Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Patent
1996-07-01
1998-04-14
Glick, Edward J.
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
25037014, 250374, G01T 102, G01T 114
Patent
active
057395411
DESCRIPTION:
BRIEF SUMMARY
OBJECT OF THE INVENTION
The object of the invention is a method for detecting ionizing radiation by means of the type of dosimeter which incorporates a MOSFET transistor provided with a floating gate. Further objects of the invention are a dosimeter for implementing the method and the use of the MOSFET transistor for detecting ionizing radiation.
1. Aims
A device for detecting ionizing radiation can be required to have the following properties: supply, in integrated radiation dose measurement. and environmental radiation monitoring. x-radiation and gamma-radiation, starting from 10 keV or a smaller value. particles, and neutrons, where the configuration surrounding the detector is suitable. rate enabling the construction of direct-reading instruments. pocket-size direct-reading dosimeters.
2. Prior Art
However, devices possessing the above properties are not known. According to the prior art, for example, the following devices can be used to detect ionizing radiation:
The photoluminescent glass dosimeter meets most of the above-mentioned requirements, with the exception of the last concerning a simple and low-cost readout method. This is due to the face that currently used readout methods are based on high-precision UV-light sources which are combined with optical filters and fluorescence detectors for measuring fluorescent light when the material is subjected to UV-radiation. In addition, the material used in this method, that is, phosphate glass, is sensitive to environmental effects and requires great care in handling and in the measuring process.
The best known capacitive dosimeter is the so-called QFD (Quartz Fiber Dosimeter) which is also known as the PIC, or Pocket Ion Chamber. It combines a capacitive osimeter with an integrating electrometer, which the user can read by viewing the position of the fiber, that is, the deflection of the fiber. In principle, the capacitive dosimeter meets all the requirements set out above with the exception that it lacks a simple and non-destructive electronic readout method.
Electronic readout methods based on optically determining the position of the electrometer fiber have been developed earlier, but these methods have not functioned sufficiently well on the readout of a pocket-size device. Other capacitive dosimeters, including so-called electret dosimeters, also lack non-destructive readout methods.
The MOS dosimeter is based on measuring the trapping of permanent charges, which cause the degradation of the insulating silicon dioxide layer in a MOSFET transistor caused by radiation. These devices meet all other requirements except that of sufficient sensitivity. They are, therefore, suited for measuring high doses, starting from about 1 rem or 10 mSv.
One known MOS dosimeter is disclosed in U.S. Pat. publication No. 4,788,581. In this dosimeter, there is a silicon oxide layer with a floating gate embedded in it on the silicon substrate, for collecting ion pairs from solid matter. Since the mobility of the ion pairs in solid matter is poor, a live gate is added on the floating gate to allow more effective collection of charges on the floating gate. This means that the area between the gates forms a radiation-sensitive area in this device.
Due to the structure of the dosimeter presented in U.S. Pat. publication No. 4,788,581, its sensitivity is poor. It is suitable for measuring radiation of an intensity of 1 rem or 10 mSv or higher. It is, therefore, unsuited for personal radiation monitoring, which would require a measuring sensitivity within the range of 1 .mu.Sv or 0.1 mrem.
The most common drawback of radiation measuring devices is that the effect of radiation is permanent, or at least `quasi-permanent`. This means that the special treatment is required to reverse the effects of radiation in order for the devices to become re-usable. A general requirement is, however, that the radiation measurement device is electrically reversible.
BRIEF DESCRIPTION OF THE INVENTION
The aim of the present invention is to eliminate the above problem and to achieve a new m
REFERENCES:
patent: 3896309 (1975-07-01), Halsor et al.
patent: 4605946 (1986-08-01), Robinson, Jr.
patent: 4769547 (1988-09-01), Uber, III
patent: 4788581 (1988-11-01), Knoll et al.
patent: 5117113 (1992-05-01), Thomson et al.
patent: 5332903 (1994-07-01), Buehler et al.
Glick Edward J.
Rados Technology Oy
LandOfFree
Radiation detector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radiation detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiation detector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-637527