Characterization of the low accelerating voltage performance of a microchannel plate based detector system for scanning microscopy

1991 ◽  
Vol 49 ◽  
pp. 364-365
Author(s):  
Raymond F. Cochran
Keyword(s):  
Detection Efficiency ◽  
Direct Analysis ◽  
Microchannel Plate ◽  
Axis Orientation ◽  
Backscattered Electrons ◽  
Low Energy Electrons ◽  
High Detection Efficiency ◽  
Voltage Performance ◽  
Beam Currents

The Galileo SEM2000 microchannel plate (MCP) detector collects onaxis symmetrical secondary electron images at accelerating voltages as low as 200 eV and beam currents less than 5 picoamps. Symmetrical images are particularly useful in metrology and for viewing features that are shielded by topology from an off-axis detector. Backscatter images from the same on-axis orientation can be obtained at accelerating voltages below 500 eV and beam currents less than 10 picoamps.The ability to image secondary and backscattered electrons in the same orientation, together with extremely high detection efficiency for low energy electrons make it a valuable tool for direct analysis of beam-sensitive or dielectric samples. Additional topographic enhancement can be obtained by A-B signal processing at accelerating voltages as low as 200 eV.

Effect of energy filtering on micro-diffraction in the SEM

1994 ◽  
Vol 52 ◽  
pp. 604-605
Author(s):  
James F. Mancuso ◽  
Leo A. Fama ◽  
William B. Maxwell ◽  
Jerry L. Lehman ◽  
Hasso Weiland ◽  
...  
Keyword(s):  
Detection Efficiency ◽  
Ccd Camera ◽  
High Gain ◽  
Microchannel Plate ◽  
Electrostatic Energy ◽  
Energy Filtering ◽  
Electron Channelling ◽  
Low Energy Electrons ◽  
Low Sensitivity ◽  
Angular Field Of View

Micro-diffraction based crystallography is essential to the design and development of many classes of ‘crafted materials’. Although the scanning electron microscope can provide crystallographic information with high spatial resolution, its current utility is severely limited by the low sensitivity of existing diffraction techniques (ref: Dingley). Previously, Joy showed that energy filtering increased contrast and pattern visibility in electron channelling. This present paper discribes the effect of energy filtering on EBSP sensitivity and backscattered SEM imaging.The EBSP detector consisted of an electron energy filter, a microchannel plate detector, a phosphor screen, optical coupler, and a slow scan CCD camera. The electrostatic energy filter used in this experiment was constructed as a cone with 5 coaxial electrodes. The angular field-of-view of the filter was approximately 38°. The microchannel plate, which was the initial sensing component, had high gain and had 50% to 80% detection efficiency for the low energy electrons that passed through the retarding field filter.

High detection efficiency neutron sensitive microchannel plate

2013 ◽  
Vol 8 (01) ◽  
pp. P01015-P01015 ◽  
Author(s):  
J Pan ◽  
Y Yang ◽  
Y Tian ◽  
M Zeng ◽  
T Deng ◽  
...  
Keyword(s):  
Detection Efficiency ◽  
Microchannel Plate ◽  
High Detection ◽  
High Detection Efficiency

Low - Voltage Scanning Electron Microscopy Imaging, Secondary and Backscatter, With Microchannel Plate Detector

1990 ◽  
Vol 48 (1) ◽  
pp. 442-442
Author(s):  
Galen Powers ◽  
Ray Cochran
Keyword(s):  
Low Voltage ◽  
Beam Current ◽  
Microchannel Plate ◽  
Normal Operation ◽  
Microscopy Imaging ◽  
Backscatter Signal ◽  
Vacuum Interface ◽  
Width Measurements ◽  
Working Distance ◽  
Beam Currents

The capability to obtain symmetrical images at voltages as low as 200 eV and beam currents less than 9 pico amps is believed to be advantageous for metrology and study of dielectric or biological samples. Symmetrical images should allow more precise and accurate line width measurements than currently achievable by traditional secondary electron detectors. The low voltage and current capability should allow imaging of samples which traditionally have been difficult because of charging or electron beam damage.The detector system consists of a lens mounted dual anode MicroChannel Plate (MCP) detector, vacuum interface, power supplies, and signal conditioning to interface directly to the video card of the SEM. The detector has been miniaturized so that it does not interfere with normal operation of the SEM sample handling and alternate detector operation. Biasing of the detector collection face will either add secondaries to the backscatter signal or reject secondaries yielding only a backscatter image. The dual anode design allows A−B signal processing to provide topological information as well as symmetrical A+B images.Photomicrographs will show some of the system capabilities. Resolution will be documented with gold on carbon. Variation of voltage, beam current, and working distance on dielectric samples such as glass and photoresist will demonstrate effects of common parameter changes.

