NaI Spectrometer Research Articles

THE CONCENTRATION OF NATURAL RADIATION SOURCES (NRS), MAINLY 238U, 232Th, and 40K, IN BUILDING MATERIALS (SAND, CLAY BRICKS, AND CONCRETE BLOCKS) USED ALONG KANGUNDO ROAD, NAIROBI KENYA

This research aimed at assessing the concentration of Natural Radiation Sources (NRS), mainly 238U, 232Th, and 40K, in building materials (sand, clay bricks, and concrete blocks) used along Kangundo Road in Nairobi City County. Human exposure to ionising radiation is largely due to Natural Radiation Sources (NRS). These radioactive elements with long half-lives are found in the Earths lithosphere and in construction materials with radiation levels varying due to their geology. A purposive random sampling method was deployed in this work to collect samples of building materials for analysis. The radioactivity concentration levels in the sampled building materials were determined using a NaI (TI) spectrometer at Kenyatta University laboratory. The activity concentration of 40K varied from 151 ± 8 to 2392 ± 120 Bq/kg, 238U varied from 27 ± 2 to 412 ± 21 Bq/kg and 232Th ranged from 54 ± 3 to 612 ± 31Bq/kg. More than 70 per cent of the samples analysed had activity concentration surpassing the world permissible limits of 420 Bq/kg, 33 Bq/kg, 45 Bq/kg for 40K, 238U and 232Th respectively. The study therefore recommended that assessment of radioactivity concentration for samples with high radioactivity values.

Neutron capture cross section measurement of $$^{129}$$I and $$^{127}$$I using the NaI(Tl) spectrometer of the ANNRI beamline at J-PARC

Neutron capture cross section measurement of $$^{129}$$I and $$^{127}$$I using the NaI(Tl) spectrometer of the ANNRI beamline at J-PARC

An enormous increase in atmospheric positron flux during a summer thunderstorm on Mount Aragats

On July 11, 2023, we observed a remarkable 500% increase in positron flux, coinciding with a significant Thunderstorm Ground Enhancement (TGE). The enhanced flux of electrons and gamma rays was attributed to relativistic runaway electron avalanches (RREAs) generated within the dipole formed between the main negatively charged layer in the middle of the thundercloud and the Lower Positively Charged Region (LPCR) at the bottom of the thundercloud. Concurrently, a substantial enhancement in the 511 keV gamma-ray flux resulting from electron-positron annihilation was recorded. This surge is intricately linked to the LPCR within the thundercloud. The emergence of the LPCR induces a polarity change in the atmospheric electric field (AEF) below the LPCR (fourth dipole), leading to the deceleration of electrons and the acceleration of positrons.Particle flux measurements were conducted using scintillation and NaI(TL) spectrometers. To mitigate the contamination of natural gamma radiation and refine the 511 keV flux measurements, the ORTEC spectrometer was shielded with a 4 cm thick lead filter. CORSIKA simulations corroborate the observed positron flux enhancement.Highlighting the synergy between high-energy physics in the atmosphere and astroparticle physics, we introduce a new scenario to elucidate the enigmatic large flux of galactic positrons measured by the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station (ISS).

An Ultra-Throughput Boost Method for Gamma-Ray Spectrometers

(1) Background: Generally, in nuclear medicine and nuclear power plants, energy spectrum measurements and radioactive nuclide identification are required for evaluation of strong radiation fields to ensure nuclear safety and security; thereby, damage is prevented to nuclear facilities caused by natural disasters or the criminal smuggling of nuclear materials. High count rates can lead to signal accumulation, negatively affecting the performance of gamma spectrometers, and in severe cases, even damaging the detectors. Higher pulse throughput with better energy resolution is the ultimate goal of a gamma-ray spectrometer. Traditionally, pileup pulses, which cause dead time and affect throughput, are rejected to maintain good energy resolution. (2) Method: In this paper, an ultra-throughput boost (UTB) off-line processing method was used to improve the throughput and reduce the pileup effect of the spectrometer. Firstly, by fitting the impulse signal of the detector, the response matrix was built by the functional model of a dual exponential tail convolved with the Gaussian kernel; then, a quadratic programming method based on a non-negative least squares (NNLS) algorithm was adopted to solve the constrained optimization problem for the inversion. (3) Results: Both the simulated and experimental results of the UTB method show that most of the impulses in the pulse sequence from the scintillator detector were restored to δ-like pulses, and the throughput of the UTB method for the NaI(Tl) spectrometer reached 207 kcps with a resolution of 7.71% @661.7 keV. A reduction was also seen in the high energy pileup phenomenon. (4) Conclusions: We conclude that the UTB method can restore individual and piled-up pulses to δ-like sequences, effectively boosting pulse throughput and suppressing high-energy tailing and sum peaks caused by the pileup effect at the cost of a slight loss in energy resolution.

