The experiments with an internal target at a storage ring have many advantages. However, it is difficult to determine the absolute cross section of a reaction where luminosity cannot be simply established through macr...The experiments with an internal target at a storage ring have many advantages. However, it is difficult to determine the absolute cross section of a reaction where luminosity cannot be simply established through macroscopic measurements. Here we present an experimental determination of the effective target thickness from the beam energy losses at the internal target in HIRFL-CSRe. The measurements here are expected to provide the accurate target thickness and luminosity for the absolute cross-section study on future internal target experiments, and also provide some reference values for the study of beam loss mechanism of the heavy ion at HIRFL-CSRe.展开更多
According to the classical over-barrier model[1;2], as a slow highly charged Xeq+ ion approaches a critical distance R =p 2q from the surface with the work function W, it begins to resonantly capture conduction electr...According to the classical over-barrier model[1;2], as a slow highly charged Xeq+ ion approaches a critical distance R =p 2q from the surface with the work function W, it begins to resonantly capture conduction electrons into high Rydberg states (principal quantum number around n q).展开更多
Double K-shell ionization of atoms by collisions with charged ions is one of typical two-electron processes andattracts considerable attention both in term of basic theory and experiment. Radiative de-excitation of th...Double K-shell ionization of atoms by collisions with charged ions is one of typical two-electron processes andattracts considerable attention both in term of basic theory and experiment. Radiative de-excitation of the doubleK-shell vacancy states of atoms leads to the emission of so called K X-ray hyper-satellites (Kh,Kh . . . )[1], whichgives us the insight into the decay modes of multiply ionized ions as well as the ionization processes during ion-atomcollisions. Contrary to the long-winded and difficult experiments with heavy target due to the low detection efficiencyof K X-ray hyper-satellites with crystal spectrometers[2??4], the bulk of knowledge concerning double K-shellionization in ion-atom collisions has been obtained for light target.展开更多
A highly charged ion (HCI) has a large potential energy, which is equal to the binding energies of all the elec-trons removed to create the ion. When such a slow HCI approaches and then enters into a solid surface, an...A highly charged ion (HCI) has a large potential energy, which is equal to the binding energies of all the elec-trons removed to create the ion. When such a slow HCI approaches and then enters into a solid surface, an \abovethe surface" and a \below the surface" hollow atom will be formed, respectively, by capturing electrons from thesurface into its empty levels. Not only new aspects of atom physics has been introduced by hollow atoms, but alsoHCI applications in material science has promising prospects, such as surface analysis, the synthesis of materialswith new properties, and the formation of nanostructure that have been an active area of research in recent years[1??6].展开更多
When an energetic highly charged ion (HCI) collides with an atom, the target electrons may be captured by theprojectile ion, either radiatively or non-radiatively. During a radiative electron capture (REC), a target e...When an energetic highly charged ion (HCI) collides with an atom, the target electrons may be captured by theprojectile ion, either radiatively or non-radiatively. During a radiative electron capture (REC), a target electronis transferred to the projectile accompanying with a photon emission, which carries away the excess energy andmomentum. During a non-radiative electron capture (NRC), the energy and momentum conservations are ensuredby the target nucleus[1]. If the captured electrons are populated in excited states, photons maybe emitted duringthe following stabilization processes, and therefore the X-ray spectrum can provide information about the initialpopulation. However, if a solid target is employed, the single-collision condition cannot be ensured when consideringthe capture processes, as well as strong background will be produced[2]. With the development of heavy ioncooling storage rings, the experimental luminance is enhanced by the strong ion beams when a gaseous target isprerequisite[3].展开更多
First we calibrated the spectrometer in atmosphere using the peak-channel of 241Am, Thc-c' standard radioactive source while the window diameter isφ3. 0 mm and gained following formula with respect to the energy ...First we calibrated the spectrometer in atmosphere using the peak-channel of 241Am, Thc-c' standard radioactive source while the window diameter isφ3. 0 mm and gained following formula with respect to the energy (E/MeV) ofαand the channel (Ch): E=1. 507 55 + 0. 016 31×Ch+6. 235 24×10-6×Ch2 So, when E=5. 486 MeV, the Ch is equal to 221. 493. When changing the diameter of incident window toφ1.5 mm, we find the peak-channel of展开更多
The X-ray radiation of comets is caused by solar wind ions.The measurement of such X-rays can predict solar activity and“space weather”,which is of great significance for space development[1].
