The increasing availability of small satellites such as CubeSats have improved low cost access to space. New scientific measurements may be made, and new concepts may be tested for larger scale missions in the future. Particle detection instruments in conventional size spacecraft have to meet significant constraints on mass, power and volume. These constraints are more substantial in the CubeSat platform. Microchannel plate (MCP) electron multipliers are frequently used in particle detection instruments because of their high gain, low mass, and thin planar configuration. However, non-planar MCPs can be used to improve instrument performance and make better use of available volume by adopting a shape that is compatible with the natural instrument geometry. Non-planar MCPs have been made in this work using a novel method, in which a glass microchannel substrate is coated with thin films that provide the necessary resistive and secondary electron emissive properties. The glass substrates were first slumped at a high temperature to a mandrel of the desired shape, after which the thin films were applied. The MCPs were cylindrically curved, with radii of curvature of 75 mm and 20 mm, and with angular spans of 90 degrees and 180 degrees respectively. The azimuthal gain and resistance uniformity was measured and will be presented.
Bundles of hollow glass capillaries can be tapered to produce quasi-focusing x-ray optics. These optics are known
as Kumakhov lenses. These optics are interesting for lab-based sources because they can be used to collimate
and concentrate x-rays originating from a point, such as a laser focus or an electron-beam focus in a microtube.
We report pilot production and advanced development performance results achieved for Large Area Picosecond
Photodetectors (LAPPD). The LAPPD is a microchannel plate (MCP) based photodetector, capable of imaging with
single-photon sensitivity at high spatial and temporal resolutions in a hermetic package with an active area of 400 square
centimeters. In December 2015, Incom Inc. completed installation of equipment and facilities for demonstration of
early stage pilot production of LAPPD. Initial fabrication trials commenced in January 2016. The “baseline” LAPPD
employs an all-glass hermetic package with top and bottom plates and sidewalls made of borosilicate float glass. Signals
are generated by a bi-alkali Na2KSb photocathode and amplified with a stacked chevron pair of “next generation” MCPs
produced by applying resistive and emissive atomic layer deposition coatings to borosilicate glass capillary array (GCA)
substrates. Signals are collected on RF strip-line anodes applied to the bottom plates which exit the detector via pinfree
hermetic seals under the side walls. Prior tests show that LAPPDs have electron gains greater than 107, submillimeter
space resolution for large pulses and several mm for single photons, time resolutions of 50 picoseconds for
single photons, predicted resolution of less than 5 picoseconds for large pulses, high stability versus charge extraction,
and good uniformity. LAPPD performance results for product produced during the first half of 2016 will be reviewed.
Recent advances in the development of LAPPD will also be reviewed, as the baseline design is adapted to meet the
requirements for a wide range of emerging application. These include a novel ceramic package design, ALD coated
MCPs optimized to have a low temperature coefficient of resistance (TCR) and further advances to adapt the LAPPD
for cryogenic applications using Liquid Argon (LAr). These developments will meet the needs for DOE-supported RD
for the Deep Underground Neutrino Experiment (DUNE), nuclear physics applications such as EIC, medical, homeland
security and astronomical applications for direct and indirect photon detection.
We report a cost-effective and production achievable path to fabricate robust large-area microchannel plates
(MCPs), which offers the new prospect for larger area MCP-based detector technologies. We used atomic Layer
Deposition (ALD), a thin film growth technique, to independently adjust the desired electrical resistance and secondary
electron emission (SEE) properties of low cost borosilicate glass micro-capillary arrays (MCAs). These capabilities
allow a separation of the substrate material properties from the signal amplification properties. This methodology enables
the functionalization of microporous, highly insulating MCA substrates to produce sturdy, large format MCPs with
unique properties such as high gain (<107/MCP pair), low background noise, ~10ps time resolution, sub-micron spatial
resolution and excellent stability after only a short (2-3days) scrubbing time.
The ALD self-limiting growth mechanism allows atomic level control over the thickness and composition of
resistive and secondary electron emission (SEE) layers that can be deposited conformally on high aspect ratio (~100)
capillary glass arrays. We have developed several robust and consistent production doable ALD processes for the
resistive coatings and SEE layers to give us precise control over the MCP parameters. Further, the adjustment of MCPs
resistance by tailoring the ALD material composition permits the use of these MCPs at high or low temperature detector
applications. Here we discuss ALD method for MCP functionalization and a variety of MCP testing results.
Very large (20 cm × 20 cm) flat panel phototubes are being developed which employ novel microchannel plates (MCPs). The MCPs are manufactured using borosilicate microcapillary arrays which are functionalized by the application of resistive and secondary emissive layers using atomic layer deposition (ALD). This allows the operational parameters to be set by tailoring sequential ALD deposition processes. The borosilicate substrates are robust, including the ability to be produced in large formats (20 cm square). ALD MCPs have performance characteristics (gain, pulse amplitude distributions, and imaging) that are equivalent or better than conventional MCPs. They have low intrinsic background (0.045 events cm-2 sec-1)., high open area ratios (74% for the latest generation of borosilicate substrates), and stable gain during >7 C cm-2 charge extraction after preconditioning (vacuum bake and burn-in). The tube assemblies use a pair of 20 cm × 20 cm ALD MCPs comprised of a borosilicate entrance window, a proximity focused bialkali photocathode, and a strip-line readout anode. The second generation design employs an all glass body with a hot indium seal and a transfer photocathode. We have achieved >20% quantum efficiency and good gain uniformity over the 400 cm2 field of view, spatial resolution of <1 cm and obtained event timing accuracy of close to 100 ps FWHM.
