Alpha Particles In Air Research Articles

Registration of alpha particles using CR-39 nuclear detector

The use of CR-39 as a fast alpha particles detector using a new etching condition have been optimized. 241Am source was used for irradiating CR-39 detectors with alpha particles in air at normal pressure and temperature. A chain of experimental work has been carried out using new etchants to register alpha particle in short time. The chemical etching parameters, etching time, temperature and etchant have been investigated. The etching efficiency, the sensitivity and the critical angle were exhibited a clear dependence on the amount of 2- propanol in the etching solution. The optimized chemical condition obtained at this stage of development for CR-39 detectors are (10 ml of 10 N NaOH + 0.5 ml 2-C3H7OH) etching solutions. Consequently, the suggested new etchant can be developed for neutrons, fission fragments and heavy ions detection. Results of the irradiation of CR-39 detector with alpha particles along with studding the etching characteristics of track detector have been addressed and through discussed.

Experimental Study of the Pressure Effects on Stopping Power for Alpha Particles in Air

This paper is to investigate stopping power of α-particles in air at various pressure of 0 to 1 bar, using a surface barrier silicon detector. The energy loss has been obtained at a different distance from 0 to 10 cm. It was found that the energy of the passed α-particles has been decreased in a small vacuum chamber with increasing pressure. It is also studied that the amount of α-particles reaching the detector follows a decreasing behavior as the distance increases. The result of stopping power was compared with ICRU and SRIM result. Experimental, ICRU and SRIM results for stopping power are closely in good agreement.

Obtaining the Bragg curve using a low-cost detector

The Bragg curve has special significance for modern medicine. The pronounced peak of energy loss at the end of the heavy charged particle path in matter allows tumors to be treated more accurately with protons and other heavier ions beams. In order to use simple devices to experimentally illustrate the principles involved in the charged particle energy loss in matter, we present how to build a low-cost detector to study the loss of energy of alpha particles in air and obtain the Bragg curve.

A theoretical and experimental investigation of Bragg's rule for energy-loss straggling in low mean energy loss regime in air and its constituents

A theoretical and experimental investigation of Bragg's rule in low energy loss region where charge exchange straggling can be ignored is presented. Energy-loss straggling of 5.486 MeV alpha particles in air and 5N purity constituent gases was measured using high-resolution alpha spectroscopy system. Measured values are compared with Bohr, Bethe-Livingston and Yang et al. formulations. An experimental investigation of Bragg's rule to estimate the energy-loss straggling in air using the experimental data of constituents is discussed.

Study on ZnS(Ag) for alpha spectrometer using silicon based photo sensor

The measuring of alpha particles is essential in many research fields such as radiation safety, health science, high energy, and nuclear physics. One of the most hazardous background radiation sources, radon, emits alpha particles, and damages lungs. Thus, the measurement of alpha particles in air correlates with the amount of radon and indicates when to ventilate the air. To detect alpha particles decayed from radon, a silicon photon multiplier (SiPM) in the shape of a multipixel photon counter (MPPC) and a scintillator optimized for zinc sulfide phosphor [ZnS(Ag)] alpha measurement were used. In this study, a dedicated amplifier was designed. The change in the pulse shape owing to operational amplifier, feedback resistor, and capacitor affect were studied and compared to that of a photo multiplier tube (PMT).

Energy straggling and an experimental investigation of Bragg's rule for 241Am alpha particles in air and its constituents

We present here energy straggling data for alpha particles from 241Am in air and its constituents, and an experimental investigation of Bragg’s rule. High resolution alpha spectroscopy system from ORTEC with an ultra-thin source, an ion implanted thin entrance window detector of small diameter, and state of the art counting electronics with a 4096 MCA is used. In the controlled experimental environment gases of 5N purity are used to measure energy straggling. Measured values are compared with the theoretical predictions of Bohr, Bethe-Livingston, Titeica and Yang et. al. An experimental investigation on using Bragg’s rule to estimate the energy straggling in air from the experimental obtained data of constituents is presented.