Radiative electron capture(REC)and nonradiative capture(NRC)are two competing mechanisms in relativistic collisions of highly charged ions with atoms[1].REC means electron transfer from target to projectile with the e...Radiative electron capture(REC)and nonradiative capture(NRC)are two competing mechanisms in relativistic collisions of highly charged ions with atoms[1].REC means electron transfer from target to projectile with the emission of one photon for satisfying energy and momentum conservation laws.展开更多
In collisions between fast heavy ions and atoms,the strong Coulomb field of one of collision partners can cause inner-shell multiple-ionization of the second one[1].The high-resolution measurements of emitted X-rays i...In collisions between fast heavy ions and atoms,the strong Coulomb field of one of collision partners can cause inner-shell multiple-ionization of the second one[1].The high-resolution measurements of emitted X-rays in the collision are one of the most effective methods to study the multivacancy configurations in atoms or ions as well as the dynamics of the multiple ionization process.The energy shifts of X-rays from states with different vacancy configuration could be large[2].For example,the energy of the argon K hypersatellite and satellite line is between 2.9 and 3.8 keV,and the energy shift causing by per L hole is close to 20 eV[3].In order to simultaneous detection of the emitted X-rays over a wide energy range,thus avoiding the problem of changing the angle of crystal and position of the CCD in one collision system,a wide-angle and high-efficiency X-ray spectrometer based on flat HOPG(Highly Oriented Pyrolytic Graphite)crystal was developed.Due to X-ray from multi-ionized atoms.展开更多
A demonstration device for heavy-ion cancer therapy(HICT)has been built with complete intellectual property rights by Institute of Modern Physics inWuwei city.To meet the medicine security in HICT,methods for monitori...A demonstration device for heavy-ion cancer therapy(HICT)has been built with complete intellectual property rights by Institute of Modern Physics inWuwei city.To meet the medicine security in HICT,methods for monitoring the ion range on-line is necessary and urgent.A technology called Compton camera(CC)is seemed a promising set-up for prompt gamma-ray imaging because it has a wide energy-detection range from a few hundred keV up to a few MeV.However,a primary issue limits the CC technology applying actual HICT and similar therapies.This issue is related to the imaging resolution of CC which is usually larger than 1 mm and is caused by Doppler broadening and other physical reasons.展开更多
Although great attention has been paid to study the guiding effects of charged ions through insulating nanocapillaries or a single microcapillary[1]since the pioneering work of Stolterfoht et al.in 2002[2],the same hi...Although great attention has been paid to study the guiding effects of charged ions through insulating nanocapillaries or a single microcapillary[1]since the pioneering work of Stolterfoht et al.in 2002[2],the same high standard of reproducibility and accuracy among different laboratory cannot be expected because the bulk and surface conductivities of an insulating material are often not well characterized and depend strongly on the working conditions.In other words,the guiding processes are rather random than controllable.In addition,with the energy increasing,the incomplete guiding effect[3;4]limits the application of guiding a swift ion beam in a self-organizing way.展开更多
In collisions between energetic highly charged ions and atoms,the ions could remove the electrons of the target atoms,or be excited into high-level states.In the first case,the target electrons not only be captured in...In collisions between energetic highly charged ions and atoms,the ions could remove the electrons of the target atoms,or be excited into high-level states.In the first case,the target electrons not only be captured into ground and excited states of the projectile ions,but also be ionized to free.Non-radiative capture(NRC)and radiative electron capture(REC)are two competing mechanisms in fast collisions[1].NRC means electron transfer from a bound state of the target to a bound states of the projectile without the emission of radiation;REC is produced with simultaneous the emission of photon for satisfying energy and momentum conservation laws.The physical essence is the competition between the“electron-nucleus”interaction and the“electron-vacuum”interaction.NRC is dominant in collisions of high-Z ions with heavy target atoms at moderate energies.REC entirely determine the electron capture channel for high collision velocities and light targets[1].Measuring the relative strength of the projectile x-ray emission associated with electron capture could determine state-selective population,angular distribution of single capture Ly 1 or double capture Kα1 and Kα2,would provide new detailed information on the dynamics of ion-atom collisions and atomic structure studies[1].展开更多
