Journal of Nuclear Physics, Material Sciences, Radiation and Applications
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Study of Solid-State Radiolysis of Behenic, Fumaric, and Sebacic Acids for their Possible Use as Gamma Dosimeters Measured Via ATR-FT-IR Spectroscopy
Get PDFThe intensive use of ionizing radiation has promoted the constant investigation of adequate dosimetric systems in the measurement of doses applied in irradiated products. The objective of this work is to propose gamma dosimetric systems, using carboxylic acids in a solid state and measuring the change via infrared spectroscopy (carboxylic acid/ ATR-FT-IR1). We worked with three systems: (1) behenic acid/ATR-FT-IR, (2) sebacic acid/ATR-FT-IR, and (3) fumaric acid/ATR-FT-IR. The change in absorbance corresponding to the stretching vibration frequency of the carbonyl group to the absorbed dose (in the range of kGy) was measured. The results showed that the acid/ATR-FT-IR systems have a linear response with respect to the absorbed dose, for behenic acid/ATR-FT-IR from 0 to 122 kGy, for ATR-FT-IR sebacic acid from 0 to 61 kGy, and for fumaric acid/ATR-FT-IR from 0 to 34 kGy. The results indicated that the linear response of the absorbance dose in the three systems allows us to continue studying other variables to be able to propose them as chemical dosimeters
Shape Coexistence in Hot Rotating 100Nb
Get PDFTemperature and angular momentum induced shape changes in the well deformed 100Nb have been investigated within the theoretical framework of Statistical theory combined with triaxially deformed Nilson potential and Strutinsky prescription. Two shape coexistence, one in the ground state of 104Nb between oblate and triaxial shapes and another one between oblate and rarely seen prolate non-collective shapes in excited hot rotating 100Nb at the mid spin values around 14-16h are reported for the first time. The level density parameter indicates the influence of the shell effects and changes drastically at the shape transition. The band crossing is observed at the sharp shape transition
Signal of h → µτ, ττ in ν2HDM⊕S3
No full textNowadays in particle physics, the exploration of the flavor physics through the Higgs boson phenomenology is one of the main goals in the field. In particular we are interested in the Lepton Flavour Violation (LFV) processes. In this work, we explore the processes h → µτ, ττ in the theoretical framework of a flavored extension of the Standard Model, which has two Higgs fields and the horizontal permutation symmetry S3 imposed in the Yukawa sector, this extension is called v2HDM⊗S3.We obtain the couplings Φµτ, ττ as well as Br(h → µτ) in function of the model parameters in function of the model parameters, which are constricted by means the experimental results of ΦMS → µτ reported in the literatur
Agent Based Model of the Cytosine Radiation Induced Reaction
Get PDFThe stability of cytosine in aqueous solution was studied in the laboratory, simulating prebiotic conditions and using gamma radiation as an energy source, to describe cytosine behavior under radiation. For a better understanding of the radiation-induced processes, we proposed a mathematical model that considers chemical reactions as nonlinear ordinary differential equations. The radiolysis can be computationally simulated by an agent-based model, wherein each chemical species involved is considered to be an agent that can interact with other species with known reaction rates. The radiation is contemplated as a factor that promotes product formation/destruction, and the temperature determines the diffusion speed of the agents. With this model, we reproduce the changes in cytosine concentration obtained in the laboratory under different irradiation conditions
Laser Radiation Effects on Adenine
Get PDFLaser interaction whitthe gas phase nucleobase adenine is studied. A linear TOF mass spectrometer is utilized for measurements that require high mass resolution, high sensitivity, and sufficient ion yields of low mass fragment cations. The ion mass spectra are discussed at different laser energy intensities and two temperatures. In contrast to previous studies a number light ion is present in the mass spectra. The ion formation curves for 23 different ions are measured for the laser energy range from about 109 to 1010 W cm–2 and masses between 1 and 43 besides mass 57 which was present in the mass spectra and will be discuss. Data were taken heating the sample at 235 Co. The number of 355nm absorbed photons was calculated accordingly to Keldysh theory and similar results were found using adenine -Ar mixture. Our results are compared with those reported formed by protons, electrons or multiple charged ions interactions. Different ions were found indicating the possible effect of multiphoton absorption
Effect of the Target Size in the Calculation of the Energy Deposited Using PENELOPE Code