Characterization study of NaI(Tl) γ-summing spectrometer

The accurate information regarding the β-decay half-life, feeding pattern from the neutron-rich nuclei have utmost importance in the field of nuclear waste management from the fission reactors as well as correct understanding about the r-process nucleosynthesis in stellar sites. The low capture cross-section measurements are also considered as major task by experimental nuclear astrophysicists. These kinds of measurements are really difficult with conventional high-resolution gamma spectroscopy techniques due to less efficiency of the detectors. For this purpose, we have an almost 4π γ-summing NaI(Tl) spectrometer at SINP, Kolkata. It is basically a cylindrical shaped detector with six sectors of NaI(Tl) crystals read by 6 photomultiplier tubes (PMT) at one end. The detailed characterization of the spectrometer via experiment using laboratory standard sources and GEANT4 simulation model to interpret all the interesting properties will be presented here in this paper.

241Am Neutron Capture Cross Section Measurement using the NaI(Tl) spectrometer of the ANNRI beamline of J-PARC

ABSTRACT The neutron capture cross-section of 241Am was measured from 10 meV to about 500 keV using the NaI(Tl) spectrometer of the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) beamline in the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The total energy detection principle was applied in conjunction with the pulse-height weighting technique to derive the neutron capture yield. The present cross-section results were normalized using a 197Au sample measurement by applying the saturated resonance method. The thermal cross section was measured to be 708 ± 22 b, in agreement with the evaluation in JENDL-5 of 709 b within uncertainties. In the keV region, the evaluated libraries of JENDL-5, ENDF/B-VIII.0 and JEFF-3.3 are in good agreement with the present results over 10 keV but show values lower by 30% to 70% below that energy. Moreover, the results of a resonance shape analysis of the resolved resonance region are also provided in the present paper.

Radiation monitoring after experimental dirty bomb explosion.

Experiments simulating radioactive dirty bomb explosions in an urban area were performed at the National Institute of NBC Protection (SUJCHBO v.v.i.), Czech Republic. A solution containing 99mTc radionuclide was dispersed by an explosion on an open-air model of a square covered with filters. Subsequently, spectra of gamma rays originating in contaminated filters were measured by a hand-held NaI(Tl) spectrometer and laboratory HPGe spectrometers. The ambient dose equivalent rate at measuring vessels was set as well. Self-made standards had been prepared by dripping a defined amount of 99mTc solution uniformly on the filters to set the 99mTc surface contamination of measured samples. The urban area model's radioactive contamination map was set using previously determined filters' locations. The defined amount of 99mTc solution was dripped non-homogenously on some filters to estimate the impact of non-homogenous filters' coverage by radioactive aerosol' particles.

