摘要:
There is provided a system and method for estimating radiation exposure in real time or in near-real time while a dosimeter is being irradiated. In the preferred arrangement, OSL will be used to calculate estimates of the radiation dose rate, preferably by using comparisons between illumination values measured during and after lighting the dosimeter with a laser light of a predetermined frequency. A first preferred embodiment utilizes quasi-equilibrium OSL intensity with periodic stimulation during continuous irradiation. Another preferred embodiment utilizes the amplitude of the transient OSL signal during periodic stimulation. Another preferred embodiment utilizes the difference between the OSL intensity at the end of one stimulation period and the beginning of the next. Finally, another preferred monitors the time constant for the return of the transient OSL signal to equilibrium, following either a change in dose rate or during a periodic optical stimulation.
摘要:
This invention relates generally to luminescence techniques for imaging radiation fields and, more specifically, to the use of experimental and mathematical methods to distinguish between dynamic irradiation and static—or other abnormal radiation—exposure conditions for applications in personnel and environ mental radiation dosimetry, or related fields. In more particular, the instant invention provides a rapid and reliable method of detecting abnormal dosimeter exposure conditions over a wide dynamic range of radiation doses, while avoiding significant background interference and stimulation light leakage. Additionally, the preferred embodiment of the instant invention uses a pulsed and synchronized luminescence detection scheme. Further, this invention teaches a complete method and system for abnormal exposure detection—including the use of a luminescent thin powder layer, the use of a periodic radiation absorbing filter, the pulsed stimulation and synchronized luminescence detection scheme, and the method of analyzing and interpreting the recorded images. Finally, the system provides a means of mathematically characterizing an image as containing either a normal or abnormal exposure.
摘要:
The optically stimulated luminescence generated from a luminescent material having a relatively long lifetime of luminescence is measured by using short pulses of laser light stimulation and detecting luminescence only between pulses of light stimulation and after a certain delay following the stimulation pulse.
摘要:
The instant invention teaches a method of preparing a luminescent detecting material for use in UV dosimetry which utilizes phototransferred luminescence. The detecting material has a set of shallow dosimetry traps for trapping electronic charge carriers, which are thermally released upon heating to a first temperature, and a set of deep traps for trapping electronic charge carriers, which charge carriers are released upon heating to a second temperature. The detecting material is prepared by irradiating the detecting material to fill the shallow and deep traps with charge carriers, heating the material to release charge carriers from the shallow traps, and then cooling the material. When the detecting material is subsequently exposed to ultraviolet light a proportion of charge carriers will be released from the deep traps to be retrapped in the shallow traps, thereby allowing for the measurement of phototransferred luminescence by thermal or optical stimulation.
摘要:
A bimodal method for determining an unknown absorbed dose of radiation. An irradiated material is illuminated with ultraviolet or visible light and the luminescence which is emitted from the material is detected. The illuminating light is pulsed, with pulse widths varying from 1 ns to 500 ms. The luminescence emission from dosimetric traps is monitored after a delay following the end of the illumination pulse. The integrated luminescence signal is related to the initial absorbed dose of radiation and thus may be used to calculate the unknown absorbed dose after calibration. In a first mode, the material is completely detrapped--that is, all the dosimetric traps are emptied by the illumination beam. In a second mode the number of illumination pulses, each being followed by the time delay and by periods during which the luminescence signal is detected, is selected such that only a portion of the radiation-induced luminescence from the material is extracted.
摘要:
Described is a dosimeter reader for reading a plurality of optically stimulated luminescence (OSL) sensors of a dosimeter sled and for reading an RFID tag on the dosimeter sled.
摘要:
A portable dosimeter reader device includes an optically stimulated luminescence (OSL) reader for reading one or more OSL sensors of a dosimeter sled; a sled slider that is driven by a sled slider motor to position in turn each of the one or more OSL sensors of the dosimeter sled at a reading position where the OSL reader reads each respective OSL sensor; a display for displaying information relating to reading the one or more OSL sensors; and a battery compartment for one or more batteries, wherein the OSL reader includes an LED light source, wherein the battery compartment is electrically connected to the OSL reader, the sled slider motor and the display, and wherein the one or more batteries provide all of the power required for operating the OSL reader, the sled slider motor and the display.