Scintillation Method Research Articles

Theoretical analysis of stack gas emission velocity measurement by optical scintillation

Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation in a stack are first introduced. Then, the principle of flow velocity measurement and its mathematical expression based on cross correlation of the optical scintillation are presented. The field test results show that the flow velocity measured by the proposed technique in this article is consistent with the value tested by the Pitot tube. It verifies the effectiveness of this method. Finally, by use of the structure function of logarithmic light intensity fluctuations, the theoretical explanation of optical scintillation spectral characteristic in low frequency is given. The analysis of the optical scintillation spectrum provides the basis for the measurement of the stack gas flow velocity and particle concentration simultaneously.

Ionic liquids as solvents for liquid scintillation technology. Čerenkov counting with 1-Butyl-3-Methylimidazolium Chloride

We report the detection of the Čerenkov luminescence after the incorporation of a few droplets of a physiological solution of 2-deoxi-2(18F)fluorine-d-glucose into the ionic liquid 1-Butyl-3-Methylimidazolium Chloride (BmimCl). The phenomenon is attributed to the β+ particles having energy above the threshold energy value for the Čerenkov radiation in this medium. The presence of another type of radiation that could eventually cause coincidences in the photodetectors was safely discarded. We show that this property serves to determine the activity of a 18F solution by means of the novel TDCR–Čerenkov technique. The results were compared with those obtained from the classic TDCR scintillation method using a commercial scintillation cocktail. The activity values obtained from both methods were found to be virtually identical within the experimental uncertainties. The fact that high energy β particles in BmimCl generates Čerenkov photons makes this ionic liquid a promising compound for future research in detection and quantification of ionizing radiation, and it provides a potential alternative for applications in nuclear technology.

Оценка оптимальных параметров многоэлементных твердотельных детекторов для сцинтилляционного атомно-эмиссионного спектрального анализа

Introduction. In recent years, there has been an increased use of atomic emission spectral ( AES ) scintillation analysis with multi-element solid-state detectors ( SSD ) recording sequences of spectra for the rapid determination of trace impurities in powdered geological samples. The objectives of this study were to evaluate the optimal exposure time that provides the maximum signal-to-noise ratio ( SNR ) of the recorded spectral scintillations and, hence, the lowest detection limits of elements, and to estimate the effect of the SSD performance on this ratio. Derivation of the formula of the SNR. The time variation of the spectral line intensity is represented by a Gaussian function with the following parameters: the scintillation time and the number of photoelectrons generated by the scintillation. The SNR as a function of the scintillation intensity and time, spectral background intensity, exposure time, readout noise, and SSD area and dark current was determined for the two cases where the scintillation peak occurs at the beginning and middle of the exposure period. Analysis of the effect of the exposure time and SSD parameters on the SNR. The analysis was performed using three SSDs: BLPP-369M1 and BLPP-4000 photodiode arrays produced by VMK-Optoelektronika and a TCD1304DG charge-coupled device array produced by Toshiba. The experimentally obtained parameters of a 1 ms duration gold spectral line scintillation, during powder samples excitation on the spill injection method realizing equipment “Potok”, have been used in analysis. Results. It has been found that for achieving the maximum SNR for a 1 ms duration scintillation, the optimal exposure time is 0.8 ms for BLPP-4000, 1.1 ms for BLPP-369M1, and 1.2 ms for TCD1304DG. The expected reduction of the detection limits in the AES scintillation method compared to the conventional AES techniques is a factor of 30 for TCD1304DG, a factor of 50 for BSSA-369M1, and a factor of 110 for BSSA-4000. To obtain the AES method lowest detection limits, the intrinsic noise of the SSD (readout noise and dark current noise) should be less than the spectral background shot noise, the exposure time should be optimal, and the height of the photocell should be equal to the spectral line height. Keywords: time-resolved spectroscopy, atomic emission spectral analysis, scintillation, multi-element solid-state detectors, optimal exposure time. (Russian) DOI: http://dx.doi.org/10.15826/analitika.2014.18.1.004 S. A. Babin 1, 2 and Labusov 1, 2, 3 1 Institute of Automation and Electrometry, SB RAS, Novosibirsk, Russian Federation 2 VMK-Optoelektronika, Novosibirsk, Russian Federation 3 Novosibirsk State Technical University, Novosibirsk, Russian Federation

The Zero Model by Using Coincidence Scintillation (ZoMBieS) Method of Absolute Radioactivity Measurement

A new method for the absolute radioactivity measurement of radionuclides using a liquid scintillation detector comprising three photomultipliers has been described. The method does not contain any a priori model of the photomultiplier detection efficiency and uses a modified Compton Coincidence technique, therefore it has been named the Zero Model By using Coincidence Scintillation (ZoMBieS) method. Validation measurements of the activity of a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">63</sup> Ni source against the Triple to Double Coincidence Ratio method are presented and the results agree within their standard uncertainties.

