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It was confirmed that the pH of NaOH solution (pH 12) could be lowered to pH 6 or less, where I2 was chemically stable, by radiolysis products of air and water. It was also confirmed that acetic acid (CH3COOH) or formic acid (HCOOH) can act as a source material for CH3I formation if these organic acids and I− have specific concentration ratios and the solution pH is maintained within a specific range under gamma irradiation conditions. In the case of CH3COOH mixed solutions, a high concentration of CH3I was formed at a pH lower than the pKa (= 4.76), where the radiolysis rate of CH3COOH was relatively low. In the case of HCOOH mixed solutions, the formation of CH3I was confirmed under the conditions of satisfying a pH of 3 or more, where radiolysis of HCOOH is inhibited, and a pH of 6 or less, where I2 is stably present. [ABSTRACT FROM AUTHOR]

The Comprehensive Test Ban Treaty (CTBT) bans nuclear weapons testing and establishes the International Monitoring System (IMS) for the purpose of treaty verification. IMS is a detector network that confirms that global nuclear activity is peaceful in nature. These detector systems use β-γ coincidence measurements to characterize atmospheric samples containing radioxenon isotopes. The purpose of this work is to use the system consisting of two sodium iodide detectors and two PIPSbox detectors to characterize isotopically pure samples of 131mXe, 133mXe, 133Xe, and 135Xe via β, γ, and β-γ coincidence measurements. [ABSTRACT FROM AUTHOR]

The International Monitoring System arm of the Comprehensive Nuclear-Test-Ban Treaty Organization utilizes sampling of atmospheric radioxenon to scan the world for nuclear testing events. Current designs utilized in the field involve plastic scintillator cells run in coincidence with sodium iodide (NaI) or high purity germanium (HPGe) detectors. The use of plastic scintillators as electron detectors exhibit some issues in comparison to other materials. Silicon detectors are analyzed as an alternative to plastic scintillators for beta detection based on their higher energy resolution and lowered memory effect. A radioxenon detection setup was created with the intent of measuring radioxenon samples using coincidence counting between silicon and NaI detectors as well as silicon and HPGe. The absolute efficiency of both setups is calculated and compared. [ABSTRACT FROM AUTHOR]

A feasibility study of gamma-gamma coincidence measurements in prompt gamma neutron activation analysis is carried out experimentally with a pulsed DT neutron generator, a polyethylene graphite cell and eight large NaI(Tl) scintillators. Detection limits are measured with multidimensional energy spectra created in gamma-gamma coincidence and compared to HPGe detector spectra. With a neutron emisison of 2.5 × 108 n.s−1, the detection limit for sulfur is about 15 g in 20 min, while the detection limit is larger than 200 g when using the HPGe detector spectra. Processing the summ of up to three coincident gamma-ray energies highlights useful signal for a dysprosium sample, and allows for detecting permanent magnets containing 4% mass dysprosium within a rotor mock-up composed of stainless steel. [ABSTRACT FROM AUTHOR]

In the present study, the activity concentration of radioactive nuclides (226Ra, 232Th and 40K) in different types of rocks in the lesser Himalayan mountainous region in Jammu and Kashmir, India have been measured using Sodium Iodide and High purity germanium detectors. The advanced smart RnDuo monitor was utilized for assessing radon and thoron exhalation rates and the results vary from 14.82 to 37.85 mBqkg−1 h−1 and 124–372 mBqm−2 s−1 respectively. The radium equivalent activities of the studied samples have been calculated to assess the radiation hazards arising due to the use of these rocks in the construction of dwellings. All the rock samples have radium equivalent activities lower than the limit set in the OECD report (370 Bq Kg−1). [ABSTRACT FROM AUTHOR]

The COSINE experiment is searching for dark matter using ultra-low background NaI scintillating crystals. In order to reduce the internal contamination of the initial NaI powder to grow NaI crystals, NaI powder samples with different purities were purified by fractional recrystallization using de-ionized water. The concentrations of the main radioactive elements, K, Pb, Th, and U, which are major backgrounds for the dark matter search, were reduced to the level required for the experiment. Further, the concentrations of other impurities, e.g., Ba, Ca, Cr, and Fe, were also reduced, which is important to realize good quality NaI crystals. [ABSTRACT FROM AUTHOR]

