Apparatus for detecting low intensity alpha particles

Abstract

The present invention relates to a device for radiation detection and analysis, in particular to a portable alpha particle sensor adapted for the identification and quantification of radioactive decay products - alpha particles. The proposed invention is a battery-powered pulse 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 with a zero potential electrode disposed therein. The ionization chamber K is designed so that a source of alpha particles can be disposed therein. Furthermore, the at least one battery is electrically connected to the voltage converter DC / DC by means of the switch S, the operation of which is controllable by the processor MCU. The voltage converter DC / DC is electrically connected to the capacitor C and the ionization chamber K. The electrodes of the ionization chamber K are electrically connected to the processor MCU through the current pulse amplifier A. The processor MCU is further adapted to execute the following instructions: (i) counting the electrical pulses N coming from the K electrode of the ionization chamber and amplified by the amplifier A; (ii) controllably and periodically electrically connecting, by means of at least one switch S, the supply of electrical energy from at least one battery to the voltage converter DC / DC and thus in the circuit; and (iii) determining the voltage value of the capacitor C and, when a preset maximum voltage is reached, electrically disconnecting, by means of the switch S, the supply of electrical energy from the battery to the voltage converter DC / DC and thus in the circuit.

Description

[Technical Field]

[0001] Technical Field The present invention relates to devices for radiation detection and analysis, and in particular to a portable alpha particle sensor adapted for the identification and quantification of radioactive decay products - alpha particles. [Background technology]

[0002] Background of the Invention Alpha particles are a type of ionizing radiation; they are helium nuclei emitted during certain radioactive decay processes. Their detection and measurement involve various types of sensors, including ionization chambers, scintillation detectors, and semiconductor detectors, which are used to detect and analyze radioactive sources. Conventional alpha particle detectors are typically stationary and require an external power source, limiting their application to particularly remote or difficult-to-reach locations.

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

[0004] An X-ray and gamma radiation detection device is known that includes an ionization chamber detector. The detector is connected to an electrometer-level preamplifier circuit, which in turn is coupled to a range-switching circuit, an auto-zeroing circuit, and a microcontroller. The range-switching circuit includes a relay, a triode, a resistor, and a capacitor. This known device allows the creation of a two-level switched X-ray and gamma radiation detection circuit (Patent Document 1).

[0005] A portable ionization chamber designed to monitor the amount of radiation irradiated from an X-ray source onto an X-ray film is known, and is housed in an insulating enclosure along with a portable power source to minimize electrical hazards to patients and operators involved in X-ray examinations (Patent Document 2).

[0006] An alpha particle detector (Patent Document 3) is known, which includes an ionization chamber having multiple holes for air circulation and a voltage application means for generating an electric field. This device also includes a main probe and a sub-probe for absorbing ion charges and leakage currents, and a guard band. This device also includes two preamplifiers and a differential amplifier for amplifying the signal and removing noise.

[0007] The Alpha Surface Contamination Survey Instrument is known, which features a flexible air pump pipe connected to a fan and an ionization chamber, the fan being driven by a power supply. The electrode plates of the ionization chamber are connected to a power supply and an IV converter, which is connected to an A / D converter and then to a single-chip computer. The computer interfaces with a keyboard, alarm, and memory, while the power supply is also connected to the A / D converter (Patent Document 4). [Prior art documents] [Patent documents]

[0008] References [Patent Document 1] China Utility Model No. 216351253U [Patent Document 2] U.S. Patent No. 4,427,946A [Patent Document 3] International Publication No. 2017 / 034158A1 [Patent Document 4] Chinese Patent Application Publication No. 1811376A Summary of the Invention [Means for solving the problem]

[0009] Brief Summary of the Invention The present invention is a battery-powered pulse 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 into which a zero potential electrode is inserted. The ionization chamber K is designed so that an alpha particle source can be placed therein. Furthermore, the at least one battery is electrically connected to the voltage converter DC / DC by means of the switch S, the operation of which is controllable by the processor MCU. The voltage converter DC / DC is electrically connected to the capacitor C and 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) counting the electric pulses N arising from the electrodes of the ionization chamber K and amplified by the amplifier A; (ii) controllably and periodically electrically connecting, using at least one switch S, the supply of electric energy from at least one battery to the voltage converter DC / DC and thus in the circuit, and (iii) determining the voltage value of the capacitor C and, when a preset maximum voltage value is reached, electrically disconnecting, using the switch S, the supply of electric energy from the battery to the voltage converter DC / DC and thus in the circuit. According to an embodiment of the present invention, the processor MCU may further be adapted to execute instructions for determining the intensity of alpha radiation, guided by the received information on the number of electric pulses N arising from the electrodes of the ionization chamber. The processor MCU may further include instructions for controlling the time during which charging of the capacitor C takes place and for determining when the voltage of the capacitor C, and therefore the voltage of the ionization chamber K, has reached a preset maximum value.

[0010] According to another embodiment of the invention, the device comprises two switches, namely a first switch S1 and a second switch S2, whose operation is controllable by a processor MCU. The first switch S1 in the electrical circuit is located before the voltage converter DC / DC, and the second switch S2 in the electrical circuit is located after the voltage converter DC / DC but before the capacitor C and the ionization chamber K.

