Deyang Yu

Transmission of electrons through a tapered glass capillary

The transmission of high-current electrons through a tapered SiO2 capillary was investigated. The angular distribution and incident energy dependence of transmitted electrons were observed. We found that the transmitted fraction decreases with the incident energy. The transmitted electrons had significant energy loss but could not be focused by the tapered capillary.

Transmission of low-energy electrons through SiO2 tube

The transmission of low-energy (1100eV-1500eV) electrons through SiO2 tube was investigated, the distribution of transmitted beam current was observed. Results indicate that the intensity of transmitted electrons is proportional to the relative incident beam intensity and the angular divergence of the transmitted electrons is reduced when incident energy increased.

Note: a real-time beam current density meter.

We have developed a real-time beam current density meter for charged particle beams. It measures the mean current density by collimating a uniform and large diameter primary beam. The suppression of the secondary electrons and the deflection of the beam were simulated, and it was tested with a 105 keV Ar(7+) ion beam.

Note: A timing micro-channel plate detector with backside fast preamplifier

A timing micro-channel plate detector with a backside double-channel fast preamplifier was developed to avoid distortion during signal propagation from the anode to the preamplifier. The mechanical and electronic structure is described. The detector including its backside preamplifier is tested by a (241)Am α-source and a rise time of ~2 ns with an output background noise of 4 mV(rms) was achieved.

A 128-channel picoammeter system and its application on charged particle beam current distribution measurements

A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking advantage of a high electric potential and narrow bandwidth in DC energetic charged beam measurements, a current resolution better than 5 fA can be achieved. Two sets of 128-channel strip electrodes are implemented on printed circuit boards and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O(3+) ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

Note: A charge sensitive spectroscopy amplifier for position sensitive micro-channel plate detectors.

A compact and low noise charge sensitive spectroscopy amplifier which can be integrated into position sensitive micro-channel plate (MCP) detectors has been constructed. The amplifier was optimized by using a wave form generator and tested by a chevron shape MCP detector. The output noise of 4 mV(rms) was achieved while the gain is 10(12) V/C and the shaping time is 700 ns.

Note: A two-dimensional position-sensitive micro-channel plate detector with a cross-connected-pixels resistive anode and integrated spectroscopy amplifiers

Based on the charge-division method, a compact detector system for charged particles is constructed. The system consists of a pair of micro-channel plates, a novel two-dimensional position-sensitive cross-connected-pixels resistive anode, and specially designed front-end electronics that can directly drive analog-to-digital converters. The detector is tested with an 241Am α-source. A position resolution of better than 0.3 mm and a maximum distortion within 0.5 mm in the active dimensions of 100 mm diameter are achieved.

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.

Electron beam guiding by grooved SiO2 parallel plates without energy loss

Using a pair of grooved SiO2 parallel plates, stably guided electron beams were obtained without energy loss at 800–2000 eV. This shows that the transmitted electrons are guided by a self-organized repulsive electric field, paving the way for a self-adaptive manipulation of electron beams.

One-dimension position sensitive MCP detector using a parallel strips readout anode

We have developed a one-dimension position sensitive MCP detector based on a new parallel micro-strips readout anode. The position resolution of the detector is 0.2mm.