Alpha Detector Research Articles

Estimation of radon concentration in groundwater in the mining zone of Haryana, India, for lungs and stomach annual effective dose.

The groundwater is being used for drinking and irrigation purposes in vast swathes of the Aravalli Mountain range. Since the radioisotope presence in groundwater is affected by the local mining processes, the radiation monitoring in groundwater of mining regions is of paramount importance. In the present work, we have estimated the 222Rn presence in the mining region of Aravalli in the southern part of Haryana. We measured the Radon concentration in 51 water samples from the intended area using the RAD7 alpha detector. The measured radon concentration in some of the water samples collected from the vicinity of the mining zone is higher than that of the United Nations Scientific Committee on the Effects of Atomic Radiation recommended value. Furthermore, we have estimated the annual effective doses for the lungs and stomach contributed by ingestion and inhalation. Though the calculated dose values in collected samples are not in the critical range, further monitoring of background radiation in the Aravalli region is required.

Low and high-resolution gamma-ray spectroscopy for the characterization of uranium contamination

Decommissioning is the last step in the life cycle of a nuclear facility. After the evacuation of the facility components, the remaining structures such as concrete walls and floors must be controlled to ensure that no residual contamination remains. As it is a costly and time consuming activity, CEA develops fast measurement methods allowing a complete scanning of very large areas (hundreds of thousands of square meters) in legacy uranium enrichment plants based on gas diffusion, at Pierrelatte nuclear site, France. After fast alpha and beta measurements, HPGe and NaI gamma-spectroscopy detectors are used to characterize more precisely uranium contamination. HPGe has excellent energy resolution but requires very long acquisition times. On the contrary, NaI(Tl) detectors enable rapid measurement, but extracting the contamination signal from the natural background is difficult due to their low resolution. Using an innovative approach based on energy bands of the NaI spectra, contamination activity and enrichment are consistent with that measured with HPGe but in only 15 min vs. 65 h, and with a sufficiently low relative uncertainty of about 15 % and 20 %, respectively, on activity and enrichment. Large area NaI(Tl) detectors will allow cost-effective scanning of the Gaseous Diffusion Plant (UDG) nuclear site (hundreds of thousands of squared meters) within practical times, in complement to alpha and beta contamination detectors.

Advancements in Remote Alpha Radiation Detection: Alpha-Induced Radio-Luminescence Imaging with Enhanced Ambient Light Suppression.

Heavy nuclides like uranium and their decay products are commonly found in nuclear industries and can pose a significant health risk to humans due to their alpha-emitting properties. Traditional alpha detectors require close contact with the contaminated surface, which can be time-consuming, labour-intensive, and put personnel at risk. Remote detection is urgently needed but very challenging. To this end, a candidate detection mechanism is alpha-induced radio-luminescence. This approach uses the emission of photons from radio-ionised excited nitrogen molecules to imply the presence of alpha emitters from a distance. Herein, the use of this phenomenon to remotely image various alpha emitters with unparalleled levels of sensitivity and spatial accuracy is demonstrated. Notably, the system detected a 29 kBq Am-241 source at a distance of 3 m within 10 min. Furthermore, it demonstrated the capability to discern a 29 kBq source positioned 7 cm away from a 3 MBq source at a 2 m distance. Additionally, a 'sandwich' filter structure is described that incorporates an absorptive filter between two interference filters to enhance the ambient light rejection. The testing of the system is described in different lighting environments, including room light and inside a glovebox. This method promises safer and more efficient alpha monitoring, with applications in nuclear forensics, waste management and decommissioning.

