Synchronous gating in dilation x-ray detector without 1:1 image ratio.

An x-ray detector using a pulse-dilation technology to achieve high temporal resolution is reported. The electron pulse generated from the photo-cathode (PC) is first dilated by a pulse-dilation device and then imaged onto the microchannel plate (MCP) by a magnetic lens imaging system. Finally, the dilated electron pulse is detected by a gated MCP. A resolution of 14 ps is achieved. In addition, the synchronous gating is studied in the dilation x-ray detector without a 1:1 image ratio. The results show that while the time of flight (TOF) of the electrons is identical, the MCP gating pulse can be timed relative to the PC excitation pulse to gate the dilated electron signal in a single area, and they are unsynchronized in the other area. To avoid the single area synchronization effect, the magnetic lens imaging system used in the detector should allow photoelectrons with a large energy spread to be imaged onto the MCP. This effect can also be reduced by using an MCP gating pulse with a width larger than 500 ps. Moreover, a 1:1 image ratio can avoid this effect. Furthermore, a decreasing electron TOF can eliminate the single area synchronization effect.

Dilation x-ray framing camera and its temporal resolution uniformity.

An x-ray framing camera based on pulse-dilation technology is reported. This camera first dilates the electron signal generated from a pulsed photo-cathode (PC), and then detects the dilated electron pulse by using a gated microchannel plate (MCP). While the PC is only applied with a direct current (DC) voltage, the camera's temporal resolution without pulse-dilation is about 81 ps. It is the gated MCP's temporal resolution. While an excitation pulse is applied on the PC, the electron pulse's temporal width is dilated, and the resolution is improved to 14 ps. Furthermore, the camera's temporal resolution uniformity is measured and simulated. The results show a 3.5 × drop in temporal resolution along the pulse propagation direction, due to the 5 × decrease of the PC excitation pulse gradient.

A theoretical study of diffraction limit breaking via coherent control of the relative phase in coherent anti-Stokes Raman scattering microscopy.

We present a theoretical investigation of how coherent control of the relative phase in coherent anti-Stokes Raman scattering (CARS) microscopy can break the diffraction limit. In quantum theory, it is found that the relative phase of the pump and Stokes pulses can be used to periodically tune the intensity of the anti-Stokes signal. Thus, by controlling the relative phase around the center of the pump and Stokes pulses, the anti-Stokes signal can be tuned to zero in this region. In turn, the useful spot-generating anti-Stokes signal is substantially suppressed to a much smaller dimension, and scanning of the spots renders CARS images with sub-diffraction resolutions. Such super-resolutions can greatly enhance the advantage of using CARS microscopy in many potential applications.

Transparent conductive films based on quantum tunneling.

We theoretically propose an approach for designing transparent conductive films based on quantum tunneling effects. These films are constructed from insulator and metallic materials overlapped with one another. To approach the quantum tunneling regime and improve the conductivity, the thicknesses of the insulator layers should be 1 nanometer or less. The optical properties (transmittance, reflectance and admittance) are studied in detail. However, the quantum tunneling effect would have an impact on the imaginary part of the permittivity of the insulator material. Therefore, the influence of the incoming quantum tunneling effect on the transparency is also analyzed by a quantum-corrected model. Finally, we have also studied the conductivity of the films.

The impact of information presentation on self-other risk decision-making.

To explore the impact of social distance and information presentation types on self-other risk preferences in monetary tasks. Risk preferences were examined in decision-making tasks and experiential information tasks within different frameworks when participants made decisions for themselves and others. Experiment 1 employed experiential decision tasks and revealed individual differences in decision-making for oneself and others. In gain situations, participants exhibited more risk aversion when deciding for others compared to themselves. Experiment 2 presented both types of information simultaneously to investigate whether risk decisions for oneself and others are influenced by information types. Results indicated that experiential information led participants to make more conservative choices for others, while descriptive information eliminated this effect. This study discovered the influence of social distance on self-other risk decisions and the role of information presentation types in self and other risk decision-making. Future research could further explore self-other decision-making from the perspectives of decision-makers' traits and culture.

Luminescence Properties of Green Phosphor Ca2Ga2(Ge1-xSix)O7:y%Eu2+ and Application.

Rare earth luminescent materials demonstrate significant advantages in lighting and energy saving, and detection etc. In this paper, a series of Ca2Ga2(Ge1-xSix)O7:y%Eu2+ phosphors were synthesized by high-temperature solid-state reaction and characterized by X-ray diffraction and luminescence spectroscopy methods. The powder X-ray diffraction patterns reveal that all the phosphors are isostructural with a space group of P4¯21m. The excitation spectra of Ca2Ga2(Ge1-xSix)O7:1%Eu2+ phosphors exhibit significant overlapping of the host and the Eu2+ absorption bands, which facilitates Eu2+ absorbing the energy to increase its luminescence efficiency when excited by visible photons. The emission spectra show that the Eu2+ doped phosphors have a broad emission band with a peak centered at 510 nm arising from the 4f65d1→4f7 transition. Variable temperature fluorescence reveals that the phosphor has a strong luminescence at low temperature but has a severe thermal quenching effect when temperature rises. The optimal Ca2Ga2(Ge0.5Si0.5)O7:1.0%Eu2+ phosphor shows promise for application in the field of fingerprint identification based on the experimental results.

Observation of electron beam moiré fringes in an image conversion tube.

An image conversion tube with a magnetic lens was designed to observe electron beam moiré fringes. Electron beam moiré fringes result from the interference between the photocathode and the anode meshes. The photocathode had a strip line structure with a spatial frequency of 10L/mm. The anode mesh had a fixed spatial frequency of 10L/mm, and could be rotated around the axis of the image tube. The changes to the fringe direction and the spacing as a function of the rotation angle between the photocathode and the anode mesh were examined. The experimental results agreed with the theoretical analysis. Moiré fringes with a modulation of ~20% were obtained using a 3keV electron beam.