A new spectrometer design that will result in a highly efficient, easy to handle, low-cost, high-resolution spectroscopy system with excellent background suppression is being developed for the NSLS-II Inner-Shell Spectroscopy beamline. This system utilizes non-diffractive optics comprised of fused and directed glass capillary tubes that will be used to collect and pre-collimate fluorescence photons. There are several advantages enabled by this design; a large energy range is accessible without modifying the s-stem, a large collection angle is achieved per detection unit: 4-5% of the full solid angle, easy integration in complex and harsh environments is enabled due to the use of a pre-collimation system as a secondary source for the spectrometer, and background from a complex sample environment can be easily and efficiently suppressed.
The polycapillary X-ray focusing optics segment of this application has been under development. This includes improvement in manufacturing methods of polycapillary structure for x-ray optics, forming the polycapillary structure to produce X-ray optics to achieve the required solid angle collection and transmission efficiency, and measurement of X-ray focusing properties of the optics using an X-ray source. Two promising advances are large open area ratios of 80% or more, and the possibility of adding coatings in the capillaries using Atomic Layer Deposition techniques to improve reflection efficiency.
Borosilicate microcapillary arrays have been functionalized by Atomic Layer Deposition (ALD) of resistive and secondary emissive layers to produce robust microchannel plates (MCPs) with improved performance characteristics over traditional MCPs. These techniques produce MCP’s with enhanced stability and lifetime, low background rates, and low levels of adsorbed gas. Using ALD to functionalize the substrate decouples the two and provides the opportunity to explore many new materials. The borosilicate substrates have many advantages over traditional lead glass MCPs, including the ability to be fabricated in large areas (currently at 400 cm2).
Microchannel plates that have been constructed by atomic layer deposition of resistive and
secondary emissive layers, onto borosilicate glass microcapillary arrays provide a novel alternative
to conventional microchannel plates for detection of radiation and particles. Conventional
microchannel plates can also benefit from atomic layer deposition of highly efficient secondary
emissive layers. Our evaluations of these techniques have revealed unique features of atomic layer
functionalized microchannel plates, including enhanced stability and lifetime, low background rates,
and low levels of adsorbed gas. In addition borosilicate glass microcapillary arrays show enhanced
physical and thermal robustness, which makes it possible to successfully fabricate large area devices
(20 cm) with good uniformity of operational characteristics.
A new method of fabricating microchannel plates has been investigated, employing
microcapillary arrays of borosilicate glass that are deposited with resistive and secondary emissive
layers using atomic layer deposition. Microchannel plates of this kind have been made in sizes from
33 mm to 200 mm, with pore sizes of 40 μm and 20 μm, pore length to diameter ratios of 60:1, bias
angles of 8°, and open areas from 60% to 83%. Tests with single MCPs and MCP pairs have been
done and show good imaging quality, gain comparable to conventional MCPs, low background rates
(~ 0.085 events sec-1 cm-2), fast pulse response, and good ageing characteristics. The quantum
efficiency for bare and alkali halide coated MCPs is similar to conventional MCPs, and we have
also been able to deposit opaque GaN(Mg) cathodes directly onto these MCPs.
We demonstrate a cost-effective and robust route to fabricate large-area microchannel plate (MCP) detectors, which
will open new potential in larger area MCP-based detector technologies. For the first time, using our newly
developed process flow we have fabricated large area (8"x8") MCPs. We used atomic layer deposition (ALD), a
powerful thin film deposition technique, to tailor the electrical resistance and secondary electron emission (SEE)
properties of large area, low cost, borosilicate glass capillary arrays. The self limiting growth mechanism in ALD
allows atomic level control over the thickness and composition of resistive and SEES layers that can be deposited
conformally on high aspect ratio capillary glass arrays. We have developed several robust and reliable ALD
processes for the resistive coatings and SEE layers to give us precise control over the resistance (106-1010Ω) and
SEE coefficient (up to 5). This novel approach allows the functionalization of microporous, insulating substrates to
produce MCPs with high gain and low noise. These capabilities allow a separation of the substrate material
properties from the amplification properties. Here we describe a complete process flow to produce large area MCPs.
Utilizing nanotechnology, proprietary chemistry, and microfluidics, innovative firms are developing biochips and instrument systems that enable high-speed automated biomedical sequencing. Incom Inc. presents development results on five novel biochip technologies based on FiberOptic MicroSlide and microcapillary technology. FiberOptic MicroSlides are fiber optic interrogated (FOI) biochips made up of millions of fused optical fibers, and are uniquely suited as a platform for microarray applications. FiberOptic MicroSlides (henceforth referred to as "MicroSlides" or "slides" in this paper) act as a 'zero thickness substrate' transmitting optical signals from top to bottom without spreading, so that fluorescent or luminescent activity on the surface or within a well can be directly coupled to a CCD device without additional optics. In contrast to bulk optics, the slides are compact and have excellent light-gathering power. They are an alternative to conventional microscope slides for applications involving moderate-resolution bottom viewing (inverted microscopy). The surface of the MicroSlides can be etched or patterned with a permanent polymer to form microwell arrays, or microfluidic structures suitable for genomic and proteomic analysis, cell migration studies and other applications. Low-cost microcapillary array plates have also been developed. These plates act as microscopic test tubes, which enable picoliter reactions to be detected, counted and analyzed. Progress in developing large area (300 mm X 300 mm) arrays with up to 100 million capillaries, and diameter / length aspect ratios up to 10,000: 1 is presented. Results demonstrate negligible optical cross talk between capillaries, resulting in improved signal-to-noise ratios while minimizing false hits.