The dispersion analysis of drift velocity in the study of solar wind flows

In this work I consider a method for the study of the solar wind flows at distances from the Sun more than 1AU. The method is based on the analysis of drift velocity dispersion that was obtained from the simultaneous scintillation observations in two antennas. I considered dispersion dependences for different models of the solar wind, and I defined its specificity for each model. I have determined that the presence of several solar wind flows significantly affects the shape and the slope of the dispersion curve. The maximum slope angle is during the passage of the fast solar wind flow near the Earth. If a slow flow passes near the Earth, the slope of the dispersion curve decreases. This allows a more precise definition of the velocity and flow width compared to the traditional scintillation method. Using the comparison of experimental and theoretical dispersion curves, I calculated the velocity and width of solar wind flows and revealed the presence of significant velocity fluctuations which accounted for about 60% of the average velocity.

Using stellar scintillation for studies of turbulence in the Earth’s atmosphere

Stellar scintillation observed through the Earth's atmosphere is the result of interaction of light waves and the turbulent atmosphere. This review is dedicated to using stellar scintillation measurements for studies of turbulence in the Earth's atmosphere. We present an overview of ground-based, air-borne and satellite stellar scintillation measurements, discuss the approaches to data analyses and give an overview of the main geophysical results. We also discuss the benefits of the scintillation method in studies of the structure of air density irregularities and its limitations.

Scintillation Measurements of the Solar Wind Velocity in Strong Scattering near the Sun

The multi-antenna scintillation method of measuring the solar-wind velocity has been very effective, particularly near the Sun and at high heliographic latitudes where direct measurements are rare or non-existent. However, scintillation observations inherently involve an LOS integration. Several methods have been used to deal with this problem, but they all require the basic assumption that contributions from different parts of the LOS add linearly. This assumption is valid for weak scintillations where the Born approximation holds, but it is not correct for strong scintillations. In this article we compare simultaneous observations of the same radio source, and therefore the same solar wind, at radio wavelengths of 32 cm and 92 cm. The 32-cm observations at the European Incoherent Scatter Radar (EISCAT) were made in weak-scattering and those at 92 cm at the Solar-Terrestrial Environment Laboratory (STEL) were made in strong-scattering mode. The results showed no significant bias in velocity caused by strong scattering, confirming that the LOS inversion techniques can be extended into the strong-scattering regime.

Efects of Newly-synthesized Peptide Mimetics on Exploratory Behaviour, Memory and Serotonin Release in the Hippocampus of Rats with Social Isolation Syndrome

The effects of two newly-synthesized peptide mimetics (containing L-valine and nicotinamide/isonicotinamide residues) – M6 and P6 – were studied on Wistar rats after 6 weeks of social isolation. Their influence on changed cognitive functions in experimental aggression in rats was studied with the Hole board test (for exploratory behaviour) and also Step-through test on the 7th and on the 30th day (for short-term and long-term memory). The influence of the compounds on serotonin (5-HT) release in the hippocampus of aggressive rats was also studied, using a scintillation method. It has been found that the new peptide mimetics – M6 and P6, demonstrated different modulating effects on the exploratory behaviour and memory and on the 5-HT release in the hippocampus of grouped and socially-isolated male rats. The two compounds had different effects on the exploratory behaviour and the process of habituation in aggressive animals, probably due to their isomeric structure. M6 increased significantly the memory in grouped animals, but had the opposite effect in aggressive rats. Due to its intrinsic peptidomimetic nature, it is possible that M6 has an affinity towards 5-HT receptors in hippocampus.

Detection and Identification of Contraband in Air Cargo Containers Using Neutron Based Techniques

Detection and Identification of Contraband in Air Cargo Containers Using Neutron Based Techniques This paper describes and discusses the combined system which was installed to allocate and identify contraband materials hidden in air cargo containers by fast neutron radiography and neutron elemental analysis techniques. A slit of fan beam of fast neutrons emitted from Pu-Be source was used. The fast neutron fluxes passed through different lines crossing the hidden object were detected by a neutron spectrometer applies stilbene scintillator and pulse shape method to discriminate agnist undesired pulses of gamma-rays. A two channel spectroscopy method was used to eleminate the effect of spectrum shift caused by the benign materials surrounding the hidden object. The recognetion of the allocated suspected object was performed by measuring the gamma-ray spectrum emitted from the suspected object by a gamma spectrometer with NaI(Tl) detector fixed at the middle point of the container and at a vertical plane to the incident beam. Tests were carried out using 2.5 kg of RDX explosive material hidden withen materials of pasta, onion and ceramic tiles. The results of fast neutron radiography are presented in the form of attenuation relation profiles and 2D constructed images. The measured spectra of emitted gammarays were used to determine the energy and intensity of gamma lines emitted from different elemental constituent of the suspected object. The analysis of the constructed images and gamma-ray spectra obtained for different tests indicated the reliability and capability of the installed combined system for inspection of small and medsize containers for illicit traficking.