Measurement of Naturally-Occurring Radioactive Materials (NORM) using a scintillator-based alpha detector

It is important to differentiate between natural and artificial radioactive materials such as plutonium in nuclear facilities. In this study, a scintillator-based alpha-particle detector was developed using YAP:Ce scintillator and Multi-Anode PhotoMultiplier Tube. The detector was used to measure various naturally occurring radioactive materials (NORM) samples including radon progeny, lead plate, lantern mantle, and radium ceramic ball. The measurement results were compared with Monte Carlo simulation calculations and were found to be in agreement. The energy resolution of the detector is 8.6%FWHM. In the measurement results of radon progeny, peaks of 212Bi (6.1 MeV), 214Po (7.7 MeV), and 212Po (8.8 MeV) can be observed. The lead plate contains 210Po and emits 5.3 MeV alpha particle. The simulation with the same energy was able to reproduce the actual measurement. The results showed the energy and distribution of the alpha particles emitted by the NORM samples. The study successfully demonstrated the capability of the developed alpha-particle detector in identifying NORM.

Determination of the Radioactive Nature of the Sediments of the Bays of the Ebrié Lagoon of Abidjan, Ivory Coast

In Ivory Coast, the lagoons represent the transit point for the majority of continental inputs. They are thus increasingly vulnerable and their ecological balance is rapidly modified under the influence of certain natural or anthropogenic factors. The objective of this study is to evaluate the level of presence of lead 210 in sediments. The sediments were sampled during the campaigns of the National Water Quality Observation Network on the bays spread over thirteen study sites. Analysis by alpha spectrometry was carried out in three stages (mineralization with concentrated acids, self-deposition on a silver disk, counting in an alpha detector with a silicone surface barrier). The highest lead-210 activities were obtained in the bays of Koumassi 1 (228.57 ± 12.21 Bq/kg) and Marcory (198.91 ± 9.46 Bq/kg). However, no seasonal variation in lead-210 contamination of sediments in the bays of Abidjan was observed. We wish to extend this study to other aquatic matrices.

Searching for WIMPs with TREX-DM: achievements and challenges

The TREX-DM detector, a low background chamber with microbulk Micromegas readout, was commissioned in the Canfranc Underground Laboratory (LSC) in 2018. Since then, data taking campaigns have been carried out with argon and neon mixtures, at different pressures from 1 to 4 bar. By achieving a low energy threshold of 1 keV ee and a background level of 80 counts keV-1 kg-1 day-1 in the region from 1 to 7 keV ee , the experiment demonstrates its potential to search for low-mass WIMPs. Two of the most important challenges currently faced are the reduction of both, background level and energy threshold. With respect to the energy threshold, recently a new readout plane is being developed, based on the combination of Micromegas and GEM technologies, aiming to have a pre-amplification stage that would permit very low energy thresholds, close to the single-electron ionization energy. With respect to the background reduction, apart from studies to identify and minimize contamination population, a high sensitivity alpha detector is being developed in order to allow a proper material selection for the TREX-DM detector components. Both challenges, together with the optimization of the gas mixture used as target for the WIMP detection, will take TREX-DM to explore regions of WIMP's mass below 1 GeV c -2.

Characteristics of 210Po in Asian overbite clam (Potamocorbula laevis) from the coastal area at Thai Binh province, Vietnam

210Po concentration in the edible muscle tissue and digestive diverticulum organs of Asian overbite clam at the near-shore Thai Binh, Vietnam was analyzed using alpha detectors. The 210Po activity in muscle tissue and digestive diverticulum organs ranged from 5 ± 1 to 178 ± 10 and from 118 ± 7 to 812 ± 12 Bq.kg−1 with the average value of 25 and 324 Bq.kg−1, respectively. Results showed that 210Po activity in the digestive diverticulum was significantly higher than in the muscle tissue. There was a slightly inverse correlation between 210Po activity in muscle tissue, digestive diverticulum, and clam weight and size. The annual committed effective dose was calculated from 210Po due to the consumption of Asian overbite clam for adults in the study area was higher than the guideline value of 0.2 - 1 mSv.y−1.

