Nuclear Power Plant at risk in war zone: past and presents

During the past decades design of nuclear installations has improved and there have been many developments to establish a higher safety level to such an extent that the probability to experiment a severe accidents in GEN-III and III⁺ nuclear power plants (NPP) is well below the values estimated for previous generations. However, the Zaporizhzhia NPP (Ukraine) military attack by the Russian army produced a destabilizing sequence of events. The possibility of a severe nuclear accident as a consequence of an intense fire fight was reported and at the same time, stressing reports on worst-case scenarios such as radioactive release. Damage to the GEN-II; III⁺ reactor dome by any military ordinance can only be estimated from data gained during past nuclear accidents and military attacks. Here we report reactors in war zone or direct military attack attack to installations. Based on available data we will discuss possible events for few nuclear reactors and nuclear installation in Ucrania. The concrete containment buildings protecting the nuclear vessel and its LEU-fuel loaded core, are NOT designed against an external air attack by military devices. Possible consequences of a severe weapon-damage are estimated for the VVER-1000 Zaporizhzhia NPP built near the city of Enerhodar, Ucrania, considered of the class GEN-III⁺. The reactor with a steel-reinforced 2m+ concrete containment (including concrete missile shield) even if withstand extreme events it is recommended to take further provisions specificly age-related degradation of a concrete dome. We conclude that, spent fuel reservoirs for their vulnerability in war zones, are exposed to a higher risk of a severe radioactive material release, than NPP reactor´s core.

Evaluación del porcentaje de dosis en profundidad en el eje central de referencia de un fantoma de agua sometido a rayos X de 6 y 15 MV por medio de redes neuronales artificiales

Una de las variables mas importantes al momento de calibrar un instrumento de medida de radiaciones ionizantes utilizados en el campo de la radioterapia, lo constituye el porcentaje de dosis en profundidad en el eje central de referencia de un fantoma de agua (PDD). Un fantoma de agua es un dispositivo que nos permite simular el comportamiento de la dosis absorbida en el agua, variable que el IAEA en su código de práctica 398 nos describe como la adecuada para calibrar los instrumentos de medida utilizados en radioterapia, esto en función de que el cuerpo humano esta constituido en mas de un 70 % por agua. Así, en cierta manera, el fantoma de agua es un dispositivo que nos permite simular el comportamiento del cuerpo humano bajo la acción de una radiación ionizante. Por esta razón, un fantoma de agua también es de amplio uso en la planeación de las dosis de radiación prescritas a un paciente de radioterapia por un profesional de la salud. El PDD depende del tipo de radiación y de la energía que se maneja. En este trabajo, el PDD se evalúa por medio de una poderosa herramienta de la inteligencia artificial, las redes neuronales artificiales. La evaluación se realiza para rayos X de 6 y 15 MV.

Theoretical and experimental study on the possible contribution of airborne radon/thoron progeny to the track density recorded in DRPS/DTPS

Radon and thoron progeny represent a significant contributor to human natural radiation exposure. Active and passive devices have been developed for their measurements. The most common passive devices are Direct Radon/Thoron Progeny Sensors (DRPS/DTPS). These sensors are based on an absorber-mounted LR-115 detector on which the radon/thoron progeny is deposited. Direct Progeny Sensors record alpha particles emitted from its surface, but in principle they could also record alpha particles emitted from the air, an issue that has not been considered so far. The objective of this work was to evaluate theoretically and experimentally if sensors register alpha particles emitted from the air by the radon/thoron progeny. Results show the contribution to the track density of alphas emitted from the air, which should be considered in the design or redesign of these devices.

