Incom Inc. is developing and commercializing microchannel plate (MCP) electron multiplier devices made from leadfree glass capillary array (GCA) substrates that are functionalized using atomic layer deposition (ALD) thin film coating technology. Notable benefits over conventional lead-oxide based MCP technology are larger MCP size, high and stable gain, low dark counts and gamma-ray sensitivity, improved mechanical and thermal stability, and the unique ability to tune the MCP resistance and electron amplification characteristics over a much wider range and independently from the glass substrate. Incom now routinely produces ALD-GCA-MCPs with 10 and 20 m pore size at MCP dimensions up to 20 cm x 20 cm. ALD-GCA-MCPs are used for photon counting and charged particle detection in analytical instruments, high energy physics, nuclear physics, and space science applications. For future astronomical applications such as LUVOIR, HabEx, and CETUS, large-area, high-performance MCP electron amplifiers are paired with high-performance cross-strip readout systems and integrated into large format (≥ 50 mm sq.) photodetectors operating in the UV and optical regimes. Incom’s large area ALD-MCP-GCA technology is critical for realizing such large format photodetectors. In this paper, we provide a brief update on recent developments addressing the quality of the glass substrate as well as the thermal stability of the MCPs.

1131 Objectives: We are developing novel TOF-PET detector designs by adopting a Large Area Picosecond PhotoDetector (LAPPD), a photosensor technology originally designed for high energy and nuclear physics experiments. The goal is to achieve large detector area with high timing resolution but at low readout channel count, a potential diametric solution to the ongoing silicon photomultiplier based quest with one-one coupling detection scheme. In this work we have measured the fundamental response of a generation-1 (Gen-I) LAPPD device to pairs of coincident Single Photo-Electrons (SPE) using a femtosecond laser. The LAPPD device features a 20x20 cm2 detector area with 28 anode strips with 7 mm anode pitch and a total of 56 readout channels. METHODS: The LAPPD obtains 2D coordinates for each photoelectron in transaxial direction between the strips using charge division of collected multiplied charge clouds at the anode, and in axial direction along the strips using pulse time differences at the two strip ends. This spatial information that can be obtained for SPE (as well as multiple photoelectrons) with our measured LAPPD SPE time response and with independent LAPPD pulse shape and known amplitude distributions, enables accurate system response modeling for design iteration. We have illuminated a Gen-I LAPPD using 230-fs laser pulses at 514 nm and 96 kHz repetition rate. In the optical path between the laser output and LAPPD, we used Thorlabs NB1-K13 mirrors and dual wheel ND filter FW2AND to reduce laser power to single photon level to provide ~35% photoelectron detection efficiency per pulse. We used Thorlabs 50/50 CCM1-BS013 beam splitter to split the laser beam to two spots each 1mm Dia. (by using a 1 mm diameter precision optical pinhole Thorlabs P1000D sitting 2 cm above the LAPPD) illuminating a single LAPPD anode strip. The two spots were at 49 mm separation (7 strips apart) to eliminate potential charge sharing across the strips. In our measurements, we read out four signals, both ends of two anode strips with a 4GHz Tektronix MSO64 oscilloscope running at 25GS/s and 12-bit vertical resolution. We used the scope’s 2-Ch coincidence trigger function, with 5mV thresholds (from one end each of the two illuminated strips), to collect a digitized waveform record for each event. For each of the acquired 100k coincidence triggers, we recorded 1000 data points with 40 ps time binning. Photocathode voltage was set at 100V, while the voltage across both upstream and downstream MCPs in the Chevron pair was set to 900V. Results: Observed pulses were uniform in near-Gaussian shape, with ~1ns FWHM. The time difference jitter between pulses on the two strips was consistent with previously measured SPE time response widths times √2 as expected for two independent photons. SPE time response and widths reflect multiplied charge cloud transit time spread convolved with a uniform pulse shape collected at the stripline anodes, as we observed in previous measurements using the laser’s synced output to trigger the oscilloscope. With coincidence trigger, we measured a pulse arrival time distribution difference (using digital constant fraction discriminators) for coincident single photoelectrons with ~350ps FWHM. The distribution was principally Gaussian, with an expected tail from photoelectrons scattering off the entry MCP before entering a microchannel pore and being multiplied. The time width was nearly independent of LAPPD pulse amplitude for pulses above our fixed 5mV threshold. CONCLUSION: The LAPPD response function measured is specific to this generation of LAPPD, which has 20 microns MCP pores, and where MCP-PMT performance is known to be strongly dependent on pore size and other device design parameters. A 10-micron LAPPD is currently under development, with anticipated improvement of coincidence SPE which will potentially pave the way for large-area TOF-PET detector technology at very modest readout channel count.

