An integrated atomic layer deposition synthesis-catalysis (I-ALD-CAT) tool was developed. It combines an ALD manifold in-line with a plug-flow reactor system for the synthesis of supported catalytic materials by ALD and immediate evaluation of catalyst reactivity using gas-phase probe reactions. The I-ALD-CAT delivery system consists of 12 different metal ALD precursor channels, 4 oxidizing or reducing agents, and 4 catalytic reaction feeds to either of the two plug-flow reactors. The system can employ reactor pressures and temperatures in the range of 10(-3) to 1 bar and 300-1000 K, respectively. The instrument is also equipped with a gas chromatograph and a mass spectrometer unit for the detection and quantification of volatile species from ALD and catalytic reactions. In this report, we demonstrate the use of the I-ALD-CAT tool for the synthesis of platinum active sites and Al2O3 overcoats, and evaluation of catalyst propylene hydrogenation activity.

SynopsisThe high electrical resistance of a microchannel plate at cryogenic temperatures presents a severe limitation on the detection count rate at low temperatures. We are currently investigating the detector properties of a novel atomic layer deposition activated MCP developed by Gorelikov et al [1]. This is of particular interest to us as MCPs are used for particle detection at the cryogenic DESIREE facility at Stockholm University.

Atomic layer deposition (ALD) technology is used to nanoengineer functional films inside the pores of microchannel plate (MCP) electron multipliers, enabling a novel MCP manufacturing technology that substantially improves performance and opens novel applications. The authors have developed custom tools and recipes for the growth of conformal films, with optimized conductance and secondary electron emission inside very long channels (∼6–20 μm diameter and >600 μm length, with tens of millions of channels per single MCP) by ALD. The unique ability to tune the characteristics of these ALD films enables their optimization to applications where time-resolved single particle imaging can be performed in extreme conditions, such as high counting rates at cryogenic temperatures. Adhesion of the conductive and emissive nanofilms to the 20 μm pore MCP glass substrates and their mechanical stability over a very wide range of temperatures (10–700 K) were confirmed experimentally. Resistance of ALD MCPs was reproducible during multiple cool-down cycles with no film degradation observed. Optimizing resistance of novel MCPs for operation at cryogenic temperature should enable high count rate event detection at temperatures below 20 K.

The performance of novel plastic Microchannel plates (MCPs) with nano-engineered conduction and emission films have been shown to match the performance of conventional glass MCPs, widely used in image intensifying and event counting devices. In this paper we investigate the timing resolution of event detection with a 5 mm-thick polymethyl methacrylate (PMMA) microchannel plate with 50 μm circular pores hexagonally packed at 70 μm center-to-center spacing, which was developed for fast neutron detection. A detector consisting of the PMMA plastic MCP followed by a chevron stack of conventional glass MCPs for event multiplication was used in the timing experiments. The resolution of event counting was measured with Co-60 (1.17, 1.33 MeV γ) source. The timing accuracy was derived from the time difference of event detection with plastic MCP and a detector with liquid scintillator (BC519) coupled to a photomultiplier tube . The measured ∼4 ns FWHM timing accuracy of gamma photon counting agrees well with the results of our predictions performed with the help of a fully 3-dimensonal model of the MCP amplification process. The same model and measurements of photon detection with conventional glass MCPs indicate that substantially better (sub-ns) accuracy can be achieved with smaller pores. Although we could not directly measure the timing accuracy of fast neutron detection with our plastic MCP due to the time of flight limitation of non-monoenergetic source the fast neutron timing resolution should be on the same scale due to the similarity of amplification process once the secondary electrons are produced within a pore.

Since their invention decades ago, microchannel plate (MCP) performance has been defined by the properties of the substrate material, which defines both mechanical structure and electron amplification within the device. Specific glass compositions have been developed to provide the conduction and electron emission layer at the surface of the pores. Alternative technologies using quartz and alumina substrates have not matured enough to become a viable substitute to lead–glass-based MCPs. In this paper we report on the development of new MCP devices from plastic substrates. The plastic substrate serves only as a mechanical structure: the electron amplification properties are provided by nano-engineered conduction and emission layers. The film deposition procedures were optimized for low temperatures compatible with the polymethyl methacrylate (PMMA) plastic chosen for this work. The gain of the PMMA MCP with aspect ratio of ∼27:1 and pore diameter ∼50 μm spaced on 70 μm hexagonal grid exceeded 200 at 470 V accelerating bias. Development of hydrogen-rich plastic MCPs should enable direct detection of fast neutrons through proton recoil reaction. Recoil protons with escape ranges comparable to the wall thickness will initiate an electron avalanche upon collision with the pore walls. The electron signal is then amplified within the MCP pore allowing high spatial and temporal resolution for each detected fast neutron. We expect to achieve ∼1% detection efficiency for 1–15 MeV neutrons with temporal resolution <10 ns, spatial resolution of <200 μm and very low background noise.