Rn progeny diffusion, deposition and track distribution in diffusion chamber with permeable membrane

Objective of this work is to define method by which sensitivities of CR-39 and LR-115 in diffusion chamber could be determined. Method is based on initial physical processes that occurs in diffusion chamber: diffusion, deposition and decay of radon (isotopes 222Rn and 220Rn) and their progeny. Cylindrical shape of chamber was considered due to availability of experimental data for validation of presented method. The shape was not limitation factor and can be extended to any geometry. Diffusion equations for radon in two mediums (membrane and chamber volume) and their progeny in volume were solved using Finite Difference Method – FEM, and solutions are their spatial distributions inside of diffusion chamber. Calculation of flux towards the chamber walls determine distribution pattern and deposited progeny fractions. It has been shown that volume and deposited distributions are not uniform. Visible tracks on CR-39 for defined etching conditions are determined by considering range of alpha particles in air and empirical critical angle function θC=θC(E). For LR-115 mean critical angle of 〈θc〉=500 and energy window from Emin=1.7MeV to Emax=4.2MeV was adopted from literature to determine number of visible tracks. The track density distributions on detector are found to be non-uniform and radially dependent.Thickness of permeable membrane has important influence on presence of thoron and its progeny tracks on detector. Sensitivities of CR-39 and LR-115 in diffusion chamber were determined using method presented in this work and compared with other theoretical models and experiment with good agreement. This shown applicability of the presented method.One of important conclusion is that detector sensitivity, given as one simple number, is not the best parameter for calibration due to the existence of radial variation of track density.For cylindrical chamber with 10cm length and 4cm radius, covered with membrane in form of one-layer filter paper 0.25mm thickness, and for equal concentrations of 222Rn and 220Rn in front of the chamber, contribution of 220Rn and its progeny to total track density is about 3%.

The Effect of Gamma and Beta Radiation on a UVTRON Flame Sensor: Assessment of the Impact on Implementation in a Mixed Radiation Field.

Due to the short path length of alpha particles in air, a detector that can be used at a distance from any potential radiological contamination reduces the time and hazard that traditional alpha detection methods incur. This would reduce costs and protect personnel in nuclear power generation and decommissioning activities, where alpha detection is crucial to full characterisation and contamination detection. Stand-off alpha detection could potentially be achieved by the detection of alpha-induced radioluminescence, especially in the ultraviolet C (UVC) wavelength range (180–280 nm) where natural and artificial background lighting is less likely to interfere with detection. However, such a detector would also have to be effective in the field, potentially in the presence of other radiation sources that could mask the UVC signal. This work exposed a UVC sensor, the UVTRON (Hamamatsu, Japan) and associated electronics (driver circuit, microprocessor) to sources of beta and gamma radiation in order to assess its response to both of these types of radiation, as may be found in the field where a mixed radiation environment is likely. It has been found that the UVTRON is affected by both gamma and beta radiation of a magnitude that would mask any UVC signal being detected. 152Eu generated 0.01 pulses per second per Bq through beta and gamma interactions, compared to 210Po, which generates 4.72 × 10−8 cps per Bq from UVC radioluminescence, at 20 mm separation. This work showed that UVTRON itself is more susceptible to this radiation than the associated electronics. The results of this work have implications for the use of the UVTRON as a sensor in a stand-off detection system, highlighting the necessity for shielding from both potential gamma and beta radiation in any detector design.

Alpha Particle Detection Using Alpha-Induced Air Radioluminescence: A Review and Future Prospects for Preliminary Radiological Characterisation for Nuclear Facilities Decommissioning.

The United Kingdom (UK) has a significant legacy of nuclear installations to be decommissioned over the next 100 years and a thorough characterisation is required prior to the development of a detailed decommissioning plan. Alpha radiation detection is notoriously time consuming and difficult to carry out due to the short range of alpha particles in air. Long-range detection of alpha particles is therefore highly desirable and this has been attempted through the detection of secondary effects from alpha radiation, most notably the air-radioluminescence caused by ionisation. This paper evaluates alpha induced air radioluminescence detectors developed to date and looks at their potential to develop a stand-off, alpha radiation detector which can be used in the nuclear decommissioning field in daylight conditions to detect alpha contaminated materials.

First Results of Using a UVTron Flame Sensor to Detect Alpha-Induced Air Fluorescence in the UVC Wavelength Range.

In this work, a robust stand-off alpha detection method using the secondary effects of alpha radiation has been sought. Alpha particles ionise the surrounding atmosphere as they travel. Fluorescence photons produced as a consequence of this can be used to detect the source of the alpha emissions. This paper details experiments carried out to detect this fluorescence, with the focus on photons in the ultraviolet C (UVC) wavelength range (180–280 nm). A detector, UVTron R9533 (Hamamatsu, 325-6, Sunayama-cho, Naka-ku, Hamamatsu City, Shizuoka Pref., 430-8587, Japan), designed to detect the UVC emissions from flames for fire alarm purposes, was tested in various gas atmospheres with a 210Po alpha source to determine if this could provide an avenue for stand-off alpha detection. The results of the experiments show that this detector is capable of detecting alpha-induced air fluorescence in normal indoor lighting conditions, as the interference from daylight and artificial lighting is less influential on this detection system which operates below the UVA and UVB wavelength ranges (280–315 nm and 315–380 nm respectively). Assuming a standard drop off in signal, the limit of detection in this configuration can be calculated to be approximately 240 mm, well beyond the range of alpha-particles in air, which indicates that this approach could have potential for stand-off alpha detection. The gas atmospheres tested produced an increase in the detector count, with xenon having the greatest effect with a measured 52% increase in the detector response in comparison to the detector response in an air atmosphere. This type of alpha detection system could be operated at a distance, where it would potentially provide a more cost effective, safer, and faster solution in comparison with traditional alpha detection methods to detect and characterise alpha contamination in nuclear decommissioning and security applications.