scholarly journals Characterization of Highly Irradiated ALPIDE Silicon Sensors

Universe ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 91
Author(s):  
Valentina Raskina ◽  
Filip Křížek
Keyword(s):  
Nuclear Physics ◽  
Detection Efficiency ◽  
Tracking System ◽  
Physics Institute ◽  
Total Ionization ◽  
Silicon Sensors ◽  
Active Pixel ◽  
Academy Of Sciences

The ALICE (A Large Ion Collider Experiment) experiment at CERN will upgrade its Inner Tracking System (ITS) detector. The new ITS will consist of seven coaxial cylindrical layers of ALPIDE silicon sensors which are based on Monolithic Active Pixel Sensor (MAPS) technology. We have studied the radiation hardness of ALPIDE sensors using a 30 MeV proton beam provided by the cyclotron U-120M of the Nuclear Physics Institute of the Czech Academy of Sciences in Řež. In this paper, these long-term measurements will be described. After being irradiated up to the total ionization dose 2.7 Mrad and non-ionizing energy loss 2.7 × 10 13 1 MeV n eq · cm - 2 , ALPIDE sensors fulfill ITS upgrade project technical design requirements in terms of detection efficiency and fake-hit rate.

Elemental composition of mantle tissue granules in Hyridella depressa (Unionida) from the Hawkesbury-Nepean River system, Australia: inferences from catchment chemistry

2000 ◽  
Vol 51 (2) ◽  
pp. 183 ◽  
Author(s):  
Maria Byrne ◽  
Peter A. Vesk
Keyword(s):  
Freshwater Mussel ◽  
River System ◽  
Direct Analysis ◽  
Common Elements ◽  
Mantle Tissue ◽  
South Wales ◽  
The Common ◽  
Australian Freshwater ◽  
River Site

The Australian freshwater mussel Hyridella depressa sequesters elements in calcium phosphate (CaP) granules that form extensive aggregations in its tissues. Elements contained in these granules were determined by X-ray microanalysis of river and lake mussels from the Hawkesbury–Nepean River system, New South Wales. Granules in freeze-substituted mantle tissue were analysed to determine the variation in element profiles in granules among mussels and among sites. For the common elements Ca, P, Fe, Mg and Mn, granule composition reflected catchment lithology and site trophic status and indicated exogenous input. These were most important for differentiation among lake sites and also indicated differences between lake and river mussels. Site differences seen with some common elements in granules from lake mussels correlated with differences in water chemistry. Trace elements, particularly Al, Cu, Zn and Pb, were also important in lake and river site differentiation. The granules play a major role in element dynamics in freshwater mussel tissues and provide a focal structure for direct analysis of element accumulation by these bivalves. The results indicate that characterization of element content of granules in mussel populations would provide valuable insights into animal–element interactions in freshwater systems for ecological and ecotoxicological investigations.

scholarly journals First measurements with the new 3He-filled Monoblock Aluminium Multitube neutron detector developed at the ILL for ANSTO PLATYPUS reflectometer

2020 ◽  
pp. 1-15
Author(s):  
Luis Abuel ◽  
Friedl Bartsch ◽  
Andrew Berry ◽  
Jean-Claude Buffet ◽  
Sylvain Cuccaro ◽  
...  
Keyword(s):  
Research Collaboration ◽  
Detection Efficiency ◽  
Mechanical Design ◽  
Performance Parameters ◽  
Detector Performance ◽  
High Detection ◽  
Neutron Wavelength ◽  
High Detection Efficiency ◽  
Main Detector ◽  
Characterisation Methods

A detector upgrade was carried out on the PLATYPUS instrument dedicated to neutron reflectometry at the Australian Nuclear Science and Technology Organisation (ANSTO). The new detector, developed in the framework of a research collaboration between the ILL and ANSTO, is based on the Monoblock Aluminium Multi-tube (MAM) detector design already in use on several reflectometers and SANS instruments at the ILL. This article provides a technical description of the mechanical design and read-out electronics of the PLATYPUS detector and its commissioning on the PLATYPUS instrument. The main detector performance parameters have been measured and are presented here as well as the characterisation methods and the results of several reflectometry measurements. These measurements show an improvement in experimental data quality resulting from high positional resolution, high detection efficiency and reduced neutron scattering background in the 2.5–19 Å neutron wavelength range used in PLATYPUS instrument.

scholarly journals Status of the two-dimensional, multi-wire proportional chamber detector for the China Spallation Neutron Source

