Glow Intensity Research Articles

Ultrafast deposition of ultrahard Cr films in tubes by bipolar-HiPIMS with small target-substrate distance

The PVD deposition of films with excellent surface properties has been a persistent area of research. In this paper, bipolar high power impulse magnetron sputtering with small target-substrate distance is proposed, and ultra-hard Cr films have been deposited with a higher rate in tubes. The microstructure and mechanical properties of the films were characterized using X-ray diffraction, scanning electron microscopy, nanoindentation and scratch test, and compared with films prepared under conventional conditions. With target-substrate distance of 7.5 mm, the ultrafine columnar structure is fabricated due to intensive glow discharge and direct particle-bombardment in high-density plasma. The small grain size of 7.4 ± 0.3 nm is observed although deposition rate as high as 10 μm/hr. The nanohardness of the films reaches 19.94 ± 1.14 GPa, much higher than that reported in the literatures. Meanwhile, the adhesion between film and substrate may be as high as 77 ± 5 N.

Dose-dependent effect of cadaverine on hydroxyl radicals’ production by human peripheral blood leukocytes

Objective. To assess changes in the generation of hydroxyl radicals by leukocytes under the influence of cadaverine at concentrations of 1, 5 and 25 mmol/L. Materials and methods. Peripheral venous blood samples were obtained from 40 apparently healthy donors. To assess the production of hydroxyl radicals, a luminol-dependent chemiluminescence reaction with blood leukocytes, which were pre-incubated with cadaverine at concentrations of 1, 5 and 25 mmol/L was carried out. The study was conducted on a Luminoskan Ascent® Thermo Labsystems (USA) luminometer for 180 minutes. For statistical analysis, the integral chemiluminescence indicator for the entire measurement period (RLU) was used. The time to reach the maximum of light flashes in minutes, the intensity of the utmost glow, and the area under the luminescence extinction curve were calculated. Results. It was determined that pre-incubation of cells with cadaverine significantly reduces their time to reach the maximum generation of hydroxyl radicals. In addition, cadaverine enhances the intensity of the reaction of luminol-dependent chemiluminescence of leukocytes of healthy donors, and the greatest stimulating effect was recorded at a polyamine concentration of 5 mmol/L (p =0,009 to samples with a spontaneous reaction, p =0,007 and 0,010 to samples with cadaverine 1 mmol/L and 5 mmol/L respectively). Cadaverine increases the area under the reaction curve, it being the most significant at a concentration of 5 mmol/L – 20.89±3.00 c.u. versus 0.86±0.07 c.u. with a spontaneous reaction (p=0,001). Conclusions. The results of the study indicate a possible effect of cadaverine on the mechanisms of hydroxyl radical formation, as well as the activity of the diamine oxidase enzyme in leukocytes. It can be supposed that the combination of these effects contributes to the development of the environment favorable for microorganisms at the focus of inflammation. Thus, microorganisms that produce cadaverine, which modulates the generation of hydroxyl radicals by leukocytes, adapt to their environment, creating a special type of microenvironment, which probably results in an asymptomatic course of the inflammatory process.

Ignition of Coal Microparticles by Laser Pulses of The Second Harmonic of a Ndodymium Laser in the Q-Switched Regime

The ignition of pelletized samples of hard coals of the long-flame gas (DG), gas (G), fat (L), coke (K) grades with particle sizes ≤63 μm by laser pulses (λ = 532 nm, τi = 10 ns) was studied. When the critical radiation energy density Hcr(1), specific for each grade of coal, is exceeded, an optical breakdown occurs and a dense plasma with a continuous emission spectrum is formed. As the plasma expands and rarefies, the spectra show the emission of carbon ions CII, excited nitrogen atoms N, excited carbon molecules C2, and carbon monoxide CO. The plasma glow intensity peaks at the end of the laser pulse, and the glow relaxation time is ~1 μs. The plasma glow amplitude increases nonlinearly with increasing laser pulse energy density. At radiation energy density H ≥ Hcr(2), specific for each grade of coal, thermochemical reactions are initiated in the volume of microparticles and coal particles are ignited in a submillisecond time interval.