[0011] According to another embodiment of the invention, the device comprises a diode D, which is located in the electric circuit after the voltage converter DC / DC but before the capacitor C and the ionization chamber K. The device further comprises a voltage divider made of resistors R1 and R2, which is located in the electric circuit after the voltage converter DC / DC but before the diode D, the point between the resistors R1 and R2 being electrically connected to the processor MCU, making it possible to detect the voltage on the capacitor C.

[0012] According to this embodiment, the voltage converter DC / DC is designed to have an output voltage in the range between 40V and 200V. [Brief explanation of the drawings]

[0013] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] One embodiment of the proposed battery-powered pulsed ionization chamber alpha particle sensor. [Figure 2] Another embodiment of the proposed battery-powered pulsed ionization chamber alpha particle sensor. DETAILED DESCRIPTION OF THE INVENTION

[0014] The proposed sensor is intended for the detection of low-intensity alpha particles. The proposed device consumes relatively little energy and can therefore be operated for long periods on a battery. A source of alpha particles is placed inside the ionization chamber K. The alpha particles ionize the gas in the air inside the chamber K. By recording the ionization events, it is also possible to record each alpha particle and therefore determine the intensity of the radiation. An electrode at zero potential is placed inside the ionization chamber K, and its supply voltage is connected to the chamber (Figure 1). The current pulses generated by the ions are amplified by an amplifier A.

[0015] According to one embodiment of the present invention, the processor MCU can have two modes with the following functions: (i) process the signal of the amplifier A and count the number of pulses N in a time unit proportional to the intensity of the alpha radiation, and (ii) measure the voltage applied to the capacitor C and the time taken to charge the capacitor C and control the supply circuit based on the measured voltage value.

[0016] The supply voltage for the ion chamber K must have minimal pulsations, i.e., it must not cause unnecessary operation of the processor MCU at the output of the amplifier A. Because the sensor's sensitivity depends on the voltage, the desired voltage value must be within certain limits (40-200 V). To meet these conditions and use as little energy as possible, the following technique can be used: From the battery voltage (usually between 3 V and 6 V), the camera voltage is obtained using a DC / DC voltage converter. This voltage converter is periodically connected to the battery voltage via switch S1 and to capacitor C via switch S2, which is then connected to the ion chamber K (Figure 1). At the moment of switching on (or changing the processor MCU mode), a pulse occurs at the output of amplifier A, but this does not count toward the total number of pulses N. The repetition period is chosen so that the voltage on capacitor C never falls below a selected minimum voltage value. In this way, the self-consumption of the voltage converter is excluded from the analysis of the acquired data.

[0017] According to another embodiment, the voltage converter DC / DC is switched on and off by the processor MCU, which controls the switch S1 (Fig. 2). At its output, there is a voltage divider made up of resistors R1 and R2, from which the processor MCU receives a voltage proportional to the voltage converter's output voltage. Using a diode D, this voltage is connected to a capacitor C. When a set voltage value is reached, the processor MCU switches off the voltage converter, and the circuit operates in pulse count mode for a specified period of time. By controlling the time for which capacitor C is repeatedly charged at the end of this period, it is possible to indirectly conclude whether the capacitor voltage (and thus the voltage at box K) has fallen below the permissible limit. This circuit implementation ensures that the voltage converter DC / DC operates only long enough to restore the voltage value at C, thus not wasting unnecessary energy.

[0018] The proposed portable autonomous device can be used to monitor radioactive contamination of the environment.

Claims

1. 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 with an electrode of zero potential arranged therein, said ionization chamber K being designed so that a source of alpha particles can be arranged therein, at least one battery is electrically connected to said voltage converter DC / DC by means of a switch S, the operation of which is controllable by said processor MCU, said voltage converter DC / DC is electrically connected to said capacitor C and said ionization chamber K, said electrode K of said ionization chamber being electrically connected to said processor MCU through said current pulse amplifier A, said MCU processor: - a command to count the electrical pulses N coming from the electrodes of the ionization chamber K and amplified by the amplifier A; a command to periodically electrically connect, by means of at least one switch S, the supply of electrical energy from at least one battery to said voltage converter DC / DC and thus to the circuit, to determine the voltage value of said capacitor C, and to electrically disconnect, by means of switch S, said supply of electrical energy from said battery to said voltage converter DC / DC and thus to the circuit, when said voltage reaches a preset maximum value; An apparatus adapted to perform the steps of:

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

3. 2. The device according to claim 1, further comprising a diode D located in the electrical circuit after the voltage converter DC / DC but before the capacitor C and the ionization chamber K, the device further comprising a voltage divider formed by resistors R1 and R2 located in the electrical circuit after the voltage converter DC / DC but before the diode D, the point between the resistors R1 and R2 being electrically connected to the processor MCU, allowing the voltage of the capacitor C to be detected.

4. 4. The device according to claim 1, wherein the processor MCU is further adapted to execute instructions for determining an intensity of alpha radiation based on received information on the number of electrical pulses N originating from the electrodes of the ionization chamber.

5. The device according to any one of claims 1 to 4, wherein the voltage converter DC / DC is designed to have an output voltage ranging between 40V and 200V.

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

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