Alpha-particle Counting Research Articles

Counting alpha particles produced by radon daughters using commercial off-the-shelf complementary metal oxide semiconductor (COTS CMOS) image sensors

Radon (Rn-222) is the main source of radiation exposure to human beings from natural radiation; it is of great significance to study the measuring methods and measuring instruments of radon for natural radiation protection. In recent years, the application of pixel detectors in radiation detection has attracted attention. In this paper, a Commercial Off-the-Shelf Complementary Metal Oxide Semiconductor (COTS CMOS) image sensor which replaces the glass for protection covering in front of the sensors was used to perform a series of measurements to identify alpha particles. During the experiment, the CMOS image sensor was used to record a video during the sampling period, and then use the FFmpeg software to take screenshots of the video by frame. MATLAB was used to count bright spots from the image frames. A measurement chamber was designed to measure radon concentrations, and when the relative humidity was constant, the count of alpha particles by the CMOS image sensor increased along with the increase of the concentration. The experiments verified the feasibility of the low-cost COTS CMOS image sensors to monitor radon.

A new approach to measure radon by Thick Gas Electron Multiplier

In this article, a novel approach to the use of the Micro Pattern Gas Detector (MPGD) to detect the radon gas contamination in air is presented. It consists in operating the Thick Gas Electron Multiplier (THGEM) in Self-Quenched Streamer (SQS) mode. This detector works based on counting alpha particles emitted from radon and its short-lived daughters, Po-218 and Po-214. If this detector is compared to a scintillation detector, its THGEM can be considered as a scintillator and conventional light sensors as photomultipliers or sensitive photodiodes. A laboratory layout of the recommended system was designed to measure radon concentration in air based on measuring the alpha emitted of radon and its short-lived daughters. One of the advantages of this detector over the scintillation and semiconductor detectors is a vast sensitive surface (5*5 cm2) uninfluenced by noises and background rays. The practical results show that this recommended detector uninfluenced by background rays has a very low limit of detection about zero. Consequently, this detector can measure very low radon gas concentrations in the air.

Standardisation of 241Am activity for a key comparison

The JRC applied six measurement techniques to standardise the activity of an 241Am solution in the frame of the 2003 key comparison CCRI(II)-K2.Am-241. The methods used were alpha-particle counting at a defined small solid angle, high-efficiency particle and photon counting with a windowless 4π CsI(Tl) sandwich spectrometer, 4π alpha counting with a pressurised proportional counter, alpha-gamma coincidence counting and sum counting with a small pressurised proportional counter and a NaI(Tl) well detector, and 4π counting with a liquid scintillation counter. All results were consistent and an unusually low measurement uncertainty of 0.054% was achieved. An overview is presented of the outcome of the key comparison exercise, which demonstrates international equivalence.

The study of determining the levels of radon gas concentrations (soil, water and plants) in the areas exposed to military operations in Suq Al-Shuyoukh district, south of Thi-Qar province, Iraq

In this study, the radon concentration of Al-Khamisiyah (A) stores and the adjacent residential areas (Al-Twirat area (B), and the Al-Khamisiyah (C) residential area) located in the southwest of Dhi Qar governorate were measured by five samples for each area for the study models (soil, water, Plants) by using the alpha particle counting technique emitted from radon in the nuclear trace detector (CR-39). The study included three parts, the first part is to measure the radon concentration in samples from the soil and with depths of 60 cm, 15cm, 2cm)) for areas (A, B, C) where the highest concentration was at 2cm depth and the lowest concentration was at the depth 60cm and for all study areas, the highest concentration was in Region A, for all depths, and the lowest concentration in region B. The second part included determining the concentrations of radon gas in the waters of passing rivers in regions (A, B, C), where the highest concentration was in area A and the lowest concentration in region B. As for the third part, it included determining radon concentrations in some types of plants that grow in those regions (A, B, C) such as reeds, sedge and brains, where the highest concentration was in the reed plant and the lowest concentration in the clematis plant and for all areas of study. Finally, we would like to point out that the current study is considered one of the important and vital studies because it is related to the health and safety of humans.

243Am certified reference material for mass spectrometry

The Joint Research Centre, in cooperation with the Commissariat à l’Energie Atomique et aux Energies Alternatives, produced a novel 243Am spike reference material for mass spectrometry. Americium solution with an isotopic composition of 88% 243Am and 12% 241Am was used as the source for the preparation of the spike material. The certified value of 5.696 (11) nmol g−1 for the amount content of 243Am and 0.136138 (54) for the n(241Am)/n(243Am) amount ratio were assigned. The assigned values from mass spectrometry were confirmed by alpha-particle spectrometry, alpha-particle counting at a defined solid angle, and high-resolution gamma-ray spectrometry. Furthermore, an external validation of the certified values was obtained from the results of an interlaboratory comparison exercise, using this americium reference solution as the test sample.

