New sensors and different embodiments of multi-channel integrated circuit are provided. The new high energy and spatial resolution sensors use both solid state and scintillator detectors. Each channel of the readout chip employs low noise charge sensitive preamplifier(s) at its input followed by other circuitry. The different embodiments of the sensors and the integrated circuit are designed to produce high energy and/or spatial resolution two-dimensional and three-dimensional imaging for widely different applications. Some of these applications may require fast data acquisition, some others may need ultra high energy resolution, and a separate portion may require very high contrast. The embodiments described herein addresses all these issues and also other issues that may be useful in two and three dimensional medical and industrial imaging. The applications of the new sensors and integrated circuits addresses a broad range of applications such as medical and industrial imaging, NDE and NDI, security, baggage scanning, astrophysics, nuclear physics and medicine.

Integrated circuit and sensor for imaging

A method and apparatus for detecting and measuring radiation is disclosed. The apparatus includes a scintillator crystal and a photodetector optically coupled to the scintillator crystal as well as first and second analyzing means. The first analyzing means is coupled to an output of the photodetector for counting discrete electronic pulses generated by the photodetector. The second analyzing means operates simultaneous with the first analyzing means and is coupled to another output of the photodetector for integrating current generated by the photodetector. The method includes the steps of irradiating a scintillator with x-ray energy, detecting light emitted from the scintillator and converting the light into a flow of electrons, detecting and counting discrete pulses of the flow of electronics and simultaneously integrating electronic current corresponding to the flow of electrons.

Dual mode radiographic measurement method and device

An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

Extended range radiation dose-rate monitor

A method for measuring a density profile of a fluid in a process vessel is disclosed The method includes emitting gamma rays into the fluid and acquiring a backscattered gamma ray counts distribution using at least one position sensitive gamma ray detector disposed proximate the vessel The method further includes determining the density profile of the fluid contained in the process vessel based on the backscattered gamma ray counts distribution

Density profile measurement by detecting backscattered radiation with position-sensitive detector

Described is herein a radiation measuring apparatus in which a detected pulse signal having a wave height value proportional to energy of radiation is transmitted through an optical fiber and a detected pulse signal received from the optical fiber is supplied to an external apparatus. Even if the transmission loss of the optical fiber is subjected to change with passage of time, a monitor pulse signal having a polarity reverse to that of a detected pulse signal is overlapped on the detected pulse signal lest the wave height of the detected pulse signal be not varied on the transmitting side, and a wave height value of a monitor pulse signal passed through the optical fiber is detected to compensate the wave height of the received detected pulse signal using the detected value.

Radiation measuring apparatus

A radiation dose-rate monitor is provided which operates in a conventional linear mode for radiation in the 0 to 0.5 R/h range and utilizes a nonlinear mode of operation for sensing radiation from 0.5 R/h to over 500 R/h. The nonlinear mode is achieved by a feedback circuit which adjusts the high voltage bias of the proportional counter, and hence its gas gain, in accordance with the amount of radiation being monitored. This allows compression of readout onto a single scale over the range of 0 to greater than 500 R/h without scale switching operations.

Wide-range radiation dose monitor

A radiation dose-rate meter is provided which uses an energy-sensitive detector and combines charge quantization and pulse-rate measurement to monitor radiation dose rates. The charge from each detected photon is quantized by level-sensitive comparators so that the resulting total output pulse rate is proportional to the dose-rate.

Radiation dose-rate meter using an energy-sensitive counter

A position-sensitive proportional counter circuit is provided which allows the use of a conventional (low-resistance, metal-wire anode) proportional counter for spatial resolution of an ionizing event along the anode of the counter. A pair of specially designed active-capacitance preamplifiers are used to terminate the anode ends wherein the anode is treated as an RC line. The preamplifiers act as stabilized active capacitance loads and each is composed of a series-feedback, low-noise amplifier, a unity-gain, shunt-feedback amplifier whose output is connected through a feedback capacitor to the series-feedback amplifier input. The stabilized capacitance loading of the anode allows distributed RC-line position encoding and subsequent time difference decoding by sensing the difference in rise times of pulses at the anode ends where the difference is primarily in response to the distributed capacitance along the anode. This allows the use of lower resistance wire anodes for spatial radiation detection which simplifies the counter construction and handling of the anodes, and stabilizes the anode resistivity at high count rates (>106 counts/sec).

Manfred K. Kopp

Papers

Wide-range radiation dose monitor

Radiation dose-rate meter using an energy-sensitive counter

Position-sensitive proportional counter with low-resistance metal-wire anode