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[en] The High Luminosity upgrade of the Large Hadron Collider highlighted the need for a time-tagging of tracks with a precision of tens of picoseconds. This requirement motivated the development of radiation hard silicon sensors dedicated to the time-of-interaction measurement of minimum ionizing particles. Low Gain Avalanche Detectors (LGADs) are silicon sensors with internal charge multiplication and are the baseline for the timing systems of the ATLAS and CMS experiments. These sensors use the gain to improve the signal to noise ratio (SNR) of detector systems and have been engineered to withstand the harsh radiation environment of the experiments. Fondazione Bruno Kessler (FBK) developed the LGAD technology through several production runs. The improved SNR and excellent time resolution made LGADs suitable also for medical, x-ray, and space applications. A feature of LGADs is the presence of a termination structure between regions with gain that results in areas without gain between the readout channels, reducing the fill factor of the devices. Different strategies to improve the fill factor of LGADs are being developed, such as double-sided LGADs, resistive AC-coupled LGADs, and trench isolated LGADs. This talk summarizes the experience acquired at FBK with the realization of more than ten sensor batches. Selected results in radiation hardness, time resolution, fill factor, and different LGAD applications will be discussed.

[en] Optical surveillance is one of the important safeguards measures applied by the IAEA. Surveillance equipment currently in use (twin and triple tine-camera systems and one-or multi-channel closed circuit TV systems) was designed more than a decade ago and some of the systems authorized for inspection use - specifically the single-channel TV systems - have failure rates that contribute significantly to the overall number of safeguards surveillance failures. In fact, the technical failure of surveillance equipment had been the largest single cause of inconclusive surveillance results at reactor facilities. The move from the current surveillance equipment to digital image surveillance (DIS) equipment has been one of the directions in the activities of the Department of Safeguards in the instrumentation area. In October 1995 the Department finalized its policy for transition to DIS, meant to provide inter alia a considerably higher reliability level of surveillance equipment, and agreed on the essential requirements for DIS systems. To be sure about the improved reliability of the new equipment, it was decided that all DIS systems must be tested for at least 150 equipment months in the field before their acceptance by the Agency. Three DIS systems have been approved for evaluation: Gemini, developed under a task of the US Support Programme to Agency safeguards; EMOSS-1, a product of the French Hymatom company; and VDIS, being completed under a task of the German Support Programme. Department-wide field test activities have been formulated with surveillance systems installed in nuclear facilities under safeguards in different countries. To expedite the testing, the Support Programmes of Finland, Germany, Hungary and the United States provided additional test locations. In September 1997 it was estimated that the field tests for EMOSS-1 would be completed by the end of October, and for Gemini and VDIS-One Channel the testing would be finished, respectively, late in 1997 and early in 1998. (author)

[en] This study aims to find the best mixture of mortar (cement + sand + water) using local natural materials and choose the best mix in terms of radiation and technical properties so that they can be used for radiation shielding especially in shielding facilities which are not designed primarily to contain radiation. in this study samples of mortar with different mixing ratios were prepared used three different types of sands: barite, hematite and normal sand we focused in this study on the effect of increasing sand proportion in each sample on the linear attenuation coefficient for x-rays with energy 80,100,110,120keV and gamma photons with energy 662keV using trans rays method and using X-COM to calculate these coefficient. Results showed that the addition of barite and hematite sands to concrete mix increases the density of samples compared with normal sand samples and the linear attenuation coefficient values increases with increase of samples density and decreases with the increase of X-rays energy ( and gamma photons energy) and barite samples attenuate more than hematite and normal sand samples. (author)

[en] This research studies the optimal conditions for extraction, separation and determination of Tylosin & Spiramycin compounds in poultry samples, using High Performance Liquid Chromatography technique with Diode Array Detector (HPLC-DAD).The best recovery ratios for Tylosin and Spiramycin were 90.0, 93.0% respectively at 0.10ppm, and 91.90, 92.90% respectively at 1.0ppm; using an extraction solvent of Mcllvaine-EDTA at pH:2.6. The study revealed an excellent recovery ratios of 96.50, 97.50% respectively for Tylosin and Spiramycin at 0.10ppm and 98.10, 100.50% respectively at 1.0ppm, at the extraction by ultrasonic water bath with a percentage relative standard deviation less than 1.1% during half an hour. On the other hand, Cartridges solid phase extraction Oasis HLB. (Hydrophilic Lipophilic Balance Copolymer) (500mg, 5ml) showed also an excellent response for the recovery of Tylosin and Spiramycin: 96.50, 97.50% respectively at 0.10ppm and 100.10, 100.40% respectively at 1.0ppm in comparison with other cartridges. The results showed that the recovery ratios of Tylosin and Spiramycin were not affected by increasing the volume of methanol used in elution more than 3.5ml. The study showed that the holding time needed for the quantitative determination of both compounds from six poultry samples was about four hours, which considered as a good time for the application of this method in the control laboratories (Food Section). The calibration curves of Tylosin and Spiramycin were found to have an excellent linearity and correlation coefficients; R2= 0.99990, 0.99997 respectively within a range of concentrations between 0.080-1.20ppm. (author)

