Outdoor Background Radiation Levels in Mining Locations and Major Activity Areas of Ebonyi State, South-Eastern, Nigeria and Their Radiological Impacts

Background: Miners and the people living close to mining sites are exposed to elevated levels of ionizing radiation with or without their knowledge. This study was designed to evaluate the outdoor background radiation levels in some selected mining locations and major activity areas of Ebonyi State, South-Eastern, Nigeria and their radiological impacts. Materials and Methods: The levels of background radiation in these mining areas were estimated using a well calibrated International Medicom CRM-100 Digital Radiation Monitor (survey meter). A cross-sectional survey was adopted for this study. Based on standard method, the radiation monitor was held at a distance of 1.0 meters above the ground and three readings taken at each location and the mean recorded. The radiation dose rates were calculated. A descriptive statistic and inferential statistic were used to summarize the data using statistical package for social Sciences SPSS version 21. Results: The mean dose rate for all the mining locations studied is 0.269+0.039(µSv/hr) and OAEDR of 0.470+0.068(mSv/yr). The excess life cancer risk for adult and children are 1.645 x 10-3 and 1.175 x 10-3 in the mining areas respectively. The mean outdoor Annual Equivalent Dose Rate (OAEDR) for the mining locations of Ebonyi States was 0.470±0.068 and mean of the radiation dose values recommended by UNSCEAR (2008) was 2.4± 0.48. There was statistically significance mean difference between the mean of OAEDR and the UNCEAR recommended value (p = 0.001). Conclusion: the outdoor background radiation levels emitted from the study area are within permissible limits for the general population. Therefore there is little risk of instantaneous radiation hazard within the mining areas of Ebonyi State. Key words: Absorb dose, excess life Cancer risk, radiation hazard.

The BepiColombo Radiation Monitor

<p>The Space environment is known to be populated by highly energetic particles. These particles originate from three main sources: (1) Galactic Cosmic Rays (GCRs), a low flux of protons (90%), heavy ions, and to some extent electrons, with energies up to 10<sup>21</sup> eV, arriving from outside of the Solar System; (2) Solar Energetic Particles (SEPs), sporadic and unpredictable bursts of electrons, protons, and heavy ions, travelling much faster than the Space plasma, accelerated in Solar Flares and Coronal Mass Ejections; and (3) planetary trapped particles, a dynamic population of protons and electrons trapped around planetary magnetospheres first discovered at Earth by Van Allen. Solar activity is responsible for transient and long-term variation of the radiation environment. During periods of low activity, the GCR flux increases as a result of the lower heliospheric modulation exerted on charged particle from outside the solar system and the probability of SEP events decreases; vice-versa, during high activity, GCR fluxes decrease, and the probability of SEP events increases. Extreme Solar Events also affect the Earth’s magnetosphere and the radiation belts which can lead to ground-level enhancements. These three components of radiation in space combine into a hazardous environment for both manned and unmanned missions and are responsible for several processes in planetary bodies. Therefore, it is important to monitor and comprehend the dynamics of energetic particles in space. </p><p>BepiColombo is the first mission of the European Space Agency to the Hermean System. It was launched in 2018 and will enter Mercury’s orbit in 2025 with the first flyby to Mercury planned for 2021. It is composed of two Spacecraft, ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO). Both Spacecraft carry a rich suite of scientific instruments to study the planet geology, exosphere, and magnetosphere. In particular, the MPO spacecraft carries the BepiColombo Radiation Monitor (BERM), which is capable of measuring electrons with energies from ~100 keV to ~10 MeV, protons with energies from 1 MeV to ~200 MeV, and heavy ions with a Linear Energy Transfer from 1 to 50 MeV/mg/cm<sup>2</sup>. While BERM is part of the mission housekeeping, it will provide valuable scientific data of the energetic particle population in interplanetary space and at Mercury. Because BERM is in operation during most of the cruise phase, it is able to detect and characterize SEP events. In fact, two events were already registered and will be included in a multi-spacecraft analysis.  </p><p>BERM is based on standard silicon stack detectors such as the SREM and the MFS. It consists of a single telescope stack with 11 Silicon detectors interleaved by aluminum and tantalum absorbers. Particle species and energies are determined by  charged particle track signals registered in the Si stack. Because of the limited bandwidth, particle events are processed in-flight before being sent to Earth. Particles are then assigned to 18 channels, five corresponding to electrons, eight to protons, and five to heavy ions. In this work, we will present the response of the 18 detector channels obtained by comparing Geant4 simulations with the BERM beam calibration data. The response functions are validated using measurements made during of the BepiColombo Earth flyby and during the cruise phase. Special focus is given  to the synergies between BERM and the Solar intensity X-ray and particle Spectrometer (SIXS) instrument signals. The latter measures electrons from ~50 keV to ~3 MeV and protons from ~1 to ~30 MeV. The availability of two instruments with overlapping energy ranges allows to validate and cross-calibrate their data, namely during Earth flyby at the radiation belts, and to maximize the scientific output of the mission. In fact, lessons learned during this joint analysis are expected to set the basis for a similar collaboration between the RADiation hard Electron Monitor (RADEM) and the Particle Environment Package (PEP) instruments aboard the future JUICE mission.</p>