Absolute and relative measurement of the 243Am half-life

The half-life of 243Am has been measured by an absolute and a relative method, i.e. by determining the specific activity of 243Am and the specific activity ratio with 241Am. A mixed 241,243Am reference material was produced and certified for its americium mass content and its isotope amount ratios. The characterisation of the mass content of 243Am was established by isotope dilution mass spectrometry using an 241Am spike, produced from highly enriched 241Pu material. The isotope amount ratios n(241Am)/n(243Am) and n(242mAm)/n(243Am) were measured by thermal ionisation mass spectrometry. Activity measurements were performed by alpha-particle counting at a defined solid angle, as well as high-resolution alpha-particle spectrometry. From the 243Am/241Am activity and isotopic amount ratios, a value of 16.988 (24) was derived for the 243Am/241Am half-life ratio. Using a value of 432.6 (6) a for the 241Am half-life, the corresponding 243Am half-life value, 7349 (15) a, is in good agreement with the result obtained from the absolute method, 7342 (14) a. The mean value, 7345 (14) a, agrees well with data from literature and lowers the relative standard uncertainty to 0.2%.

Gross Alpha-Based Continuous Air Monitor: Mathematical Modeling, Measurements, and Interpretation

The detection and measurement of transuranic activity in ambient air by counting alpha particles is confounded due to the presence of short-lived alpha-emitting isotopes due to radon and thoron. This paper describes an algorithm intended for use in a gross alpha-based continuous air monitor. The algorithm is capable of generating the variation of gross alpha count rate with time from air filter samples using in situ–measured radon progeny data. The required input of atom concentration can be obtained from a simple experimental technique, which is discussed here.

A nappies management by-product for the treatment of uranium-contaminated waters

The direct disposal of municipal solid waste such as nappies to the environment may create serious pollution problems. Based on the circular economy and waste management concepts, the conversion of nappies and/or their ingredients (such as super absorbent polymer (SAP)) to high added value products is of great importance. In this work, a modified SAP (MSAP) was examined as an adsorbent for treatment of contaminated waters and uranium recovery. Batch experiments and spectroscopic techniques were used to examine the effect of various parameters (pH, contact time, temperature, initial concentration, and ionic strength), and the mechanism of adsorption U(VI) and desorption process. The U(VI) concentration was determined by alpha spectroscopy after addition of 232U standard tracer solution to account for possible interferences during electrodeposition and alpha particle counting. The maximum adsorption monolayer capacity was found to be 217.4 mg/g at pH 4.0 and at 298 K. The adsorption of U(VI) on MSAP seems to occur mainly via the formation of inner-sphere surface complexes between U(VI) and the carboxylic surface moieties of MSAP. The MSAP could satisfactorily be regenerated with 0.1 M Na2CO3 (>90%) and it also shows a promising applicability to real wastewaters contaminated with U(VI).

Quantitative imaging of 226Ra ultratrace distribution using digital autoradiography: Case of doped celestines

The ability of the autoradiographic device BeaQuant™ is evaluated herein to quantitatively map the ultratrace element 226Ra distributed spatially in celestine (SrSO4) grains/crystals. 226Ra doped celestines have been obtained from coprecipitation and recrystallization experiments, and have been characterized with high purity germanium gamma detector (HPGe), giving specific activities ranging from 3251 to 32523 Bq.g−1. Alpha autoradiographs of polished sections from doped celestines have been obtained using BeaQuant™. These alpha maps have been compared to the celestine grains/crystals arrangement observed with a scanning electron microscope (SEM). At the sample scale, celestine grains are responsible of an alpha signal, indicating that 226Ra is detectable in celestine from its alpha emissions. 226Ra distribution has also been investigated at the celestine grains/crystals scale: the crystal/grain properties do not allow to decide if the distribution process is homogeneous or not, i.e. if there is a chemical zoning into the crystal/grain. The counting of alpha particles by autoradiography has been compared with the total activity of the 226Ra doped celestines by gamma counting (HPGe technique). This comparison was performed by standardizing the measured activities to the same celestine volume, which has been determined by performing a threshold on SEM grey level images to assess to the celestine surface and using Geant4 Monte Carlo simulation toolkit to assess to the emission depth of the particles in celestine. A very good linear correlation between gamma activity and alpha counting from autoradiographs is obtained for all the samples, demonstrating the ability of BeaQuant™ to quantify 226Ra in any points of the millimetric section samples, at a resolution of 20 μm.