Effect of helium ion and gamma irradiation on the TL and OSL properties of Tb-doped LiF nanophosphors

Lithium Fluoride (LiF) stands out as a extensively researched material in Thermally Stimulated Luminescence Dosimetry (TLD). This study specifically delves into nanocrystalline Tb-doped LiF TL dosimeters, synthesized through the co-precipitation method, and evaluates their efficacy under He ion and gamma rays radiation. Morphological examination via transmission electron microscopy has revealed cubic-shaped particles. These particles were subjected to irradiation by 120 keV He ion beams ranging from 1014 to 1016 ions/cm2 and gamma rays ranging from 10 to 1000 Gy, facilitating a comprehensive comparative analysis. Deconvolution of the glow curves enabled the extraction of trapping parameters. Under gamma irradiation, the nanophosphor exhibited a distinctive, intense single TL glow peak centered at 400 K with a minor hump at 512 K, diminishing with increasing doses. Conversely, under He ion irradiation, the nanophosphor displayed a peak at 492 K, accompanied by a slight shoulder around 600 K. Additionally, gamma doses displayed a highly promising response to Optically Stimulated Luminescence (OSL). Fading studies further underscore its suitability for radiation dosimetry applications. The unique characteristics of the TL glow curve, dose-response behaviours, and OSL responses highlight the versatility and effectiveness of these nanophosphors in radiation dosimetry, making significant contributions to advancements in this field.

Long afterglow (LAG) photoluminescence effect in ce-doped optical fiber

Ce-doped optical fibers were irradiated with various light sources, which are purple, blue, green, and red LEDs, for 30 minutes to investigate their long-after glow (LAG) characteristics. Photons were counted with a photo-multipliers tube (PMT) for 30 min, depending on the time immediately after irradiation. Depending on the wavelength of the LED, the maximum count was obtained as a result of excitation with a purple LED. The glow time was found to be about 90 minutes. The photon counting was performed for 30 minutes to characterize the irradiation time effect, depending on the irradiation time (2, 5, 10, and 30 minutes) with the purple LED. Consequently, the glow intensity and duration increased due to increased irradiation time. Additionally, the Ce-doped optical fibers were irradiated with a fluorescent lamp for 30 and 60 minutes and direct sunlight for 30 minutes. All results were fitted by a function that obtained decay time parameters. The decay times increase as the better LAG characteristics and the results confirm the decay times increase.

Mechanisms of Antioxidant Resistance in Different Wheat Genotypes under Salt Stress and Hypoxia

Various stressors lead to an increase in ROS and damage to plant tissues. Plants have a powerful antioxidant system (AOS), which allows them to neutralize excess ROS. We detected an intense fluorescent glow of ROS in the cells of the cap, meristem, and elongation zones in the roots of wheat Triticum aestivum (Orenburgskaya 22 variety) and Triticum durum (Zolotaya variety). An increase in ROS was accompanied by DNA breaks in the nuclei of wheat root cells, the release of cytochrome c from mitochondria into the cytoplasm, and the translocation of phosphatidylserine into the outer layer of the plasma membrane under salt stress and hypoxia. The different resistances of the two wheat varieties to different abiotic stresses were revealed. The soft wheat variety Orenburgskaya 22 showed high resistance to salt stress but sensitivity to hypoxia, and the durum wheat variety Zolotaya showed tolerance to hypoxia but high sensitivity to salt stress. Different activations of AOS components (GSH, MnSOD, Cu/ZnSOD, CAT, PX, GPX, and GST) were revealed in different wheat genotypes. The basis for the tolerance of the Zolotaya variety to hypoxia is the high content of glutathione (GSH) and the activation of glutathione-dependent enzymes. One of the mechanisms of high resistance to salt stress in the Orenburgskaya 22 variety is a decrease in the level of ROS as a result of the increased activity of the MnSOD and Cu/ZnSOD genes. Identifying the mechanisms of plant tolerance to abiotic stress is the most important task for improving breeding varieties of agricultural plants and increasing their yield.