Measurements and computational analysis of the natural decay of Lu176

Background: Mainly because of its long half-life and despite its scientific relevance, spectroscopic measurements of $^{176}\mathrm{Lu}$ forbidden $\ensuremath{\beta}$ decays are very limited and lack formulation of shape factors. A direct precise measurement of its Q value is also presently unreported. In addition, the description of forbidden decays provides interesting challenges for nuclear theory. The comparison of precise experimental results with theoretical calculations for these decays can help to test underlying models and can aid the interpretation of data from other experiments.Purpose: Perform the first precision measurements of $^{176}\mathrm{Lu}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-decay spectra and attempt the observation of its electron capture decays, as well as perform the first precision direct measurement of the $^{176}\mathrm{Lu}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-decay Q value. Compare the shape of the precisely determined experimental $\ensuremath{\beta}$ spectra to theoretical calculations, and compare the end point energy to that obtained from an independent Q value measurement.Method: The $^{176}\mathrm{Lu}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-decay spectra measurements and the search for electron capture decays were performed with an experimental setup that employed lutetium-containing scintillator crystals and a NaI(Tl) spectrometer for coincidence counting. The $\ensuremath{\beta}$ decay Q value was determined via high-precision Penning trap mass spectrometry (PTMS) with the LEBIT facility at the National Superconducting Cyclotron Laboratory. The $\ensuremath{\beta}$-spectrum calculations were performed within the Fermi theory formalism with nuclear structure effects calculated using a shell model approach.Results: Both $\ensuremath{\beta}$ transitions of $^{176}\mathrm{Lu}$ were experimentally observed and corresponding shape factors formulated in their entire energy ranges. The search for electron capture decay branches led to an experimental upper limit of $6.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ relative to its $\ensuremath{\beta}$ decays. The $^{176}\mathrm{Lu}\phantom{\rule{4pt}{0ex}}\ensuremath{\beta}$-decay and electron capture Q values were measured using PTMS to be 1193.0(6) and 108.9(8) keV, respectively. This enabled precise $\ensuremath{\beta}$ end point energies of 596.2(6) and 195.3(6) keV to be determined for the primary and secondary $\ensuremath{\beta}$ decays, respectively. The conserved vector current hypothesis was applied to calculate the relativistic vector matrix elements. The $\ensuremath{\beta}$-spectrum shape was shown to significantly depend on the Coulomb displacement energy and on the value of the axial vector coupling constant ${g}_{A}$, which was extracted according to different assumptions.Conclusion: The implemented self-scintillation method has provided unmatched observations of $^{176}\mathrm{Lu}$, independently validated by the first direct measurements of its $\ensuremath{\beta}$-decay Q value by Penning trap mass spectrometry. Theoretical study of the main $\ensuremath{\beta}$ transition led to the extraction of very different effective ${g}_{A}$ and ${log}_{10}\phantom{\rule{0.16em}{0ex}}f$ values, showing that a high-precision description of this transition would require a realistic nuclear structure with nucleus deformation.

Neutron Capture Cross Section Measurement and Resonance Analysis of 107Pd Using ANNRI at MLF/J-PARC

The neutron capture cross sections of 107Pd were measured using the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) at the Japan Proton Accelerator Research Complex (J-PARC). Capture γ-rays were detected with a NaI(Tl) spectrometer. The incident neutron energy was determined by the time-of-flight method. The preliminary cross section was derived from thermal to resonance energy region. In the resonance region, resonance parameters were derived by resonance analysis using REFIT code. The resonance parameter was close to the value of JENDL-4.0.

Neutron total and capture cross-section measurements of 155Gd and 157Gd in the thermal energy region with the Li-glass detectors and NaI(Tl) spectrometer installed in J-PARC·MLF·ANNRI

ABSTRACT Neutron total and capture cross–section measurements of 155Gd and 157Gd were performed with Li-glass detectors and a NaI(Tl) spectrometer in the ANNRI at the MLF of the J-PARC. The neutron total cross sections were determined in the energy region from 5 to 100 meV, and those at the thermal neutron energy were obtained to be 59.4 1.7 and 251.9 4.6 kilobarn for 155Gd and 157Gd, respectively. The neutron capture cross sections were determined in the energy region from 3.5 to 100 meV with an innovative method, and those at the thermal energy were obtained as 59.0 2.5 and 247.4 3.9 kilobarn for 155Gd and 157Gd, respectively. The present total and capture cross sections agree well within the standard deviations. The results for 155Gd were found to be consistent with the values in JENDL-4.0 and the experimental data given by Møller et al., Mastromarco et al. and Leinweber et al. Those for 157Gd agreed with the evaluated data in JENDL-4.0 and the experimental data by Møller et al. and Mastromarco et al. However, they disagree (11% larger) with the experimental result by Leinweber et al.