The North-West University’s High Altitude Radiation Monitor programme

Since the discovery of cosmic radiation by Victor Hess in 1912, when he reported a significant increase in radiation as altitude increases, concerns about radiation effects on human bodies and equipment have grown over the years. The secondary and tertiary particles which result from the interaction of primary cosmic rays with atmospheric particles and commercial aircraft components, are the primary cause of the radiation dose deposited in human bodies and in electronic equipment (avionics) during aircraft flights. At an altitude of about 10 km (or higher) above sea level, the dose received by frequent flyers, and especially flight crew, is a serious concern. Also of concern is the possible failure of sensitive equipment on board commercial aircrafts as a result of flying through this mixed radiation field. Monitoring radiation in the atmosphere is therefore very important. Here we report on the first measurements by the High Altitude Radiation Monitor (HARM) detector during a commercial flight from Johannesburg (O.R. Tambo International Airport) to Windhoek (Hosea Kutako International Airport). As part of a public awareness activity, the HARM detector was placed on a high-altitude balloon, and these measurements are also shown here. Model calculations (estimations) of radiation levels for the commercial aircraft flight are shown and the results are used to interpret our measurements.

The RADiation hard Electron Monitor (RADEM) for the JUICE mission

<p>The JUpiter ICy moons Explorer (JUICE) is the European Space Agency (ESA) next large class mission to the Jovian system. The mission, scheduled to launch in 2022, will investigate Jupiter and characterize its icy moons, Callisto, Europa and Ganymede for a period of 3.5 years after a 7.5-year cruise to the planet. JUICE is planned to flyby Europa and Callisto, perform a high latitude tour of the Jovian system, and finally, at the end of the mission, it will orbit Ganymede at different altitudes inside the moon’s intrinsic magnetosphere.<br /><br />While radiation is one of the major threats for all Space missions, in the Jovian system this problem is exacerbated due to the existent of very large fluxes of energetic electrons, with energies up to dozens of MeV, which can damage and eventually destroy the spacecraft systems. The existence of this electron population, and to a lesser extent of a proton and heavy ion population, is a consequence of Jupiter’s huge magnetosphere which can accelerate these particles to energies higher than those found in other known planetary magnetospheres. Although the Galileo mission, and to a lesser extent the Cassini, Pioneer and Voyager missions have provided ample information about the radiation environment in the Jovian, several questions about particle origin, acceleration mechanisms, Jovian-Solar magnetosphere coupling, and overall dynamics of the system still need to be answered with implications in magnetospheric physics, astrobiology and others, as well as in development of future manned and unmanned missions to both the inner and outer Solar System.<br /><br />For these reasons, the JUICE mission will include the RADiation hard Electron Monitor (RADEM), a low power, low mass radiation monitor, that will increase the range of long-term spectral measurements acquired by the Energetic Particle Detector (EPD) aboard the Galileo spacecraft, from 11 to 40 MeV for electrons and from 55 to 250 MeV for protons. RADEM consists of three detector heads based on traditional silicon stack detector technologies: the Electron Detector Head (EDH), the Proton Detector Head (PDH), and the Heavy Ion Detector Head (HIDH), that will measure electrons from 0.3 MeV to 40 MeV, protons from 5 MeV to 250 MeV and Heavy Ions from Helium to Oxygen with energies from 8 to 670 MeV, respectively. Because the detectors have limited Field-Of-View, a fourth detector, the Directionality Detector Head (DDH) will measure electron angular distributions which can vary greatly along the Jovian System as observed by the Galileo spacecraft.<br /><br />Although RADEM is a housekeeping instrument that will provide in-situ Total Ionizing Dose (TID) measurements and serve as a radiation level alarm, it has a broad scientific potential. Besides the Jovian system, the instrument will be fully operated during the cruise of the Solar System, which includes three Earth flybys, a Venus flyby and a Mars flyby, that offer additional scientific opportunities including but not limited to studying the cosmic ray gradient in the Solar System, characterizing Solar Energetic Particle (SEP) events, and others. In this work, we will present RADEM from a technical point-of-view, as well as the scientific opportunities that will be addressed by the radiation monitor during the JUICE mission.</p>