Estudio de la radio química del agua causada por radiación de alta LET utilizando el método de tiempos de reacción independientes

En el presente trabajo se simularon los procesos de la radiólisis de agua líquida en el código Monte Carlo Track-Structure TOPAS-nBio, comparando los resultados con datos disponibles en la literatura. Buscando una forma de correlacionar los rendimientos de los productos químicos con alguna cantidad física en específico se hace el estudio de la relación de estos rendimientos con la LET y el parámetro $MZ^2/E$, ya que estos dependerán principalmente de las características únicas de cada ion pesado incidente en un medio. La configuración para las simulaciones de la LET restringida a 100 eV, y la LET sin restringir consistió en un mundo de 10 cm por lado con un volumen sensible de agua de las mismas dimensiones, al que se le irradiaron protones, electrones e iones pesados (alphas y carbono) con rangos de energía 0.5-100 MeV, 0.001-1 MeV, 4-50 MeV y 10- 430 MeV, respectivamente. Utilizando solo segmentos de track entre un intervalo de 0.5-20.0 μm de tamaño. Mientras que para los valores G, se utilizó un mundo de 1 m por lado con un volumen sensible de agua de las mismas dimensiones. Se usaron las mismas partículas utilizando los mismos rangos de energía para estas, además de los rangos de LET para protones, electrones y los iones pesados previamente simulados. Los datos de las simulaciones se validaron con los resultados de ambas LET ’s (Ramos Mendoza J. et al (2011)), mientras que la base a corroborar para el parámetro $MZ^2/E$ (A. LaVerne J. (2004)), se observó que estos tienden a seguir las trayectorias en base a los datos experimentales. A partir del análisis de la ecuación de balance oxido reducción se encontraron distintos porcentajes de error de correlación entre las especies oxidativas y reductivas, que van desde el 0.5% hasta el 6% dependiendo de la partícula incidente. Por lo cual se concluye que el código Monte Carlo TOPAS-nBio es capaz de llevar simulaciones químicas a alta LET con buena concordancia.

GEANT4 dose estimations of solar protons: Al and PMMA-Bi2O3 shielding for space exploration

Adverse effects of long-term exposure to galactic cosmic radiation (GCR) pose a clear obstacle to future space exploration programs. In addition to GCR we have solar particle radiation. We simulate the latter using a scaled fluence profile of solar protons taken from a literature study that comprises about three solar cycles. The model is a three-layer stack that includes the shielding material and muscular tissue. Our simulation strategy uses protons as precursor radiation of neutrons. Subsequently, the shield is adjusted for thickness, at which neutrons are created through various processes during the simulation. Neutrons are then energy-binned and a corresponding neutron flux is simulated. Particles generated during the second phase of the simulation, i.e. neutrons, are then counted toward absorbed dose within the muscular tissue layer. Clearly, the dynamics of the process is not captured by the simulation, nevertheless an overview of neutron yield can be estimated and the absorbed dose. The objective is to provide some insight about the effect of the new composite shield, PMMA-Bi2O3, that has an intrinsic capability for gamma dose reduction, compared to a more traditional aluminum shield.

Escalamiento de secciones de producción de rayos X L por impacto de iones de $^{12}$C y comparación con modelos teóricos

Se compilaron resultados experimentales de secciones eficaces de producción de rayos X L inducidos por el impacto de iones $^{12}$C para proponer posibles escalamientos universales. Se calcularon dos variables reducidas diferentes con respecto a la energía incidente de los iones, tanto para la sección total como para la línea L$_{\alpha}$ (L$_{3}$M$_{4}$ + L$_{3}$M$_{5}$). Aunque los datos siguen curvas bien resueltas para cada variable reducida, una de ellas da mejores resultados. También se demuestra que la predicción teórica de un escalamiento adicional cuando las secciones se dividen por el cuadrado del estado de carga inicial del ion no es exacta. Finalmente, una comparación general de datos experimentales con los modelos ECPSSR y PWBA muestra que el primero describe mejor los datos experimentales.

Implementación del algoritmo de Gillespie para la simulación de la etapa homogénea de la radiólisis del agua

