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In order to clearly understand the physical images of incident ions passing through the insulating nanocapillary, in this work we establish a theoretical model, in which the matlab program is combined with the Monte Carlo method, to estimate the time evolution of transmission features, such as the angular and deposited charge distribution, three-dimensional (3D) trajectories of H+ particles with proton incident energies of 10 keV, 100 keV and 1 MeV at -1 title angle. The simulation results show that the transmission mechanism of 100 keV protons is different from those of 10 keV and 1 MeV protons. After a sufficiently charging and discharging stage, 10 keV H+ particles are guided along the direction of capillary axis, indicating that the guiding force from the surface charge patches is significant, and the small-angle scattering of 1 MeV protons under the capillary inner wall is a physical process that determines the transport of H+ particles through the nanocapillary. However, for 100 keV H+ particles, the centroid angle gradually shifts from the guiding direction to the direction close to the incident beam, which is attributed to the fact that the stochastic inelastic binary collision below the surface is the main transmission mechanism at the beginning. After the charging and discharging reach an equilibrium state, the H+ particles are likely to pass through the nanocapillary, and the main transmission mechanism is the charge-patch-assisted specular scattering. This mechanism deepens the understanding of the transport behavior of protons through the nanocapillary, which will contribute to the control and application of the 100 keV proton beam.

In recent years, by using the etching techniques with great precision, the ion tracks in materials were converted into insulator and metal nanocapillaries. The physical and chemical properties of the inner surface on micro and nano-scales of these capillaries can be investigated by the interaction of ions with the surfaces. Stolterfoht et al. (2002 Phys. Rev. Lett. 88 133201) have found the evidence for capillary guiding in studying the transmission of 3 keV Ne7+ ions (energy/charge E/q approximate to 10(0) kV) through the polymer nanocapillaries. The self-organized charge-up process was thought to inhibit close contact between the ions and the inner capillary walls. Skog et al. (2008 Phys. Rev. Lett. 101 223202) investigated the guiding effect of 7 keV Ne7+ ions (E/q approximate to 10(0) kV) transmitted through SiO2 nanocapillaries, and found the evidence of sequentially formed charge patches along the capillary. For these keV highly charged ions with E/q approximate to 10(0) kV, the charge patches were formed in a very short time, and then the repulsive electric field rapidly becomes strong enough to deflect the ions, then the ions move along the capillary axis without charge exchange. Zhou et al. (2016 Acta Phys. Sin. 65 103401) have investigated the transmission of 100 keV protons (E/q approximate to 10(2) kV) through the nanocapillaries in polycarbonate (PC) membrane. It was found that the transmitted ions are located around the direction of the incident beam, rather than along the capillary axis. This indicated that the transmission mechanism of hundreds of keV protons through nanocapillaries is significantly different from that for keV highly charged ions. For 100 keV protons, several charge patches suppress the protons to penetrate into the surface, and the protons are transmitted via twice specular scattering near the surface and finally emitted along the incident direction. However, the study of the transmission of E/q approximate to 10(1) kV ions through nanocapillaries is still lacking. In this work, we measure the time evolution of the relative transmission rate, charge state and angular distribution as well as the full width at half maximum of 20 keV protons (E/q approximate to 10(1) kV) transmitted through the nanocapillaries in PC membrane at a tilt angle of +1 degrees. We observe a very long time pre-guiding period before the stable guiding process is established. During the pre-guiding period the direction of the transmitted H+ ions changes to the direction of capillary axis gradually. The transmitted H-0 particles are composed of two peaks: the higher and sharper one is nearly in the beam direction, the wider and lower one is around the guiding direction. With the continuous charging-up process, the intensities of the narrow and sharp peak of transmitted H-0 near the beam direction will decrease and disappear at the end. The data indicate that the scattering and guiding forces are both important for E/q approximate to 10(1) kV ions during the period of pre-guiding process, and the guiding force is dominant till a long time pre-guiding period is ended. This finding will fill in the gap between E/q approximate to 10(0) kV and 10(2) kV of previous studies of ions transmitted through nanocapillaries. It is also helpful for finding the applications of nano-and micro-sized ion beams produced by tapered glass capillary with E/q approximate to 10(1) kV.