Novel multifunctional microcapsule and its cyanate ester resin composites with self‐healing ability and gamma radiation shielding ability

AbstractResin‐based composites used in spacecraft face risks from space debris and high‐energy charged particles during their long‐term service in the space environment. This work proposes a novel microcapsule (MC) and its cyanate ester (CE) resin‐based composites (CE/MCs) with self‐healing ability and gamma radiation shielding ability. The multifunctional epoxy/lead tungstate (EP@PWO) microcapsules are developed through self‐assembly method and in‐situ precipitation method. These microcapsules and curing agent 4,4′‐diaminodiphenylsulfone (DDS) are incorporated into the CE resin to form resin‐based composites with low curing temperature, self‐healing ability, and gamma radiation shielding ability. Various approaches including chemical characterizations (X‐ray diffractometer, fourier‐transform infrared, energy dispersive spectrometer), microscopy (optical microscope, scanning electronic microscope), and thermal analysis (differential scanning calorimeter, thermogravimetric analysis) are utilized to demonstrate the successful encapsulation of the EP resin by PWO shell and good thermal stability of this material. The mechanical property, self‐healing ability, and gamma radiation shielding property are investigated via fracture toughness test and using a NaI (Tl) spectrometer. In comparison with pure CE resin, the fracture toughness of the CE/MCs composites can increase by 66.5%, and the self‐healing efficiency can reach up to 56%, indicating that the microcapsules have good toughening and self‐healing abilities. The microcapsules and their composites also exhibit good gamma radiation shielding properties.

The horizontal profile of the atmospheric electric fields as measured during thunderstorms by the network of NaI spectrometers located on the slopes of Mt. Aragats

The shape and evolution of the energy spectra of the thunderstorm ground enhancement (TGE) electrons and gamma rays shed light on the origin of TGEs, on the relationship between modification of the cosmic ray electron energy spectra (MOS) and relativistic runaway electron avalanche (RREA) processes, on the energy of the seed electrons, and on the strength and elongation of an atmospheric electric field. The network of large NaI spectrometers on slopes of Mt. Aragats 24/7 monitored secondary particle fluxes from 2013 until now, highly contributed to the understanding of the ways how RREAs are developed in the atmosphere. In 2022 we enlarge the NaI network with 2 remote detectors located at altitudes 2000 and 1700 m, and 13 and 16 km apart from the Aragats station to investigate the horizontal profile of the atmospheric electric field. We found, that the previously estimated values of the regions in the atmosphere, where RREA emerges, were highly underestimated. In the present report, we describe the NaI particle detector's network and present the first results of the experiment demonstrating that the particle fluxes from the atmospheric electron accelerators can cover large areas on the earth's (up to tens of km2).

Using γγ-Coincidence Spectroscopy to Identify Natural Radiation in Soils Near the Mississippi River

Naturally radioactive nuclides present in soils contain background radiation that humans are exposed to every day. Previous research suggests that there are high background radiation areas (HBRAs) caused by climate, geography, wind, and water currents that accumulate a higher concentration of these radionuclides. An investigation of the Nile Delta confirms the presence of minerals rich in U and Th from monazite and zircon, further suggesting that certain locations have a higher concentration of these radionuclides. The present work is a search for monazite in Great River Road State Park, near the Mississippi River. The acquired samples were measured with a low-background NaI(Tl) spectrometer and digital data acquisition system. Using γγ-coincidence spectroscopy to reduce background radiation, we were able to apply coincidence gates of known gamma-ray energies originating from 238U and 232Th decay chains to identify the presence of the radionuclides in the soil samples. From our results, we confirmed that there is an accumulation of minerals containing 238U and 232Th near the river. Our next steps will focus on calculating activities for quantitative results and collecting samples from an extended region along the river.

PERFORMANCE OF HANDHELD NAI(TL) SPECTROMETERS AS DOSIMETERS BY LABORATORY AND FIELD DOSE RATE MEASUREMENTS.