Monte Carlo simulation of a simple and fast method to experimentally determine the partial sensitivity of a bare LR-115 detector using planar alpha sources

Partial sensitivity of the bare LR-115 detector (KB) to radon or thoron, or any of their airborne progeny, is an essential component in the detector's calibration factor. Its experimental determination is complex, requires expensive and sophisticated instruments and facilities, and is time consuming. Using the TRACK_TEST and SRIM programs, and Monte Carlo simulations, the possibility of a simple and fast method to determine KB experimentally was demonstrated. The method is based on calculations of the average value of detection efficiencies (i.e., the cumulative efficiency) for alpha particles emitted by a planar alpha source placed at different distances from detectors. Source radius can be estimated from the energy of emitted alpha particles, detector radius, and parameters dependent on etching conditions. Varying the emission energy of alpha particles, the source and detector radii, and the source-detector distance step length, an average value of 0.02 tracks. cm−2 per Bq.d.m−3 (0.22 cm) was obtained assuming standard etching conditions. In addition to alpha electrodeposited sources, sealed sources such as those built with anodized aluminium sheets proved to be suitable for this proposal. Experimentally, KB can be estimated from: track densities registered in detectors exposed at different distances from the source, range of distances that produce visible tracks, and source activity. The developed method is much simpler and faster than the conventional method that uses standard sources of radon and its progeny and large chamber with controlled conditions.

High Energy Solar Particle Events and Their Relationship to Associated Flare, CME and GLE Parameters

AbstractLarge solar eruptive events, including solar flares and coronal mass ejections (CMEs), can lead to solar energetic particle (SEP) events. During these events, protons are accelerated up to several GeV and pose numerous space weather risks. These risks include, but are not limited to, radiation hazards to astronauts and disruption to satellites and electronics. The highest energy SEPs are capable of reaching Earth on timescales of minutes and can be detected in ground level enhancements (GLEs). Understanding and analyzing these events is critical to future forecasting models. However, the availability of high energy SEP data sets is limited, especially that which covers multiple solar cycles. The majority of analysis of SEP events considers data at energies <100 MeV. In this work, we use a newly calibrated data set using data from Geostationary Operational Environmental Satellite‐high energy proton and alpha detector between 1984 and 2017. Analysis of the SEP events in this time period over three high energy channels is performed, and SEP properties are compared to flare and CME parameters. In addition, neutron monitor (NM) observations are examined for the relevant GLE events. We find that correlations between SEP peak intensity and the CME speed are much weaker than for lower SEP energies. Correlations with flare intensity are broadly similar or weaker. Strong correlations are seen between >300 MeV data and GLE properties from NM data. The results of our work can be utilized in future forecasting models for both high energy SEP and GLE events.

Turning Noise Into Data: Characterization of the Van Allen Radiation Belt Using SDO Spikes Data

The Solar Dynamics Observatory (SDO) is a solar mission in an inclined geosynchronous orbit. Since commissioning, images acquired by Atmospheric Imaging Assembly (AIA) instrument on-board the SDO have frequently displayed “spikes,” pixel regions yielding extreme number of digital counts. These are theorized to occur from energetic electron collisions with the instrument detector system. These spikes are regularly removed from AIA Level 1.0 images to produce clean and reliable data. A study of historical data has found over 100 trillion spikes in the past decade. This project correlates spike detection frequency with radiation environment parameters in order to generate an augmented data product from SDO. We conduct a correlation study between SDO/AIA data and radiation belt activity within the SDO's orbit. By extracting radiation “spike” data from the SDO/AIA images, we produce a comprehensive data product which is correlated not only with geomagnetic parameters such as Kp, Ap, and Sym-H but also with the electron and proton fluxes measured by the GOES-14 satellite. As a result, we find that AIA spikes are highly correlated with the GOES-14 electrons detected by the magnetospheric electron detector and energetic proton, electron and alpha detectors instruments at the equator (where the two satellites meet) with Spearman's Correlation values of ρ = 0.73 and ρ = 0.53, respectively, while a weaker correlation of ρ = 0.47 is shown with magnetospheric proton detector protons for the 2 year period where both missions returned data uninterruptedly. This correlation proves that the SDO spike data can be proven useful for characterizing the Van Allen radiation belt, especially at areas where other satellites cannot.

