Nuclear Track Research Articles

Indication of p + 11B reaction in Laser Induced Nanofusion experiment

The NanoPlasmonic Laser Induced Fusion Energy (NAPLIFE)1 project proposed fusion by regulating the laser light absorption via resonant nanorod antennas implanted into hydrogen rich urethane acrylate methacrylate (UDMA) and triethylene glycol dimethylacrylate (TEGDMA) copolymer targets. In part of the tests, boron-nitride (BN) was added to the polymer. Our experiments with resonant nanoantennas accelerated protons up to 225 keV energy. Some of these protons then led to p + 11B fusion, indicated by the sharp drop of observed backward proton emission numbers at the 150 keV resonance energy of the reaction. The generation of alpha particles was verified by CR-39 (Columbia Resin #39) nuclear plastic track detectors.

Charge lifetime improvement of the Continuous Electron Beam Accelerator Facility photogun with a biased anode

GaAs photocathodes in dc high-voltage photoguns are highly susceptible to ion back-bombardment, which reduces the photocathode quantum efficiency and limits the useful operating lifetime for producing polarized electron beams. This paper demonstrates that applying a small positive bias to the photogun anode can significantly suppress ion back-bombardment and increase charge lifetime. This technique was studied extensively using the Continuous Electron Beam Accelerator Facility photogun, where highly polarized electron beams created using a strained-superlattice GaAs/GaAsP photocathode were used and charge lifetimes improved by almost a factor of 2. A new simulation code was developed to model ion production and tracking in order to better understand and explain the factors that led to the performance improvement. Results of the experiments and simulations are discussed in detail. Published by the American Physical Society 2024

Studying the Feasibility of Creating Anisotropic Highly Hydrophobic Polymer Surfaces by Ion-Track Technology

In the last two decades, the creation and research of superhydrophobic nanomaterials based on the “lotus effect” have attracted great interest. The effect is caused by the heterogeneous wetting of rough surfaces, when the grooves of a rough surface are filled with air (vapour) and water only contacts the tops of the protrusions. The drop forms a sphere on the surface and, if slightly inclined, rolls down and picks up the dirt particles. A wide variety of methods have been developed to produce such materials, among which potential of the ion track technology (ITT) is being explored. The aim of this research was to investigate the wettability of surface microrelief using two materials with different initial hydrophobicity degrees. By modifying the surface of polycarbonate and polypropylene films using the ITT, the samples with water contact angles of 140 ± 5° and 151 ± 5° at maximum, respectively, were obtained. It is shown that such angles are characteristic of microrelief, where the fraction f of the surface that is in contact with the droplet is decreased to the range 0 f 0.3. In order to increase the probability of droplets rolling down the material surface in a certain direction, the materials with inclined microrelief were obtained. In this case, the wettability becomes anisotropic. The droplet loses its spherical shape, deforming in the direction of inclination of needle-like surface elements. It was found that the anisotropy of wettability is higher at an inclination angle of the relief elements of 45° than that at 30° (relative to the flat surface).

Study of modulation in complex refractive indices induced by ultrafast relativistic electrons using infrared and THz probe pulses

Objective.Achieving ultra-precise temporal resolution in ionizing radiation detection is essential, particularly in positron emission tomography, where precise timing enhances signal-to-noise ratios and may enable reconstruction-less imaging. A promising approach involves utilizing ultrafast modulation of the complex refractive index, where sending probe pulses to the detection crystals will result in changes in picoseconds (ps), and thus a sub-10 ps coincidence time resolution can be realized. Towards this goal, here, we aim to first measure the ps changes in probe pulses using an ionizing radiation source with high time resolution. Approach.We used relativistic, ultrafast electrons to induce complex refractive index and use probe pulses in the near-infrared (800 nm) and terahertz (THz, 300µm) regimes to test the hypothesized wavelength-squared increase in absorption coefficient in the Drude free-carrier absorption model. We measured BGO, ZnSe, BaF2, ZnS, PBG, and PWO with 1 mm thickness to control the deposited energy of the 3 MeV electrons, simulating ionization energy of the 511 keV photons.Main results.Both with the 800 nm and THz probe pulses, transmission decreased across most samples, indicating the free carrier absorption, with an induced signal change of 11% in BaF2, but without the predicted Drude modulation increase. To understand this discrepancy, we simulated ionization tracks and examined the geometry of the free carrier distribution, attributing the mismatch in THz modulations to the sub-wavelength diameter of trajectories, despite the lengths reaching 500µm to 1 mm. Additionally, thin samples truncated the final segments of the ionization tracks, and the measured initial segments have larger inter-inelastic collision distances due to lower stopping power (dE/dx) for high-energy electrons, exacerbating diffraction-limited resolution.Significance.Our work offers insights into ultrafast radiation detection using complex refractive index modulation and highlights critical considerations in sample preparation, probe wavelength, and probe-charge carrier coupling scenarios.