Study of the Translocation and Distribution of Cadmium into Bean Plants (Phaseolus vulgaris) Using Labelled Cd-109

The motivation of this work was dictated by a concern of using bioaccumulative plant species likely to be used in the technique of bioindication. The obtained results and discussions proposed are approaches of chemist, because the mechanisms of the effect of cadmium on the various plant cells have been widely developed by several biologists. The use of labeled cadmium is important to study the uptake, the translocation and the metabolism at very low levels of this element in plants. Bean (Phaseolus vulgaris), the model chosen for the investigation, was cultivated in vermiculite for 12 days. After this period, plants were transferred into 100 ml flasks containing nutrient solution and radioactive Cd-109 (γ, t1/2 = 461.3 days) with variable activity of: 0.05, 0.1 and 1.0 micro Currie (μCi). Samples were transferred to a growth room and left for periods of 4 and 7 days, then analyzed by the solid scintillation method. The counting was carried out for roots, stems and leaves.

Studying the response of CR-39 to radon in non-polar liquids above water by Monte Carlo simulation and measurement

The application of CR-39 has been extensive for measurement of radon and progeny in air of dwellings, but limited as regards to measurements of radon in water. In this paper, a new method is introduced for efficient measurement of radon in water by registering alpha particle tracks in a CR-39 detector placed in a non-polar medium such as cyclohexane, hexane and olive oil when each mixed with water, then separated and fixed above water, as a two-phase media. The method introduced here is however different from the widely used liquid - liquid extraction technique by liquid scintillation spectrometry since it is a passive detection method (CR-39) in a non-polar liquid with enhanced absorption of radon in the liquid, it has a capability for long sample counting to decrease the minimum detection limit (MDL), it does not require sophisticated low light counting systems, and it has the potential for simultaneous measurements of large number of samples for large-scale applications. It also has a low cost and is readily available. A new Monte Carlo calculation of energy-distance travelled by alphas from radon and progeny in a medium was also investigated. The sensitivity of CR-39 detector to radon and progeny in water was determined under two conditions; in a single-phase and two-phase media. In a single-phase medium, CR-39 is directly placed either in air, water, cyclohexane, hexane or olive oil. When CR-39 is placed directly in water, its sensitivity is (2.4 ± 0.1) × 10 −4 (track/cm 2 )/(Bq.d/m 3 ). In the two-phase media, CR-39 is placed either in cyclohexane, hexane or olive oil when each is fixed above water. The sensitivities in the two-phase media are significantly enhanced and are respectively (1.98 ± 0.10) × 10 −2 , (2.8 ± 0.15) × 10 −2 and (2.86 ± 0.15) × 10 −2 (track/cm 2 )/(Bq.d/m 3 ). The sensitivies are about 76, 82 and 110 times more than that of when CR-39 is directly placed in water. The new method is a novel alternative for radon measurements in water with a lower MDL than that of for example liquid scintillation method with a number of advantages. The results are presented and discussed. ► A new passive detection method is introduced for efficient radon measurements in water. ► Method is based on alpha tracks of radon/progeny in CR-39 in a non-polar medium above water. ► Sensitivity was enhanced (>80 times) relative to water by radon/progeny detected in hexane. ► Monte Carlo simulation was applied to determine CR-39 sensitivity to radon/progeny in water. ► The method has a number of advantages with MDL lower than alternative wide-scale methods.

Radioactive contamination of 7LiI(Eu) crystal scintillators

The radioactive contamination of two 26g samples of low background lithium iodide crystal scintillators doped by europium and enriched in 7Li to 99.9% (7LiI(Eu)) has been investigated by scintillation method at the sea level, and by ultra-low background HPGe γ spectrometry deep underground. No radioactive contamination was detected. In particular, the contamination of the crystal scintillators by 226Ra and 228Th does not exceed 1mBq/kg, and the activity of 40K is less than 0.5Bq/kg.