We present a preliminary design and the results of simulation for a photo-detector module to be used in applications requiring the coverage of areas of many square meters with time resolutions less than 10 picoseconds and position resolutions of less than a millimeter for charged particles. The source of light is Cherenkov light in a radiator/window; the amplification is provided by panels of micro-pores functionalized to act as microchannel plates (MCPs). The good time and position resolution stems from the use of an array of parallel 50 Omega transmission lines (strips) as the collecting anodes. The anode strips feed multi-GS/sec sampling chips which digitize the pulse waveform at each end of the strip, allowing a measurement of the time from the average of the two ends, and a 2-dimensional position measurement from the difference of times on a strip, and, in the orthogonal direction, the strip number, or a centroid of the charges deposited on adjacent strips. The module design is constructed so that large areas can be `tiled' by an array of modules.

Results from a fully independent thin film process for manufacturing non-lead glass Microchannel plate (MCP) detectors using nano-engineered thin films for both the resistive and emissive layers are presented. These novel MCP devices show high gain, less gain degradation with extracted charge, and greater pore to pore and plate to plate uniformity than has been possible with conventional lead glass structures. Extension of MCP to plastic substrates, for the purpose of fast neutron detection is disclosed and preliminary MCP functionality results are presented. Simulation results, predicting fast neutron detection performance for the plastic MCP device are presented and discussed

Highly localized and very fast electron amplification of microchannel plates (MCPs) enables a large number of high-resolution and high-sensitivity detection technologies, which provide spatial and/or temporal information for each detected photon/electron/ion/neutron. Although there has been significant progress in photocathode and readout technologies the MCPs themselves have not evolved much from the technology developed several decades ago. Substantial increases in the gain of existing MCP technology have been accomplished by utilizing state-of-the-art processes developed for nano-engineered structures. The gain of treated MCPs with aspect ratio of 40:1 is reproducibly measured to reach unprecedented values of 2×10 5. This gain enhancement is shown to be stable during MCP operation. In addition, the initial experiments indicate improved stability of gain as a function of extracted charge and MCP storage conditions. We also present results from a fully independent thin-film process for manufacturing non-lead glass MCPs using engineered thin films for both the resistive and emissive layers. These substrate-independent MCPs show high gain, less gain degradation with extracted charge, and greater pore-to-pore and plate-to-plate uniformity than has been possible with conventional lead glass structures.

A novel approach for high-throughput maskless lithography is being developed by Arradiance Inc. The patented core technology is based on the combination of field emitters and microchannel electron amplifiers (MCAs) to produce a large array of individually controlled, high brightness electron beams. Brightness, stability, beam to beam uniformity, energy spread, achievable current, and many other parameters must be optimized simultaneously over a large field. Many of these parameters are determined by the characteristics of the amplification process in the MCA array that amplifies, stabilizes and shapes each electron beam. This paper describes a new three dimensional Monte Carlo model of the electron amplification process in a single microchannel. For a given input current and known MCA parameters, we calculate the (generally nonlinear) potential distribution along the channel utilizing a macroscopic saturation model. The static (3D with axial symmetry) electric field is calculated in and around the microchannel from the predicted potential distribution. That field is used to calculate individual electron trajectories along the pore length until their subsequent collision with the pore walls or arrival at the pore exit. The amplification process caused by secondary electron emission from those collisions is modelled for each electron. Evaluation of a large number of input electrons allows the MCA output to be predicted. The model is very useful for optimization of the MCA structure and operational

Development of reliable field emission devices requires detailed characterization of variability over the device lifetime. Silicon tip manufacturing processes and test equipment limitations are theoretically predicted to cause ∼5% variability in field emission currents. Long-duration emission current measurements at both constant voltage and constant current, controlled with a software feedback loop, were made. Power spectra from the two operational modes were significantly different. The software feedback loop response was determined; it is expected to contribute ∼1% of the standard deviation in emission current when used to control emission by modulating the gate voltage. Convolution of constant voltage time series with the software feedback loop response reproduced the spectral characteristics of constant current time series, indicating that many of the differences between the two operating modes were caused by the operating mode itself rather than the field emitters tested. This has implications for the operating mode of the application for which the device is intended.