Development of ultralow-background cryogenic calorimeters for the measurement of surface [formula omitted] contamination

Next-generation experiments searching for rare events must satisfy increasingly stringent requirements on the bulk and surface radioactive contamination of their active and structural materials. The measurement of surface contamination is particularly challenging, as no existing technology is capable of separately measuring parts of the 232Th and 238U decay chains that are commonly found to be out of secular equilibrium. We will present the results obtained with a detector prototype consisting of 8 silicon wafers of 150 mm diameter instrumented as bolometers and operated in a low-background dilution refrigerator at the Gran Sasso Underground Laboratory of INFN, Italy. The prototype was characterized by a baseline energy resolution of few keV and a background <100 nBq/cm2 in the full range of α energies, obtained with simple procedures for cleaning of all employed materials and no specific measures to prevent recontamination. Such performance, together with the modularity of the detector design, demonstrate the possibility to realize an alpha detector capable of separately measuring all alpha emitters of the 232Th and 238U chains, possibly reaching a sensitivity of few nBq/cm2.

Novel optical technologies for emergency preparedness and response: Mapping contaminations with alpha-emitting radionuclides

Radiological emergencies involving an accidental or deliberate dispersion of alpha-emitting radionuclides in the environment can cause significant damage to humans and societies in general. Currently, there is a metrology gap in managing such emergencies due to the lack of detectors that can measure alpha particles at distances greater than their range in air: most conventional alpha detectors are only effective when placed just a few centimeters above the contaminated area. This paper presents the development and testing of lens based optical detection systems that utilize alpha particle-induced ultraviolet (UV) luminescence of air, known as alpha radioluminescence. Telescopes based on fused silica and Poly(methyl 2-methylpropenoate) (PMMA) Fresnel lenses were investigated for their usability in facilitating emergency management related to alpha-emitting radionuclides. Careful matching of the diameter and focal length of the receiving optics, the response of the photocathode, and the passband of the filter allows detection sensitivities as high as 34s−1MBq−1 at 2m source-to-detector distance and background count rate of about 3s−1 in the UV-C spectral region, and suppression of daylight background count rate down to 16s−1. By flushing the source with nitrogen (N2) containing trace amounts of nitric oxide (NO), a groundbreaking sensitivity of 1.3×105s−1MBq−1 has been achieved, allowing detection limits as low as 100Bq with room lighting on, and 70Bq in a dark environment. In the UV-A spectral region, a detection limit of 4kBq could be achieved in a dark environment. These optical detection systems are aimed to facilitate a rapid, coordinated, and effective response in emergency situations involving the release of alpha-emitting radionuclides by mounting them on a tripod or an unmanned aerial device (UAV).

Removal of Radioactive Gas by Zeolite Filter From Nuclear Power Plants

During the normal operation of nuclear power plants, some radioactive wastes are produced in the form of particles or aerosol gas in the reactor building. Particulate radioactive aerosols can be produced in a wide variety of particle sizes, possibly in combination with non-radioactive aerosols. Emission of corrosion products and fission products that are activated by the effect of nuclear rays generate aerosols from two sources. These; are created by the adsorption of gases generated by radioactive decay and volatile radionuclides formed during the fission process on the present suspended material. The most important volatile radionuclides that form the gaseous radioactive waste produced during the normal operation of nuclear power plants are halogens, noble gases, tritium, and carbon-14. The composition and amount of radioactivity present in the various airborne waste streams depend largely on the reactor type and release path. All gaseous waste from nuclear power plants must be treated before discharging into the atmosphere. In this paper, radioactive radon gas was used to represent the radioactive gases generated from nuclear power plants and natural zeolite was used as adsorbent material for radon removal. A series of experiments were conducted to measure the performance of the filter made in the zeolite. First of all, an approximate particle distribution size in the range of 1 to 3 mm was obtained by grinding natural zeolite. The ground material was then compressed in cylindrical adsorbent moulds of 35 mm diameter and 10 mm height. After the moulds were filled with the material, they were dried by heating to 110 ° C for 24 hours. At the end of the heat treatment, the adsorbent beds were cooled and connected to the test apparatus. RAD7 radon test device was used in the experiments. The RAD7 is a portable instrument that uses a solid-state alpha detector to measure radon gas concentrations in the range of 4.0-750,000 Bq / m3. The sampler of the RAD7 device works by drawing an air sample from an inlet filter into a 0.7 L sample cell covered with an electrical conductor. At the centre of the hemisphere, the cell is a planar silicon detector implanted with an ion to measure radioactivity. As result of the experiments, it shows that the zeolite filter absorbs 85% radioactive radon gas and can be used as an air filter in nuclear power plants.