In collisions between energetic heavy ions and atoms,the strong Coulomb field of one of collision partners can cause double K-shell ionization of the second one.In previous work we have studied the mechanism of double...In collisions between energetic heavy ions and atoms,the strong Coulomb field of one of collision partners can cause double K-shell ionization of the second one.In previous work we have studied the mechanism of double K-shell ionization in krypton atom by bare xenon under different perturbation strengths κ=Zp/vp,where Zp is the charge of the projectile and vp is its velocity in atomic units.The measured double-to-single K-shell ionization cross-section ratio is proportional to the perturbation strengthin the rough region of κ<1,but shows less rapidly increasing when κ>1[1].In order to further investigate such process in a wide rang of perturbation strength,an experiment focusing on K-shell ionization of ions was carried out at HIRFL-CSR in 2017.Ni19+ions with a energy of 95 MeV/u were stored in CSRe to interact with hydrogen,argon,krypton and xenon target,respectively.The X rays produced in collisions of the ions with the target were detected by two Silicon Drift Detectors(SDD)mounted at 35◦and 60◦observation angles with respect to the ion beam direction.展开更多
基金National Natural Science Foundation of China (11105201, U1532130, U1332206)
文摘The experiments with an internal target at a storage ring have many advantages. However, it is difficult to determine the absolute cross section of a reaction where luminosity cannot be simply established through macroscopic measurements. Here we present an experimental determination of the effective target thickness from the beam energy losses at the internal target in HIRFL-CSRe. The measurements here are expected to provide the accurate target thickness and luminosity for the absolute cross-section study on future internal target experiments, and also provide some reference values for the study of beam loss mechanism of the heavy ion at HIRFL-CSRe.
文摘According to the classical over-barrier model[1;2], as a slow highly charged Xeq+ ion approaches a critical distance R =p 2q from the surface with the work function W, it begins to resonantly capture conduction electrons into high Rydberg states (principal quantum number around n q).
文摘Double K-shell ionization of atoms by collisions with charged ions is one of typical two-electron processes andattracts considerable attention both in term of basic theory and experiment. Radiative de-excitation of the doubleK-shell vacancy states of atoms leads to the emission of so called K X-ray hyper-satellites (Kh,Kh . . . )[1], whichgives us the insight into the decay modes of multiply ionized ions as well as the ionization processes during ion-atomcollisions. Contrary to the long-winded and difficult experiments with heavy target due to the low detection efficiencyof K X-ray hyper-satellites with crystal spectrometers[2??4], the bulk of knowledge concerning double K-shellionization in ion-atom collisions has been obtained for light target.
文摘A highly charged ion (HCI) has a large potential energy, which is equal to the binding energies of all the elec-trons removed to create the ion. When such a slow HCI approaches and then enters into a solid surface, an \abovethe surface" and a \below the surface" hollow atom will be formed, respectively, by capturing electrons from thesurface into its empty levels. Not only new aspects of atom physics has been introduced by hollow atoms, but alsoHCI applications in material science has promising prospects, such as surface analysis, the synthesis of materialswith new properties, and the formation of nanostructure that have been an active area of research in recent years[1??6].
文摘When an energetic highly charged ion (HCI) collides with an atom, the target electrons may be captured by theprojectile ion, either radiatively or non-radiatively. During a radiative electron capture (REC), a target electronis transferred to the projectile accompanying with a photon emission, which carries away the excess energy andmomentum. During a non-radiative electron capture (NRC), the energy and momentum conservations are ensuredby the target nucleus[1]. If the captured electrons are populated in excited states, photons maybe emitted duringthe following stabilization processes, and therefore the X-ray spectrum can provide information about the initialpopulation. However, if a solid target is employed, the single-collision condition cannot be ensured when consideringthe capture processes, as well as strong background will be produced[2]. With the development of heavy ioncooling storage rings, the experimental luminance is enhanced by the strong ion beams when a gaseous target isprerequisite[3].
文摘First we calibrated the spectrometer in atmosphere using the peak-channel of 241Am, Thc-c' standard radioactive source while the window diameter isφ3. 0 mm and gained following formula with respect to the energy (E/MeV) ofαand the channel (Ch): E=1. 507 55 + 0. 016 31×Ch+6. 235 24×10-6×Ch2 So, when E=5. 486 MeV, the Ch is equal to 221. 493. When changing the diameter of incident window toφ1.5 mm, we find the peak-channel of
文摘The X-ray radiation of comets is caused by solar wind ions.The measurement of such X-rays can predict solar activity and“space weather”,which is of great significance for space development[1].