Unveiling the luminescence of α-Zn2SiO4 phosphor: Profound influence of sintering temperatures

The zinc silicate (α-Zn2SiO4) phosphor was synthesized via a conventional sol-gel method, employing different sintering temperatures within the range of 800 to 1300 °C. To investigate the physicochemical properties of the α-Zn2SiO4 materials, a comprehensive range of analytical and spectroscopic techniques were utilized. In thermoluminescence (TL) measurements, the α-Zn2SiO4 sample sintered at 1200 °C exhibited a significantly higher intensity of glow peaks at around 115 °C and 304 °C. These enhanced glow peaks can be attributed to the presence of deep traps within the synthesized materials, which are activated upon X-ray irradiation. Additionally, dose-response measurements demonstrated a linear relationship between the TL glow peak intensity and the increment of X-ray dose. Furthermore, the photoluminescence (PL) analysis revealed that the synthesized α-Zn2SiO4 material emitted light at two distinct wavelengths at 463 nm and 542 nm which attributed to the possible electron-hole recombination of luminescent centres within the material. Combining the TL and PL results, the synthesized α-Zn2SiO4 material shows promise as a suitable candidate for dosimetry and lighting applications.

Vulcanian eruption processes inferred from volcanic glow analysis at Sakurajima volcano, Japan

Volcanic glow, which is often observed at active craters during nighttime, contains information on high-temperature zones deep in the crater that are hidden from view. We analyzed 90 eruption videos capturing volcanic glow before the onset of Vulcanian eruptions at the Showa crater of Sakurajima volcano (Japan), and found that they show clear temporal changes. The red (R)-value and the green-to-red ratio (GR ratio) are used to track glow intensity and temperature change, respectively. We found two types of temporal change in glow intensity: a short-term change approximately 1 s before the onset of explosions, and a long-term change 3 to 330 s before an explosion. Short-term changes were observed for 28 of 90 eruptions, and coincided with an increase in the GR ratio and with a modest precursory infrasound pressure increase. Since an increasing GR ratio means a temperature increase, we consider that the change was associated with the opening of tensile cracks on the crater floor before an explosion. However, the other 62 eruptions did not show short-term changes, suggesting that the opening of cracks is sporadic. Long-term changes were observed for 73 of 90 eruptions, the GR ratio did not exhibit a significant increase. We suggest that long-term changes are caused by gradual gas leakage, which precedes initiation of Vulcanian eruptions. We hypothesize that the long-term gas leakage causes gradual decompression of the conduit, which induces supersaturation of volatile-rich magma beneath the lava plug causing explosive expansion, thereby triggering an eruption.

Charge Transfer and Charge Trapping Processes in Ca- or Al-Co-doped Lu2SiO5 and Lu2Si2O7 Scintillators Activated by Pr3+ or Ce3+ Ions.

Lutetium oxyorthosilicate Lu2SiO5 (LSO) and pyrosilicate Lu2Si2O7 (LPS) activated by Ce3+ or Pr3+ are known to be effective and fast scintillation materials for the detection of X-rays and γ-rays. Their performances can be further improved by co-doping with aliovalent ions. Herein, we investigate the Ce3+(Pr3+) → Ce4+(Pr4+) conversion and the formation of lattice defects stimulated by co-doping with Ca2+ and Al3+ in LSO and LPS powders prepared by the solid-state reaction process. The materials were studied by electron paramagnetic resonance (EPR), radioluminescence spectroscopy, and thermally stimulated luminescence (TSL), and scintillation decays were measured. EPR measurements of both LSO:Ce and LPS:Ce showed effective Ce3+ → Ce4+ conversions stimulated by Ca2+ co-doping, while the effect of Al3+ co-doping was less effective. In Pr-doped LSO and LPS, a similar Pr3+ → Pr4+ conversion was not detected by EPR, suggesting that the charge compensation of Al3+ and Ca2+ ions is realized via other impurities and/or lattice defects. X-ray irradiation of LPS creates hole centers attributed to a hole trapped in an oxygen ion in the neighborhood of Al3+ and Ca2+. These hole centers contribute to an intense TSL glow peak at 450-470 K. In contrast to LPS, only weak TSL peaks are detected in LSO and no hole centers are visible via EPR. The scintillation decay curves of both LSO and LPS show a bi-exponential decay with fast and slow component decay times of 10-13 ns and 30-36 ns, respectively. The decay time of the fast component shows a small (6-8%) decrease due to co-doping.