Radon dosimetry using Solid State Nuclear Track Detectors in different environments: a review

Radon and its progeny are the major cause of natural radiation emission and its activity concentration is measured by alpha detectors, such as Solid-State Nuclear Track Detector (SSNTD). This work aims to present the applications of CR-39-type SSNTD according to the Natural Radiation Laboratory (LRN) and reports in the literature, aiming to ensure the radioprotection of public and occupationally exposed individuals in indoor and outdoor environments. Therefore, it was reinforced that CR-39 is an important detector for radon radioprotection and dosimetry.

The Characterisation of an Alpha Spectrometry System using a Certificated Standard Source

The calibration parameters of a high resolution two-chamber alpha spectrometer dedicated to detect alpha radiation in environmental samples were evaluated and confirmed using a certified standard source containing 237Np, 241Am and 244Cm nuclides. The resolution and efficiency characteristics for the two ion-implanted solid state detectors (ULTRA AS series) in this system were evaluated at all possible detector-source distances. The characteristics related to the performance of alpha detectors against the alpha radiation emitted from the standard source used in the measurements and the results obtained were compared in detail.

Study of the natural radioactivity of ore deposits

In the article, the authors present experimental data on the specific power equivalent dose (EDR) of radiation gamma, beta, and alpha radiation in samples containing copper, zinc and lead of pyrite-polymetallic ores, which were mined at the Zhezkent mining and processing plant (The East Kazakhstan region, Borodulikhinsky district). The measurements were carried out by dosimeters and radiometers "RKS-01-SOLO" with alpha, beta and gamma scintillation detectors. For ores, the dependences of the specific power of the equivalent dose of gamma radiation on the content of various concentrations of copper, zinc and lead were revealed. The analysis of natural decay chains, the daughter products of which are stable isotopes of copper and zinc, is carried out. A relationship has been proposed between the concentrations of nickel, copper, lead and EDR, which gives prospects for further spectrometric studies of these samples to identify the corresponding lines of accompanying gamma radiation during decays of radionuclides contained in the samples under study and radiation conversion of stable isotopes. The results of this work will make it possible to build a model for studying the radiation of ores, the distribution of natural radionuclides in the earth's crust, which will undoubtedly provide prerequisites for the verification and clarification of the sources and mechanisms of emanation and coagulation of radon isotopes, which form the natural radiation background of the surface atmospheric layer.

Radon concentration measurement in water reservoirs for some areas of north Baghdad by RAD7

Radon is a naturally occurring, odorless, colorless, radioactive, tasteless, and noble gas. Radon concentrations have been measured by the usage of alpha spectroscopy (RAD-7). The RAD-7 measuring process is based on detecting alpha particles produced from the disintegration of radon and its products using a solid-state alpha detector (usually silicon), and then converting alpha radiation directly to an electrical signal. The radioactivity of radon gas was measured in forty-two samples from reservoir water for different areas north of Baghdad utilizing a RAD7 detector. This study proved that the high value of radon concentrations was less than the permissible limit as recorded by the World Health Organization.

