Research closely related to that reported in the preceding article has shown that δ-doped charge-coupled devices (CCDs) could be used to detect incident protons and perhaps other positive ions, and to measure the kinetic energies of the ions, down to about 1.25 keV. Prior to the development of δ-doped CCDs, the minimum kinetic energy for detectability of protons by solid-state devices was about 10 keV, for the reasons described in the preceding article.
Heretofore, a typical instrument for detecting low-kinetic-energy charged particles and measuring the particle kinetic energies has comprised a relatively heavy, power-hungry electrostatic- or magnetic-energy analyzer followed by a microchannel-plate detector. In contrast, δ-doped CCDs offer the capability for measuring kinetic energies directly in the detection process, without need for electrostatic or magnetic energy analyzers; this opens up the possibility of developing simpler, smaller, low-power-consumption instruments for measuring low-kinetic-energy charged particles.
An experiment was performed to demonstrate the use of a δ-doped CCD to detect incident protons and measure their kinetic energies. A δ-doped CCD with associated camera electronics was placed in a vacuum chamber, attached to a magnetically analyzed low-kinetic-energy proton-beam apparatus. The responses of the CCD were then measured at proton kinetic energies from 12 down to 1.25 keV. The CCD output signals were found to vary monotonically with proton kinetic energy throughout the energy range of the experiment.
This work was done Shouleh Nikzad, Stythe Elliott, Thomas Cunningham, Walter Proniewicz, D. R. Croley, G. B. Murphy, and Dale Winther of Caltech forNASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com under the Electronic Components & Circuits category.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to
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Overview
The document discusses the innovative development of delta-doped charge-coupled devices (CCDs) by personnel at NASA's Jet Propulsion Laboratory (JPL) for the detection of low-energy charged particles, specifically protons. Traditionally, solid-state detectors have faced challenges in detecting low-energy particles due to the "dead layer," which causes energy loss as particles penetrate the insensitive surface regions of the detector. This limitation typically sets the energy threshold for detection at around 10 keV.
The delta-doped CCD technology addresses this issue by confining the surface potential barrier close to the detector's surface, allowing for effective charge collection from particles that do not penetrate deeply. Recent tests demonstrated that these delta-doped CCDs can detect signals from low-energy protons down to 1.25 keV, significantly below the threshold of conventional detectors.
The document details the experimental setup, where a delta-doped Reticon 512 x 512 pixel CCD was placed in a vacuum chamber connected to a magnetically analyzed low-energy proton beam system at The Aerospace Corporation's laboratory in El Segundo, California. The CCD's response was measured, showing that the output signals varied consistently with the proton energy, confirming the device's sensitivity and effectiveness at low energy levels.
This advancement opens up new possibilities for miniaturized low-energy particle instruments that can directly measure particle energy, which is particularly beneficial for space exploration. Such instruments are expected to be less complex and consume less power compared to traditional heavy detectors, making them more suitable for use in space missions.
The document is part of a technical support package from NASA, highlighting the contributions of various inventors involved in the research and development of this technology. It emphasizes the potential applications of delta-doped CCDs in measuring energies of positive ions, showcasing a significant step forward in the field of space microelectronics and particle detection.
Overall, the development of delta-doped CCDs represents a significant technological advancement that could enhance the capabilities of scientific instruments used in space exploration, allowing for more efficient and accurate measurements of low-energy particles.