The transmission of 1.5 keV-electrons through a conical glass capillary is reported. This study aims to understand the so-called guiding effect for the negatively charged particles (e.g. electrons). The guiding mechanism is understood quite well with positively charged particles in particular highly charged ions, but not clear with electrons, i.e., even the basic scheme mediated by the existence of negative charge patches to guide the electrons is still somewhat controversial. The study of the charging-up dynamics causing the electrons transport inside the capillary will shed light on this issue. In order to perform this, a data acquisition system has been setup to follow the time evolution of the twodimensional angular distribution of the transmitted electrons. The electrons are detected by the multi-channel plate (MCP) detector with a phosphor screen. The image from the phosphor screen is recorded by a charge-coupled device camera. The timing signals for the detected events are extracted from the back stack of the MCP detector and recorded by the data acquisition system, synchronized with the acquired images. The electron beam has a size of 0.5 mm0.5 mm and a divergence of less than 0.35. The inner diameter of the straight part of the capillary is 1.2 mm and the exit diameter is 225 m. A small conducting aperture of 0.3 mm in diameter is placed at the entrance of the capillary. Two-dimensional angular distribution of the transmitted electrons through conical glass capillary and its time evolution are measured. The results show that the transmission rate decreases and reaches to a constant value for the completely discharged glass capillary with time going by. The centroid of the angular distribution moves to an asymptotic value while the width remains unchanged. These transmission characteristics are different from those indicated in our previous work (2016 Acta Phys. Sin. 65 204103). The difference originates from the different manipulations of the capillary outer surface. A conducting layer is coated on the outer surface of the capillary and grounded in this work. This isolates various discharge/charge channels and forms a new stable discharge channel. The transmission rate as a function of the tilt angle shows that the allowed transmission occurs at the tilt angle limited by the geometrical factors, i.e., the geometrical opening angle given by the aspect ratio as well as the beam divergence. The transmission characteristics suggest that most likely there are formed no negative patches to facilitate the electron transmission through the glass capillary at this selected beam energy. It is different from that of highly charged ions, where the formation of the charge patches prohibits the close collisions between the following ions and guides them out of the capillary.

Graphene was first discovered in 2004 (Novoselov K S, et al. 2004 Science 306 666), it is a single atomic layer of sp2-bonded carbon atoms arranged in a honeycomb-like lattice. According to its extraordinary electronic, mechanical, thermal and optical properties, one can expect it to have a variety of applications in nanoscale electronics, composite materials, energy storage, and biomedicine fields. Although many experimental and theoretical studies on graphene have been carried, there still exist many obstacles to its applications. A representative example is nanoscale electronics (e.g., field-effect transistors and optoelectronic devices) that requires non-zero band-gap. Therefore, introducing defects into graphene and leading to band-gap opening are key steps for its technique applications.Recently, ion beam irradiation as a defects introducing technique was performed by Lee et al. (2015 Appl. Surf. Sci. 344 52) and Zeng et al. (2016 Carbon 100 16) through 5, 10, and 15 MeV protons and highly charged ions (HCIs) irradiating the graphene separately. Considering the advantages of simplity for preparing samples and feasibility in atmospheric condition of Raman spectroscopy compared with common characterization techniques (high resolution transmission electron microscopy, scanning electron microscopy, atomic force microscopy) for nano-materials, in both studies, Raman spectroscopy is used to obtain the evolution of ID/IG (ID is the peak intensity excited by defects, IG is the peak intensity origining from lateral vibration of carbon atoms) with different energies and fluences, respectively. In this work, considered are the following points:1) the absence of quantitive characterization for defects in the above two studies; 2) the low displacement energy of 25 eV required for a carbon atom to be knocked out (Zhao S J, et al. 2012 Nanotechnology 23 285703); 3) the complex interaction between HCIs and material. The irradiation effects of single layer graphene on silicon substrate are investigated by 750 keV and 1 MeV proton bombarding. This introduces the defects into graphene and thus leads to band-gap opening. By comparing Raman spectra of the samples before and after irradiation, a quantitive characterization about defects in graphene is achieved. Detailed analysis shows that 1) the value of ID/IG increases with the energy loss of incident proton, which is consistent with the result of SRIM simulation; 2) the average distance of defects LD increases with the incident proton energy; 3) the defect density nD decreases with the incident proton energy. These indicate that the damage effect for MeV protons in single layer graphene with substrate is similar to those in three-dimensional materials. The method presented here may facilitate the understanding of the physical mechanism of MeV proton interaction with two-dimensional materials, and provide a potential way of controlling the electronic structure and band-gap.