Spectroscopic investigation of atmospheric pressure cold plasma jet produced in dielectric barrier discharge

Non-thermal cold atmospheric pressure plasma jet (APPJ) produced in multi-pulse dielectric barrier discharge (DBD) preferentially heats the electrons that subsequently transfer their energy to the other plasma species converting them into reactive species. Therefore the characterization of different energy groups of electrons is essential for efficient production and control of reactive plasma species contributing to surface modifications. Here we present the spectroscopic investigations of the APPJ produced in multi-pulse DBD using pin electrode configuration. Boltzmann plot relates the emission intensities of the several Ar–I spectral lines to their corresponding threshold excitation energies to give the electron temperature more precisely. The Stark broadening of the Ar–I (696.54 nm) line profile gives the electron number density after de-convoluting the contributions of the Doppler and instrumental broadenings. Plasma measurements correlate the gas flow rate, applied jet power across the electrodes, and a group of electrons contributing to optical emission. Sequential imaging correlates the size of the plasma bullets momentarily with the discharge pulse for different argon flow rates and applied jet powers. With an increasing flow rate of up to 1.4 L/min, the plasma plume of the jet becomes more elongated, intense, and spatially uniform. However, the glow intensity and size of the plume start reducing with a further increase in gas flow rate. Experimental findings propose plasma processing for small-scale localized plasma surface treatments.

Вплив опромінення електронами з Е = 2 МеВ на електрофізичні та оптичні характеристики зелених InGaN/GaN світлодіодів

We studied light-emitting diodes (LEDs) with quantum dots маde on the basis of a solid solution of In0.21Ga0.79N. Measurements of current-voltage characteristics and electroluminescence characteristics were carried out in the range of 77 ÷ 300 K. On the current-voltage characteristics in the range of 77 ÷ 150 K, areas of negative differential resistance, as well as a fine structure of radiation spectra, were detected. The results of the influence of electron irradiation (Ee = 2 MeV) on electroluminescence characteristics intensity and quantum yield of the studied samples are presented; the features of the temperature dependence of the glow intensity of irradiated LEDs were revealed.

FLAME ANALYSIS BY SELECTED METHODS IN THE FREQUENCY DOMAIN

Diagnostics of pulverized coal combustion can be carried out in the field of process monitoring and analysis of measurement data. The information about changes in the flame is presented in the form of time series, which can be analyzed in the time and frequency domain. The paper presents an analysis of signals of changes in the intensity of the flame glow during pulverized coal combustion using power spectral density. On the basis of the periodograms determined using the Welch method, it was possible to determine the frequency components present in the signal.