Simulation excess lifetime lung cancer risk due to indoor radon exposure in Eastern Iran - Monte Carlo Simulation method

Indoor environmental radiation, primarily from natural radionuclides, can pose a significant health risk due to continuous exposure. This study investigated the excess lifetime cancer risk (ELCR) associated with indoor radon exposure in Gonabad, eastern Iran, using the Monte Carlo Simulation (MCS) method. CR-39 solid-state nuclear track detectors (SSNTD) were employed to measure radon levels in 50 samples across various geographical directions. The highest ELCR was observed at location S23, with a value of 64 Bq/m³, while the lowest ELCR was found at location S25, with a value of 1 Bq/m³. Further analysis using Duncan's multiple comparison tests revealed significant differences in radon concentration among geographical groups (P ≤ 0.05). MCS analysis indicated that a majority of the population had a relatively low ELCR (approximately 0.001). Notably, individuals aged 65 and over exhibited a higher ELCR from radon exposure, while smokers displayed an increased tendency toward higher ELCR. Additionally, males demonstrated a greater risk compared to females. The cumulative probability distribution showed that a significant proportion of individuals had a relatively low risk of cancer (ELCR ≃ 0.001) from radon exposure. The interquartile range (IQR: 0.0005–0.0015) suggests that most individuals experienced a relatively low cancer risk from radon exposure. This study provides crucial information for developing targeted public health strategies to mitigate the risks of radionuclide exposure in Gonabad City, ultimately improving the well-being of its residents.

Spectroscopic analysis of alpha particles from radioactive nuclides with CR-39 plastic nuclear track detectors.

A spectroscopy method of alpha particles with the track geometry parameters in CR-39 plastic nuclear track detectors is proposed. The relationship between the track registration sensitivity and incident angle of each etch pit is analyzed. The components of alpha particles emitted from radon, thoron and 241Am can be roughly separated when the etching level is not exceeded beyond the range in CR-39. This work aims at improving the dose assessment accuracy from exposure to indoor radon and thoron.

Assessment of photon and proton-induced activation in particles accelerators.

Nuclear activation affects all operating, future, or dismantled particle accelerators used in various fields, from medical applications to industrial applications. This work is concerned with the study of the radioactivity induced in various materials (Sc, Cu, Tb, Ta, W, Au) irradiated by hard Bremsstrahlung photons from an electron beam and by secondary neutrons induced by a proton beam. In both cases, the primary beam features an 18 MeV kinetic energy. We have performed Monte Carlo simulations with MCNP, GEANT4, FLUKA, and PHITS, coupled with the analytical codes CINDER'90 or FISPACT-II, to estimate the threshold reaction rates and the induced radioactivity in the samples. We compared the simulations with experimental activation measurements performed by high-resolution gamma spectrometry at a decommissioned medical LINAC and around the CYRCé cyclotron. We also used CR-39 solid-state nuclear track detectors to characterize the thermal and fast neutron components of the secondary fields.

Evaluation and optimization of measurement conditions for heavy ions with fluorescent nuclear track detectors.

In applying fluorescent nuclear track detectors for heavy ion measurement, the fluorescence intensity directly influences linear energy transfer (LET) estimation. However, the conventional analysis highly depends on the analyzed depth and the reference frames from the optical readout. To improve the accuracy of measurements of heavy ions, the gradient of intensity and moving average fluorescence intensity were acquired and calculated to optimize the measurement conditions. The results indicate that the intensity gradient is an alternative quantity to discriminate ions with different LET, and the moving average fluorescence intensity is readily differentiated among individual ions without overlapping values in fluorescence intensity. The scanned range of 25-45μm is suggested to be the most suitable depth for measurement. To exclude the impact of the variation in fluorescence intensity on evaluation, it is recommended to use the quantities calculated in moving averages with depth in the future.