Registration of alpha particles in Makrofol-E nuclear track detectors

Fast detection of alpha particles in the range from 1 to 5MeV in Makrofol-E polycarbonate nuclear track detectors (PCTDs) using a new chemical etchant was investigated. 252Cf and 241Am-thin open sources were used for irradiating Makrofol-E detectors with fission fragments and alpha particles in air at normal pressure and temperature (NPT). A chain of experimental work has been carried out using new etchants to register alpha particle in short time in Makrofol-E polycarbonate detectors. The etching efficiency were exhibited a clear dependence on the amount of methanol in the etching solution and etching time. The optimized chemical condition obtained at this stage of development for 200μm Makrofol-E detectors are (8ml of 10N NaOH+2ml CH3OH) etching solutions at 60°C for 3h. In this study; it is possible to observe energy detection windows for Makrofol-E detectors according to applied etching duration. Makrofol-E introduced the characteristic Bragg peak, which indicates the advantages of this detector as alpha spectrometer. Consequently, the suggested new etchant can be developed for heavy ions detection and monitoring radon levels and its daughters.

Fast detection of alpha particles in DAM–ADC nuclear track detectors

Abstract Fast detection of alpha particles in DAM–ADC nuclear track detectors using a new chemical etchant was investigated. 252Cf and 241Am sources were used for irradiating samples of DAM–ADC SSNTDs with fission fragments and alpha particles in air at normal temperature and pressure. A series of experimental chemical etching are carried out using new etching solution (8 ml of 10 N NaOH+ 1 ml CH3OH) at 60 °C to detect alpha particle in short time in DAM–ADC detectors. Suitable analyzing software has been used to analyze experimental data. From fission and alpha track diameters, the value of bulk etching rate is equal to 8.52 μm/h. Both of the sensitivity and etching efficiency were found to vary with the amount of methanol in the etching solution and etching time. The DAM–ADC detectors represent the best efficiency applicable in detectors in the entire range of alpha energies (from 1 to 5 MeV). The activation energies of this etchant have been calculated; track activation energy, ET, has been found to be lower than the bulk activation energy, EB, for the DAM–ADC nuclear track detectors. These results are in more agreement with the previous work.

Monte Carlo simulation experiments on box-type radon dosimeter

Epidemiological studies show that inhalation of radon gas (222Rn) may be carcinogenic especially to mine workers, people living in closed indoor energy conserved environments and underground dwellers. It is, therefore, of paramount importance to measure the 222Rn concentrations (Bq/m3) in indoors environments. For this purpose, box-type passive radon dosimeters employing ion track detector like CR-39 are widely used. Fraction of the number of radon alphas emitted in the volume of the box type dosimeter resulting in latent track formation on CR-39 is the latent track registration efficiency. Latent track registration efficiency is ultimately required to evaluate the radon concentration which consequently determines the effective dose and the radiological hazards.In this research, Monte Carlo simulation experiments were carried out to study the alpha latent track registration efficiency for box type radon dosimeter as a function of dosimeter’s dimensions and range of alpha particles in air. Two different self developed Monte Carlo simulation techniques were employed namely: (a) Surface ratio (SURA) method and (b) Ray hitting (RAHI) method.Monte Carlo simulation experiments revealed that there are two types of efficiencies i.e. intrinsic efficiency (ηint) and alpha hit efficiency (ηhit). The ηint depends upon only on the dimensions of the dosimeter and ηhit depends both upon dimensions of the dosimeter and range of the alpha particles. The total latent track registration efficiency is the product of both intrinsic and hit efficiencies. It has been concluded that if diagonal length of box type dosimeter is kept smaller than the range of alpha particle then hit efficiency is achieved as 100%. Nevertheless the intrinsic efficiency keeps playing its role.The Monte Carlo simulation experimental results have been found helpful to understand the intricate track registration mechanisms in the box type dosimeter. This paper explains that how radon concentration from the experimentally obtained etched track density can be obtained. The program based on RAHI method is also given in this paper.