Introducción$\\$ El estudio de la descomposición del agua por radiación ionizante (radiólisis del agua) es fundamental para comprender los mecanismos de daño indirecto al ADN por radiación de baja LET en ambientes acuosos, ya que la mayoría de los rompimientos simples y dobles (SSB y DSB) se deben a la reacción entre especies químicas radiolíticas; como él peróxido de hidrogeno ($H_2 O_2$) o el hidroxilo ($^•OH$), y el material genético [Chatterjee N., Walker G.C. (2017)]. El objetivo de este trabajo es implementar el algoritmo de Gillespie [Gillespie D.T. (1976)]; desarrollado para resolver de manera eficiente la ecuación maestra de un sistema químico homogéneo mediante métodos estocásticos [Hoang N. T. et al. (2021)], para simular la evolución temporal de la concentración de especies radiolíticas producidas por una fuente de rayos gamma en agua pura. $\\$Metodología$\\$ El algoritmo de Gillespie, también llamado Algoritmo de Simulación Estocastica (SSA), fue implementado en Python 3.9, permitiendo desarrollar software de código abierto. Fue comparado con el software de simulación estocástica para la cinética química, Kinetoscope, utilizado como referencia. La configuración simulada se basó en datos experimentales disponibles en la literatura: Se empleó un esquema reducido de 10 reacciones químicas (ya que el esquema completo es de alrededor de 80 reacciones), su tasa de reacción y la concentración inicial de especies químicas determinada a partir de los rendimientos de escape fueron obtenidos del trabajo “Effect of Molecular Hydrogen on Hydrogen Peroxide in Water Radiolysi” por Pastina B. & LaVerne J. A. (2001). $\\$Resultados y Conclusiones$\\$ Nuestros resultados para la implementación del SSA muestran una correlación razonable con los resultados del software de referencia, con las excepciones para la concentración final del $H_2$ y $H_2 O_2$, cuyas diferencias relativas porcentuales máximas fueron de 9.9 y 10.3 % respectivamente.

Natural radioactivity and radon exhalation study from building materials proceedings from Peruvian coast

Radon contributing about 50% of the annual average dose mainly comes from the soil, but radon exhalation from building materials and its natural radioactivity contribute to the radiation dose received by humans. Therefore, it is essential to assess the activity concentration levels of primordial radionuclides (226Ra, 232Th and 40K) in these materials. Cement is one of the major components of the building materials and is used on a large scale in Peru; binds bricks, gypsum, and aggregates to produce concrete. Some studies have been conducted in an attempt to radiometrically and radiologically characterize some of these building materials. Radon exhalation rate was measured using a closed chamber and an active monitor, while the concentration of radionuclides content was determined by using gamma-ray spectroscopy. Results of measurements of radon exhalation rates of some building materials (cement, bricks, gypsum, and concrete aggregates) from different locations on the Peruvian coast are presented, as well as the effective dose and Gamma Index calculated for these samples.

Simulation of diffusion and decay of radon/thoron exhaled from a wall and its newly created progeny. Response of a bare LR-115 detector placed on the wall

Nuclear track detectors enclosed in diffusion chambers are commonly used for long-term radon concentration measurements in dwellings. Unlike closed passive detectors that only measure radon and/or thoron, the bare LR-115 detector also measures their airborne progenies which contribute the most to inhalation dose. However, when placed on an exhaling medium, such as a wall, its response may differ from that obtained when placed away from any object. Being on the source itself, the large differences in the diffusion lengths of 222Rn and 220Rn, and the plate-out effect of their progenies, may be causes for the differences. In this work, Monte Carlo techniques are used to simulate the air diffusion of exhaled radon/thoron from a medium, the formation and decay of different radioactive species during transport, and the response of a bare LR-115 detector placed on the exhaling medium. The spatial distributions of radionuclide decays and the detector's partial and total sensitivities to radon/thoron and their progenies were determined. Results of simulations were numerically validated and some of them were experimentally proved in a radon chamber. It was possible to know what the detector really measures in the studied configuration and its ability to measure indoor radon concentrations.

Deviation to the Tri-Bi-Maximal flavor pattern with an equivalent class with two texture zeros

In the model-independent context, where the neutrino mass matrix is assumed to be diagonalized by means of a unitary matrix that possess the Tri-Bi-Maximal (TBM) flavor mixing pattern. We present an analysis where the TBM deviation is explored by considering a two texture zeros charged lepton mass matrix. These last mass matrices are classified into equivalent classes and are parameterized in terms of the masses of charged leptons and some free parameters. We are interested in the charged lepton mass matrices with the minimum free parameter number, that allows us to correctly reproduce the reactor mixing angle value. We show a deviation from the TBM pattern in terms of the charged lepton masses as well as the theoretical expressions and their parameter space for the mixing angles. Finally, we present the phenomenological implications of numerical values of the ``Majorana-like'' phase factors on the neutrinoless double-beta decay.