When a lambda hyperon was embedded in a nucleus, it can form a hypernucleus. The lifetime and its mass dependence of stable hypernuclei provide information about the weak decay of lambda hyperon inside nuclear medium. This work will introduce the Jefferson Lab experiment (E02-017) which aims to study the lifetime of the heavy hypernuclei using a specially developed fission fragment detection technique, a multi-wire proportional chamber operated under low gas pressure (LPMWPC). Presented here are the method and performance of the reconstruction of fission position on the target foil, the separation of target materials at different regions and the comparison and verification with the Mote Carlo simulation., Comment: 10 pages

It has been found that the transmission rate of the electrons through insulating capillaries as a function of time/incident charge is not the same as that of the ions. The question arises that by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the following electrons, thereby substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolutions of the transmission of electrons through a straight glass tube and a tapered glass capillary. This will reveal the details of how and (or) if the negative charge patches can be formed when the electrons transport through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform is developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams are obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitting through the glass tube/capillary is observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then appear again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fact that fast discharge of the deposited charge leads to the increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge leads to the decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate the transmission of electrons. This suggests that if the stable transmission needs to be reached for producing the electron micro-beam by using tapered glass capillaries, the steps must be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference in transmission through the insulating capillary between electrons and highly charged ions.

The X-ray emission spectra produced by 2.4-6.0 MeV Xe20+ ions impacting on vanadium surface were measured. The V K-shell X-ray production cross sections were extracted from the experimental yield data and compared with the theoretical predictions of the binary encounter approximation (BEA), the plane wave born approximation (PWBA), and the energy-loss coulomb-repulsion perturbed-stationary-state relativist (ECPSSR). In order to predict reasonably the inner-shell ionization induced by highly charged heavy ions during the asymmetric collisions at near the Bohr velocity, the corrections of BEA model are discussed. It is found that the X-ray production cross section induced by highly charged heavy ions moving at near the Bohr velocity is on the magnitude of 1 barn, which is almost four orders of magnitude larger than that induced by proton. The ECPSSR, which is regarded as the best model to simulate the inner-shell ionization by light ions, may underestimate the experimental data at least three orders of magnitude. The PWBA model presents a prediction to the results on an order of magnitude better than the ECPSSR simulation, but gives a worse tendency than the BEA model. The BEA calculations, corrected both by Coulomb repulsion and effective nuclear charge, present the best agreement with the experimental results. It is proposed, that in the energy region near the Bohr velocity, during the asymmetric collisions of Xe20+ ions with V atoms, the K-shell electron of V is ionized by direct ionization, and that it can be described by the binary encounter process between the xenon ions and the bound electrons. The X-ray production cross section can be simulated by BEA model, but the corrections of Coulomb repulsion and effective nuclear charge must be considered.