[en] Highlights: • Effects of crack deflection angle, normalized crack depth and crack shape aspect ratio are investigated. • As the deflection angle increases, mode-I stress intensity factors decrease, mode-II and -III stress intensity factors increase. • Normalized stress intensity factors for midsize-thick-walled vessels are higher than those of thin-walled spherical vessels. • Crack deflection angle is shown to have the highest influencing effect among all parameters. • Especially for higher crack deflection angles, crack surfaces come into contact partially or fully. -- Abstract: In this paper, three-dimensional mixed-mode stress intensity factor solutions are obtained for deflected inner surface cracks contained in thin- and midsize-thick-walled spherical pressure vessels. In an effort to build a library of stress intensity factor solutions for different realistic cases, main parameters affecting the problem, which are crack deflection angle, normalized crack depth and crack shape aspect ratio, are changed systematically to cover all combinations. The results show that as the deflection angle increases, mode-I stress intensity factors decrease and mode-II and mode-III stress intensity factors increase for a given case. It is also observed that as the normalized crack depth increases, stress intensity factors increase along the crack front. The results show that magnitudes of the normalized mixed mode stress intensity factors for midsize-thick-walled vessels are higher than those of thin-walled spherical vessels. Crack deflection angle is shown to have the highest influencing effect among all parameters. It is also observed that especially for higher crack deflection angles, which have higher mode-mixity, crack surfaces may come into contact partially or fully.

[en] To estimate blood lead levels (BLL) by atomic absorbance spectrometry in small scale local battery workers in Pakistan. Study Design: Comparative cross sectional study. Place and Duration of Study: Department of Chemical Pathology & Endocrinology, Armed Forces Institute of Pathology, Rawalpindi, from Feb 2017 to Apr 2018. Methodology: We measured blood lead levels of 100 male workers from local battery dealing workshops (minimum exposure of 10 years) on atomic absorption spectrometry and compared with that of 100 healthy nonexposed controls living at least 30 km away from the industrial area. Independent sample t-test and chi-square were used to test the significance mean difference and association, respectively. Results: Blood lead levels in exposed and unexposed group were 38.31 ± 3.78 and 1.84 ± 0.085 µg/L respectively. 22 (22%) workers had blood lead levels >100 µg/L and 78 (78%) had <100 µg/L which were statistically significant. In group with high BLL, 5 (22.7%) had exposure of up to 10 years while 17 (77.3%) had more than 10 years showing significant association with duration of exposure. Health problems included infertility 5 (5%), hypertension 10 (10%), gastric problems 11 (11%), confusion and headache 18 (18%), with no significant association with lead levels (p=0.306). Conclusion: Workers involved in various processes of battery handling in local shops have elevated blood lead levels and subsequent health issues, thus necessitating improvement in health awareness in both industrial and small scale employees. (author)

[en] We have synthesized the nano-crystalline samples of GdFe_1−xMn_xO₃(0 ≤ x ≤ 0.3) via solid state reaction route and studied their dielectric properties and ac conductivity in detail. X-ray diffraction patterns show monophase structure of the samples in orthorhombic crystal symmetry (space group Pbnm). The enhancement in dielectric constant is registered on Mn doping at room temperature as well as with the rise in temperature at a constant frequency. The fitting of Cole–Cole plots indicate the non-Debye kind relaxation mechanisms in the samples. The real (Z′) and imaginary (Z″) components of impedance reduce with the increase in frequency and Mn ions in GdFeO₃ lattice. Nyquist plots are fitted to a single semicircle that hints towards the single relaxation process. The ac conductivity (σ_ac) is also increased with the frequency and follow the power law,σ_ac(ω) = Aω^s wherein the exponent ‘s’ reduces with frequency. We have estimated the activation energies with the help of ln(σ) versus 1/T plots that remain almost constant below 350 K and show variation with the Mn doping in GdFeO₃ perovskite at temperatures 620–673 K. The polaron hopping energy (W_M) in the framework of the correlated barrier hopping (CBH) and non-overlapping small polaron tunneling (NSPT) models have been calculated and its variation with temperature signifies thermally activated conduction mechanism in the studied materials.

[en] Uranium is the most common element in the nuclear fuel cycle. Different techniques have been used for analyzing the isotopic composition of uranium. Precise determination of uranium isotopic ratios for an efficient control of nuclear material was carried out through the modification of the used chromatographic method of uranium. Alpha spectrometry was utilized to identify different types of natural, depleted and enriched samples for safeguard purposes. Uranium element was extracted from other interfering radionuclides, purified, electrodeposited on a stainless-steel disc, and measured using alpha-spectrometer, then isotopic ratios were calculated. For comparison purposes, the samples were also measured using a hyper pure germanium (HPGe) spectrometer and the uranium isotopic ratios were obtained. The results obtained by both techniques were in agreement within difference ranged from -8.7 to 12%. It was concluded that alpha spectrometric measurements of uranium isotopes preceded by efficient radiochemical separation using extraction chromatography is a fast and reliable technique for safeguard purposes

[en] Normalized mixed-mode stress intensity factor equations are presented for deflected and inclined circular surface and corner cracks in finite-thickness plates under uniform remote tensile loading. The equations are obtained by performing non-linear regression analyses on the data from previous numerical solutions based on three-dimensional enriched finite elements. In the equations, the effects of deflection/inclination angles and plate thickness on mixed-mode stress intensity factors are included. The comparisons of normalized stress intensity factors from the equations with those of the finite element analyses show good agreement. Thus, it is concluded that, as a reasonable approximation, the presented equations can be used to assess stress intensity factors and fracture conditions of mixed-mode circular surface and corner cracks in finite-thickness plates. - Highlights: → Normalized mixed-mode stress intensity factor equations for 3D cracks in plates. → Equations developed using non-linear regression. → Effects of deflection/inclination angles and plate thickness considered. → Equations to be used to assess stress intensity factors and fracture conditions.