The use of CH3OH additive to NaOH for etching alpha particle tracks in a CR-39 plastic nuclear track detector

Fast detection of alpha particles in CR-39 detectors was investigated using a new chemical etchant. 252Cf and 241Am sources were used for irradiating samples of CR-39 SSNTDs with fission fragments and alpha particles in air at normal temperature and pressure. A series of experimental chemical etching are carried out using new etching solution (8ml of 10N NaOH+1ml CH3OH) at 60°C to detect alpha particle in short time in CR-39 detectors. Suitable analyzing software has been used to analyze experimental data. From fission and alpha track diameters, the value of bulk etching rate is equal to 2.73μm/h. Both the sensitivity and etching efficiency were found to vary with the amount of methanol in the etching solution. Pure NaOH was used as a control to compare with the result from etching in NaOH with different concentrations of CH3OH. The etching efficiency is determined and compared with conventional aqueous solution of 6.25N NaOH at 70°C for etching time equals 5h. In this study, the obtained etching efficiency shows a considerable agreement with the previous work.

Effective air thickness in a glass capillary for the in-air material analysis

In order to establish in-air material analysis techniques with a glass capillary, we have measured energy distributions of extracted alpha particles in air using the glass capillary. We have estimated the effective air thickness in the glass capillary and found it to be compatible with a simple calculation.

Fluorescence-Assisted Gamma Spectrometry for Surface Contamination Analysis

A fluorescence-based alpha-gamma coincidence spectrometry approach has been developed for the analysis of alpha-emitting radionuclides. The thermalization of alpha particles in air produces UV light, which in turn can be detected over long distances. The simultaneous detection of UV and gamma photons allows detailed gamma analyses of a single spot of interest even in highly active surroundings. Alpha particles can also be detected indirectly from samples inside sealed plastic bags, which minimizes the risk of cross-contamination. The position-sensitive alpha-UV-gamma coincidence technique reveals the presence of alpha emitters and identifies the nuclides ten times faster than conventional gamma spectrometry.

A novel experiment to investigate the attenuation of alpha particles in air

A simple student experiment investigating dependence on air pressure of the attenuation of alpha particles in air is described. An equation giving the pressure needed to absorb all alpha particles of a given energy is derived from the Bethe–Bloch formula. Results are presented for the attenuation of alpha particles from americium 241 and radium 226. The experimental results are in close agreement with the theoretical predictions.

An experimental quantification of the NO X production efficiency of energetic alpha particles in air

An experimental study on the production of NO X by alpha particles impact in air at atmospheric pressure is presented. A mixed radioactive source of 208Po and 209Po with an integrated activity of 9.6 MBq over a solid angle of 2π and an average alpha particle energy of 4.5 MeV was used for ionization of atmospheric air in an airtight chamber and the NO X production was measured by the chemiluminescence method. The NO X production rate is found to be about 1.2 NO X molecules per ion-pair. The NO X production efficiency per Joule of dissipated energy is calculated to be 20×10 16 NO X molecules per Joule. This efficiency is comparable to that of hot laboratory sparks discharges.

Remote alpha imaging in nuclear installations: new results and prospects

For more than ten years the CEA has been using gamma imaging systems for radiological characterization purposes during decommissioning operations. This technology is very effective for detecting high-energy gamma emitters, but less so for characterizing actinides, which are mainly alpha emitters. In order to provide a full range of decommissioning tools, the gamma-cameras were supplemented by another imaging system capable of generating images directly from alpha emissions. This paper describes the initial laboratory and field test results obtained with a prototype camera capable of displaying alpha radioactivity. The system is based on the detection of ultraviolet radiation emitted by nitrogen when irradiated by alpha particles. The alpha contamination is localized by superimposing it on a visible-light image. All measurements must be carried out in complete darkness. Laboratory tests showed that the system is capable of detecting point sources and extended sources at levels as low as 430 Bqmiddotcm-2. Profile measurements of point sources revealed a scintillation bubble with dimensions corresponding to the range of alpha particles in air. The device is also capable of detecting the phenomenon through translucent materials such as glove box panels. The camera has been implemented for in situ examination of various fuel cycle facilities, and under these conditions has revealed alpha contamination without any breach of containment through several millimeters of plexiglas

Incidence characteristics of alpha particles on detectors irradiated in a radon + progeny atmosphere

The angular and energetic distribution of alpha particles from the 222 Rn chain in air incident on a detector have been determined by the Monte Carlo method. Stopping power of alpha particles in air have been taken from the ICRU49 report. The incident alpha-particle spectrum was found for various equilibrium factors. It has been shown that the spectrum between 5.5 and 7.69 MeV depends on the equilibrium factor. High resolution alpha spectrometry can enable the measurements of concentrations of 214 Po and 218 Po in air. The maximal sensitivity coefficient has also been determined for measurements of 214 Po concentrations.