The most accurate method for the analysis of complex gamma ray spectra from scintillation detectors is least squares method. The major requirement of this method is individual standard spectra of all nuclides expected in the complex spectrum which is not possible and feasible for some nuclides. In the present work, an approach of using simulated standard spectrum of the radionuclides for the least squares analysis is studied. The paper describes the methodology used for the generation of simulated spectrum which is the main objective, and validation of results using standard sources in the Sodium Iodide (NaI(Tl)) based gamma ray spectrometer. [ABSTRACT FROM AUTHOR]

The resolving time values of the coincidence spectrometers composed by NaI(Tl) inorganic, BC408 type and BC418 type organic scintillation detectors were obtained in this work. For this purpose, fast-fast coincidence measurements were carried out. Best timing performance was obtained by BC418 type plastic scintillator for various source-detector distances. [ABSTRACT FROM AUTHOR]

In this study, a Monte Carlo program has been developed to simulate the response function of the NaI(Tl) detector with all features for Co and Cs and to investigate the effects of detector housing material on response function. The pulse height spectra in a 2″ × 2″ NaI(Tl) detector due to these gamma ray sources have been measured. Comparison of the experimentally obtained and simulated spectra shows that there is good agreement between both spectra. Energy distributions of gamma photons that generate the backscattering peak in the response function were obtained and the contribution of single, double and multiple Compton scattering events to these distributions was investigated. [ABSTRACT FROM AUTHOR]

Gamma-ray energy spectrum of a Cs radioisotope was obtained by using a NaI(Tl) scintillation detector. Improvement of the energy resolution of the detector was aimed. To achieve this, constant fraction timing method was used. Energy resolution of the photopeak of the isotope was improved from 7.1 to 6.7% through the timing application. [ABSTRACT FROM AUTHOR]

At the Whole Body Monitoring Laboratory, from IFIN-HH, Bucharest, Romania, there were performed in vivo gamma-ray spectrometry measurements on 108 Romanian males in order to evaluate the mineral natural potassium content in human body, as total value and concentration. The measurements were performed with a shadow shield whole body counter, tilted chair geometry, based on a shielded NaI(Tl) scintillation detector of 12.5 cm (diameter) × 10 cm (height) crystal size. The results revealed a calculated value of the mean total body potassium (TBK) of 135.03 ± 2.94 g and a value of 1.9 ± 0.022 g of potassium/kg of body weight for the mean body potassium concentration, for the measured males. These values are similar with the values declared for the Reference Man, in ICRP23. Correlations between total body potassium, potassium concentration and age, weight and Body Build Index were investigated and peculiar conclusions were resulted. [ABSTRACT FROM AUTHOR]

The relative yield of 3γ to 2γ annihilation was measured for a positron emitter, Na, with the new scintillator detectors lanthanum chloride (LaCl:Ce) and lanthanum bromide (LaBr:Ce), which had been characterised for comparison with high-purity germanium (HPGe) and sodium iodide (NaI(Tl)) detectors. The information obtained from the ortho-positronium 3γ decay in positron emission tomography (PET) can be a measure of the oxygen content in biological tissues by determination of this relative yield. However, it requires high resolution spectroscopy and detection efficiency. Characterisation of the new generation of scintillator detectors determines whether they could replace conventional scintillators and semiconductors. A series of experiments was carried out with different samples in order to study the effect of ortho-positronium formation. The peak-to-peak and the peak-to-valley methods were compared in the measurement of the relative yield of 3γ to 2γ annihilation. [ABSTRACT FROM AUTHOR]

The ASEDRA (Advanced Synthetically Enhanced Detector Resolution Algorithm, patent pending) has been successfully applied as a post processing algorithm to both sodium iodide (NaI(Tl)) and cesium iodide (CsI(Na)) scintillator detectors to synthetically enhance their realized spectral data resolution by as much as a factor of three, wherein from these detectors the 'raw' unprocessed spectra are traditionally of poor resolution. ASEDRA uses noise reduction and built-in high resolution Monte Carlo radiation transport based detector response functions (DRFs) to rapidly post-process a spectrum in a few seconds on a standard laptop; gamma lines are extracted with an accuracy that makes the scintillator detectors competitive with higher resolution, higher material cost detectors. ASEDRA differs from other tools in the field, such as Sandia's GADRAS software, in that ASEDRA performs a differential spectrum attribution and cumulative extraction from the sample spectrum, rather than an integral-based approach, as in GADRAS. Previous publications have highlighted the successful application of ASEDRA in samples with plutonium and various isotopes. A new SmartID nuclide identification package to accompany ASEDRA has recently been implemented for test and evaluation purposes for sample attribution; in addition, the application of ASEDRA+SmartID has occurred with success in long dwell cargo monitoring and SNM detection applications, enabling new protocols for HEU detection. Overall, this paper presents recent developments and results along with a discussion of follow-on steps in the development of ASEDRA as an effective field gamma spectrum analysis tool for low cost scintillators. [ABSTRACT FROM AUTHOR]