Metallic Ca Aggregates Formed Along Ion Tracks and Optical Anisotropy in CaF2 Crystals Irradiated with Swift Heavy Ions

It is known that swift heavy ion (SHI) irradiation induces the shape elongation of metal nanoparticles (NPs) embedded in transparent insulators, which results in anisotropic optical absorption. Here, we report another type of the optical anisotropy induced in CaF2 crystals without including intentionally embedded metal NPs. The CaF2 samples were irradiated with 200 MeV Xe14+ ions with an incident angle of 45° from the surface normal. With the increasing fluence, an absorption band at ~550 nm, which is ascribed to Ca aggregates, increases both the intensity and the anisotropy. XTEM observation clarified the formation of the continuous line structures and the discontinuous NP chains parallel to the SHI beam. Numerical simulations of the optical absorption spectra suggested the NP chains but not the continuous line structures as the origin of the anisotropy. The optical anisotropy in CaF2 irradiated with SHIs is different from the shape elongation of NPs.

Deep learning-based alpha particles spectroscopy with solid-state nuclear track detector CR-39

A novel approach for alpha particles energy spectroscopy utilizing a sophisticated deep learning machine learning algorithm is introduced. The approach we employ classifies the alpha particles trajectories on a CR-39 detector into six discrete energy levels: 0.5 MeV, 1.5 MeV, 2.5 MeV, 3.5 MeV, 4.5 MeV, and 5.4 MeV. Some 57 different CR-39 detectors were exposed to alpha particles of the stated energy levels using a241Am source. The dosimeters were then subjected to etching and imaging utilizing a Landauer Neutrak© system. A self-developed computer vision method was used to separate the energy-tagged alpha tracks from the CR-39 images. These tracks images were then inputted into an artificial neural network (ANN) algorithm for training. After completing the training, a test dataset was run to assess the algorithm's performance. An average accuracy rate exceeding 98% was attained across the six energy levels.This algorithm has the potential to enhance the precision of alpha particle dosimetry. Furthermore, once generalized to a continuous energy spectrum, as well as for other types of particles such as protons, this algorithm is anticipated to prove highly beneficial for analyzing the outcomes of various laser-driven high-energy particle experiments in general, and specifically for fusion experiments.

Impact of the Abrasive Solution Heating Process With Different Techniques on the Etching Parameters for the SSNTD (CN-85)

Abstract The presented work aims to compare and analyze the impact of the abrasive solution heating process using three different techniques on the etching parameters for the solid-state nuclear track detector (SSNTD) (CN-85). Water bath technique (WB) is using water as a conduction medium of heat transfer to heat the etching solution. The thermal oven technique (TO) is using air as a convection heat transfer medium to heat the etching solution. Finally, the micro-wave technique (MW) as electromagnetic radiation no need for a medium to heat the etching solution. That comparison will be achieved at different irradiation times to an Americium-241 source (241Am) of 5.486 MeV energy and 10 μCi activity as an alpha particle's emitter. Two irradiation times 10 s and 20 s are applied. Small pieces of CN-85 detectors (1 × 1) cm2 were used. CN-85 detector parameters of the etching process, with the three applying techniques (WB, TO, and MW), are estimated and compared. The obtained results from the three techniques are compared. The etching process time is developed to nearly 5 min for MW with heating by radiation mechanism compared to 25–35 min for etching techniques (WB and TO) with heating by conduction and convection mechanisms, respectively. The efficiency of MW technique with range of from 70% to 75% are five times greater than that for WB and TO techniques.

Radon Concentration Assessment in Urban Romanian Buildings: A Multistory Analysis

Radon (Rn 222) is a significant contributor to natural radiation exposure in residential environments such as single-family houses and multistory buildings. This study monitored radon activity concentration (RAC) in 455 apartments in 30 multistory buildings in Buzău, Romania. Integrated measurements of the RAC using CR-39 nuclear track detectors were conducted for a period of 3 to 4 months. The results revealed that the RAC varies between buildings, with an annual average between 33 and 77 Bq/m3. This variation may be attributed to poor ventilation and the chimney effect in common ventilation ducts, which may facilitate radon displacement vertically. Also, apartments with low occupancy or inadequate ventilation showed higher radon levels of up to 285 Bq/m3. The study highlights the potential risk of increased radon exposure in energy-efficient buildings due to poor ventilation, emphasizing the need for special attention to radon mitigation measures in building design. The results emphasize that the RAC is influenced by building characteristics, room use, and ventilation, with significant implications for health risks in urban residential environments.