Insights into the effect of hollow cathode with external injection of fast ions in a sputter-type negative ion source

In sputter-type negative ion sources, the negative ion currents and ionization efficiencies are very dependent upon the creation of a sputter crater and formation of an intense plasma glow. This effect has many similarities with the well-known phenomena of hollow cathode discharges (HCDs). This paper discusses the phenomenological model related to conventional HCDs, including modes with injection of external energetic particles. We propose that HCDs play a major role in sputter-type negative ion sources. In this study, we evaluate the phenomenology of a discharge with a hollow cathode and derive an analytical formula that defines the neutral particle density inside the cathode cavity and substantiates how the classic HCD occurs in sputter-type negative ion sources. The cathode pit geometry was revealed by optical microscopy. Volt–ampere characteristics were investigated in order to compare it to typical discharges with hollow cathodes. In sputter-type negative ion sources, known as SNICS, discharge characteristics and observed light glow inside the cathode pit after its formation were very similar to data published on HCDs. The HCD phenomenon explains how the cathode current increases by orders of magnitude after creation of the cathode pit. The HCD effect in SNICS and similar sputter sources compliments existing mechanisms of negative ion production, especially ion pair production close to the cathode surface due to low energy ionization based on the collision–radiation model. The wealth of information accumulated over the last century on HCDs can be used to describe and explain the phenomenology of physics and operation of sputter negative ion sources.

FEATURES OF THE DYNAMICS OF EROSION PLUMES AT THE ACTING OF INTENSIVE NANOSECOND LASER PULSES ON A GRAPHITE TARGET IN VACUUM

The temporal characteristics of the glow intensity of erosion laser plumes near the surface under the action of nanosecond laser pulses on a carbon target are experimentally studied. The interaction of laser radiation with the destruction products of plume is minimal due to the formation of erosion plasma with a delay relative to the acting laser pulse. Using a modernized spectrometer, the spectral characteristics of an erosion
 laser plume near the surface of a carbon target with a time resolution of 10–8 s are studied, and the characteristic plasmodynamic times in the plume are ~10–6 s. It is shown that the emission of spectral lines of carbon appears with a delay relative to the glow of the continuous background, when the erosion plume is cooled during expansion. The results of the study make it possible to optimize some characteristics of the laser-
 plasma source for the deposition of nanocoatings.

COMPREHENSIVE ASSESSMENT OF THE HEALTH OF YOUNG PEOPLE LIVING IN THE FAR NORTH

The paper considers the creation of a diagnostic system based on morphological and biophysical indicators that allows us to understand the influence of the climatic component, as well as stress factors on the general physiological state of young people for further correction of preventive measures and preservation of the health of the peoples of the Far North. The aim of the study is a comprehensive assessment of the health of young people living in the Far North based on the results of bioluminescent saliva activity, stress-emotional state obtained before and after intense mental stress, as well as anthropometric and bioimpedance indicators. 117 students of the Medical Institute of Surgut State University took part in the survey at a young age (18-23 years) during the educational process (rest) and during the examination session (mental load) in the first half of the year of study (autumn-winter 2021). The stress-emotional state was assessed using the Spielberger-Khanin test, the functional state of students They were studied using bioluminescent salivary fluid testing, anthropometric and bioimpedance methods. Samples were obtained by spitting unstimulated saliva into a test tube.
 As a result of the study, regional features of the physique of young people were revealed, which indicates the formation of a phenotype adapted to living conditions in the northern region. The relationship between the stress-emotional status of adolescents and the level of inhibition of the bioluminescent enzymatic system by saliva samples taken before and after mental stress was shown. The value of the residual glow had an increased indicator for the state of rest and significantly reduced the intensity of the bioluminescent glow under mental stress. The methodological development obtained in the future will make it possible to effectively manage the methods and methods of diagnosing young people, taking into account the influence of external factors, climatic zones and conditions.