Alpha spectrometry with the inexpensive open-source detector Alphaino

Abstract A photodiode-based inexpensive detector working as counter and spectrometer for alpha particles , named Alphaino , is described and analyzed in depth. Prior to detector construction, Monte Carlo simulations by means of MCNPX ver. 2.7.0 code have been carried out to select the most suitable sensitive element for the intended applications. The detector has been tested for low-rate alpha-particle counting and spectroscopy , demonstrating a maximum achievable count rate of 4 ⋅ 1 0 3 s−1, with an energy resolution corresponding to a Full Width Half Maximum of 160 keV over the entire energy range of measured alpha, namely 4 − 6 . 5 MeV, the intrinsic efficiency being 100%. Alphaino can be used for fast and qualitative analyses to radionuclides identification, and quantitative analyses when radionuclides monitored are characterized by well distinguished energy lines in spectra. Its applications will include 222 Rn progeny monitoring by mechanical air sampling on a millipore filter, and disposable applications to qualitative measuring of potentially alpha-contaminated liquids (containing plutonium isotopes) by a droplet put on the photodiode itself, for a quick and cheap evaluation prior to initiate proper chemical treatments to classical alpha spectrometry by electrodeposition . Alphaino is completely open-source. The repository for the project is available on GITHUB at https://github.com/bemxgm/Radon-Monitor .

An experimental cross-section measurement of 10B(n,α)7Li reaction on counting alpha particles track density

The present work determines the particle size based only on the number of tracks detected in a cluster created by a hot particle on the CR-39 solid state nuclear track detector and depending on the exposure time. The mathematical model of the cross section developed here gives the relationship between alpha particle emitting from the (n, α) reaction and the number of tracks created and distribution of tracks created on the surface of the track detector. In an experiment performed during this work, disc of boron compound (boric acid or sodium tetraborate) of different weights were prepared and exposed to thermal neutron from the source. Chemical etching is processes of path formation in the detector, during which a suitable etching solution attacks the detector at a sufficient speed and the damaged regions along the ion trails (latent track) are preferentially dissolved, removed and get transformed into a hollow channel. The most common etching for plastics is the aqueous solutions of NaOH and temperatures in between 50˚C - 80˚C.The program (CR-39) processing counting and calculations only take place depending on the number of tracks.

Measurement of absolute γ-ray emission probabilities in the decay of 227Ac in equilibrium with its progeny

The emission probabilities of γ rays produced in the 227Ac decay series were determined by high-resolution γ-ray spectrometry of sources with standardised activity. The sources were prepared quantitatively on glass discs by drop deposition of a solution with 227Ac in radioactive equilibrium with its daughter nuclides. Their activity was measured by a primary standardisation technique based on alpha-particle counting at a defined low solid angle. Four laboratories performed γ-ray spectrometry and derived absolute γ-ray intensities. Mean values were calculated and compared with literature data and the currently recommended evaluated data. New values on certain γ-ray emission probabilities are proposed.

RADIONUCLIDE AND MAJOR ELEMENT ANALYSIS OF THERMAL AND MINERAL WATERS IN CROATIA WITH A RELATED DOSE ASSESSMENT.

Major elements concentrations (Na, K, Ca, Mg) and the activity concentrations of 226,228Ra, 234,238U, 210Po, 210Pb, 40K and 137Cs in northern and eastern Croatian thermal and mineral waters, collected directly from springs (or wells), are presented herein with total effective doses assessed for those waters that are considered as drinking 'cures' and are available for consumption. The methods used for radionuclide determination included alpha-particle spectrometry, gas-proportional counting and gamma-ray spectrometry, while the major element composition was determined by ICP-MS. The activity concentrations of all of the radionuclides were found to be below the guidance levels set by the WHO and EC Directive, with the exception of one water sample that measured 0.26 Bq L-1 of 228Ra. The effective ingestion dose assessment for the consumption of the so-called water 'cures' during 1, 2 or 4 weeks' time period throughout 1 year was well below the recommended 0.1 mSv for drinking water.

Identification of 210Pb and 210Po in the bulk of copper samples with a low-background alpha particle counter

We established a method to assay 210Pb and 210Po contaminations in the bulk of copper samples using a low-background alpha particle counter. The achieved sensitivity for the 210Pb and 210Po contaminations reaches a few mBq/kg. Due to this high sensitivity, the 210Pb and 210Po contaminations in oxygen free copper bulk were identified and measured for the first time. The 210Pb contaminations of our oxygen free copper samples were 17–40 mBq/kg. Based on our investigation of copper samples in each production step, the 210Pb in oxygen free copper was understood to be a small residual of an electrolysis process. This method to measure bulk contaminations of 210Pb and 210Po could be applied to other materials.

