Bernhard W. Adams

The Accelerator Neutrino Neutron Interaction Experiment (ANNIE) is both a physics experiment and a technology testbed for next-generation light-based neutrino detection. In this paper, we report the first demonstration of a fully integrated Large Area Picosecond Photodetector (LAPPD) operating in a running neutrino beam experiment. Particular focus is given to the design, commissioning, and successful deployment of the Packaged ANNIE LAPPD (PAL), a waterproof, self-triggering module incorporating fast waveform digitization and precision timing synchronized to the ANNIE detector subsystems. We identify beam-correlated LAPPD data frames consistent with charged-current neutrino interactions observed in multiple detector subsystems, establishing the first detection of neutrino-induced Cherenkov light with an LAPPD. These results validate the system-level performance of LAPPDs under realistic experimental conditions — including long-term stability, timing synchronization, and event matching with conventional PMT and muon detector systems — marking a critical step toward their deployment in future large-scale neutrino and particle detectors.

Concentrating solar power (CSP) facilities need to ensure alignment of all sun-tracking heliostats onto the sunlight receiver. A method is proposed to keep all heliostats in a CSP facility under closed-loop pointing control while also providing feedback on the detailed alignment of the segment mirrors of each heliostat. The method is based on the sunlight directed toward the receiver, and thus works under full operational conditions and without the need of secondary optical alignments. It is based on retroreflectors (“retros”) to simultaneously return samples of the sunlight reflected by each mirror back to that same mirror. It goes beyond previous efforts at using retros by placing them into the concentrated sunlight, instead of in its periphery. Quartz glass will be used for its heat tolerance, and reflectivity modulation for visibility is achieved by rotating the retros. The technology can be retrofitted into existing CSP facilities to improve operational efficiency, and it can be used to relax the stability requirements of heliostats, and thus their cost, in the planning of new ones.

We have designed and prototyped the process steps for the batch production of large-area micro-channel-plate photomultipliers (MCP-PMT) using the “air-transfer” assembly process developed with single LAPPD^TM modules. Results are presented addressing the challenges of designing a robust package that can transmit large numbers of electrical signals for pad or strip readout from inside the vacuum tube and of hermetically sealing the large-perimeter window–body interface. We have also synthesized a photocathode in a large-area low-aspect-ratio volume and have shown that the micro-channel plates recover their functionality after cathode synthesis. These steps inform a design for a multi-module batch facility employing dual nested low-vacuum and ultra-high-vacuum systems in a small-footprint. The facility design provides full access to multiple MCP-PMT modules prior to hermetic pinch-off for leak-checking and real-time photocathode optimization.

Incom, Inc. is now producing commercially available Large Area Picosecond Photo-Detectors (LAPPD™) usable in applications by early adopters. The first generation LAPPD™ is an all-glass 230 x 220 x 22 mm³ 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 α≤52 ps. Typical performance metrics include electron gains of 10⁷ at 1 kV per MCP, low dark noise rates (15-30 Hz/cm² 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™ are under development to optimize the photodetector for applications requiring very high spatial resolutions.

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 μm 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/cm²), and stable, high gains (4 for single MCP and 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 (LAPPD^TM), 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.