We have measured the waveform digitized response of a Large Area Picosecond Photon Detector (LAPPD) optically coupled to a 3.0 x 5.4 x 30.0 mm3 BGO scintillator crystal (6-side polished, 5-side wrapped) placed between two LAPPD readout strip regions. We connected four LAPPD signals (two ends each for two anode strips) to a 4GHz Tektronix MS064 Real Time Oscilloscope running at 6.25GS/s and self-triggering. We captured 100000 triggers each with 6250 samples (1 microsecond interval) of waveform per dataset; datasets were obtained with optical grease coupling between the BGO crystal and the LAPPD. We processed these waveforms to produce single-photoelectron pulse lists, with each pulse having a 2D measured position of photoconversion in the LAPPD photocathode. While the LAPPD has sub-millimeter spatial resolution (especially between strips) for normally incident light, the optics of scintillation photon collection with its range of incident angles results in considerable spatial spreading of photons when being transmitted through a 5mm-thick LAPPD fused silica entrance window. Because many independent photon positions are detected, however, the event spatial resolution reduces in quadrature with collected pulses/event to provide a photopeak spatial resolution of <15mm) FWHM each photoelectron.

Incom Inc. is developing and commercializing a new type of microchannel plate (MCP) electron multiplier, as well as MCP-based photodetectors such as the Large-Area Picosecond Photodetector, LAPPD(TM), and the High-Resolution Picosecond Photodetector, HRPPD. This new class of MCPs is called “ALD-GCA-MCPs” because these are MCPs that are made from glass capillary arrays (GCA) – glass plates with a regular array of hollow glass capillaries – that are functionalized using atomic layer deposition (ALD) thin film coating technology. ALD-GCA-MCPs are a technology advancement that affords MCPs with significantly improved performance, as compared to conventional MCPs. We will provide a brief ALD-GCA-MCP technology overview highlighting the current state of the art of Incom’s ALD-GCA-MCP technology, as well as ongoing developments addressing the GCA glass substrate, the resistive and secondary-electron-emissive ALD coatings, and their implications for detectors used in astronomical applications.

ALD-GCA-MCPs are a technology advancement that affords microchannel plates (MCPs) with significant performance benefits compared to conventional MCP technology. Incom now routinely produces ALD-GCA-MCPs with dimensions up to 20 cm x 20 cm. Notable advancements and benefits over conventional lead-oxide based MCPs are larger size and higher mechanical stability, high and stable gain (>1e4for single MCP @ 1000 V, stable gain to ≥ 1 C/cm2 extracted charge), low dark counts (≤ 0.05 cts/sec/cm2), ~3x lower gamma-ray sensitivity, and the unique ability to individually customize and control the MCP resistance and secondary electron emission (SEE) amplification characteristics. ALD-GCA-MCPs find application in a variety of photon and charged particle counting applications and are particularly suited for applications that require fast timing, high spatial resolution, radiation hardness, and long detector life times, such as Ion-TOF, electron spectroscopies, and a variety of other analytical instruments. They can also be incorporated into low-power, low-background photodetectors suitable for applications in extreme environments such as remote sensing applications in rugged environments, in space flight instrumentation, as well as in high-energy physics and nuclear physics experiments. In this paper we will provide a brief ALD-GCA-MCP technology overview highlighting recent developments that focused on improving the glass capillary array (GCA) substrate, and their implications for large-area photodetectors and spectrometers used in nuclear and high energy physics, space science, and other sensing applications.

