摘要:
A radiation sensor of the type that acquires a charge or voltage proportil to a dose of radiation. Upon obtaining a predetermined value to the associated voltage proportional to the dose, the voltage is caused to be discharged. A counter keeps track of the number of discharges which is proportional to the total dose of radiation to which the radiation sensor has been exposed. The radiation sensor is thereby prevented from achieving a high charge or voltage which affects the accuracy of the radiation sensor. A calculator and a clock are used to display the value of the dose in any convenient way, such as in relation to tissue dose or average dose rate for a given period of time.
摘要:
A radiation detector which registers the radiation absorbed during the Prt Initial Radiation (PIR) phase following the detonation of a battlefield nuclear device is disclosed. The dose and dose rate attributable to gamma rays may be measured when the dose rate is low, and the total dose attributable to neutron and gamma ray radiation can be determined separately when the dose rate is high. Two silicon photodiodes are arranged on opposite sides of a slab of polyethylene to gather protons scattered by the incident neutron flux. A third photodiode is set next to a slab of silicon such that its depleted layer is surrounded by silicon. All three diodes are sensitive to gamma ray radiation. When the dose rate is low, the three diodes gather gamma ray dose information. When the dose rate is high, the two diodes adjacent to the polyethylene register combined neutron and gamma ray dose information while the remaining diode registers predominantly gamma ray dose information. Analog to digital converters are used to change the analog signals from the diodes to digital signals appropriate for a microprocessor. These digital signals can be combined with dose data stored in the microprocessor to determine gamma ray dose rates and neutron and gamma ray doses.
摘要:
A quartz fiber electroscope shunted by a variable capacitor is periodically coupled to a radiation detection capacitor formed of material of a relatively large atomic number, e.g. aluminum, completely surrounded by a material of lesser atomic number, e.g. polyethylene. An electrical charge is induced by neutron or gamma radiation on the material of relatively large atomic number which charge is then coupled to the electroscope and variable capacitor combination. The variable capacitor is set at its maximum when the voltage is transferred from the detection capacitor. The variable capacitor is then reduced, thus raising the voltage on the electroscope with the dose being determined by the reduction in capacitance necessary to raise the indicated electrometer voltage to a predetermined magnitude. The variable capacitor includes indicia thereon which is calibrated such that the voltage change provides a direct reading of the charge transfer and consequently dosage.
摘要:
A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The preferred dodecahedron embodiment of the neutron spectrometer is a solid, polyethylene dodecahedron assembly with 12 surface facets covered by a solid-state detector stacked on an absorbing layer composed of titanium. Each absorbing layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum. In this arrangement, each of the 12 surface pentagon-shaped facets provides a polyethylene substrate to convert neutrons to protons, covered by a layer of absorbing material, acting as a proton absorber, with the detector stacked on the absorbing layer to count protons passing through the absorbing layer. The dodecahedron assembly is housed concentrically within a titanium spherical shell that serves as an outer shield. The dodecahedron embodiment is sufficiently lightweight to be suitable for airborne and satellite applications.
摘要:
A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum. In this arrangement, each of the 12 surface facets provides a polyethylene substrate to convert neutrons to protons, covered by a layer of absorbing material, acting as a proton absorber, with the detector stacked on the absorbing layer to count protons passing through the absorbing layer.