Monte Carlo modeling of scintillation detectors for continuous underground radon monitoring

Nuclear simulation methods were applied to two systems that investigate radon transport within geological porous media: a) a laboratory system built to test, under controlled climate conditions, the effect of temperature on radon transport, and b) a field monitoring system comprising gamma and alpha detectors in an abandoned water well. The use of Monte Carlo simulations of NaI and BGO scintillation detectors in continuous underground radon measurements by gamma counting, to estimate the photon flux in the detector volume, is presented.The advantages of shielding side-view NaI detectors were demonstrated for a laboratory system containing ground phosphate rock, including avoiding high counting rates and reducing the effective source volume in radon transport studies. The gross gamma counting procedure was shown to result in a lower uncertainty than spectrometric measurement, by at least a factor of two, despite it being a simpler and more suitable procedure for field measurements.The calculation of simulated source volumes for a BGO detector in a borehole and the measurements in the field support the assumption that the gamma signal comes primarily from radon flowing in the bedrock's air-filled pores. As a practical outcome of this study, positioning the detector a few cm off-center from the borehole's axis increased the gamma counting efficiency; however, measurements in groundwater taken too close to the iron casing had a lower detection efficiency.The conversion factor from the scintillator signal to the radon activity concentration, for the laboratory system, was calculated. Monte Carlo simulations demonstrated the advantages of the gross counting procedures using gamma scintillation detectors in field underground high-frequency radon monitoring.

Neutron-Stimulated Gamma Ray Measurements for Chlorine Detection

Applications of neutron-gamma analysis for chlorine determination in different materials (e.g., solids, aqueous solutions, and surface contaminations) are discussed. Solid samples were measured with a pulsed fast/thermal neutron analysis (PFTNA) system consisting of a pulsed neutron generator and sodium iodide gamma detectors and an associated particle imaging (API) system consisting of a neutron generator (with a built-in alpha detector) and sodium iodide gamma detector; all sample measurements were made under similar conditions (neutron flux values and detector-side area for crossing gamma flux). The advantages of PFTNA over the API method were demonstrated based on comparison of metrological parameters (i.e., minimal detectible level for a 1-h measurement period and clock time required to reach 5% measurement accuracy). For these reasons, the PFTNA system in scanning mode effectively identified areas of artificial chlorine contamination in the field. Paired with GPS, a chlorine contamination map was created from PFTNA scanning results; this map accurately identified the actual position and size of chlorine contaminated locations in the field. Chlorine-contaminated areas of ~4.5 m2 were effectively located within the ~500 m2 field during a ~2-h scanning period. Based on the results from this work, promising directions for further application of the PFTNA method are disclosure of chlorine contamination in soil and measurements of marine water salinity.

An all-digital associated particle imaging system for the 3D determination of isotopic distributions.

Associated particle imaging (API) is a non-destructive nuclear technique for the 3D determination of isotopic distributions. By detecting the alpha particle associated with the emitted neutron in the deuterium-tritium fusion reaction with a position- and time-resolving detector, the direction of the 14.1MeV neutron and its time of emission can be determined. Employing this method, isotope characteristic gamma rays emitted in inelastic neutron scattering events can be correlated with the neutron interaction location. An API system consisting of a sealed-type neutron generator, gamma detectors, and a position-sensitive alpha detector was designed, constructed, and characterized. The system was tested with common soil elements and shown to be sensitive to 12C, 16O, 28Si, 27Al, and 56Fe. New aspects of our approach are the use of a yttrium-aluminum-perovskite scintillator, using a sapphire window instead of a fiber-optic faceplate for light transport to the photomultiplier, and the all-digital data acquisition system. We present a description of the system with simulations and experimental results that show a position resolution on the alpha detector of 1mm, a depth resolution using a LaBr3 detector of 6.2cm, and an angular resolution of 4.5°. Additionally, we present single-element gamma response measurements for the elements mentioned above together with a comparison to Monte Carlo simulations (MCNP6).