In the framework of the IAEA Coordinated Research Project (CRP) J02012 on 'Advancing Radiation Detection Equipment for Detecting Nuclear and Other Radioactive Material Out of Regulatory Control', the properties of two commercial instruments (1) InSpector 1000 analyzer (Canberra), with a 2″×2″ NaI(Tl) scintillator and (2) RIIDEYE M-G3 analyzer (Thermo Scientific), with a 3″×3″ NaI(Tl) scintillator, were evaluated as dosimeters by laboratory and field measurements. In the Ionizing Radiation Calibration Laboratory (IRCL) of the Greek Atomic Energy Commission, the NaI(Tl) spectrometers were tested in order to measure Ambient gamma Dose Equivalent Rate (ADER). The NaI(Tl) scintillators were irradiated in a homogeneous field with 662 keV photons with different ADER values from 0.17 to 100μSv h-1 at 0° incidence (irradiation field perpendicular to the detector's front window) and at 90° incidence. For each irradiation, the measured ADER by the spectrometers and the 'true' ADER values (provided by the IRCL) were compared. In addition, the angular dependence (0-359°) of the ADER response of the spectrometers was studied with a 152Eu source placed at 1, 2 and 3m from the spectrometers. The ADER dependence as function of the distance from the 152Eu source (at 0° incidence) measured by the two detectors was compared with the theoretical one. In the field studies, ADER was measured by the spectrometers at seven locations belonging to the Greek Early Warning System Network (which is based on Reuter-Stokes ionization chambers). These locations have different ADER values ranging from 20 to 120 nSv h-1. In these locations, gamma ADER were also deduced (1) by in situ gamma spectrometry measurements with portable Germanium HPGe detectors and (2) by the Reuter-Stokes ionization chambers (by subtraction of the cosmic radiation). Gamma dose measurements were also performed with the InSpector 1000 and RIIDEYE M-G3 detectors in 25 locations (beaches) of Northern Greece and compared with the ADER values deduced by sand sample analysis with gamma spectroscopy. Beaches with sand are good candidates for such type of measurements since they are commonly flat and in principle the natural radionuclides are homogenously distributed.

Photon Attenuation Coefficients of Fly-Ash Based Geopolymers Synthesized with Different Barite Proportions

Mass attenuation coefficients of fly-ash based geopolymers fabricated with different proportions of barite are measured using a high-resolution NaI spectrometer detector. After fabrication, the samples were irradiated with gamma-rays emitted from point sources of 241Am and 137Cs. The measured experimental values are found to be consistent with theoretical calculations carried out using the XCOM program. Based on the results, the radiation shielding capacity of the geopolymers is found to increase with increase in barite proportion. In addition, the fly-ash based geopolymers fall within the internationally established range and are thus acceptable for use as radiation protection devices.

Measurement of the 7Li(p,p'γ)7Li reaction cross-section and 478 keV photon yield from a thick lithium target at proton energies from 0.65 MeV to 2.225 MeV

Reliable data on 7Li(p,p'γ)7Li reaction cross section and photon yield from a thick lithium target are important for many applications including boron neutron capture therapy of malignant tumors. Experimental data on cross section differ greatly from one author to another; experimental data on photon yield are extremely scarce. Measurements of the reaction cross section and photon yield were carried out at the accelerator-based neutron source at the Budker Institute of Nuclear Physics (Novosibirsk, Russia) using a NaI and HPGe γ-ray spectrometers. The 7Li(p,p'γ)7Li reaction cross section and 478 keV photon yield from a thick lithium target at proton energies from 0.65 MeV to 2.225 MeV have been measured with high accuracy. The data obtained are presented in the form of tables.