Systematic study of particle quenching in organic scintillators

Among the different factors that affect measurements by organic scintillators, the majority of attention has been focused on those related to the scintillator (i.e., ionization, chemical, color and optical quenching), and less attention has been paid to the loss of energy before the particle (i.e., alpha or beta) arrives at the scintillator (i.e., particle quenching). This study evaluates the effect of particle quenching in different scintillation methods (i.e., using two plastic scintillation microspheres (PSm1 and PSm2), liquid scintillator and gel scintillator) by measuring solutions that contain increasing concentrations of NaCl, BaCl2 and glycerin. The results show the importance of particle quenching in PSm measurements because detection efficiency decreases with increasing concentrations of the quenching component, although the spectrum position and external standard parameter remain constant. The results have shown evidence of particle quenching, although at a lower magnitude, in the liquid scintillation or gel scintillation measurements. Moreover, the use of two PSm with different diameters and salty compound that alters the equilibrium of the liquid and gel emulsions also exemplified the importance of the transmission of optical photons through different scintillation media (i.e., optical quenching). Improvement and deterioration of the optical conditions on the scintillation media is manifested as a movement of the spectrum to higher and lower energies, respectively. The results obtained with PSm were confirmed by Monte Carlo simulation.

Deep sea hydrothermal plumes and their interaction with oscillatory flows

The acoustic scintillation method is applied to the investigation and monitoring of a vigorous hydrothermal plume from Dante within the Main Endeavour vent field (MEF) in the Endeavour Ridge segment. A 40 day time series of the plume's vertical velocity and temperature fluctuations provides a unique opportunity to study deep sea plume dynamics in a tidally varying horizontal cross flow. An integral plume model that takes into account ambient stratification and horizontal cross flows is established from the conservation equations of mass, momentum and density deficit. Using a linear additive entrainment velocity in the model (E = αUm + βU⊥) that is a function of both the plume relative axial velocity (Um) and the relative ambient flow perpendicular to the plume (U⊥) gives consistent results to the experimental data, suggesting entrainment coefficients α = 0.1 and β = 0.6. Also from the integral model, the plume height in a horizontal cross flow (Ua) is shown to scale as 1.8B1/3Ua−1/3N−2/3 for 0.01 ≤ Ua ≤ 0.1 m/s where B is the initial buoyancy transport and N is the ambient stratification, both of which are assumed constant.

Toward the probabilistic forecasting of high‐latitude GPS phase scintillation

The phase scintillation index was obtained from L1 GPS data collected with the Canadian High Arctic Ionospheric Network (CHAIN) during years of extended solar minimum 2008–2010. Phase scintillation occurs predominantly on the dayside in the cusp and in the nightside auroral oval. We set forth a probabilistic forecast method of phase scintillation in the cusp based on the arrival time of either solar wind corotating interaction regions (CIRs) or interplanetary coronal mass ejections (ICMEs). CIRs on the leading edge of high‐speed streams (HSS) from coronal holes are known to cause recurrent geomagnetic and ionospheric disturbances that can be forecast one or several solar rotations in advance. Superposed epoch analysis of phase scintillation occurrence showed a sharp increase in scintillation occurrence just after the arrival of high‐speed solar wind and a peak associated with weak to moderate CMEs during the solar minimum. Cumulative probability distribution functions for the phase scintillation occurrence in the cusp are obtained from statistical data for days before and after CIR and ICME arrivals. The probability curves are also specified for low and high (below and above median) values of various solar wind plasma parameters. The initial results are used to demonstrate a forecasting technique on two example periods of CIRs and ICMEs.

Protection of sound enamel and artificial enamel lesions against demineralisation: Caries infiltrant versus adhesive

ObjectiveTo compare the protective potential of a conventional adhesive, a caries infiltrant and a combination of both against acidic challenge in vitro. MethodsOne-hundred-and-fifty discs from bovine lower central incisors were fabricated. Seventy-five samples remained untreated, whereas the other half was subjected to a demineralisation process (14 days, acidic buffer, and pH 5) to create artificial enamel lesions. Specimens were then radioactively irradiated, and each 15 sound and demineralised specimens were treated with a caries infiltrant (Icon, DMG), an unfilled adhesive (Heliobond, IvoclarVivadent) or a combination of infiltrant and adhesive. Specimens treated with the adhesive followed by a flowable composite (TetricEvoFlow, IvoclarVivadent) served as positive control, while untreated specimens served as negative control. All samples were then subjected to lactic acid for 3 weeks at pH 4. Loss of apatite was determined using the radiochemical method of liquid scintillation. Data were statistically analysed by Kruskal–Wallis-test, one-way ANOVA and Scheffe's post hoc tests (p≤.05). ResultsIn both sound enamel and artificial caries lesions, untreated specimens showed the highest rate of apatite loss, whereas enamel treated with the adhesive and the flowable composite showed almost complete protection surface against dissolution. The caries infiltrant, the adhesive and the combination of both were able to decrease enamel dissolution, but the adhesive and the combination of adhesive and infiltrant were more effective than the infiltrant alone. ConclusionWithin the limitations of this in vitro study, the application of an adhesive (alone or in combination with the caries infiltrant) is more effective to protect enamel dissolution than the infiltrant alone.

