DEVELOPMENT OF AN IOT DEVICE BASED ON A GEIGER COUNTER

. The threat of radiation exposure is always present in modern world. In recent years, this threat has become even more pronounced due to Russian aggression on Ukrainian territory. Therefore, the need for remote data collection and analysis of radiation background information has become even more important, and research in the field of creating small, low-cost devices that can monitor radiation levels of a certain area in real-time and provide information to local government agencies responsible for the safety of populated areas can be considered relevant. Radiation background level monitoring is essential to ensuring that people are


Introduction
Currently, people are exposed to many radioactivity threats related to russian aggression in Ukraine.This includes the possibility of missile attacks on nuclear power plants, irresponsible actions at the occupied Zaporizhzhia nuclear power plant, and threats of tactical nuclear weapon usage [1].Hence, the need for remote monitoring and analysis of radiation background information has become very important.
A proposed solution is to create a network of monitoring stations that will provide real-time information on the background radiation.The MQTT (Message Queue Telemetry Transport) protocol is used for information transfer [2].It is a simplified network protocol that works on TCP/IP and allows for the creation of devices that transmit information from sensors based on cheap and easy to use microcontroller components.

Literature analysis
Typically, radiation measurement with a dosimeter is performed once (on demand) and is not regular.Thanks to wireless communication, readings from such devices can be viewed from several meters away [3].At the same time, the radiation background can change while performing specific activities, for example, after maintenance work (laying gravel coverage, decoration with granite, e. g. installing granite panels/countertops, etc.), observation on a spiral computer tomography, after inhalation of radioactive aerosol, etc.After trips through areas with significant radiation contamination (e.g. the Chornobyl exclusion zone), air filters in car engines and cabins can retain radioactive dust and carry it over long distances.
An effective solution would be deploying networked radiation detectors to measure radiation characteristics in realtime.For example, the European MPX ATLAS network has been operating for 20 years [4].However, this equipment is solely for scientific research and doesn't monitor background radiation for population protection.
In Ukraine, the issue of creating an automated radiation control system as the main component of radiation safety for the population has been discussed for over 10 years [5].However, the resolution of organizational issues regarding this problem has stalled, and currently such a system does not function.Only well-known automated systems for monitoring radiation are operating in Ukraine and are located around nuclear power plants.At the same time, similar systems are already functioning in some countries of the world.
For example, in Finland, the radiation control system consists of 290 stations that are evenly distributed throughout the country.The measurement results are stored in the National Data Bank.This information is available to the government in real-time.The automated system also receives information from other Scandinavian countries [6].
The UK National Radiological Monitoring and Emergency Response Network (RIMNET) was established in 1988 to track the impact of foreign nuclear incidents on the country [7].RIMNET consists of 94 posts throughout the country and the data received is stored in the UK National Nuclear Database.Similar computerized systems for automatic determination of radiation situation are also available in Bulgaria, Belgium, Japan, and other countries.
Thus, research in the field of creating small, low-cost devices that can monitor radiation levels of a certain area in real-time and provide information to local government agencies responsible for the safety of populated areas is considered relevant.

Object, subject, and methods of the research
The object of the research is the process of remote monitoring and data processing for radiation background.Research methods: The ionization method of radiometry and radiation control using gas-discharge devices (Geiger counter).Practical significance: As a result of the studies, it will be possible to generalize and process the results of remote radiation background measurement in a distributed network of monitoring stations for timely notification of the agencies responsible for ensuring people from the consequences of radioactive contamination.

Device development 4.1. Hardware components
Now, let's examine the components that comprise the system for collecting information about the background radiation levels of the surrounding area.
Geiger counter sensor module (Fig. 1) is the main component responsible for radiation levels measurement [8].
1 -J305 tube, 2,4 -555 timer ICs, 7microcontroller connection terminal,9buzzer,10power switch,12power input screw terminal,13,16 calibration potentiometer, 17 -J2 calibration mode jumper, 18 -SBM-20 tube connector Fig. 1 -Geiger counter sensor module Description of components: 1) J305 tube (alternative to М4011), capable of capturing gamma-and beta-radiation; 2, 4) 555 timer ICs, which are responsible for initiating data capture; 3) LM358P, dual channel op-amp; 5) J1 jumper, responsible for enabling or disabling buzzer sound; 6) J4 jumper, used during the calibration process; 7) Microcontroller connection terminalresponsible for supplying power to the board via GND and 5V pins.INT pin is responsible for transferring data to the MCU.External interrupts configuration on the MCU is required for setting up data collection based on received impulses; 8) 3.5 mm TRRS (audio jack) terminal, which enables data collection on smartphones.Special mobile application can be installed in order to collect and process the data, which is then displayed on the screen; 9) Buzzer, that emits a clicking sound every time an impulse is registered; 10) Sliding switch for turning the sensor on and off; 11) Auxiliary 5V power supply socket (5.5 mm × 2.5 mm); 12) Auxiliary screw terminal block for supplying 5V power; 13) LED power indication; 14) LED indicating impulse registration; 15) NPN-transistors S8050; 16) Calibration potentiometer; 17) J2 calibration jumper; 18) Additional contact plates for switching the J305 tube to SBM-20.MCU module ESP32-CAM was used for data collection and transferring (Fig. 2).It is Wi-Fi and Bluetooth-enabled and equipped with OV2640 camera module [9].An additional programming shield can be connected, which allows flashing the board and communicating via USB.