Determination of the Radon Progeny Activity Size Distribution in Laboratory Conditions

Knowledge of the active size distribution of radon daughters is one of the main parameters for determining the effective dose from inhalation of short-term radon decay products. However, this parameter is crucial for accurately determining an effective dose; there are currently very limited possibilities for determining it. This paper describes the laboratory validation of a method for determining the activity size distribution of radon decay products using the Dekati ELPI+ cascade impactor and the Graded Screen Array Diffusion Battery (GSA DB). Using nuclear track detectors placed on individual impaction plates of the cascade impactor, the equivalent equilibrium activity concentration of individual size classes can be determined in the range from 17 nm to 10 μm. A diffusion battery was used to detect smaller particles in the unattached fraction area. The presented method can further refine the knowledge of the activity size distribution of radon decay products in different types of workplace atmospheres. Workplaces with higher radon concentrations differ significantly in the size distribution of aerosol particles, radon activity concentration, and equilibrium equivalent activity concentration.

Velocity Effect in Synthesis of Noncircular Nanopores by Etching Tracks of Swift Heavy Ions in Olivine

The velocity effect was studied in the synthesis of nanopores with a noncircular cross section by etching tracks of swift heavy ions in olivine. The developed atomistic model for the etching of olivine irradiated with swift heavy ions predicts the possibility of synthesizing nanopores with a noncircular cross section in it. The model consists of connected blocks that describe the sequential stages of track formation and etching. The TREKIS Monte Carlo model describes the initial electronic and lattice excitations in the nanoscale vicinity of the trajectory of an incident ion. These results are used as initial conditions for molecular dynamics simulation of structural changes along the ion trajectory. The obtained atomic coordinates after cooling of the structurally damaged area serve as the initial data for the original atomistic model of track etching in olivine. The results of the model application show that it is possible to control the cross section of these pores by changing the orientation of the crystal relative to the direction of irradiation. The presented simulation results for Xe ions demonstrate that the size of the resulting pores depends on the velocity of the incident ion, and not only on its linear energy loss.

Isotopically Enriched Lithium Fluoride Crystals for Detection of Neutrons with the Fluorescent Track Technique.

In this work, the properties of LiF crystals grown using Li of different isotopic compositions are described from the standpoint of their application as fluorescent nuclear track detectors used in measurements in the neutron radiation fields. The crystals were grown using two techniques: the Czochralski method and the micro-pulling-down method. Three isotopic compositions of Li were studied: natural, highly enriched in 6Li, and highly enriched in 7Li. It was found that 6LiF detectors are about six times more sensitive to thermal (low energy) neutrons than natural LiF, which significantly decreases the lower detection limit. 7LiF detectors are insensitive to thermal neutrons, which makes it easier to detect tracks due to other radiation modalities, such as energetic ions or nuclei recoiled in collisions with high-energy neutrons. Besides the response to neutron radiation, no other significant differences in the crystal properties were identified, irrespective of the isotopic composition and crystal growth method employed.

Commissioning of the MIGDAL detector with fast neutrons at NILE/ISIS

Many dark matter experiments are exploiting the Migdal effect, a rare atomic process, to improve sensitivity to low-mass (sub-GeV) WIMP-like dark matter candidates. However, this process is yet to be directly observed in nuclear scattering. The MIGDAL experiment aims to make the first unambiguous measurement of the Migdal effect in nuclear scattering. A low-pressure optical Time Projection Chamber is used to image in three-dimensions the characteristic signature of a Migdal event: an electron and a nuclear recoil track sharing a common vertex. Nuclear recoils are induced using fast neutrons from a D–D source, which scatter in the gaseous volume of the detector. The experiment is operated with 50 Torr of CF4 using two glass GEMs for charge amplification. Both light and charge are read-out, and these measurements are combined for track reconstruction. Commissioning data has been recorded with fast neutrons at the Neutron Irradiation Laboratory for Electronics (NILE) at Rutherford Appleton Laboratory in the UK. Results of the experiment’s commissioning and the performance of the detector with a high rate of highly ionising nuclear recoils are presented, along with results from low energy electrons. Initial results of light and charge read-out with low pressure noble gas mixtures are also presented.