2018 ◽  
Vol 48 ◽  
pp. 1860121 ◽  
Author(s):  
Zhiwen Wen ◽  
Huirong Qi
Keyword(s):  
Neutron Source ◽  
Neutron Detector ◽  
Detection Efficiency ◽  
Spallation Neutron Source ◽  
Two Dimensional ◽  
Large Area ◽  
Position Resolution ◽  
Proportional Chamber ◽  
High Detection Efficiency ◽  
Under Construction

The re-designed two-dimensional, multi-wire proportional chamber (MWPC) detector based on the [Formula: see text]He operation gas has been developed for the multifunctional reflection spectrum detection requirements in China Spallation Neutron Source (CSNS), which is under construction in Guangdong province, China. This efficient thermal neutron detector with large area (200 mm [Formula: see text] 200 mm active area), two-dimensional position sensitive (<2 mm of position resolution), high detection efficiency (>65% in the wavelength of 1.8Å) and good n/[Formula: see text] discrimination would meet some requirements in CSNS The neutron detector consists of a MWPC detector and a high-pressure gas vessel. The wire readout structures of the detector and the gas purity device have been optimized based on previous design and testing. The re-designed MWPC detector with an absorber thickness of 10 mm and 8.5 atm operating gas mixture of [Formula: see text]He and C[Formula: see text]H[Formula: see text] was constructed. Using the non-return valve manufactured by Swagelok, the gas purity device was developed to clean the water and remove gas impurities. The effective cycle time can be up to 50 min per sequence. The performance of the position resolution and the two-dimensional imaging accuracy by the traditional center of gravity readout method was studied with an X-ray radiation source and the neutron source. At the end of this year, the detector will be mounted at CSNS and studied using the neutron source.

scholarly journals Simultaneous profiling of multiple chromatin proteins in the same cells

2021 ◽  
Author(s):  
Sneha Gopalan ◽  
Yuqing Wang ◽  
Nicholas W. Harper ◽  
Manuel Garber ◽  
Thomas G Fazzio
Keyword(s):  
Rna Polymerase Ii ◽  
Direct Analysis ◽  
Cell Types ◽  
Regulatory Elements ◽  
Genome Wide ◽  
Distinct Cell ◽  
Direct Measurements ◽  
Cell Type Specific ◽  
Chromatin Proteins

Methods derived from CUT&RUN and CUT&Tag enable genome-wide mapping of the localization of proteins on chromatin from as few as one cell. These and other mapping approaches focus on one protein at a time, preventing direct measurements of co-localization of different chromatin proteins in the same cells and requiring prioritization of targets where samples are limiting. Here we describe multi-CUT&Tag, an adaptation of CUT&Tag that overcomes these hurdles by using antibody-specific barcodes to simultaneously map multiple proteins in the same cells. Highly specific multi-CUT&Tag maps of histone marks and RNA Polymerase II uncovered sites of co-localization in the same cells, active and repressed genes, and candidate cis-regulatory elements. Single-cell multi-CUT&Tag profiling facilitated identification of distinct cell types from a mixed population and characterization of cell type-specific chromatin architecture. In sum, multi-CUT&Tag increases the information content per cell of epigenomic maps, facilitating direct analysis of the interplay of different proteins on chromatin.

scholarly journals A Simulation of a Novel High Quantum Efficiency Scintillating Fiber Detector with Anti-scatter Properties for Megavoltage X-Ray Imaging

2021 ◽  
Author(s):  
James Day
Keyword(s):  
Spatial Resolution ◽  
Detection Efficiency ◽  
Original Design ◽  
High Quantum Efficiency ◽  
Imaging Device ◽  
X Ray ◽  
Image Guided Radiation Therapy ◽  
X Ray Imaging ◽  
High Detection Efficiency ◽  
Square Array

To further develop a MV x-ray portal imaging device with high detection efficiency and adequate spatial resolution for image guided radiation therapy, the experimental results for a prototype detector were matched using Monte-Carlo software to then improve upon the design. The simulation and experiment were carried out using a 6 MV beam from a linear accelerator machine. An adequate match was obtained with the spatial resolution matching up to a MTF value of 0.2 and then diverging and the total signal registered in the central fiber was matched for field sizes ranging from 3 cm by 3 cm to 20 cm by 20 cm for 5 cm, 15 cm and 25 cm air gaps within 3%. The design was altered from a hexagonal array of round double cladded fibers to a square array of single cladded square fibers. The spatial resolution was improved from 0.242 lp mm-1 to 0.359 lp mm-1 at an MTF value of 0.5 from the original design to a square array of square fibers 0.5 mm wide separated by 0.25 mm of lead foil. With further optimization of the detector design it may be possible to increase spatial resolution for MV x-ray imaging while maintaining an adequate detection efficiency.

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