Incom Inc. is developing and commercializing a novel type of microchannel plate (MCP) electron multipliers. These new devices are called "ALD-GCA-MCPs" and are made from glass capillary arrays (GCA), glass plates with a regular array of hollow glass capillaries that are functionalized using atomic layer deposition (ALD) thin film coating technology. ALD-GCA-MCPs are a technology advancement that affords MCPs with significantly improved performance, as compared to conventional MCPs. Notable benefits over conventional lead-oxide based MCPs are larger size, high and stable gain, low dark counts and gamma-ray sensitivity, improved mechanical stability, and the unique ability to tune the MCP resistance and electron amplification characteristics over a much wider range and independent from the glass substrate. Incom now routinely produces ALD-GCA-MCPs with 10 and 20 mu m pore size at MCP dimensions up to 20 cm x 20 cm. The MCPs show a number of favorable characteristics, such as 3x lower gamma-ray sensitivity compared to conventional MPCs, low background (< 0.05 cts/s/cm(2)), and stable, high gains (>1x10(4) for single MCP and >1x10(7) for a chevron pair configuration, at 1000V/MCP). ALD-GCA-MCPs find use in a variety of photon counting applications and are particularly suited for charged particle detection that requires high timing and spatial resolution, such as Ion time-of-flight (TOF), electron spectroscopies, analytical and space instruments, and MCP-based photomultipliers such as the Large-Area Picosecond Photodetector (LAPPDTM), which is also being developed by Incom Inc. In this paper, we provide a brief technology overview highlighting the current state of the art of Incom's ALD-GCA-MCP technology, as well as current and future development efforts that address the GCA glass substrate as well as the resistive and electron emissive ALD coatings.

In proton therapy treatment, proton residual energy after transmission through the treatment target may be determined by measuring sub-relativistic transmitted proton time-of-flight velocity and hence the residual energy. We have begun developing this method by conducting proton beam tests using Large Area Picosecond Photon Detectors (LAPPDs) which we have been developing for High Energy and Nuclear Physics Applications. LAPPDs are 20cm x 20cm area Micro Channel Plate Photomultiplier Tubes (MCP-PMTs) with millimeter-scale spatial resolution, good quantum efficiency and outstanding timing resolution of ≤70 picoseconds rms for single photoelectrons. We have constructed a time-of-flight telescope using a pair of LAPPDs at 10 cm separation, and have carried out our first tests of this telescope at the Massachusetts General Hospital's Francis Burr Proton Therapy Center. Treatment protons are sub-relativistic, so precise timing resolution can be combined with paired imaging detectors in a compact configuration while still yielding high accuracy in proton residual energy measurements through proton velocity determination from nearly monoenergetic protons. This can be done either for proton bunches or for individual protons. Tests were performed both in "ionization mode" using only the Microchannel Plates to detect the proton bunch structure and also in "photodetection mode" using nanosecond-decay-time quenched plastic scintillators to excite the photocathode within each of the paired LAPPDs. Data acquisition was performed using a remotely operated oscilloscope in our first beam test, and using 5Gsps DRS4 Evaluation Board waveform digitizers in our second test, in each case reading out both ends of single microstrips from among the 30 within an LAPPD. First results for this method and future plans are presented.