Concentración de actividad de radionucleidos naturales en agua y sedimento de la zona arrecifal de Xcalak y Mahahual, Mexico

Los niveles de radionucleidos naturales en ecosistemas acuáticos es de gran importancia para la evaluación de riesgo radiológico, tasas de sedimentación, datación radiométrica, entre otros. Los radionucleidos de las series naturales del uranio-238, torio-232 y uranio-235 se encuentran presentes en agua, sedimento y biota de zonas costeras. En este trabajo se realiza la caracterización radiométrica de muestras ambientales del Parque Nacional Arrecifes de Xcalak y la costa de Mahahual. Los métodos incluyen las técnicas de espectrometría de rayos gamma y espectrometría de partículas alfa. Los resultados en sedimento presentan valores de $22.8\pm4.0$, $25.0\pm3.1$, $17.9\pm6.2$, $31.9\pm2.4$ $Bq/kg$ para el $^{238}U$, $^{234}U$, $^{210}Pb$ y $^{210}Po$, respectivamente; y un bajo contenido de $^{232}Th$ y $^{235}U$, con valores de $0.44\pm0.14$ y $0.90\pm0.32$ $Bq/kg$, respectivamente. Por su parte, el agua presenta valores del orden de $41.3\pm9.5$ y $54.9\pm8.7$ $mBq/L$ para el $^{238}U$ y $^{234}U$. La concentración de actividad de estos radionucleidos en agua y sedimento de Xcalak y Mahahual son similares a los encontrados en otros sistemas acuáticos a nivel global y proporcionan una línea base de esta region para fines de comparación.

Radiation-induced reactions of hydroxyl acids

Research on the radiolysis of hydroxy acids is of considerable interest since these compounds are essential nutritional constituents in foods and dietary supplements. Despite these considerations, there are few data, and very often are difficult to compare in their radiolytic behavior of hydroxy acids. This work is focused on studying the radiolysis of glycolic acid, malic acid, and citric acid in aqueous solutions. To this end, carboxylic acids were exposed to different doses of gamma radiation. Gas chromatography and UV-spectroscopy followed the irradiation procedure. The results showed a dependence of the decomposition as a linear function of the dose. The principal pathway to decomposition is the loss of the hydroxyl group.

Repositorio de material audiovisual para el Taller de Física de Radiaciones del Departamento de Física de la Facultad de Ciencias de la UNAM

El Taller de Física de Radiaciones (TFR-1) es un laboratorio que fue diseñado inicialmente para la docencia de las materias optativas del área de física de radiaciones de la licenciatura de Física de la Facultad de Ciencias de la UNAM. A través del tiempo ha evolucionado para que en la actualidad se le identifique como el Taller de Física de Radiaciones I, el cual se encuentra ligado al Taller de Radiaciones II (preparado de muestras para el análisis en el Laboratorio Nacional de Espectrometría de Masas con Aceleradores e isótopos cosmogónicos). En este trabajo se presenta la primera versión de un repositorio de material audiovisual para la realización de prácticas de laboratorio de los cursos del área de la física de radiaciones y temas afines para las licenciaturas de Física y Física Biomédica, principalmente. El material incluye las guías de las prácticas, infografías, presentaciones para PC y videos cortos. Los materiales se presentan agrupados en secciones de equipos y materiales, prácticas de seguridad radiológica, prácticas de dosimetría de la radiación, espectrometría gamma, espectrometría visible y datos típicos de diversos experimentos, además la dirección de la página web del Taller de Física de Radiaciones. Este trabajo fue patrocinado por el proyecto PAPIME PE104515 y PE109521.

Análisis de la composición espectral de la radiación de sincrotrón en la teoría clásica

En la literatura aparecen descripciones no tan detalladas del espectro de la radiación de sincrotrón en la teoría clásica y cuántica. En este trabajo se presenta una descripción de la distribución espectral clásica de la radiación de sincrotrón que involucra la integral de la función de Bessel. Partiendo de los resultados del cálculo numérico de la integral, se grafica la distribución espectral completa y se compara con las aproximaciones de bajas y altas frecuencias. Los resultados muestran la coincidencia de la distribución completa con las aproximaciones.