A coincidence method for measuring Cs, K, Ra and Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of Cs, Ra and Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer ones. [ABSTRACT FROM AUTHOR]

The activity concentration of radionuclides, such as U, Ra and K of limestone rocks in northern Iraq was measured using gamma spectroscopy. The radionuclide activities were obtained and discussed. CR-39 nuclear track detector was used to measure the radon exhalation rates as well as the effective radium contents of these samples and are found to correspond with uranium concentration values measured by NaI(Tl) detector in the corresponding limestone rocks samples. The absorbed gamma dose rates in air due to the presence of U, Ra, K and cosmic ray contribution varied between 105.3 and 223.11 nGy/h. The annual effective dose of each sample has been calculated. The correlation between activities of Ra, Rn exhalation rates and U is explained. Results show a symmetrical distribution of activity concentrations of primordial of radionuclides in selected samples. The values of all studied radionuclides are considered to be a typical level of natural background and compared with results of similar investigations carried out else where. [ABSTRACT FROM AUTHOR]

Multidimensional gamma-spectrometry is a powerful technique for making low-level nuclear measurements. The systems typically utilise multiple sodium iodide detectors to measure coincident or anti-coincident gamma-energies. This allows significant background reduction and high selectivity of cascading radionuclides including Na. As events are rejected or selected based on their event time, the timing resolution of the multi-channel analyser (MCA) is important. This has been assessed for three compact MCA systems produced by Canberra and Ortec. The Canberra Osprey and Lynx provided the best timing performance, capturing 88.3 and 97.9% of Na positron emissions within 200 ns. In comparison only 12.5% of events were measured within 200 ns by the Ortec digiBASE-E. However all systems captured the majority of events within 1000 ns, providing multidimensional spectra that allow the evaluation of simultaneous energy combinations. [ABSTRACT FROM AUTHOR]

Accurate nuclide identification depends on the ability to determine if specific peaks are present in the spectrum. Several current handheld nuclide identifiers and portal monitors use a variant of a peak quality value for this. The peak quality is usually calculated as the peak area divided by the uncertainty of the peak area and when this quotient is above a threshold value, the peak is said to be present. Other works [Terracol et al. In: 2004 IEEE Nuclear Science Symposium Conference Record, Rome, Italy, 2004, Ryder In: Scanning Electron Microscopy/1977 V. 1, Proceedings of the Workshop on Analytical Electron Microscopy, Chicago, 1977] have developed a formalism to calculate the peak uncertainty for interfering peaks based on the detector resolution, background, individual peak areas, and peak separation. The threshold on peak uncertainty determines the minimum activity that will be identified or detected. Care must be used in the selection of the threshold in order to comply with the false positive and false negative requirements of the detection system regime, or “concept of operations”. The performance standards for the handheld identifiers and portal monitors specify the nuclides required to be identified. From this list and other commonly expected nuclides, the energies of the expected gamma rays can be tallied, yielding a table of the separations of adjacent peaks possible in the collected spectrum. Using the formalism, the peak quality value can be determined as a function of the detector resolution, peak area and background for the energy separations in the table determined above. Results are shown for the cases of HEU and plutonium with the masking nuclides of NORM, 133Ba, or 57Co for both germanium and sodium iodide detectors. Typical resolutions, efficiencies and counting times were used. [ABSTRACT FROM AUTHOR]

This report assesses the utility of lanthanum-halide detectors for isotope identification and total mass measurements for uranium and plutonium isotopes. Comparisons to similar measurements with NaI detectors are made. [ABSTRACT FROM AUTHOR]