Get PDFThe specific and linear energy was calculated in target sizes of 10 μm, 5 μm, 1 μm, 60 nm, 40nm and 20 nm by taking into account the contribution of the primary photon beams and the electrons generated by them in LiF: Mg, Ti (TLD-100). The simulations were carried out by the code PENELOPE 2011. Using different histories of primary particles, for each energy beams the mean deposited energy is the same, but to achieve a statistical deviation lower than 1% the value of 108was fixed. We find that setting the values C1 = 0.1 C2 = 0.1 and Wcc = Wcr = 50 eV the time of simulation decreases around the 25%. The uncertainties (1 SD) in the specific energy increases with energy for all target sizes and decreases with target size, with values from 1.7 to 94% for 20 nm and between 0.1 and 0.8% for 10 μm. As expected, the specific and linear energies decrease with target size but not in a geometrical behavior
Synthesis of MgB4O7:Dy3+and Thermoluminescent Characteristics at Low Doses of Beta Radiation
Get PDFThe synthesis and thermoluminescent characteristics of dysprosium-doped MgB4O7 are analyzed. The phosphor at different concentrations (0, 0.1, 0.5, 1, 2 and 4 mol%) of the dopant was prepared by the solution-assisted method. The magnesium borate compound was confirmed by X-ray diffraction. The annealing and dopant concentrations effects on the crystalline matrix were investigated. The highest thermoluminescent sensitivity was found with 450°C of annealing temperature and at high Dy3+ concentration too. The un-doped MgB4O7 phosphor shows a broad glow curve which peaked at 199°C and about 306 °C. Introducing Dy3+ dopant in the matrix that behavior was strongly changed. The wide glow curve shows three glow peaks; two small shoulders at 124 and 195 °C, and a highest peak between 323 and 336 °C temperature range. A large linear dose-response (5 – 2000 mGy) beta dose was obtained. The complex glow curves were deconvolved and the kinetics parameters were determined considering the general order kinetics model
Enhancement in the Photoluminescence Properties of SiO2:Ge Embedded in a Polymeric Matrix
Get PDFPolymer films of styrene butadiene copolymer (SBC) mixed with SiO2:Ge powder were successfully obtained by the drop casting method. The SBC concentration (in chloroform solution) was 10%w/v and the SiO2:Ge powder was mixed (mass ratio 80:20 respectively). The thicknesses of the films obtained were 50, 100, and 200 μm. In addition, polymer films of polytetrafluoroethylene (PTFE) preparation (60% dispersion in water), were obtained mixing 2 ml of PTFE and 0.05g of SiO2:Ge powder with a mass relation of 98% polymer and 2% SiO2:Ge. The photoluminescence emission spectra (PL) of SBC doped with SiO2:Ge resulted in similar characteristics to those for SiO2:Ge powders, although their intensity shows an increase 3.5 times approximately, compared with the pure powder. On the other hand, the PTFE films with SiO2:Ge present just one peak in the PL emission at 439 nm but their intensity increases 18 times respect to the powder. The photoluminescence excitation (PLE) spectra of the SiO2:Ge powders show the characteristic peaks at 248 nm (most intense) and at 366 nm. However, when the powder is embedded either in SBC or PTFE the peak at 366 nm shows an important increase which seems to indicate an energy transfer from the polymer to the SiO2:Ge
Redistribution of Nickel Ions Embedded within Indium Phosphide Via Low Energy Dual Ion Implantations
Get PDFTransition-metal doped Indium Phosphide (InP) has been studied over several decades for utilization in optoelectronics applications. Recently, interesting magnetic properties have been reported for metal clusters formed at different depths surrounded by a high quality InP lattice. In this work, we have reported accumulation of Ni atoms at various depths in InP via implantation of Ni- followed by H– and subsequently thermal annealing. Prior to the ion implantations, the ion implant depth profile was simulated using an ion-solid interaction code SDTrimSP, incorporating dynamic changes in the target matrix during ion implantation. Initially, 50 keV Ni- ions are implanted with a fluence of 2 × 1015 atoms cm-2, with a simulated peak deposition profile approximately 42 nm from the surface. 50 keV H- ions are then implanted with a fluence of 1.5 × 1016 atoms cm-2. The simulation result indicates that the H- creates damages with a peak defect center ~400 nm below the sample surface. The sample has been annealed at 50°C in an Ar rich environment for approximately 1hr. During the annealing, H vacates the lattice, and the formed nano-cavities act as trapping sites and a gettering effect for Ni diffusion into the substrate. The distribution of Ni atoms in InP samples are estimated by utilizing Rutherford Backscattering Spectrometry and X-ray Photoelectron Spectroscopy based depth profiling while sputtering the sample with Ar-ion beams. In the sample annealed after H implantation, the Ni was found to migrate to deeper depths of 125 nm than the initial end of range of 70 nm
Annihilation of Dipolar Dark Matter: χχ→γγ
Get PDFIn this work we study the annihilation of dark matter, considering it as a neutral particle with magnetic and/or electric moments not null. The calculation of the effective section of the process χχbar→γγ is made starting from a general form of coupling χ χbar γ in the framework of an extension of the Standard Model. We found, when taking into account an annihilation of DDM-antiDDM to monoenergetic photons, that for small masses, mχ ≤ 0 GeV, an electric dipole moment ~10–6 e cm is required to satisfy the current residual density, while for the range of greater sensitivity of HAWC, 10 TeV < Eg < 20 TeV, the electrical dipole moment must be of the order of 10–8 e cm