Radiation Chemistry as Tool in Earth Science Studies

The study of the interaction of gamma radiation with some relevant elements on our planet is important for Earth Sciences to understand some current phenomena that our planet is going through and suggest some solutions such as the remotion of dyes in residual waters (e.j. bromothymol blue, green malachite, etc.). The goal of this work shows the importance of some previous results in which the interaction of gamma radiation with organic compounds can give clues to solve current problems by making use of gamma radiation interaction with matter. Our results show that gamma irradiation could be an alternative to the removal of emerging contaminants, a topic of current relevance.

Respuesta Termoluminiscente del TLD-100 irradiado con protones de 5 keV

En este trabajo se presenta el estudio realizado al material termoluminiscente TLD-100, su respuesta TL total, la evolución de las curvas de brillo irradiadas con protones de 5 keV a diferentes fluencias de 1.30×1010cm-2 a 1.13×1014cm-2, una comparación con las curvas de brillo de para protones de 0.7, 1.5 y 3.0 MeV y para rayos gamma de 137Cs. Los TLD-100 fueron irradiados en el acelerador lineal del Taller de Colisiones y procesados en el Taller de Física de Radiaciones I de la Facultad de Ciencias de la UNAM. Los resultados presentados muestran que las formas de las curvas de brillo difieren de las reportadas para protones de otras energías y de las obtenidas para rayos gamma de 137Cs, pero son consistentes con las curvas de brillo para protones y argón de 8 keV. Nuestras conclusiones podrían ser útiles y motivar el desarrollo de nuevos proyectos de relacionados con la irradiación del TLD-100 con iones de muy muy bajas energías. Proyecto apoyado por PAPIIT, IN115718.

Method for the identificacion of 60Co in an industrial gamma irradiator

This study presents a method for the identification of a set of radioactive sources of 60Co in an industrial irradiator. This identification was requested by the Mexican regulatory agency in nuclear matters. To meet this requirement, a procedure was developed to make the identification using the gamma spectrometry method. The complexity in the measurement lies in the fact that the set of sources has an activity of 500,000 Ci of 60Co and the identification is complicated because with this intensity one has to have a strategy to reduce the phenomenon of saturation, pile up and dead time and achieve that photopeaks generated in the gamma spectrum of the gamma energies of 60Co are clearly visible. A low efficiency and relatively high resolution CZT detector was selected, which was placed in an acrylic box with a collimated lead shield to carry out the measurements inside the irradiator pool to reduce scattered radiation and to be able to clearly determine the spectrum gamma of 60Co.

Numerical modeling of radiation-induced reactions: Fricke dosimeter at 298, 198 and 77 K

The Fricke dosimeter is a widely used gamma radiation dosimetry system. The detection of Fe2+ to Fe3+ oxidation in an aqueous solution of ferrous sulfate in sulfuric acid exposed to ionizing radiation in the presence of oxygen is the system's basis. A series of chemical reactions are generated in this system, all of which are highly dependent on one another. A numerical model of coupled differential equations based on the mass balance was developed in this work, in which each equation incorporates information about the molecules that are generated, those that breakdown, and a source term that represents an external source of radiation. The model can reproduce the linear behavior of the dosimeter's experimental data at room temperature. A correction factor is proposed to simulate the behavior of the dosimeter at temperatures of 198 K and 77 K, respectively, when the system is in a dry ice and liquid nitrogen thermal bath. Due to the possibility of simulating reactions in comets and other exoplanetary bodies, this model could support a variety of experimental challenges in domains of industry involving radiation at low temperatures, as well as astrobiological and astronomical problems.

Influence of depth and capping of soil radon measurement wells on the gas distribution within the well

Measurement of soil gas radon/thoron concentration using passive monitors is normally carried out using a PVC tube inserted into the surface. This tube is open at the lower end to allow the diffusion of radon into the inside volume. For measurements, the radon monitor can be placed at a certain distance from the bottom by suspending it by a thread tied to the tube top. If the tube cap causes a tight seal, the average radon concentration could be approximately constant throughout the volume of a short tube. However, the measured concentration might depend on the monitor placement depth for a long tube due to the influence of the radon diffusion length. In order to test these hypotheses, field experiments were carried out in wells of different depths using different well-capping systems. Results are presented and recommendations are given for conducting radon measurements in soil gas using E-PERM monitors. The good sealing of the tube cap allowed to obtain results more related to the physical and chemical properties of the soil and less influenced by seasonal and daily changes in atmospheric parameters.