Странные следы "странного" излучения

A review of the main works on the study of "strange" radiation is presented - an intense glow that occurs above the explosion chamber during an electric discharge of metal foils in water in it. Photographs of the most diverse structures of tracks-traces of "strange" radiation are presented. Existing hypotheses of particles that leave such traces are outlined: Lochak's magnetic monopole hypothesis, the magneto-toro-electron radiation hypothesis, the tachyon hypothesis, the hypothesis of an intermediate quasi-molecular state of paired electrons, and the "dark" hydrogen hypothesis. Numerical estimates of all discussed hypotheses are given with an explanation of the mechanism of trace formation. The hypothesis of miniature ball lightnings - multiply charged clusters - spherical clusters with a radius of 2.14·10-6 m, having a charge of 4.5·10-12 C is presented. The electric field strength on the surface of such clusters can reach up to 1010 V/m, which is comparable to the electric field strength in an atom. When such a cluster is introduced into the crystal lattice, a strong polarization of the substance is possible, which can facilitate the conditions for the approach of protons and nuclei of elements. This forces us to consider the possibility of nuclear reactions proceeding through the process of overcoming the potential barrier, which lasts for a time that is many orders of magnitude longer than the nuclear collision time in a conventional nuclear process.

A Comparative Study of the Application of Glowworm Swarm Optimization Algorithm with other Nature-Inspired Algorithms in the Network Load Balancing Problem

Vast amounts of data are transferred through communication networks resulting in node congestion, which varies according to peak usage times. The Glowworm Swarm Optimization (GSO) algorithm is inspired by the rummaging and courtship behavior of glowworms. The glow intensity of glowworms is a measure of fitness that attracts other glowworms in its neighborhood. This work applies the GSO algorithm to the computer network congestion problem in order to lessen the network burden by shifting loads to the fittest neighborhood nodes, thereby enhancing network performance during peak traffic times, when the response of systems on the network would go down. The proposed solution aims to alleviate the burdened nodes, thereby improving the flow of traffic throughout the network, improving the users’ experience and productivity, and efficiency. In this paper, three swarm algorithms, namely Particle Swarm Optimization (PSO), Cuckoo Search (CK), and GSO have been employed to solve the network load balancing problem. The results produced by GSO show improvement of 71.17%, 74.14%, and 84.15% in networks consisting of 50, 100, and 200 nodes in peak hour load, while PSO shows 13.87%, 11.75%, and 23.72%, and CK 10.61%, 3.19%, and 6%. The results prove the superior performance of GSO.

Chronic neurogenic pain inducing chemiluminescence of mitochondrial associates in cardiomyocytes.

e21560 Background: Mitochondrial dysfunction is has a significant impact on the development of heart disease and is a characteristic feature of the heart physiopathology. Our purpose was to analyze some mechanisms of apoptosis regulation and self-organization in the mitochondria of the heart cells in mice with melanoma growing in presence of chronic neurogenic pain (CNP). Methods: The study included female C57BL/6 mice (n = 105) divided into groups: intact animals (n = 21); controls (C, n = 21) with a CNP model created by bilateral sciatic nerve ligation under xylazine/zoletil anesthesia; main group (CNP+B16/F10, n = 63) with B16/F10 melanoma transplanted after CNP creation. After decapitation, mitochondria of the heart were isolated by differential centrifugation. Levels of cytochrome C (ng/mg of protein), caspase 9 (ng/mg of protein), Bcl-2 (ng/mg of protein), AIF (ng/mg of protein), Ca2+ (mmol/g of protein) were determined in mitochondrial samples by ELISA. Results: CNP downregulated levels of Ca2+ by 3.2 times, Bcl-2 by 1.3 times (p < 0.05) and caspase 9 by 1.5 times (p < 0.05), compared to intact mice. AIF levels, on the contrary, were elevated by 2.3 times, and cytochrome C did not differed statistically significantly from intact values. After a week of B16/F10 growth in presence of CNP, levels of Ca2+ in the mitochondria of the heart increased by 5.3 times relative to C values. Further on, Ca2+ decreased to almost undetectable values. The AIF levels changed abruptly: after 1 week it increased by 3.7 times, after 2 weeks it declined to C levels, and after 3 weeks it became 5.2 times lower than in C and 2.3 times lower than in intact animals. Bcl-2 and cytochrome C changed similarly: Bcl-2 after 1 week of melanoma growth in presence of CNP increased 1.7 times (p < 0.05) compared to C, and then after 2-3 weeks it declined and became on average 2.2 times lower than in the mitochondria of the C group; levels of cytochrome C after 1 week did not differed significantly from the values in C, and after 2-3 weeks they decreased by 2.2 times. The levels of caspase 9 in CNP+B16/F10 were on average 2.4 times higher than C values throughout the study. The cold light of high brightness - chemiluminescence was recorded in samples of mitochondrial suspension after 2-3 weeks of CNP+B16/F10. The glow in heart mitochondrial samples was accompanied by bright flashes and a 10-15 second intense white glow with a gradual fading and settling of a large filamentous aggregation of mitochondria on the substrate layer. CNP contributed to the energy supply system blocking in the energy systems of cardiomyocytes. Conclusions: Mitochondrial mechanisms of apoptosis and self-organization of subcellular energy structures in the conditions of malignant tumor growth in presence of CNP are mediated by disruption of polyenzymatic apoptosis regulation systems, and a high level of oxidative stress that induces chemiluminescence of cardiomyocyte mitochondrial associates.

