Zhangyong Song

Production and decay of K -shell hollow krypton in collisions with 52–197-MeV/u bare xenon ions

X-ray spectra of K-shell hollow krypton atoms produced in single collisions with 52 - 197 MeV/u Xe54+ ions are measured in a heavy-ion storage ring equipped with an internal gas-jet target. Energy shifts of the K{\alpha}_1,2^s, K{\alpha}_1,2^(h,s), and K\b{eta}_1,3^s transitions are obtained. Thus, the average number of the spectator L-vacancies presented during the x-ray emission is deduced. From the relative intensities of the K{\alpha}_1,2^s and K{\alpha}_1,2^(h,s) transitions, the ratio of K-shell hollow krypton to singly K-shell ionized atoms is determined to be 14 - 24%. In the considered collisions, the K-vacancies are mainly created by the direct ionization which cannot be calculated within the perturbation descriptions. The experimental results are compared with a relativistic coupled channel calculation performed within the independent particle approximation.

Energy spectra of sputtering ions induced by Ar7, 9+ ions on graphite collisions

The Sputtering Ion Energy Spectra (SIES) produced by Ar7, 9+ ions at velocities of 0.9 vBohr, 1.35 vBohr and 1.8 vBohr bombardment at 45o to high oriented graphite target were obtained for the first time.

Dynamics of slow electrons transmitting through straight glass capillary and tapered glass capillary

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 continuous and discrete molecular orbital x-ray bands from Xeq+ (12≤q≤29) +Zn collisions

In this paper, the x-ray emissions are measured by the interaction of 1500–3500 keV Xeq+ (q = 12, 15, 17, 19, 21, 23, 26 and 29) ions with Zn target. When q < 29, we observe Ll, Lα, Lβ1, Lβ2 and Lγ characteristic x-rays from Xeq+ ions and a broad M-shell molecular orbital (MO) x-ray band from the transient quasi-molecular levels. It is found that their yields quickly increase with different rates as the incident energy increases. Besides, the widths of the broad MO x-ray bands are about 0.9–1.32 keV over the energy range studied and are proportional to v1/2 (v = projectile velocity). Most remarkably, when the projectile charge state is 29, the broad x-ray band separates into several narrow discrete spectra, which was never observed before in this field.

Determination of internal-target thickness and experimental luminosity from beam energy loss at HIRFL-CSRe*

The target thickness for nitrogen was determined from the beam energy loss in HIRFL-CSRe during the experimental study of the K-REC process in 197 MeV/u Xe54+-N-2 collisions. Furthermore, the corresponding integrated luminosity of (1.15 +/- 0.06) x 10(30) cm(-2) was obtained. As an independent check on the energy-loss method, we have also determined the integrated luminosity by measuring the produced X-rays from the K-REC process with a known differential cross section. The values of (1.12 +/- 0.06) x 10(30) and (1.09 +/- 0.06) x 10(30) cm(-2) were obtained by using two high-purity germanium (HPGe) detectors which were oriented at 90 degrees and 120 degrees with respect to the beam path, respectively. The consistent results confirmed the feasibility of the energy-loss method, which may have an important impact on future internal target experiments at HIRFL-CSRe.

Double K-shell ionization of Kr induced by swift Xe54+ ions

Kα satellite and hypersatellite lines of Kr induced by 52-, 94-, 146-, and 197-MeV/u Xe54+ ions were measured. Experimental values were compared with theoretical ones obtained within the independent electron model (IEM) employing single electron probabilities calculated with the semi-classical approach (SCA). This comparison suggests that first order perturbation approximation is consistent well with the experimental result at 197-MeV/u projectile collision while breaks down for the lower energies.

Single and double electron capture by fast Xe54+ from Kr and Xe

Decay X-ray spectrum of the scattered ions in 52-197 MeV/u Xe54+ collision with Kr and Xe atoms are measured. The transitions form the single capture ion Xe53+* and from the double capture ion Xe52+* are observed, both in a single collision. The single capture is the dominate channel at high energies while the double capture becomes dominate at lower energies.

Test run of 185 MeV/u Ni19+-Kr collisions at CSRe internal target

X-rays from both the target atoms and the ions were observed in 185 MeV/u Ni19+-Kr collisions at the CSRe internal target. The internal target of krypton was online verified, and the X-ray background was shield quite well.