We report performance results achieved for fully functional sealed Large Area Picosecond Photodetectors (LAPPD (TM)) in tests performed at Incom Inc., as well as independent test results reported by our early adopters. The LAPPD is a microchannel plate (MCP) based large area picosecond photodetector, capable of imaging with single-photon sensitivity at high spatial and temporal resolutions in a hermetic package. The LAPPD has an active area of 350 square centimeters in an all-glass hermetic package with a fused silica window and bottom plate and sidewalls made of borosilicate float glass. Signals are generated by a bi-alkali Na2KSb photocathode and amplified with a stacked chevron pair of MCPs produced by applying resistive and emissive atomic layer deposition coatings to glass capillary array (GCA) substrates. Signals are collected on RF stripline anodes applied to the bottom plates which exit the detector via pin-free hermetic seals under the side walls. LAPPD test and performance results for product produced and delivered to early adopter customers during the first half of 2018 are reviewed. These results include electron gains >= 7.5 x 10(6) @ 850/950 V (entry/exit MCP), low dark noise rates (22 Cts/s/cm(2)), single photoelectron (PE) timing resolution of 64 picoseconds RMS, and single photoelectron spatial resolution along and across strips of 2.8 mm and 1.3 mm RMS respectively. Many of these devices also had very high QE photocathodes that were uniform over the full 195 mm x 195 mm window active area (LAPPD #15 QE% @ 365 nm Max/Avg/Min = 25.8/22.3 +/- 3/15.7). An update is also provided of developments that enable capacitive signal coupling from the detector to application specific pads or stripline readout patterns deployed on printed circuit boards positioned beneath the file, outside of the vacuum package. We conclude with examples of how sensors offering picosecond timing, in diverse applications can bring transformative change to detector technology and applications in future experiments.

Incom, Inc. is now producing commercially available Large Area Picosecond Photo-Detectors (LAPPDT) usable in applications by early adopters. The first generation LAPPD (TM) is an all-glass 230 x 220 x 22 mm(3) flat panel photodetector with a chevron stack of glass capillary array microchannel plates functionalized by atomic layer deposition, a semitransparent bi-alkali photocathode, and a strip-line anode. The photodetector is being optimized for applications requiring picosecond timing and millimeter spatial resolution and has achieved single photoelectron (PE) timing resolutions of sigma <= 52 ps. Typical performance metrics include electron gains of 10(7) at 1 kV per MCP, low dark noise rates (15-30 Hz/cm(2) at moderate gains), single PE spatial response along and across strips of 1.8 mm and 0.76 mm respectively and quantum efficiencies that are typically >= 20% at 365 nm. Changes to the "baseline" LAPPD (TM) are under development to optimize the photodetector for applications requiring very high spatial resolutions.

The Large Area Picosecond PhotoDetector (LAPPD) is a 200 mm square microchannel plate photomultiplier (MCP-PMT). It is a large area, position-sensitive, high speed, high gain device. It is suitable for detection of light such as Cherenkov or scintillation light. The large area is well-matched to large detection volumes, or imaging applications where tiling of small detectors is undesirable because of cost or lost sensitive area. Time resolution has been measured as a function of both MCP and photocathode voltage. A rapid improvement was observed as the photocathode voltage was raised to 50 volts. At higher voltages, the time resolution continued to improve, but at a diminishing rate. A similar improvement occurred with an increase in MCP voltage, up to a point beyond which there was no further benefit. This point corresponded to a gain of 3.2x106. Gain has been measured as a function of light pulse repetition rate. As the laser trigger rate was increased, the LAPPD gain fell to approximately half of the initial value at repetition rates of 12 to 38 kHz/mm2. These gain measurements were made in the mid 106 gain range. Gain recovery time has also been measured. The LAPPD was triggered with a laser repeatedly at a high rate, then allowed to recover before the next laser pulse. The gain recovered to its initial value with a 15 mS recovery time, and half the initial value with a 5 mS recovery time.

