Apparatus for detecting low intensity alpha particles

Abstract

The invention relates to a device for radiation detection and analysis, in particular to a portable alpha particle sensor suitable for the identification and quantification of the radioactive decay product-alpha particles-. The proposed invention is a battery-powered pulsed ionization chamber alpha particle sensor comprising at least one battery, at least one switch S, a voltage converter DC / DC, a capacitor C, a processor MCU, a current pulse amplifier A and an ionization chamber K in which a zero potential electrode is placed. The ionization chamber K is designed such that an alpha particle source can be placed therein. Furthermore, at least one battery is electrically connected to the voltage converter DC / DC via a switch S, the operation of which can be controlled by the processor MCU. And the voltage converter DC / DC is electrically connected with the capacitor C and the ionization chamber K. And the electrode of the ionization chamber K is electrically connected with the processor MCU through the current pulse amplifier A. Furthermore, the processor MCU is adapted to execute the following instructions: (i) count the electrical pulses N from the K electrode of the ionization chamber and amplified by the amplifier A; (ii) electrically connecting a supply of electrical energy from the at least one battery to the voltage converter DC / DC and other parts of the circuit in a controllable, periodic manner through the at least one switch S; (iii) determining the value of the voltage across the capacitor C and electrically disconnecting the supply of electrical energy from the battery from the voltage converter DC / DC and other parts in the circuit by the switch S when a previously set maximum value of the voltage is reached.

Description

Technical Field

[0001] The present invention relates to devices for radiation detection and analysis, and in particular to portable alpha particle sensors suitable for identification and quantification of radioactive decay products - alpha particles. Background Art

[0002] Alpha particles are a type of ionizing radiation emitted by helium nuclei during certain radioactive decay processes. To detect and measure these particles, various types of sensors are used, including ionization chambers, scintillation detectors, and semiconductor detectors, which are used to detect and analyze radioactive radiation sources. Traditional alpha particle detectors are typically stationary and require an external power source, which limits their use in remote or difficult-to-reach locations.

[0003] The concept of using an ionization chamber to detect alpha particles and measure radiation intensity is a well-known principle in nuclear physics and radiation detection technology. The ionization chamber works by ionizing the gas within it when radiation, such as alpha particles, passes through it. This ionization event releases electrons and positively charged ions, which can be detected as electrical signals.

[0004] An X-ray and gamma radiation detection device is known that includes an ionization chamber detector. The detector is connected to an electrometer-stage preamplifier circuit that is coupled to a range adjustment and auto-zero circuit and a microcontroller. The range switching circuit includes a relay, a transistor, a resistor, and a capacitor. The known device is capable of creating a switched two-stage X-ray and gamma ray detection circuit [1].

[0005] A mobile ionization chamber is known that is designed to monitor the amount of radiation transmitted from an x-ray source to an x-ray film. The ionization chamber is housed in an insulating housing together with a portable power supply to minimize electrical hazards to the patient and operator during the x-ray examination process [2].

[0006] An alpha particle detection device is known [3], which includes an ionization chamber having a plurality of holes for air circulation and a device for applying a voltage to generate an electric field. The device also includes a main probe, a secondary probe, and a guard band, wherein the main probe and the secondary probe absorb ion charges and leakage current. The device also includes two preamplifiers and a differential amplifier, wherein the differential amplifier amplifies the signal and eliminates noise.