Radionuclides distribution in soils and radon level assessment in dwellings of Mungo and Nkam Divisions, Cameroon.

Radionuclide and radon levels have been investigated in soil samples and residential environments within the Mungo and Nkam Divisions of the Littoral Region. These analyses employed gamma spectrometry facilitated by a NaI (Tl) detector for soil samples, yielding average activity concentrations of 226Ra, 232Th, and 40K at 23.8, 72, and 105Bqkg-1, respectively. Various radiological parameters were calculated to evaluate radiological hazards. Additionally, the indoor radon concentrations were quantified utilizing the CR-39 solid-state nuclear track detector (Radtrack), revealing an average concentration of 25Bqm-3 and an associated inhalation dose of 0.66mSv y-1. Risk assessments for lung cancer attributable to indoor radon exposure incorporated models such as the Harley model. An observed moderate correlation between indoor radon levels and external 226Ra concentrations implies that radon intrusion indoors might be substantially influenced by the 226Ra present in the subjacent soil, considering the construction of residential structures directly upon these terrains.

CYGνS: detecting solar neutrinos with directional gas time projection chambers

Cygnus is a proposed global network of large-scale gas time projection chambers (TPCs) with the capability of directionally detecting nuclear and electron recoils at ≳keV energies. The primary focus of Cygnus so far has been the detection of dark matter, with directional sensitivity providing a means of circumventing the so-called “neutrino fog”. However, the excellent background rejection and electron/nuclear recoil discrimination provided by the 3-dimensional reconstruction of ionisation tracks could turn the solar neutrino background into an interesting signal in its own right. For example, directionality would facilitate the simultaneous spectroscopy of multiple different flux sources. Here, we evaluate the possibility of measuring solar neutrinos using the same network of gas TPCs built from 10 m3-scale modules operating under conditions that enable simultaneous sensitivity to both dark matter and neutrinos. We focus in particular on electron recoils, which provide access to low-energy neutrino fluxes like pp, pep, 7Be, and CNO. An appreciable event rate is already detectable in experiments consisting of a single 10 m3 module, assuming standard fill gases such as CF4 mixed with helium at atmospheric pressure. With total volumes around 1000 m3 or higher, the TPC network could be complementary to dedicated neutrino observatories, whilst entering the dark-matter neutrino fog via the nuclear recoil channel. We evaluate the required directional performance and background conditions to observe, discriminate, and perform spectroscopy on neutrino events. We find that, under reasonable projections for planned technology that will enable 10–30-degree angular resolution and ∼10% fractional energy resolution, Cygnus could be a competitive directional neutrino experiment.

Determination the concentration for uranium in phosphrous fertilizers by using nuclear track detector CR-39

The aim of this research was to study the concentrations of Uranium in the phosphorus fertilizers using Nuclear track detector (CR-39). Our present investigation is based on the study of 10 types samples for different kinds of phosphorus fertilizers which were available in the local market Some of them were Iraqi made and the others from different countries like, (Iran, Italy, Holland, Lebanon and Jordan) .. The result obtained shows that the Uranium concentration in phosphorus fertilizers samples varies from (3.59ppm) to(2.59ppm). Based on the radioactive concentration of Uranium in the samples all the results obtained between(3.59ppm) in the Iraqi super phosphate to (2.59ppm) in the mixture Iraqi phosphate fertilizer are within the international levels as given by IAEA (International atomic Energy Agency) date if compares that equal by 12ppm .

Measurement of Alpha Emitters Concentration in Tomato Fruits Using CR – 39 Plastic Track Detector

Our country suffered from pollution translation as a result to the wars events, so, it is necessary to measure the amount of radiation in the fields that are of indirect contact with human life and health. The main aim of the present work is to measure the concentration of alpha emitters in tomato fruits collected from different farms in Al – Basra governorate in the south of Iraq. Nuclear track detectors of type CR – 39 are used as a detection device and Can technique as a detection technique. Results show that the maximum concentration recorded is sample no.7 of site Al – Rafidhya which was equal to (6.9621 ± 0.111) ppm and sample no.1 of site Lothan with concentration equals to (4.9236 ± 0.117) ppm. The minimum concentrations were in sample 6 of site Al – Lehaiss (1.5360 ± 0.084) ppm followed by sample 9 of site Malhan which recorded (1.6840 ± 0.111) ppm (20.208 ± 1.332 Bq/m3).