摘要:
A radiation sensor and/or imager is formed by sandwiching two materials having different atomic numbers (Z) around a radiation detector, such as scintilator or Geiger-Mueller type radiation counters, or solid state radiation detectors, such as those made of silicon). In one embodiment of the present invention, a thin layer of lead (Pb) is placed on one side of a Geiger-Mueller radiation counter and a layer of Lucite.TM. is disposed on the opposite side. One example, of a preferred Geiger-Mueller counter which may be used in the present invention is a modified pancake Geiger-Mueller counter with thin ruby mica windows, approximately 2.8 mg/cm.sup.2 thick on both sides. By disposing a high Z material on one side of a radiation detector such as a Geiger-Mueller (GM) or a Scintillator Counter (SC) and a low Z material on an opposite side of either type of the counter, it is possible to detect the photo-Compton electrons emitted from the high or low Z material in the forward or backward directions and the attenuation of the emitted electrons by the high Z material. Because the Geiger-Mueller or scintillation counter can detect single events, the directional radiation detector according to the present invention can detect radiation intensities down to background radiation levels, which is approximately 0.15 .mu.Gy h.sup.-1. Given the difference in the count rate (or intensity), the direction of the radiation source may be easily calculated by simply rotating the detector or by having two counters displaced in different angles (such as 180 degrees) so as to be able to take the difference of the number counts (or mirrors of the intensities).
摘要:
An alpha particle counter for detecting individual alpha particles with a detection medium which is ambient air. Energetic alpha particles from radioactive decay products or other sources enter the detector volume through a durable wire screen window and ionize the ambient air detection medium. Ions of one polarity are driven to the central collector electrode by an electric field due to a battery imposed potential difference between the outer electrode and the central electrode and housing. One pulse is produced for each alpha particle losing its energy in the detector. The counting efficiency is substantially one hundred percent (100%) and is relatively noise free because the collector electrode is essentially at ground potential. The collector electrode signal is amplified in a field effect transistor (FET) emitter follower circuit, the output of which is fed to an external counter. Rugged construction and minimum maintenance are inherent features of this alpha particle detector.
摘要:
A solid state gamma ray dosimeter which measures radiation in terms of absorption in a material different from the detector material. A solid state detector, an amplifier, an analog-to-digital interface and a microprocessor are combined in circuit to correct for differences between absorption of radiation in detector material and absorption in other materials, especially tissue. A suitable cladding may surround the detector. A method of generating dose translation data for calibrating the microprocessor is also disclosed. The solid state detector is attached to a multichannel analyzer circuit and subject to known doses of various monochromatic gamma rays. Output pulses from the detector are amplified and introduced into the multichannel analyzer. The spectrum produced is used to determine an average channel number (or pulse height) for a given dose of monochromatic radiation. The given dose is in units specific to material different from the detector material. The partial dose represented by a single detector pulse at that energy is computed. Partial doses for other energies are likewise computed. Dose translation data associates a partial dose with a given detector pulse height. Dose translation data is set in the microprocessor of the dosimeter. Such dose translation data can be used to calculate total dose and dose rate in units peculiar to material other than detector material.
摘要:
This circuit comprises a solid state crystal radiation counter having its plified output connected in parallel to a pair of pulse height discriminators with thresholds of V.sub.1 and 2V.sub.1 volts, wherein V.sub.1 is above the counter noise level. A pair of pulse counters are arranged to count the outputs of the discriminators and a processor circuit is connected to the pulse counter outputs and is arranged to calculate the quotient of the square of the output of the pulse counter connected to the discriminator with the lower threshold and the output of the other pulse counter. A display circuit is arranged to provide a reading related to the output of the processor circuit.
摘要:
A neutron spectrometer is provided by a series of substrates covered by a solid-state detector stacked on an absorbing layer. As many as 12 substrates that convert neutrons to protons are covered by a layer of absorbing material, acting as a proton absorber, with the detector placed within the layer to count protons passing through the absorbing layer. By using 12 detectors the range of neutron energies are covered. The flat embodiment of the neutron spectrometer is a chamber, a group of detectors each having an absorber layer, with each detector separated by gaps and arranged in an egg-crate-like structure within the chamber. Each absorber layer is constructed with a different thickness according to the minimum and maximum energies of neutrons in the spectrum. In this arrangement, each of the 12 surface facets provides a polyethylene substrate to convert neutrons to protons, covered by a layer of absorbing material, acting as a proton absorber, with the detector stacked on the absorbing layer to count protons passing through the absorbing layer.