In recent years, the guiding effect of highly charged ions (HCIs) through insulating nanocapillary membrane has received extensive attention. It is found that slow highly charged ions at keV energies can be guided along the capillary even when the title angle of membrane is a few degrees and larger than geometry opening angle of the capillary. Initially, Stolterfoht et al. (2002 Phys. Rev. Lett. 88 133201), according to the incident ions deposit positive charges on the capillary surface in a self-organizing manner, proposed scattering and guiding regions to explain this guiding phenomenon. Hereafter, a detailed experiment and simulation performed by Skog et al. (2008 Phys. Rev. Lett. 101 223202) provided clear evidence that the guiding process is actually attributed to the self-organized charge patches formed on the inner capillary walls. HCIs entering into a capillary may hit the surface, leaving their charge on the inner wall of the capillary. When the capillary axis is tilted with respect to the beam incidence direction, a charge patch is formed in the capillary entrance, simultaneously a repulsive electric field is created. After sufficient charge deposition this field is strong enough to deflect the subsequent ions in the direction of the capillary exit. Therefore, the ions are guided through the capillary. The deflection at the charge patch only occurs at relatively large distances from the capillary wall so that the incident charge state of the ions is kept during the passage through the capillary. Further experimental and theoretical studies on various target materials, such as polyethylene terephthalate (PET), polycarbonate (PC), SiO2, and Al2O3 indeed found that a single or a small number of charge patches near the entrance formed in the charge up process dominate the observed oscillatory variations of the ion emission angle and the final guiding process. Besides, measurements and simulations of the steering of swift ions at MeV energies have shown that the transmission mechanism of the high energy ions in a tapered tube is primarily dominated by multiple random inelastic collisions below the surface and the charge patches are not responsible for the transmission process. However, the studies of the transmission of hundreds keV ions through nanocapillaries are still lacking so far. In this work, we observe the evolution of the angular distribution, charge state distribution, FWHM and transmission rate of 100 keV H+ ions incident on a polycarbonate (PC) membrane at +1 tilt angle. It is found that the transmitted particles are located around the direction along the incident beam, not along the capillary axis, which suggests that the mechanism of hundreds keV (E/q~100 kV) protons through capillaries is significantly different from that for the guiding effect of keV protons. We present a qualitative explanation based on the data: that the 100 keV H+ are transmitted by multiple random inelastic collisions below the surface is attributed to the absence of the deposited charges on the surface of the capillary at the beginning of the experiment. After the equilibrium, several charge patches are formed on the inner wall of the capillary, which suppresses the ions to penetrate into the surface of the capillary, while the H+ is transmitted via specular scattering above the surface (or closest to the surface) assisted by the charge patches, and finally is emitted in the incident direction through twice specular scattering. This finding increases the knowledge of charged ions through nanocapillaries, which is conducible to the applications of nanosized beams produced by capillaries or tapered glass within hundreds keV energies in many scientific fields.

The transmission of 60 keV O+ ions through Al2O3 nanocapillaries at a series of different tilt angles is measured. The capillaries with diameters of 50 nm and 30 nm respectively and 10 μm in length are used. The angular distribution and the transmission yields of transported ions are investigated. Our results indicate both the existence of guiding effect when ions pass through the capillary and a significant dependence on the tilt angle. The results also show that the transmission yield increases as the diameter of capillary decreases，and the theoretical model used in our work explains it well.

The K X-rays emitted from the incident slow highly charged Ar17+ ions are investigated in the interaction with various metal target such as Be, Al, Ni, Mo and Au. The Kβ/Kα ratios and the mean energies of the emitted X-rays are extracted and analyzed from our previous experimental results . It is found that the ratios and the energies are almost independent of the ion velocity and the target element. Meanwhile, a model based on the conductive-electron capture and the cascading de-excitation model is proposed to interpret the experiment. Excellent agreement is found between the theoretical results and the experimental data.

In this work, the ionizations involving the charge transfer and single capture processes in low charge state ion-atom collisions in low-to-medium energy region, are investigated by the position sensitive and time-of-flight techniques. For a given charge state of the incoming projectiles, the dependence of the ratio RTS of the transfer ionization to the single capture changing with the projectile velocity is obtained, and the conclusion that the ionized electron in the transfer ionization process comes from the outermost sub-shell of the target atom is confirmed by comparing our theoretical results with the experimental data.

The 10—20qkeV Ar16+ and Ar17+ ions produced by SECRAL enter on metallic surface of Zr. In this interaction，the multi-electron excitation possibly occurred in the neutralization of the highly charged Ar16+ ions，which produced vacancy in the K shell. Electron of the high n state de-excited to K vacancy gives off X-ray. The experimental results show that X-ray intensities for the Ar hollow atom decrease with increase of incidence energy，and Lβ X-ray intensities of target atom Zr increase with increasing incidence energy. Kα X-ray yield per ion for Ar17+ was five orders of magnitude greater than that for Ar16+.

