Jingsheng Pan

High detection efficiency neutron sensitive microchannel plate

Direct addition of neutron-absorbing atoms into MCP glass, such as 10B and 155,157Gd, without changing the remainder of MCP fabrication process, can make MCP sensitive to neutrons. Since the much larger cross section of 157Gd, the MCP doped with natGd2O3 is more efficient than one doped with enriched 10B2O3, theoretical indicates that the detection efficiency of a MCP doped with 3 mole% of natGd2O3 is equivalent even superior to a MCP doped with 20 mole% of 10B2O3. In this paper a 50 mm diameter rimless format 10 μm pore diameter MCP doped with 3 mole% natGd2O3 was fabricated, but the MCP glass doped with 20 mol% of natB2O3 failed to pass through the corrosive chemical processing necessary in MCPs manufacture. A primary experimental tests proved the MCP doped with 3 mole% natGd2O3 is capable of imaging thermal neutrons with 35% detection efficiency. A potential of enhancement on detection efficiency should be achieved for a optimized geometry MCP with an appropriate selection between bias angle, open area ratio and length to diameter ratio.

Detection efficiency evaluation for a large area neutron sensitive microchannel plate detector

In this paper, the detection efficiency of a large area neutron sensitive microchannel plate detector has been evaluated. A 6LiF/ZnS scintillator detector 65 mm in diameter and 0.32 mm in thickness, with product code, EJ426HD2, produced by Eljen Technology, was employed as the benchmark detector. The TOF spectra of these two detectors were simultaneously measured and the energy spectra were then deduced to calculate the detection efficiency curve of the nMCP detector. Tests show the detection efficiency@25.3 meV thermal neutrons is 34% for this nMCP detector.

Innovative microchannel plate with reformulation of composition and modification of microstructure

The signal-to-noise ratio (SNR) and mean time to failure (MTTF) are two important attributes to describe the performance and operation life of an image intensifier. The presents of the ion barrier film (IBF) in Gen. III image intensifier, which used to suppress MCPs ion feedback, while dramatically improve the MTTF but significantly reduce the SNR, so more completely diminishing the ion poisoning source within the channels of MCP are crucial for improved Gen. III; image intensifier to thinned thickness IBF and achieving this two conflicting attributes promotion simultaneously. This research was originally initiated to develop a MCP with glass composition redesigned specially for GaAs photocathode image intensifier, proved which can be imposed an exceedingly intensive electron bombard degassing but without suffering a fatal gain degrade, and had achieved significantly improved SNR of Gen. III image intensifier but with a short distance to meet the lifetime success, so that our research work step forward to intent upon the restriction of ion poisoning source formation within the MCP substrate, we reformulated the MCP glass composition, and modified the microstructure of this MCP glass substrate though a glass-crystal phase transition during the MCP fabricate heating process, we present an innovative MCP based on a glass-ceramic substrate, with reformulated composition and close-linked network microstructure mix with many of nanometer size crystal grains, provide this MCP with sustainable high gain, lower ion feedback and less outgasing performance, this glass-ceramic MCPs are assembled to Gen. III image intensifiers which results showing promoting both the MTTF and SNR of Gen. III image intensifier.

Fabrication of a bulk conductive glass microchannel plate

Extension of Microchannel Plate (MCP) to a bulk conductive substrate was considered to be an effective approach to eliminate ion feedback problem, and a vanadium iron lead phosphate glass had been identified can be tailored to have appropriate volume conductivity and suitable for MCP fabrication. In this paper, a new reformulated vanadium iron lead alumina phosphate glass was used to fabricate a bulk conductive glass MCP, the fabrication process is in the same way as the conventional lead silicate glass MCP fabrication, but in the absence of a hydrogen firing treatment, although it was succeed in fabricating some experimental samples of 25mm diameter full active area MCP with 10μm pore diameter and 40:1~60:1 length to diameter ratio, the experimental sample also demonstrated its bulk conductivity and certain secondary electron emission property, but its gain is very low, especially its mechanical strength is insufficient. The physical and chemical properties of this vanadium iron lead alumina phosphate glass, and the performance and behavior of this glass during the bulk conductive glass MCP fabrication process, as well as its experimental sample test results were detail described.

Design and fabrication of a fiber optic image inverter based on a new high numerical aperture fiber optic glasses system

A fiber optic image inverter is a special type of fiber optic faceplate that rotate an image through a 180 degrees, and the development of fiber optic image inverter is used to concentrated on the heat twisting process experiment based on an existing glass system for production of fiber optic faceplate, but the conventional high expansion fiber optic faceplate billets are hardly capable of withstanding a fast heat twisting operation without the billets broken which occurred during the twisting operation, due to the thermal shock resistance property is defective in these conventional high expansion fiber optic faceplate, so a long time heat twist operation cycle was normally adopted in most high expansion fiber optic image inverter products manufacturers, caused a low yield efficiency and other shortages. In response, a program of design and fabrication of fiber optic image inverters which originally initiated to develop a new high expansion fiber optic glasses system with improved thermal shock resistance property, this program has yielded a new high numerical aperture fiber optic glasses system which is capable of experience a fast heat twist operation process, and has been demonstrated to produce a high numerical aperture fiber optic image inverter with a higher transmission property and improved contrast transfer characteristic. In this paper we review the fundamental and design principle, fabrication experiments process, and properties and performance of the fiber optic image inverters from a pilot run.

Extended dynamic range of ultra-high speed gated microchannel plate for x-ray framing camera

X-ray framing cameras (XFC) based on an ultra-high speed gated microchannel plate (MCP) as a routine diagnostic in laser-driven Inertial Confinement Fusion (ICF) experiment have deployed on domestic facility for several years, typically, these XFC devices used a normal MCP with 500μm thick and 12μm pore size, and achieved an optical temporal gate leas than 100 picoseconds, but which are vulnerable to suffer a time broadened temporal response when encounter heavy expose, due to the limited dynamic range of the normal MCP. We developed a 56mm format MCP with 250μm thickness and 6μm pore diameter, which objective is to promote the optical temporal gate and dynamic range for the upgrade XFC, this MCP is fabricated by a special designed low resistance glass, the reduced thickness, small pore size and increased gain linearity, offered which with ultra-fast temporal response and extended dynamic range characters. In this paper, we review the mechanisms that limiting the temporal response and gain linearity of this ultra-high speed gated MCP applied to XFC, and describe the design principle and development work of this ultra-fast temporal response, extended dynamic range and larger format MCP, this MCP will assemble to the upgrade XFC which is designed by CAEP and is currently in the final design stages.

Low noise and high resolution microchannel plate

To improve the Figure of Merit (FOM) and reduce the Equivalent Background Input (EBI) and Fixed-Pattern-Noise (FPN) in image intensifier, NVT (North Night Vision Technology Co., Ltd) has been researching and developing a low noise and high resolution Micro Channel Plate (MCP). The density of dark current of this new MCP is less than 0.5PA/cm2 (when MCP voltage at 1000V). The FPN and scintillation noise are reduced remarkably. Channel diameter is 6 &mgr;m and open area ratio is 60&percent;∼70&percent;. The vacuum bakeout temperature could be as high as 500°C. This new kind of MCP will be extensively used in the supper generation and the third generation image intensifiers.