An approximation to estimate the total radium from measurements of the effective radium

According to several studies, the distribution of parent radium atoms (226Ra) in soil grains, and grain size distribution are important factors affecting radon emanation. Thus, we have conducted experiments and simulation studies to estimate the radon emanation factor and the effective radium content as a function of grain size. Experimentally, the effective radium was determined by using the nuclear track methodology and the total radium by gamma-ray spectrometry. A calculation algorithm, based on Monte Carlo simulations, was applied to the simple single-grain spherical model to study the radon emanation process. The SRIM software was used to calculate the minimum grain radius at which radon can escape completely from the grain. Results indicate that as the grain size decreases it is possible to obtain an approximate value of the total radium by means of the corresponding effective radium measurements.

A classroom alternative to simulate radioactive decay of nuclei

There are many methods that simulate the radioactive decay of various unstable nuclei, these methods range from mechanical (1) to electronics (2) and computers (3). In this work, a method is proposed that consists of a kind of lottery game in which a not-so-large number of students participate -about 40 of a group of undergraduates, for example- Each one of the students is asked to write a set of random numbers between 1 and 50, let's say about 20, together we will have 800 numbers that represent the unstable nuclei. Someone is then asked to choose a range of numbers, for example from 11 to 15, and they are asked to cross off all the numbers that match that range on their list. There will be about 80 that cross out, which represents the nuclei that decayed. You now have 720 surviving nuclei. With the numbers that were not crossed out, now someone decides to cross out the numbers in the range of 46 to 50, now there will be about 72, and 648 survive. The procedure is repeated now with the numbers 21 to 25, with which some 65 and 583 survive. Each time you ask to cross out, a time interval is defined to record the "nuclear radiation". Repeating this procedure several more times with different ranges of size 5 will give you 525, approximately, then 473, 426, etc. We have a simulation quite close to the reality of what happens in radioactive decay. If the results of the surviving nuclei were plotted as a function of the number of plays, we will observe that N(t)~800exp(-0.107t), and with the numbers that were "winning" we will have the way in which the number of stable nuclei will grow, which will be given by Nst~ 800[1-exp(-0.107t)]. 1. C. E. Swartz, Used Math, pp. 59-61,Prentice-Hall, Englewood Cliffs, NJ, (1973) 2. Electronic analog of radioactive decay, F. J. Wunderlich and Mark Peastrel, Am. J. Phys. vol 46, p. 189 (1978) 3. Computer Simulation of Rad. Decay, K. E. Jesse, The Physics Teacher vol. 41, p. 542, (2003) We acknowledge Conacyt and VIEP-BUAP.

Analyzing an experimental simulation of Titan’s atmosphere that use a laser-induced plasma as a bolide recreation

Titan, the largest moon of Saturn, is one of the most-intriguing planetary bodies across the solar system. It has a gorgeous atmosphere with a unique composition that can work like a simile of the Primitive Earth, making research about it a "look-back" in the past and evolution of Earth's atmosphere. This work involves the chemical analysis of an experimental simulation of Titan's atmosphere that interacts with a bolide (using a laser-induced plasma), evaluating the series of gas compounds formed in terms of astrobiological interests. The evaluation of the chemical compounds found in this work can specifically serve in the comprehension of how life evolved in the past Earth and if it is possible to find earthlike life on Titan or other planetary bodies.

Degradación de materia orgánica por radiación ionizante en suelos del desierto de Mojave

La búsqueda de material orgánico en la superficie de Marte tiene varias dificultades debido a la condiciones físicas y químicas de la superficie marciana. La radiación ionizante es probablemente una de las principales causas de degradación de moléculas orgánicas de interés biológico en el suelo marciano, considerando que el Marte antiguo tuvo las condiciones climáticas necesarias para el origen y sostén de la vida. En este trabajo, irradiamos con rayos gamma (γ) una muestra de suelo del Desierto de Mojave-EUA, asemejando la exposición del suelo marciano a la radiación ionizante proveniente de la radiación cósmica galáctica. Utilizando técnicas como reacciones químicas en vía húmeda y de análisis como lo son la cromatografía de gases y la espectrometría de masas, se obtienen resultados que ayudarán a comprender como fue el proceso de descomposición de la materia orgánica en Marte por el efecto de la radiación ionizante y evaluar si en la actualidad es posible encontrar estos compuestos orgánicos en la superficie marciana.