This paper presents the measurement results of absolute cross-sections of ion-atom collision in detail. The pure cross-sections of Nei+(i=1—4) induced by C3+ were investigated using coincidence technique. Comparing our experimental results with those of n-body classical trajectory Monte Carlo method, it is found that the changes of pure cross sections with increasing energy have the same trend in the two cases. The causes of discrepancies between them are discussed. The mechanism of multiple-ionization is analyzed. The highly charged recoil ions come mainly from the Auger effect. The electron-electron interaction comes in to effect as the incident energy increases. The cross-sections of all kinds of reactions can be measured in this way using the same equipment and projectile ions can be various within a wide range of energy.

he cross-section ratios for the double-to-single ionization of He associated with no projectile charge change ( R q , q ), single-electron capture ( R q , q -1 ) and single-electron loss ( R q , q +1 ) were measured using coincidence technique. The coincidences resulted from the signals of recoil ions and scattered projectiles. For a given incoming projectile charge state the double-to-single ionization ratios vary strongly with the outgoing reaction channel. It is found that R q , q R q , q +1 R q , q -1 . For direct ionization, R q , q is nearly independent of the incident projectile charge state. However, for ionization associated with single-electron capture and single-electron loss by the projectile, R q , q -1 and R q , q +1 depend strongly on the incident charge state of the projectile. These ionization ratios are interpreted in terms of theories of the atomic polarization effect and the screening and antiscreening effect of the electrons around the core.

This paper studies the X-ray spectra produced by the interaction of highly charged ions of Arq+(q=16,17,18) with metallic surface of Be, Al, Ni, Mo and Au respectively. The experimental results show that the Kα X-ray emerges from under the surface of solid in the interaction of ions with targets. The multi-electron excitation occurred in the process neutralization of the Ar16+ in electronic configuration of 1s2 in metallic surfaces, which produces vacancy in the K shell. Electron from high n state transition to K vacancy gives off X-ray. We find that there is no obvious relation between the shape of X-ray spectra and the different targets. The X-ray yield of incident ions are associated with initial electronic configuration. The X-ray yield of target is related to the kinetic energy of the incidentions.

We have measured the spectra and yields for Ar K and Mo L x-rays from Ar 15+ and Ar16+ ions colliding with molybdenum (Mo) surfaces . The spec tra and yields are measured as a function of the projectile kinetic energy. In t he case of Ar15+ -Mo, both Ar K x-rays and Mo L x-rays are observe d, and the yields of Ar K x-rays are related to the projectile kinetic energ y, the potential energy of hollow atom formed in the interaction, the competitio n of the x-rays emitting from the projectile and the target etc. But in the case of Ar15+-Mo, Mo L x-rays are observed only. The yields of Mo L x- rays induced in both cases increase with the projectile kinetic energy.

The x-ray spectra of hollow atoms in the interaction of highly charged argon ions with beryllium solid surface are reported. The interaction ions, provided by t he electron cyclotron resonance (ECR) ion source in the National Laboratory of t he Heavy Ion Research Facility in Lanzhou(HIRFL), include bare argon ions, which are produced by the ion source for the first time, and hydrogen-like, helium-li ke and lithium-like argon ions. We found that the K-shell x-ray yield of single particles in the interaction of hydrogen-like argon ions is 36×10-3, wh ich is 5 orders more than that of helium-like argon ions, and the K-shell x-ray cannot be measured in the interaction of lithium-like argon ions with beryllium surface.

The cross section ratios of the double to single electron transfer of helium target induced by Xeq+(q=15,17,19,21,23) ions are measured by means of the position sensitive and timeofflight techniques. By considering an onestep transfer mechanism, we modify the extended classical overbarrier model. It is found that the calculated single and double electrontransfer cross sections using the modified model show excellent agreement with the experimental data of Andersson et al. and Selberg et al, and improves the agreement with the present measured double to single electrontransfer ratio considerably.

Rare earth elements Tb, Er and Lu were bombarded by protons with energies of 0.2-1.2 MeV, L-subshell ionization cross sections were obtained. Experimental ionization cross sections were compared with the predictions of the ECPSSR theory.