New Parameter for Analysis of Ionospheric Disturbances and the Search for Ionospheric Precursors of Earthquakes Based on Barbier’s Formula

A new relative parameter (δBarbier) is proposed for the analysis of ionospheric disturbances and the search for ionospheric precursors of earthquakes. The parameter is derived on the basis of the semiempirical Barbier’s formula, in which directly and simultaneously measured ionospheric parameters are used: the critical frequency of F2 layer of the ionosphere foF2 and the virtual minimum height of F region h'F. The time prior to a 6.2-magnitude earthquake that occurred in the vicinity of the ground-based station of vertical ionospheric sounding MAUI (Hawaii) on June 26, 1989, is considered as an example of the use of this parameter and its interpretation. We show that δBarbier ≤ 0 during dark hours, from 2000 to 0400 local time, against the geomagnetically quiet background (Kp ≤ 2+) on June 25, 1989, i.e., the day before the earthquake. This behavior is interpreted as a decrease (as compared to the median) in the glow intensity of the atomic oxygen O(1D) emission in the red line (630 nm) estimated from ionospheric data, which is associated with the dissociative recombination of {text{O}}_{2}^{ + } ions at altitude of the F region during this time. The studied effect can be seismogenic and can serve an ionospheric precursor of an earthquake.

A thermoluminescence study of CaF2:Dy under different types of irradiation sources towards environmental dosimetric applications

CaF2:Dy dosimeters are widely used in radiation dosimetry, especially in environmental dosimetry measurements, owing to their high sensitivity. In this study, TL dosimetric properties of CaF2:Dy dosimeters under different irradiation sources (90Sr/90Y,137Cs, and X-rays) were investigated within environmental dose limits. The TL glow curves obtained for each case were deconvolved according to the general order of kinetics (GOK) model. As a result of deconvolution, the TL glow curve shape and trap parameters (E,s, and b) did not change according to irradiation sources and dose value. The dose-response features were investigated for each thermoluminescence glow-peak towards three different irradiation sources. Furthermore, the f(D) supralinearity index was presented for each TL peaks, yielding linear behavior for the TL peaks 2nd - 5th and non-linear behavior for the 1st and 6th peaks. Thermal quenching was rigorously investigated for heating rates of 1–25 °C/s. Although the intensity of each TL peak differently behaved with increasing heating rates, it was not observed a significant change on the total intensity. As a result, thermal quenching was not observed when the entire TL glow intensity value was considered. Therefore, the heating process of dosimeters to ≤400 °C could be performed at any heating rate. Additionally, light-induced effect was investigated for fluorescent, daylight, and ultraviolet lamp (UV-254nm). The results of light-induced effect following irradiation showed that the TL intensity was affected the most in the case of UV-254 nm, showing a reduction of ∼70% after 120 min of exposure. The effect of daylight and fluorescent light was observed as the values of ∼54% and ∼7%, respectively. Therefore, the dosimeters should be kept in the dark to avoid loss of intensity after irradiation.