[0007] It is known an alpha surface contamination survey instrument, characterized by a flexible suction tube connected to a fan and to an ionization chamber, where the fan is powered by an electric power source. The electrode plates of the ionization chamber are connected to an electric power source and to an I-V converter connected to an A / D converter, which is in turn connected to a single-chip microcomputer. The computer is connected to a keyboard, an alarm and a memory interface, while the electric power source is connected to the A / D converter[4]. BRIEF SUMMARY

[0008] The present invention is a battery-powered alpha particle sensor with a pulsed ionization chamber, comprising at least one battery, at least one switch S, a voltage converter DC / DC, a capacitor C, a processor MCU, a current pulse amplifier A and an ionization chamber K with an inserted zero potential electrode. The ionization chamber K is designed to be able to place an alpha particle source therein. Furthermore, the at least one battery is electrically connected to the voltage converter DC / DC via the switch S, the operation of which can be controlled by the processor MCU. The voltage converter DC / DC is electrically connected to the capacitor C and to the ionization chamber K. The electrodes of the ionization chamber K are electrically connected to the processor MCU via the current pulse amplifier A. In addition, the processor MCU is adapted to execute the following instructions: (i) count the electric pulses N from the electrodes of the ionization chamber K and amplified via the amplifier A; (ii) use the at least one switch S to electrically connect the electric energy supply from the at least one battery to the voltage converter DC / DC and to other parts of the circuit in a controllable, periodic manner; (iii) determine the voltage value on the capacitor C and, when a previously set maximum value of the voltage is reached, use the switch S to electrically disconnect the electric energy supply from the battery to the voltage converter DC / DC and to other parts of the circuit. According to an embodiment of the invention, the processor MCU can be further adapted to execute instructions for determining the intensity of alpha radiation depending on the received information about the number of electric pulses N from the electrodes of the ionization chamber. The processor MCU can further contain instructions for: controlling the length of the charging time of the capacitor C; and determining the time when the voltage of the capacitor C and, consequently, the voltage of the ionization chamber K reaches a previously set maximum value.

[0009] According to another embodiment of the invention, the device comprises two switches: a first switch S1 and a second switch S2, the operation of which can be controlled by the processor MCU. The first switch S1 is located in the circuit in front of the voltage converter DC / DC, and the second switch S2 is located in the circuit behind the voltage converter DC / DC, but thus in front of the capacitor C and the ionization chamber K.

[0010] According to another embodiment of the present invention, the device includes a diode D, which is located in the circuit after the voltage converter DC / DC but before the capacitor C and the ionization chamber K. The device further includes a voltage divider formed by a resistor R1 and a resistor R2, which is located in the circuit after the voltage converter DC / DC but before the diode D; the point between the resistor R1 and the resistor R2 is electrically connected to the processor MCU, so that the voltage on the capacitor C can be detected.

[0011] According to an embodiment, the voltage converter DC / DC is designed to have an output voltage ranging between 40V and 200V. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 – an embodiment of the proposed battery-powered pulsed ionization chamber alpha particle sensor; FIG. 2 - Another embodiment of the proposed battery powered pulsed ionization chamber alpha particle sensor.

[0013] The proposed sensor is designed to detect low-intensity alpha particles. The proposed device consumes relatively low energy, so it can be powered by batteries for a long time. The alpha particle source is placed in an ionization chamber K. The alpha particles ionize the gas in the air of the ionization chamber K. By recording the ionization events, it is possible to record each alpha particle and therefore determine the radiation intensity. A zero potential electrode is placed in the ionization chamber K and the supply voltage of this electrode is connected to the ionization chamber (see FIG. 1 ). The current pulse generated by the ions is amplified by amplifier A.

[0014] According to one embodiment of the present invention, the processor MCU can have two modes, which have the following functions: (i) process the signal of the amplifier A and count the number of pulses N per unit time, where the number of pulses is proportional to the intensity of the α radiation; and (ii) measure the voltage applied to the capacitor C and the time taken to charge it, and control the power supply circuit based on the measured voltage value.