Measurement of absolute γ-ray emission probabilities in the decay of 235U

Accurate measurements were performed of the photon emission probabilities following the α decay of 235U to 231Th. Sources of highly enriched 235U were characterised in terms of isotopic composition by mass spectrometry and their activities were standardised by means of alpha-particle counting at a low defined solid angle. The standardised sources were subsequently measured by high-resolution γ-ray spectrometry with calibrated high-purity germanium detectors to determine the photon emission probabilities. Four laboratories participated in this work and reported emission probabilities for 33 γ-ray lines. Most of them agree with previously published evaluated data. In addition, new values are proposed for γ-lines which have been measured only once in the past.

Preparation and optimization of CdWO4-polymer nano-composite film as an alpha particle counter

In this research work, CdWO4/polymer composite films with different thicknesses were prepared using Poly-methyl acrylate polymer and synthesized CdWO4 powder. The CdWO4 powder was synthesized by a simple co-precipitation method in the laboratory. X-ray diffraction, photoluminescence, Fourier transformed infrared spectroscopy and energy-dispersive X-ray spectroscopy proved that the CdWO4 powder was successfully prepared. Moreover, photoluminescence analysis showed that adding polymer does not change the emission peak of CdWO4. Also, the responses of all samples were measured using an 241Am alpha source with 1860Bq activity. Results showed that the sample having thickness of 177mg/cm2 has the best counting efficiency (over 2π geometry) among the others. The efficiency measurement was further evaluated using a 230Th source whose activity is 190.7Bq. It revealed that the counting efficiency of this sample for both 241Am and 230Th was nearly equal.

Design of an alpha-particle counting system at a defined solid angle at Turkish atomic energy authority-Sarayköy nuclear research and training center (TAEK-SANAEM)

Abstract The design details of an alpha-particle counting set-up at a defined solid angle (ACS-DSA) constructed in Radionuclide Metrology Department at TAEK-SANAEM for use in the primary standardization of radioactive solutions and determination of nuclear decay data of alpha-particle emitters is presented. The counting system is designed such that the solid angle is very well-defined and directly traceable to the national standards. The design involves mechanical construction of different parts like the source chamber, various coaxial flanges, and circular diaphragms in front of the passivated implanted planar silicon (PIPS®) detector, distance tubes, a digital caliper and a sliding piston to allow for different measurement configurations. All geometric configurations are easily changeable and characterisable with high accuracy which facilitates the solid angle calculation. A mixed alpha source was counted to check performance of assembled ACS-DSA system and good energy resolution and low peak tailing in the alpha energy spectrum was observed for small diaphragm apertures and far source-to-detector geometries.

Multi-layer 235UF4–6LiF–Au targets for high-resolution fission fragment measurements

Multi-layer 235UF4–6LiF–Au targets have been produced by vacuum deposition on thin polyimide foils with an areal density, measured by spectrophotometry, of about 33µgcm−2. The foils were first covered with an Au-layer and then, with a second layer of 6LiF, both by vapour deposition. The 235UF4 layer was prepared by fluoride sublimation. Each deposited mass was characterized separately by means of differential weighing for the Au and 6LiF layers and by low-geometry alpha-particle counting for the 235UF4 layer. The atomic abundances of the uranium base material have been measured by thermal ionization mass spectrometry. The targets were prepared for measuring fission-fragment emission yields with high mass-resolution.

Selected Topics in Ultra-Low Emissivity Alpha-Particle Detection

In an effort to better understand the contribution of terrestrial protons to the counter background, we have developed a model to examine the production of protons, within an ionization counter from the interaction of incident neutrons on the counter material. Results of high energy proton irradiation on an UltraLo-1800 XIA alpha-particle counter are shown which indicate that the active signal discrimination is very effective at rejecting most of the detected events. A Poisson model is described which gives guidance on making appropriate measurement times and acceptance criteria for detectors with a range of backgrounds.

Simulation of neutron production using MCNPX+MCUNED

In standard MCNPX, the production of neutrons by ions cannot be modelled efficiently. The MCUNED patch applied to MCNPX 2.7.0 allows to model the production of neutrons by light ions down to energies of a few kiloelectron volts. This is crucial for the simulation of neutron reference fields. The influence of target properties, such as the diffusion of reactive isotopes into the target backing or the effect of energy and angular straggling, can be studied efficiently. In this work, MCNPX/MCUNED calculations are compared with results obtained with the TARGET code for simulating neutron production. Furthermore, MCUNED incorporates more effective variance reduction techniques and a coincidence counting tally. This allows the simulation of a TCAP experiment being developed at PTB. In this experiment, 14.7-MeV neutrons will be produced by the reaction T(d,n)(4)He. The neutron fluence is determined by counting alpha particles, independently of the reaction cross section.