An asymmetric dual-mode ionization chamber measurement system can include a first high-voltage plate, a second high-voltage plate and a readout plate. The first high-voltage plate can be disposed from the readout plate by a first active volume. The second high-voltage plate can be disposed from the readout plate by a second active volume. A high-voltage potential can be coupled to the first high-voltage plate during a first mode, and to the second high-voltage plate during a second mode. Ion pairs generated by a radiation stream passing through the first active volume during the first mode and the second active volume during the second mode can be measured at the readout plate to determine a radiation rate of the ionizing radiation. The asymmetric dual-mode ionization chamber measurement system can advantageously measure different radiation streams that have significantly different ranges of radiation rates flux.

A radiotherapy dose rate monitor system includes an emitting electrode configured to be impinged by radiotherapy radiation; a collecting electrode configured to form an electrical circuit with said emitting electrode, a current measurement device configured to measure a current through said emitting and collecting electrodes indicative of a dose of said radiotherapy radiation, and a chamber enclosing a gas. Emission of secondary electrons from the emitting electrode provides a majority of the current.

A fissile neutron detection system includes a neutron moderator and a neutron detector disposed proximate such that a majority of the surface area of the neutron moderator is disposed proximate the neutron detector. Fissile neutrons impinge upon and enter the neutron moderator where the energy level of the fissile neutron is reduced to that of a thermal neutron. The thermal neutron may exit the moderator in any direction. Maximizing the surface area of the neutron moderator that is proximate the neutron detector beneficially improves the reliability and accuracy of the fissile neutron detection system by increasing the percentage of thermal neutrons that exit the neutron moderator and enter the neutron detector.

A fissile neutron detection system includes a neutron moderator and a neutron detector disposed proximate such that a majority of the surface area of the neutron moderator is disposed proximate the neutron detector. Fissile neutrons impinge upon and enter the neutron moderator where the energy level of the fissile neutron is reduced to that of a thermal neutron. The thermal neutron may exit the moderator in any direction. Maximizing the surface area of the neutron moderator that is proximate the neutron detector beneficially improves the reliability and accuracy of the fissile neutron detection system by increasing the percentage of thermal neutrons that exit the neutron moderator and enter the neutron detector.

A radiation source arrangement causes interaction between pump radiation (340) and a gaseous medium (406) to generate EUV or soft x-ray radiation by higher harmonic generation (HHG). The operating condition of the radiation source arrangement is monitored by detecting (420/430) third radiation (422) resulting from an interaction between condition sensing radiation and the medium. The condition sensing radiation (740) may be the same as the first radiation or it may be separately applied. The third radiation may be for example a portion of the condition sensing radiation that is reflected or scattered by a vacuum-gas boundary, or it may be lower harmonics of the HHG process, or fluorescence, or scattered. The sensor may include one or more image detectors so that spatial distribution of intensity and/or the angular distribution of the third radiation may be analyzed. Feedback control based on the determined operating condition stabilizes operation of the HHG source.

A radiotherapy dose rate monitor system includes an emitting electrode configured to be impinged by radiotherapy radiation; a collecting electrode configured to form an electrical circuit with said emitting electrode, a current measurement device configured to measure a current through said emitting and collecting electrodes indicative of a dose of said radiotherapy radiation, and a chamber enclosing a gas. Emission of secondary electrons from the emitting electrode provides a majority of the current.

An asymmetric dual-mode ionization chamber measurement system can include a first high-voltage plate, a second high-voltage plate and a readout plate. The first high-voltage plate can be disposed from the readout plate by a first active volume. The second high-voltage plate can be disposed from the readout plate by a second active volume. A high-voltage potential can be coupled to the first high-voltage plate during a first mode, and to the second high-voltage plate during a second mode. Ion pairs generated by a radiation stream passing through the first active volume during the first mode and the second active volume during the second mode can be measured at the readout plate to determine a radiation rate of the ionizing radiation. The asymmetric dual-mode ionization chamber measurement system can advantageously measure different radiation streams that have significantly different ranges of radiation rates flux.

A system for detecting a position of an ionizing radiation. The system includes a radiation detector including a plurality of cathode films, a plurality of anode strips sets, a plurality of insulator films, a conductive grid, and a drift region. Each set of the plurality of anode strips sets is disposed between a respective pair of adjacent cathode films of the plurality of cathode films. Each of the plurality of insulator films is disposed between a respective cathode film of the plurality of cathode films and a respective set of the plurality of anode strips sets. The conductive grid is disposed in parallel with the detection plane and exposed to the ionizing radiation. A drift region includes a region between the conductive grid and the detection plane. The radiation detector is configured to ionize a gas by generating an electric field inside the drift region.

A system for detecting a position of an ionizing radiation. The system includes a radiation detector including a plurality of cathode films, a plurality of anode strips sets, a plurality of insulator films, a conductive grid, and a drift region. Each set of the plurality of anode strips sets is disposed between a respective pair of adjacent cathode films of the plurality of cathode films. Each of the plurality of insulator films is disposed between a respective cathode film of the plurality of cathode films and a respective set of the plurality of anode strips sets. The conductive grid is disposed in parallel with the detection plane and exposed to the ionizing radiation. A drift region includes a region between the conductive grid and the detection plane. The radiation detector is configured to ionize a gas by generating an electric field inside the drift region.

An apparatus includes an ion chamber and a valve assembly. The ion chamber may include a housing enclosing a gas and one or more electrodes. The valve assembly is coupled to the ion chamber allowing control of replacement of the gas within the housing.