[0015] The supply voltage of the ionization chamber K must have minimal ripple, that is, it must not cause the processor MCU to generate unnecessary operations at the output of the amplifier A. The desired voltage value must be within certain limits - 40V to 200V, because the sensitivity of the sensor depends on this voltage value. In order to meet these conditions and use as little energy as possible, the following technology can be used: the camera voltage is obtained from the battery voltage (usually in the range of 3V to 6V) via a voltage converter DC / DC, which is periodically connected to the battery voltage using switch S1 and periodically connected to the capacitor C using switch S2, which in turn is connected to the ionization chamber K ( FIG. 1At the moment of switching on (or changing the processor's MCU mode), a pulse appears at the output of amplifier A, but this pulse does not add to the total number of pulses N. The cycle period is chosen so that the voltage of capacitor C never falls below the selected minimum voltage. In this way, according to the analysis of the acquired data, the self-consumption of the voltage converter is eliminated.

[0016] According to another embodiment, the voltage converter DC / DC is switched on and off by controlling the switch S1 through the processor MCU (see FIG. 2 At its output, a voltage divider consisting of resistors R1 and R2 supplies a voltage proportional to the output voltage of the voltage converter to the processor MCU. This voltage is connected to capacitor C via diode D. When the set voltage value is reached, the processor MCU shuts down the voltage converter, and the circuit operates in pulse counting mode for a specified period of time. By controlling the recharging time of capacitor C at the end of this period, it is possible to indirectly determine whether the voltage across the capacitor (and therefore the voltage of the ionization chamber K) has not fallen below the permissible limit. This circuit embodiment ensures that the voltage converter DC / DC operates only long enough to restore the voltage value to C, thus avoiding unnecessary energy waste.

[0017] The proposed portable autonomous device can be used to monitor radioactive contamination of the environment. CITED REFERENCES 1.CN216351253U. 2.US4427946A. 3.WO 2017034158A1. 4.CN1811376A.

Claims

1. A device for detecting low-intensity alpha particles, comprising at least one battery, at least one switch S, a voltage converter DC / DC, a capacitor C, a processor MCU, a current pulse amplifier A, and an ionization chamber K in which a zero-potential electrode is placed, wherein the ionization chamber K is designed to accommodate an alpha particle source; wherein: At least one battery is electrically connected to the voltage converter DC / DC via a switch S, the operation of which can be controlled by the processor MCU; the voltage converter DC / DC is electrically connected to the capacitor C and the ionization chamber K; the electrode K of the ionization chamber is electrically connected to the processor MCU via the current pulse amplifier A; wherein the MCU processor is adapted to execute the following instructions: - Counting the electric pulses N coming from the electrodes of the ionization chamber K and amplified by the amplifier A; - electrically connecting the power supply from at least one battery to the voltage converter DC / DC and other parts of the circuit in a periodic manner through at least one switch S, determining the voltage value on the capacitor C, and when a previously set maximum voltage value is reached, electrically disconnecting the power supply from the battery from the voltage converter DC / DC and other parts of the circuit through the switch S.

2. The device according to claim 1, comprising two switches: a first switch S1 and a second switch S2, the operation of which switches can be controlled by the processor MCU, wherein: The first switch S1 is located in the circuit before the voltage converter DC / DC, and the second switch is located in the circuit S2 after the voltage converter DC / DC but before the capacitor C and the ionization chamber K.

3. The device according to claim 1 , further comprising a diode D, which is located after the voltage converter DC / DC but before the capacitor C and the ionization chamber K in the circuit; the device further comprising a voltage divider formed by a resistor R1 and a resistor R2 and located after the voltage converter DC / DC but before the diode D in the circuit; a point between the resistor R1 and the resistor R2 being electrically connected to the processor MCU so as to be able to detect the voltage on the capacitor C.

4. The device according to any of the preceding claims, wherein the processor MCU is further adapted to execute instructions for determining the intensity of the alpha radiation based on the received information about the number of electric pulses N from the electrodes of the ionization chamber. 5 . The device according to claim 1 , wherein the voltage converter DC / DC is designed to have an output voltage in the range of 40 V to 200 V.

6. The device according to claim 1 , wherein the processor MCU contains instructions for controlling the charging time of the capacitor C and determining the moment when the voltage on the capacitor C and therefore the voltage of the ionization chamber K reaches a previously set maximum value.

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