The Application of Full Spectrum Analysis to NaI(Tl) Gamma Spectrometry for the Determination of Burial Dose Rates

In this study, we explored the potential of a NaI(Tl) scintillator-based gamma spectrometer for the accurate determination of burial dose rates in natural geological samples using a full spectrum analysis (FSA) approach. In this method, an iterative reweighted least-square regression is used to fit calibration standard spectra (<sup>40</sup>K, and <sup>238</sup>U and <sup>232</sup>Th series in equilibrium) to the sample spectrum, after subtraction of an appropriate background. The resulting minimum detection limits for <sup>40</sup>K, <sup>238</sup>U, and <sup>232</sup>Th are 4.8, 0.4 and 0.3 Bq·kg<sup>−1</sup>, respectively (for a 0.23 kg sample); this is one order of magnitude lower than those obtained with the three-window approach previously reported by us, and well below the concentrations found in most natural sediments. These improved values are also comparable to those from high-resolution HPGe gamma spectrometry. Almost all activity concentrations of <sup>40</sup>K, <sup>238</sup>U, and <sup>232</sup>Th from 20 measured natural samples differ by ≤5% from the high resolution spectrometry values; the average ratio of dose rates derived from our NaI(Tl) spectrometer to those from HPGe spectrometry is 0.993 ± 0.004 (n=20). We conclude that our scintillation spectrometry system employing FSA is a useful alternative laboratory method for accurate and precise determination of burial dose rates at a significantly lower cost than high resolution gamma spectrometry.

Nonresonant p -wave direct capture and interference effect observed in the O16(n,γ)O17 reaction

We measured the total capture cross section of the $^{16}\mathrm{O}(n,\ensuremath{\gamma})^{17}\mathrm{O}$ reaction, as well as partial cross sections leading to the ground (${J}^{\ensuremath{\pi}}=5/{2}^{+})$ and first-excited (${J}^{\ensuremath{\pi}}=1/{2}^{+})$ states in $^{17}\mathrm{O}$. The measurement was carried out at average neutron energies of 157, 349, 398, 427, 468, 498, and 556 keV by using pulsed neutrons produced via the $^{7}\mathrm{Li}(p,n)^{7}\mathrm{Be}$ reaction and a $\ensuremath{\gamma}$-ray detection system based on an anti-Compton NaI(Tl) spectrometer. We observed the interference effect between the $3/{2}^{\ensuremath{-}}$ resonance state at 4554 keV of $^{17}\mathrm{O}$, corresponding to a neutron energy of 411 keV in the center-of-mass system, and a nonresonant contribution in the capture process. The measured partial cross sections are in good agreement with theoretical calculations obtained taking into account the interference between the $3/{2}^{\ensuremath{-}}$ resonance and a nonresonant $p$-wave direct radiative capture contribution. Using the present results, together with our previous measurement, we derived the Maxwellian-averaged capture cross sections (MACS) for thermal energies between $kT=5$ and 100 keV, key quantities for $s$ process nucleosynthesis studies in massive stars.

Natural radionuclides in groundwater from Qena governorate, Egypt

AlphaGUARD radon gas analyzer and NaI (Tl) spectrometer were used to measure the concentration levels of 222Rn and, 226Ra, 232Th, and 40K respectively in 109 groundwater samples collected from four different districts in Qena governorate, Egypt. The average values of the activity concentration were 3.57 ± 0.08, 0.54 ± 0.03, 0.40 ± 0.03, and 5.10 ± 0.44 Bql−1 for 222Rn, 226Ra, 232Th, and 40K, respectively. The average values of 222Rn, 226Ra, and 232Th are lower than, 100, 1, and 1 Bql−1, respectively, the WHO recommended permissible levels for drinking water. For radiation exposure assessment, the annual effective doses due to ingestion of 226Ra and 232Th and inhalation of 222Rn for adults were determined and compared with the reference limits. The annual effective doses due to ingestion 139.21–201.34 µSvy−1 are higher than the public annual dose limit 100 µSvy−1 recommended by WHO. These indicate that the ingestion of groundwater from the study areas might pose radiological health hazards.

CALIBRATION OF THE EXTENDED QUADRIHEDRAL NaI(Tl) SPECTROMETER BY COSMIC MUONS

The results of cosmic muon calibration of the extended quadrihedral NaI(Tl) spectrometer are presented. The signal amplitude and energy resolution of the spectrometer in the direction transverse to the spectrometer axis have complex dependences on the photomultiplier voltage and particle entrance point to the spectrometer. At a photomultiplier divider voltage U = 1150 ± 10 V, the region of uniform signals is observed over ~90% of the spectrometer length, the relative energy resolution is δ ≈ 7%.