基金National Natural Science Foundation of China(11604345,11611530684,11674333,11774356)。
文摘Radiative electron capture(REC)and nonradiative capture(NRC)are two competing mechanisms in relativistic collisions of highly charged ions with atoms[1].REC means electron transfer from target to projectile with the emission of one photon for satisfying energy and momentum conservation laws.
文摘In collisions between fast heavy ions and atoms,the strong Coulomb field of one of collision partners can cause inner-shell multiple-ionization of the second one[1].The high-resolution measurements of emitted X-rays in the collision are one of the most effective methods to study the multivacancy configurations in atoms or ions as well as the dynamics of the multiple ionization process.The energy shifts of X-rays from states with different vacancy configuration could be large[2].For example,the energy of the argon K hypersatellite and satellite line is between 2.9 and 3.8 keV,and the energy shift causing by per L hole is close to 20 eV[3].In order to simultaneous detection of the emitted X-rays over a wide energy range,thus avoiding the problem of changing the angle of crystal and position of the CCD in one collision system,a wide-angle and high-efficiency X-ray spectrometer based on flat HOPG(Highly Oriented Pyrolytic Graphite)crystal was developed.Due to X-ray from multi-ionized atoms.
文摘A demonstration device for heavy-ion cancer therapy(HICT)has been built with complete intellectual property rights by Institute of Modern Physics inWuwei city.To meet the medicine security in HICT,methods for monitoring the ion range on-line is necessary and urgent.A technology called Compton camera(CC)is seemed a promising set-up for prompt gamma-ray imaging because it has a wide energy-detection range from a few hundred keV up to a few MeV.However,a primary issue limits the CC technology applying actual HICT and similar therapies.This issue is related to the imaging resolution of CC which is usually larger than 1 mm and is caused by Doppler broadening and other physical reasons.
文摘Although great attention has been paid to study the guiding effects of charged ions through insulating nanocapillaries or a single microcapillary[1]since the pioneering work of Stolterfoht et al.in 2002[2],the same high standard of reproducibility and accuracy among different laboratory cannot be expected because the bulk and surface conductivities of an insulating material are often not well characterized and depend strongly on the working conditions.In other words,the guiding processes are rather random than controllable.In addition,with the energy increasing,the incomplete guiding effect[3;4]limits the application of guiding a swift ion beam in a self-organizing way.
文摘In collisions between energetic highly charged ions and atoms,the ions could remove the electrons of the target atoms,or be excited into high-level states.In the first case,the target electrons not only be captured into ground and excited states of the projectile ions,but also be ionized to free.Non-radiative capture(NRC)and radiative electron capture(REC)are two competing mechanisms in fast collisions[1].NRC means electron transfer from a bound state of the target to a bound states of the projectile without the emission of radiation;REC is produced with simultaneous the emission of photon for satisfying energy and momentum conservation laws.The physical essence is the competition between the“electron-nucleus”interaction and the“electron-vacuum”interaction.NRC is dominant in collisions of high-Z ions with heavy target atoms at moderate energies.REC entirely determine the electron capture channel for high collision velocities and light targets[1].Measuring the relative strength of the projectile x-ray emission associated with electron capture could determine state-selective population,angular distribution of single capture Ly 1 or double capture Kα1 and Kα2,would provide new detailed information on the dynamics of ion-atom collisions and atomic structure studies[1].
文摘In collisions between energetic heavy ions and atoms,the strong Coulomb field of one of collision partners can cause double K-shell ionization of the second one.In previous work we have studied the mechanism of double K-shell ionization in krypton atom by bare xenon under different perturbation strengths κ=Zp/vp,where Zp is the charge of the projectile and vp is its velocity in atomic units.The measured double-to-single K-shell ionization cross-section ratio is proportional to the perturbation strengthin the rough region of κ<1,but shows less rapidly increasing when κ>1[1].In order to further investigate such process in a wide rang of perturbation strength,an experiment focusing on K-shell ionization of ions was carried out at HIRFL-CSR in 2017.Ni19+ions with a energy of 95 MeV/u were stored in CSRe to interact with hydrogen,argon,krypton and xenon target,respectively.The X rays produced in collisions of the ions with the target were detected by two Silicon Drift Detectors(SDD)mounted at 35◦and 60◦observation angles with respect to the ion beam direction.