Incom is reporting on success in its DOE SBIR Phase I feasibility demonstration of our ability to optimize and characterize the magnetic field insensitivity of Large Area Picosecond Photon Detectors (LAPPDs) which we manufacture, this was accomplished principally by decreasing MCP pore sizes. LAPPDs are cost-effective ultra-high time precision imaging quantum photodetectors that incorporate Incom’s unique large-area ALD- (Atomic Layer Deposition) GCA- (Glass Capillary Array) MCPs (Microchannel Plates). Several applications of LAPPDs, including for potential upgrades to existing DoE NP detectors or as part of proposed designs for future DoE NP experiments (including at the future EIC Electron Ion Collider) will require LAPPD operation in strong magnetic fields. We are improving and verifying the performance of LAPPDs in strong magnetic fields both by modifying their internal construction and most importantly by modifying their constituents by using smaller-pore MCPs; we and others have shown that this improves magnetic field insensitivity in MCP-PMTs like our LAPPD. We have begun a series of magnetic field tests at Argonne National Laboratory on 6 x 6cm MCP-PMTs constructed at ANL using Incom MCPs, and on 20 x 20cm LAPPDs constructed at Incom again using Incom MCPs, each in a series of devices containing MCPs of ever smaller pore diameters, from 20μ to 10μ to 5μ; in addition to improving magnetic field insensitivity, smaller pores will improve LAPPD timing and thus benefit physics performance in future DoE NP detectors, including at the EIC.

Recent performance results are presented for Large Area Picosecond Photodetectors (LAPPDTMs) being developed by Incom, Inc. The LAPPD is a micro-channel plate (MCP) based photodetector containing a bi-alkali photocathode with overall dimensions of 230 × 220 × 21 mm3, an active area of up to 400 cm2, spatial resolution ~1 mm, and timing resolutions of ~50 ps for single photoelectrons and <20 ps for multiple photoelectrons. Performance will be discussed for sealed LAPPDs with gains ~2 × 106, photocathode quantum efficiency of 30% and detector dark noise rates of ~1 ct/s/cm2. The key component of the LAPPD is the 203 × 203 mm2 large area MCP manufactured by Incom. Results will also be discussed for 203 × 203 mm2 MCPs coated with MgO emissive layers with gains >2 × 107.

The LAPPD is a 400 cm^2 microchannel plate photomultiplier with a timing resolution better than 100 pS. It has sensitivity to single photoelectrons with a gain of ~7E6. It incorporates a bi-alkali Na2KSb photocathode, with a peak sensitivity near 360 nm. Photocathodes with quantum efficiencies as high as 30% have been fabricated. The anode has a parallel stripline configuration, with a position resolution of ~4mm or better. The large area makes the LAPPD suitable for viewing large area scintillator radiation detectors. The high speed response makes it useful for applications such as neutron detectors (i.e. Weinfurther et al., 2018), or Cerenkov light detectors for high energy physics applications. Two LAPPDs were recently used as a telescope in a 150 MeV cancer therapy proton beam, in a project designed to verify beam targeting. LAPPDs are manufactured with a borosilicate glass envelope, and a fused silica window. The microchannel plates are fabricated using a glass substrate, with 20 micron pores. Thin films are applied to the substrate with the Atomic Layer Deposition technique. These films impart the resistive and emissive qualities needed for charge multiplication within the microchannels. Recently, improvements in the deposition method for an MgO secondary electron emission film have provided a breakthrough in gain, as the MgO retains a high gain throughout the manufacturing process of the LAPPD. Recent measurements of gain, timing, position and quantum efficiency will be shown, and applications discussed.

We report and review performance test results achieved for recently produced fully functional sealed Large Area Picosecond Photodetectors (LAPPD ™ ) in tests performed at Incom Inc., as well as independent test results reported by our early adopters. LAPPD #41 represents the first example of a new version incorporating a ceramic rather than all glass body, a fused silica window, and design enhancements intended to minimize dark counts including instrument related noise rates. Results for this prototype include electron gains at the recommended operating point of 5.4 x 10 6 @975 V/MCP and 300 V between the photocathode and top of the top MCP, low dark count rates of 6.6 Cts/s cm 2 @30 V on the PC and 950V/ MCP. The transit time variation, at the recommended operating point was 56ps. Sensors offering picosecond timing, can bring transformative change to detector technology and applications in future experiments.