Determining coastal mixing rates of western Taiwan Strait using 224Ra

224Ra concentrations in the coastal sea water of western Taiwan Strait in winter were measured using Mn-fiber adsorption—successive emanation scintillation method. 224Ra activities in the seawater of the western Taiwan Strait varied from 0.90 to 16.25 Bq/m3 with an average of 4.60 Bq/m3. The horizontal and vertical distributions of 224Ra were studied. The distributions of 224Ra in the surface water decreased gradually with increasing distance offshore. The apparent horizontal and vertical eddy diffusion coefficients estimated from the one dimensional steady state model of 224Ra were (5.0–55.4) × 106cm2/s and (4.0–51.7) cm2/s, respectively.

Effect of spring water on the radon concentration in the air at Masutomi spa in Yamanashi Prefecture, Japan

The concentrations of 222Rn existing in air have been studied by using a convenient and highly sensitive Pico-rad detector system at Masutomi spa in Yamanashi Prefecture, Japan. The measurements in air were carried out indoors and outdoors during the winter of 2000 and the summers of 1999 and 2005. The concentrations of 222Rn in spring water in this region were measured by the liquid scintillation method. The concentrations of natural radionuclides contained in soils surrounding spa areas were also examined by means of the γ-ray energy spectrometry technique using a Ge diode detector to investigate the correlation between the radionuclides contents and 222Rn concentrations in air at each point of interest. The atmospheric 222Rn concentrations in these areas were high, ranging from 5 Bq/m3 to 2676 Bq/m3. The radon concentration at each hotel was high in the order of the bath room, the dressing room, the lobby, and the outdoor area near the hotel, with averages and standard deviations of the concentration of 441 ± 79 Bq/m3, 351 ± 283 Bq/m3, 121 ± 5 Bq/m3, and 23 ± 1 Bq/m3, respectively. The source of 222Rn in the air in the bath room is more likely to be the spring water than the soil. The spring water plays carries the radon to the atmosphere. Our measurements indicated that the 222Rn concentration in the air was affected by the 222Rn concentration in spring water rather than that in soil.

On monitoring the tritium breeder in a lead–lithium cooled ceramic breeder (LLCB) module of the ITER

Abstract The operation of a tritium breeder is a most process among engineering problems of DEMO. In this study, a design for monitoring tritium-breeding in the reactor is discussed. Additionally, a system for the experimental estimation of the tritium-breeding ratio (TBR) and the tritium-breeding dynamics in a lead–lithium cooled ceramic breeder (LLCB) test module used in the ITER is proposed. The systems are based on tritium and neutron-flux measurements under the ITER plasma D–T experiments and the use of lithium ortho-silicate and lithium carbonate samples and neutron detectors. Different lithum-6 and lithium-7 isotope contents in the samples are used to measure neutron spectrum. The samples and detectors are delivered in containers to the test breeder module (TBM) on a monitor channel connecting the TBM to an operating zone of the ITER. The tritium content in the samples is measured in a laboratory by the liquid scintillation method. Pneumatic control is used to deliver the samples to the TBM and to extract the samples using the channel during plasma-operational pauses. Neutron calculation is performed to estimate the tritium content in the samples and the heat distribution in the materials of the channel under reactor irradiation. A measurement accuracy of the tritium content in the carbonate and orthosilicate samples can attain a level of 7% and 10%, respectively. The results of the channel-cooling calculation performed under the nominal operating conditions of the TBM (a plasma pulse) are presented in the paper.

The effect of impurities on calculated activity in the triple-to-double coincidence ratio liquid scintillation method

In the triple-to-double coincidence ratio (TDCR) method of liquid scintillation counting, unaccounted or improperly accounted impurities can result in lower-than-expected or higher-than-expected recovered activities, depending on the counting efficiency of the nuclide of interest, the counting efficiency of the radionuclidic impurity, and the amount of impurity present. We describe these general dependences using a simple model. The trends predicted by the model are tested experimentally using a series of mixed 241Am/3H and 63Ni/3H sources. An “impurity surface” is derived to facilitate an intuitive grasp of impurity phenomena in TDCR.