Uranium enrichment and holdup measurements require a detector capable of accurately obtaining the 186-keV peak area. NaI detectors have been widely used for these tasks. However, for recycled uranium, the interference of the 239-keV peak from the 232U decay chain challenges the capabilities of the NaI detectors to accurately extract the area of the 186-keV peak. Using CZT detectors, which have much better resolution than the NaI detectors, has temporarily solved this interference problem. However, the CZT detectors have setbacks in that they are generally small and have low efficiencies, which require long acquisition times for reasonable statistics. Recently, two new types of scintillator detectors have become available commercially, LaCl3(Ce) and LaBr3(Ce). These cerium-doped lanthanum halide detectors, with comparable resolution but better efficiency than the CZT detectors, appear to permanently solve the interference problem for recycled uranium measurements. In this report, we compare the uranium enrichment measurement performances of a portable NaI detector, a large coplanar-grid CZT detector, and a LaBr3 detector. [ABSTRACT FROM AUTHOR]

The concept of representing a cylindrical detector volume as a virtual point detector in order to simplify the evaluation of the detector efficiency was proposed in the past for HPGe detectors in the case of measuring point sources. In the present work, the validity of the point detector model was studied and confirmed for the direct measurement of small volume sources, when using a common 7.5×7.5 cm2 NaI(T1) detector. [ABSTRACT FROM AUTHOR]

Astatine-211 is one of the most promising a-emitters for targeted cancer radiotherapy. However, research and clinical trials involving 211At-labeled radiopharmaceuticals have often been impeded due to the irregular and sometimes inconveniently low recovery yields obtained by the currently used dry distillation procedure. Therefore, a wet harvesting procedure isolating 211At from an irradiated 209Bi target was explored. The procedure involves target dissolution in concentrated HNO3 and extraction of the high oxidation state 211At activity with butyl or isopropyl ether. This method resulted in consistent and nearly quantitative yields. The activity was re-extracted in aqueous phase and applied to NIS6 UVW human glioma cells transfected with cDNA encoding the human sodium/iodide symporter (NIS). The significant and specific uptake of 211At activity by these cells suggests that in the ether phase, high oxidation state 211At is reduced to [211At]astatide anion. The synthesis of the first astatinated organic compound derived from wet harvested 211At, 3-astatobenzoic acid (ABA), was achieved. [ABSTRACT FROM AUTHOR]

Good manufacturing practices specify that a well-type scintillation NaI(Tl) crystal detector has to be validated in order to detect radioactivity from any radiopharmaceutical used to obtain radiopharmacokinetic parameters. A 5 cm well-type NaI(Tl) scintillation detector was coupled to a multi-channel analyzer centered at the 140 keV 99mTc peak with a 20% window. The area represents counts per minute (cpm). All the net cpm were decay corrected. The activity source was 99mTc-glucarate developed as an imaging agent for acute myocardial infarction. Wistar rats were injected in a tail vein with 0.1 ml (3.7 MBq) of 99mTc-glucarate solution and 13 blood samples were taken. The cpm were the input data for the WINNONLN program which calculates radiopharmacokinetic parameters. The detector's efficiency for 99mTc was 15.03% and the sensitivity 1.12 kBq/ml in plasma. The response was linear between 0.31-14.3 kBq/ml of 99mTc-glucarate. The maximum assay variation coefficient was 2.79 and recovery of 99mTc-glucarate in plasma was 99.8%±0.2%. LOD was 0.31 kBq and LOQ = 1.12 kBq in plasma samples. 99mTc-glucarate follows a two-compartment model of distribution with Vd of 21.74 ml±2.71 ml; a Vdss of 74.36 ml±12.67 ml; t1/2a 0.74 h±0.19 h; t1/2b 18.98 h±4.36 h; AUC = 32.75 mCi/min.ml ± 3.73 mCi/min.ml; MRT = 24.35 h±5.51 h and total clearance 3.05 ml/h±0.35 ml/h. The well-type detector fulfills the quality system requirements and the radiopharmacokinetic parameters for 99mTc-glucarate in rats are reliable. [ABSTRACT FROM AUTHOR]

The retention of 131I on ceramic rod coated with silver nitrate followed by coating with a polyurethane membrane to be applied in brachytherapy was studied. The concentration of silver nitrate (20 g/l), the volume of 131I as a sodium iodide solution (100 µl), the pH of the reaction mixture (pH 9) etc., were optimized to get a maximum uptake on the ceramic rod. The concentration of coating solution (5%, polyurethane in tetrahydrofuran) was also optimized to obtain a minimum leaching of 131I activity in normal saline solution. After coating with a polyurethane membrane, the 131I absorbed on the ceramic rod exhibited low leachability (0.03%). This method can be applied for the preparation of 125I interstitial sources to be used in eye and prostate cancer therapy. [ABSTRACT FROM AUTHOR]