Fig. 2 -ESP32-CAM module with its programming shield
For this task, any module based on ESP32 or ESP8266 with built-in Wi-Fi subsystem is suitable.The mentioned module was used for the prototype because it was available.
The power supply unit with a voltage of 5V is used, both for powering the Geiger counter board and the ESP32 module.
A logic signal level converter is also used.The Geiger counter board operates with a logic level of 5V, while the ESP32 module operates with a logic level of 3.3V.A simple converter circuit is used to synchronize these levels (Fig. 3).

Fig. 3 -Logic level converter circuit
Sample of radioactive material for system testing.A so-called "Energy Pendant" was used (Fig. 4), which, according to the description, "improves the energy state of the organism".This pendant has weak radioactivity.

Fig. 4 -Radioactive material sample
When handling radioactive materials, it is important to remember that you cannot see radiation.Hence, it is crucial to know and understand their behavior.Compounds that emit even weak radiation should be stored in a refrigerator (freezer) or behind a concrete wall, etc. [10].

Software structure
For data collection and processing, the MQTT (Message Queue Telemetry Transport) protocol is used.It is a simplified network protocol that operates over TCP/ IP [11].
This protocol uses the "publisher-subscriber" principle for data exchange (Fig. 5).

Fig. 5 -The working principle of the MQTT protocol
The protocol involves the presence of the following main components: − "Publisher"devices responsible for data collection; − "Subscriber"data consuming devices; − "Broker"devices responsible for the interaction and operation of the protocol.During the process of development, a "Publisher" device was created.This device will interact with other components through the MQTT protocol.Data processing and publication will be performed using standard MQTT protocol tools.
The advantage of ESP32 boards is the ability to create programs for them in the Arduino environment, using standard libraries written for this platform.
The program consists of two main parts, which are described in the following sections.

Processing of the data received from the Geiger counter
The Geiger counter module outputs impulses which are used to interrupt the MCU program.The number of invoked interrupts per minute is calculated and then transformed into background radiation data.
Calculations are performed using the following code.General system architecture is represented on Fig. 7.

Fig. 7 -Net diagram of the monitoring stations network
Information from numerous Geiger counter sensor modules (GCSMs) in real-time arrives through Wi-Fi modules and Internet Service Providers (ISP) to the decision-making center's database (DB).The mentioned DB is located on the network storage (Fig. 6) which is also remotely accessible.Processed data is available to users who have installed an application for monitoring local radiation background.The location chosen in the app or the smartphone's geolocation (if enabled) is used to access the data.

Results Analysis
An external subscriber program was used to generate a CSV file, which stored data of the measurements with a 1minute interval.The results of the measurements are displayed in a graph, where time is plotted on the X-axis in minutes and the radioactivity value on the Y-axis in μSv/h (Fig. 8).

Fig. 8 -Measurement results
As seen on the graph, upon bringing the radioactive substance to the Geiger tube, the readings of radioactivity increase to values of 0.61−0.65 µSv/h from the background natural values of 0.11−0.14µSv/h.
The obtained spike value of 0.65 µSv/h in Fig. 7 exceeds the population's sanitary standard (which is 0.30 µSv/h) almost twice, thus special measures are required from the relevant authorities.
This indicates that all components of the chain "publisher" − "broker" − "subscriber" are functioning properly.

Conclusions
It should be noted that weather service messages regarding radiation levels correspond to reality only for a certain limited area.And it would not be accurate to say that its level is consistent throughout the city.The radiation background The subject of the study is a network of remote radiation monitoring stations based on electronic sensor modules.Tasks that were set for the research are: − Automated environmental radiation monitoring in an unlimited number of stationary or mobile points; − Data transfer from the monitoring point to the server via the Internet network; − Warning and emergency notifications for when the results of radiation background measurement exceed specified threshold levels; − Viewing of dosimetric information through the Internet from a computer or smartphone.−