Study of Gamma Radiolysis of Clays

Clays are solids widely used in different disciplines due to their physicochemical properties. Studying the radiation-matter interaction on these solids must be fundamental to consider them in interdisciplinary, multidisciplinary, and interdisciplinary topics. Montmorillonite, attapulgite, hectorite, kaolinite, and saponite were subjected to high doses of gamma radiation in the Gammabeam 651PT source at the ICN-UNAM. The principal goal of this study was to know the changes in their structures after high gamma radiation fields. The results of this interaction were analyzed by ATR-IR spectroscopy, XRD, and EPR techniques, allowing us to analyze an alteration in the structures of clays.

Análisis de propiedades ópticas y estructurales de ZnO bajo influencia de rayos $\gamma$

Películas de ZnO depositadas sobre vidrio y silicio por la técnica de erosión catódica, bajo diferentes condiciones de potencia de depósito, han sido irradiadas por radiación $\gamma$ proveniente de una fuente de $\ ^{137}$Cs, en una relativa larga exposición. Esto ha generado un efecto importante sobre las propiedades estructurales y ópticas, las cuales han sido medidas por XRD y por Espectroscopías UV-Vis y Raman. Se observa de manera determinante el efecto sobre el ancho de banda prohibida, el cual es típico encontrarlo cerca de 3.3 eV. Bajo los efectos de irradiación, el ancho de banda se incrementa a un valor medio de 3.9 eV, para todos los casos, y a su vez, se obtiene aparentemente una orientación predominante de la estructura típica hexagonal de ZnO en dirección (222). Este efecto ha sido visto previamente en polvos nanoscópicos de ZnO para efectos de irradiación con rayos $\gamma$

Computer program TRACK_REMAKE for modeling etched nuclear tracks profiles in LR-115 and CR-39 nuclear track detectors

Morphological and geometric parameters of etched tracks in solid-state nuclear track detectors (SSNTD) offer valuable information on the energy and angle of incident alpha particles. Although there is no theoretical model that fully describes the track formation process, empirical and semi-empirical models have been developed based on the V function that describes the relationship between etch rates along the latent track (Vt) and on the undamaged region (Vb). Considering the formation of a track as a result of the superposition of Vb and Vt, the computer program TRACK_REMAKE was developed. The program calculates the 2D and 3D coordinates of track profiles generated in LR-115 and CR-39 detectors, according to the chosen V function, for various initials conditions of the incident particle (angle and energy) and etching conditions (bulk etch rate and etching time). The comparison of the developed program with the TRACK_TEST program showed a very good correspondence. The use of TRACK_REMAKE is proposed as an alternative for the determination of geometric track parameters since it provides functionalities not implemented in TRACK_TEST such as sizes of the major and minor axes of the track bottom (cellulose nitrate-polyester interface) and visibility parameters for LR-115 detectors.

Estimation of the neutron flux in the irradiation channels of a Hotwizer containing a 226Ra-Be source

Neutron irradiators using isotopic sources (Neutron Howitzer) are useful tools for elemental analysis by neutron activation, radiosensitivity studies, and detector calibration, among others. For its applications, knowledge of the neutron flux and its associated energies at the irradiation site is required. The objective of this work was to experimentally determine the flux of thermal and epithermal neutrons in the channels of a Howitzer, using the activation method of uncovered and covered gold foils with cadmium filters. The irradiation time was greater than 14 days due to the low mass of the gold samples and the relatively low neutron flux. Using the gamma spectrometry technique, the radioisotope 198Au was identified by its 411.8 keV energy peak, whose net area was used to estimate the activities of gold foils. Applying the cadmium difference method, the thermal and epithermal neutron fluxes were estimated independently. Results showed thermal neutron fluxes higher than the epithermal neutron fluxes in the evaluated irradiation channels.