The large-area picosecond photodetector (LAPPD TM ) is an ultrafast imaging detector with single-photon sensitivity. The time resolution approaches the coherence time of light filtered with dielectric-layer interference filters, and so, the detector can resolve photon occupations in each longitudinal mode of light. Furthermore, if used with diffraction-limited optics matched to the spatial resolution, the detector can also resolve about 400 by 400 transverse modes. LAPPD TM is thus an enabling technology for quantum optics where photon occupation numbers in each electromagnetic-field mode in 6-dimensional phase space are relevant, for example photon- correlation experiments (Hanbury Brown - Twiss, or ghost imaging).

Microchannel plates have been made by combining glass capillary substrates with thin films. The films impart the resistance and secondary electron emission (SEE) properties of the MCP. This approach permits separate choices for the type of glass, the MCP resistance and the SEE material. For example, the glass may be chosen to provide mechanical strength, a high open area ratio, or a low potassium-40 concentration to minimize dark rates. The resistive film composition may be tuned to provide the desired resistance, depending on the power budget and anticipated count rate. Finally, the SEE material may be chosen by balancing requirements for gain, long term stability of gain with extracted charge, and tolerance to air exposure. Microchannel plates have been fabricated by Incom Inc., in collaboration with Argonne National Laboratory and UC Berkeley. Glass substrates with microchannel diameters of 10 and 20 microns have been used, typically with a length to diameter ratio of 60:1. Thin films for resistance and SEE are applied using Atomic Layer Deposition (ALD). The ALD technique provides a film with uniform thickness throughout the high aspect ratio microchannels. MCPs have been made in sizes up to 8”x8”. This three-component method for manufacturing MCPs also makes non-planar, curved MCPs possible. Life testing results will be presented for 10 and 20 micron, 60:1 l/d ratio MCPs, with an aluminum oxide SEE film and two types of glass substrates. Results will include measurements of resistance, dark count rates, gain, and pulse height distributions as a function of extracted charge.

applicability of precision machining technology to the manufacture of the AXAF objective mirrors; review of the proposed and alternative methods for manufacturing and testing: (1) the AXAF technology mirrors and (2) the AXAF high resolution mirror assembly; analysis, review and engineering support to NASA in the areas of surface shape and smoothness metrology for grazing incidence x-ray surfaces; determination, through analytical and experimental efforts, of the feasibility of applying heterodyne surface profilometry to non-flat surfaces; and three sets of scattering flats with known surface profiles and microtopographic character produced by precision machining and polished precision machine surfaces.

Atomic layer deposition (ALD) has enabled the development of a new technology for fabricating microchannel plates (MCPs) with improved performance that offer transformative benefits to a wide variety of applications. Incom uses a “hollow-core” process for fabricating glass capillary array (GCA) plates consisting of millions of micrometer-sized glass microchannels fused together in a regular pattern. The resistive and secondary electron emissive (SEE) functions necessary for electron amplification are applied to the GCA microchannels by ALD, which – in contrast to conventional MCP manufacturing– enables independent tuning of both resistance and SEE to maximize and customize MCP performance. Incom is currently developing MCPs that operate at cryogenic temperatures and across wide temperature ranges. The resistive layers in both, conventional and ALD-MCPs, exhibit semiconductor-like behavior and therefore a negative thermal coefficient of resistance (TCR): when the MCP is cooled, the resistance increases, and when heated, the resistance drops. Consequently, the resistance of each MCP must be tailored for the intended operating temperature. This sensitivity to temperature changes presents a challenge for many terrestrial and space based applications. The resistivity of the ALD-nanocomposite material can be tuned over a wide range. The material’s (thermo-) electrical properties depend on film thickness, composition, nanostructure, and the chemical nature of the dielectric and metal components. We show how the structure-property relationships developed in this work can be used to design MCPs that operate reliably at cryogenic temperatures. We also present data on how the resistive material’s TCR characteristics can be improved to enable MCPs operating across wider temperature ranges than currently possible.

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.

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.