of the projectile, considering the conservationlaws and rotational symmetry around the beam axis. It is well known that the ejected electrons will be influencedsimultaneously by a combined coulomb potential from the recoil ions and the projectile ions. Qualitatively, this展开更多
The cooling of heavy ions can provide high-quality beams that are especially important for high-precisionexperimental nuclear and atomic physics. The laser cooling of relativistic C3+ ion beams at the experimental coo...The cooling of heavy ions can provide high-quality beams that are especially important for high-precisionexperimental nuclear and atomic physics. The laser cooling of relativistic C3+ ion beams at the experimental coolerstorage ring (CSRe) is being currently prepared at Institute of Modern Physics (IMP) in Lanzhou. An electroncyclotron resonance ion source (ECRIS) will be used to produce C3+ ion beams. Meanwhile, O4+ ions could alsobe produced due to residual gas because of the same mass-to-charge ratio. Therefore, both C3+ and O4+ ion beamswill be injected and circulate in a storage ring during the laser cooling experiment at the same time. A higher ratioof C3+ ions will lead to a better result for the laser cooling experiment.展开更多
The experiment was carried out using the Reaction Microscope mounted at the 320 kV platform for multidisciplinary research with highly charged ions at the Institute of Modern Physics,CAS[1,2].For reaction channel of(A...The experiment was carried out using the Reaction Microscope mounted at the 320 kV platform for multidisciplinary research with highly charged ions at the Institute of Modern Physics,CAS[1,2].For reaction channel of(Ar2)^(2+)→Ar^(+)+Ar^(+),the kinetic energy release(KER)distribution clearly shows two peaks.The left peak locates at 3.7 eV approximately,and the right one lies at about 5.3 eV.From the classical reflection approximation KER/(Z1-Z2)=R,the internuclear distance R can be deduced.We find that the corresponding internuclear distance of the left peak is 3.8˚A,which is the equilibrium internuclear distance of the Ar2 dimer.This indicates that coulomb explosion takes place immediately after the double ionization process,without the involvement of the geometry change of the cluster ion.Therefore,the left peak dominantly arises from two-site double ionization.展开更多
The principle and technique details of recoil ion momentum imaging are discussed and summarized. The recoil ion momentum spectroscopy built at the Institute of Modern Physics (Lanzhou) is presented. The first results ...The principle and technique details of recoil ion momentum imaging are discussed and summarized. The recoil ion momentum spectroscopy built at the Institute of Modern Physics (Lanzhou) is presented. The first results obtained at the setup are analyzed. For 30 keV He2+ on He collision, it is found that the capture of single electron occurs dominantly into the first excited states, and the related scattering angle results show that the ground state capture occurs at large impact parameters, while the capture into excited states occurs at small impact parameters. The results manifest the collision dynamics for the sub-femto-second process can be studied through the techniques uniquely. Finally, the future possibilities of applications of the recoil ion momentum spectroscopy in other fields are outlined.展开更多
基金Major State Basic Research DevelopmentProgram of China (973 Program, 2010CB832902) and National Natural Science Foundation of China(11204322 and 10979007.)
文摘Electron induced ionization-excitation (IE) of helium is a basic four-body Coulomb problem in which all thefour charged particles are actively involved. It is much more challenging to both experiment and theory in contrastto direct ionization with the residual He+ ion in the ground state. The 2s or 2p separated TDCS data, especially atlow incident energy range where the high order effects are expected to play a significant role, would offer the moststringent test to theoretical models. However, only one experiment at high incident energy achieved the TDCSs for2p state till now due to the small cross section and the low detection efficiency for multi-coincidence events[1].
基金Major State Basic Research Development Program of China (973 Program, (2010CB832902), National NaturalScience Foundation of China under (10979007, 10974207, U1332128, 11004202). We would like to thank the engineers who operatedthe 320 kV platform for their assistance in running the ECR ion source
文摘The momentum projecting techniques have been well applied so as to explore the mechanisms of electronemissions as well as the dynamical effects which influenced the momentum distribution of the electrons ionized inion-atom collisions[1??3]. Usually, the emitted electrons will be projected onto the scattering plane, which was definedas the plane containing the initial and the final momentum vectors of the projectile, considering the conservationlaws and rotational symmetry around the beam axis. It is well known that the ejected electrons will be influencedsimultaneously by a combined coulomb potential from the recoil ions and the projectile ions. Qualitatively, this
基金National Natural Science Foundation of China (10979007, 91126004, 11274317)
文摘The cooling of heavy ions can provide high-quality beams that are especially important for high-precisionexperimental nuclear and atomic physics. The laser cooling of relativistic C3+ ion beams at the experimental coolerstorage ring (CSRe) is being currently prepared at Institute of Modern Physics (IMP) in Lanzhou. An electroncyclotron resonance ion source (ECRIS) will be used to produce C3+ ion beams. Meanwhile, O4+ ions could alsobe produced due to residual gas because of the same mass-to-charge ratio. Therefore, both C3+ and O4+ ion beamswill be injected and circulate in a storage ring during the laser cooling experiment at the same time. A higher ratioof C3+ ions will lead to a better result for the laser cooling experiment.
基金National Key R&D Program of China(2017YFA0402400,2017YFA0402300)National Natural Science Foundation of China(11274317,U1532129)。
文摘The experiment was carried out using the Reaction Microscope mounted at the 320 kV platform for multidisciplinary research with highly charged ions at the Institute of Modern Physics,CAS[1,2].For reaction channel of(Ar2)^(2+)→Ar^(+)+Ar^(+),the kinetic energy release(KER)distribution clearly shows two peaks.The left peak locates at 3.7 eV approximately,and the right one lies at about 5.3 eV.From the classical reflection approximation KER/(Z1-Z2)=R,the internuclear distance R can be deduced.We find that the corresponding internuclear distance of the left peak is 3.8˚A,which is the equilibrium internuclear distance of the Ar2 dimer.This indicates that coulomb explosion takes place immediately after the double ionization process,without the involvement of the geometry change of the cluster ion.Therefore,the left peak dominantly arises from two-site double ionization.
基金the National Natural Science Foundation of China (Grant No. 10434100)
文摘The principle and technique details of recoil ion momentum imaging are discussed and summarized. The recoil ion momentum spectroscopy built at the Institute of Modern Physics (Lanzhou) is presented. The first results obtained at the setup are analyzed. For 30 keV He2+ on He collision, it is found that the capture of single electron occurs dominantly into the first excited states, and the related scattering angle results show that the ground state capture occurs at large impact parameters, while the capture into excited states occurs at small impact parameters. The results manifest the collision dynamics for the sub-femto-second process can be studied through the techniques uniquely. Finally, the future possibilities of applications of the recoil ion momentum spectroscopy in other fields are outlined.
