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Adams, Bernhard W.

Publications and source records attributed to Adams, Bernhard W..

12 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Dual low vacuum-ultrahigh vacuum system for large-scale production of micro-channel plate photomultipliers

Systems and methods for the batch production of large numbers of highly uniform multichannel-plate photomultiplier tubes (MCP-PMTs) for large-scale applications are provided. The systems and methods employ dual, nested low-vacuum (LV) and UHV processing in a rapid-cycling, small-footprint, scalable, batch-production facility that is capable of fabricating many MCP-PMTs simultaneously.

Frisch, Henry J.↗
DOE OSTI2021

X-ray Transient Absorption Studies of Exciton Self-Trapping

Here, we present optical pump/X-ray absorption probe studies to probe changes in electronic distribution and local structure upon formation of a self-trapped exciton. The experiments were carried out on the mixed-valence halide-bridged transition metal linear chain charge density wave material [Pt(en 2 )][Pt(en 2 )Cl 2 ]·(ClO 4 ) 4 . Photoinduced changes in the Pt L III XANES spectrum were measured on a picosecond time scale following generation of excitons via optical excitation of the intervalence charge transfer transition. Ab initio FEFF9 modeling of the spectra and the associated angular momentum projected density of states was used to interpret the response. We find photoinduced changes reflecting electronic redistribution and local lattice distortions that correspond to strong localization of the self-trapped state.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Magnetic Field Tolerant Large Area Picosecond Photon Detectors for Particle Identification (Phase I Final Report)

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.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Advanced X-ray Collection and Collimation Optic

To develop and specify a design for a cost-effective, high-resolution x-ray spectrometer and its x-ray lenses is the goal of this proposal. Optimized polycarpellary lenses will be fabricated, characterized and implemented in the spectrometer. Based on the results a system analysis is performed and verified in a feasibility study.

47 OTHER INSTRUMENTATION↗
DOE OSTI2016

X-ray free-electron laser oscillator with nuclear-resonant cavity stabilization and quantum-optical applications

Here, x-ray free-electron-laser oscillators with nuclear-resonant cavity stabilization (NRS-XFELO) hold the promise for providing x-rays with unprecedented coherence properties that will enable interesting quantum-optical and metrological applications. Among these are atom optics with x-ray-based optical elements providing high momentum transfer, or a frequency standard far surpassing the best state-of the-art atomic clocks.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Atomic layer deposition of alternative glass microchannel plates

The technique of atomic layer deposition (ALD) has enabled the development of alternative glass microchannel plates (MCPs) with independently tunable resistive and emissive layers, resulting in excellent thickness uniformity across the large area (20 × 20 cm), high aspect ratio (60:1 L/d) glass substrates. Furthermore, the use of ALD to deposit functional layers allows the optimal substrate material to be selected, such as borosilicate glass, which has many benefits compared to the lead-oxide glass used in conventional MCPs, including increased stability and lifetime, low background noise, mechanical robustness, and larger area (at present up to 400 cm{sup 2}). Resistively stable, high gain MCPs are demonstrated due to the deposition of uniform ALD resistive and emissive layers on alternative glass microcapillary substrates. The MCP performance characteristics reported include increased stability and lifetime, low background noise (0.04 events cm{sup −2} s{sup −1}), and low gain variation (±5%)

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Timing Characteristics of Large Area Picosecond Photodetectors

The LAPPD Collaboration was formed to develop ultralast large-area imaging photodetectors based on new methods for fabricating microchannel plates (MCPs). In this paper we characterize the time response using a pulsed, sub picosecond laser. We observe single photoelectron time resolutions of a 20 cm x 20 cm MCP consistently below 70 ps, spatial resolutions of roughly 500 pm, and median gains higher than 10(7). The RMS measured at one particular point on an LAPPD detector is 58 ps, with in of 47 ps. The differential time resolution between the signal reaching the two ends of the delay line anode is measured to be 5.1 ps for large signals, with an asymptotic limit falling below 2 ps as noise-over-signal approaches zero.

LAPPD↗
DOE OSTI2015

Towards a microchannel-based X-ray detector with two-dimensional spatial and time resolution and high dynamic range

X-ray detectors that combine two-dimensional spatial resolution with a high time resolution are needed in numerous applications of synchrotron radiation. Most detectors with this combination of capabilities are based on semiconductor technology and are therefore limited in size. Furthermore, the time resolution is often realised through rapid time-gating of the acquisition, followed by a slower readout. Here, a detector technology is realised based on relatively inexpensive microchannel plates that uses GHz waveform sampling for a millimeter-scale spatial resolution and better than 100 ps time resolution. The technology is capable of continuous streaming of time- and location-tagged events at rates greater than 10(7) events per cm(2). Time-gating can be used for improved dynamic range.

Adams, Bernhard W.↗
DOE OSTI2015

Picosecond-resolved X-ray absorption spectroscopy at low signal contrast using a hard X-ray streak camera

A picosecond-resolving hard-X-ray streak camera has been in operation for several years at Sector 7 of the Advanced Photon Source (APS). Several upgrades have been implemented over the past few years to optimize integration into the beamline, reduce the timing jitter, and improve the signal-to-noise ratio. These include the development of X-ray optics for focusing the X-rays into the sample and the entrance slit of the streak camera, and measures to minimize the amount of laser light needed to generate the deflection-voltage ramp. For the latter, the photoconductive switch generating the deflection ramp was replaced with microwave power electronics. With these, the streak camera operates routinely at 88 MHz repetition rate, thus making it compatible with all of the APS fill patterns including use of all the X-rays in the 324-bunch mode. Sample data are shown to demonstrate the performance.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2015

An Internal ALD-Based High Voltage Divider and Signal Circuit for MCP-based Photodetectors

We describe a pin-less design for the high voltage (HV) resistive divider of the all-glass LAPPD (TM) 8 in,square thin photodetector module. The divider, which distributes high voltage applied to the photocathode to the two micro-channel plates (MCPs) that constitute the amplification stage, is comprised of the two MCPs and three glass mechanical spacers, each of which is coated with a resistive layer using atomic layer deposition (ALD). The three glass grid spacers and the two MCPs form a continuous resistive path between cathode and anode, with the voltages across the MCPs and the spacers determined by the resistance of each. High voltage is applied on an external tab on the top glass window that connects to the photocathode through the metal seal. The DC ground is supplied by microstrips on the bottom glass plate that form the high-bandwidth anode. The microstrips exit the package through the glass-frit seal of the anode base-plate and the package sidewall. The divider is thus completely internal, with no HV pins penetrating the low-profile flat glass package. Measurements of the performance of the divider are presented for the 8 in.-square MCP and spacer package in a custom test fixture and for an assembled externally pumped LAPPD (TM) prototype with an aluminum photocathode. (C) 2015 Elsevier B.V. All rights reserved.

Adams, Bernhard W.↗
DOE OSTI2015

Quantum optics. Gravity meets quantum physics

Albert Einstein’s general theory of relativity is a classical formulation but a quantum mechanical description of gravitational forces is needed, not only to investigate the coupling of classical and quantum systems but simply to give a more complete description of our physical surroundings. In this issue of Nature Photonics, Wen-Te Liao and Sven Ahrens reveal a link between quantum and gravitational physics. They propose that in the quantum-optical effect of superradiance, the world line of electromagnetic radiation is changed by the presence of a gravitational field.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