Physics Open最新文献

We attempted to improve semi-empirical equations for ${\beta }^{-}$-decay in the atomic number range $1\le Z\le 42$ and mass number range $3\le A\le 118$. We suggested a semi-empirical formula in terms of an atomic number of daughter nuclei and decay energy in keV. We divided the nuclei into four categories: even(Z)-even(N), even(Z)-odd(N), odd(Z)-even(N), and odd(Z)-odd(N) to propose improved semi-empirical formulae. The existing equation values are compared to the experimental results. When compared to other semi-empirical equations accessible in the literature, the standard deviation produced from the current formula is lower. The improved semi-empirical formulas are of the first kind, requiring only an atomic number of daughter and decay energy during ${\beta }^{-}$-decay. This study discovers a significance in predicting ${\beta }^{-}$-decay.

Pebble-bed High Temperature reactors (HTR) are proposed to generate heat for power production and process heat application such as Hydrogen (H₂) production. A HTR fuel pebble consists of random distribution of several thousands of fuel particles, called Tri-Structural Isotropic (TRISO), in fuel zone followed by a graphite layer. This configuration along with coolant layer results in double heterogeneity effect. A multi-group Monte Carlo code PebMC has been developed to accurately analyse molten salt cooled HTR lattice cell. Neutron transport in such a complex fuel distribution requires resonance self-shielded cross-section which is generated using rational approximation and Dancoff correction. Dancoff factor accounts for those neutrons leaving a fuel particle and directly colliding with another fuel particle, without any collision with moderator nuclei.

In this study, an analytical expression based on a two-region model developed for gas cooled HTRs is adopted to calculate Dancoff factor for pebble with salt coolant. The implementation of these analytical expressions with 172groups WIMS library in PebMC code have been discussed. Subsequently, paper describes neutron tracking in random medium of HTR lattice using Monte Carlo method. The influence of fuel salt on Dancoff factor for various packing of TRISO particles and subsequent effect on infinite multiplication factor (K-inf) calculation have been presented. In addition, effect of temperature of molten salt on Dancoff factor have been studied.

The current study reports the synthesis of Fe${}_2$O${}_3$ NPs by the co-precipitation method and the evaluation of the anticancer activity and X-ray/gamma absorption study. PXRD analysis confirmed the formation of monophase trigonal-shaped NPs, and the average crystal size is computed using both Scherrer equation and W-h plot and found to be 45 nm and 54 nm respectively. The direct energy gap is computed from the Wood-Taucs plot and found to be 1.76 eV. FTIR analysis confirmed the functional groups present in NPs. Surface morphology studies confirmed by SEM and EDAX analysis confirmed the chemical composition. Anti-cancer studies verified the efficacy of Fe${}_2$O${}_3$ NPs in cell viability and cell death when compared with Cisplatin. Finally, a NaI(Tl) detector is used to evaluate Mass attenuation co-efficient of the X-ray and gamma radiation shielding characteristics. Shielding requirements are comparable to those for lead. Thus, the synthesized Fe${}_2$O${}_3$ nanoparticles can be used for anticancer activities, particularly in tailored drug delivery systems, and radiation shielding instead of toxic lead shielding.

We investigated ²⁵³Cf ternary fission followed by a light-charged particle (LCP) accompanied ternary fission. The many LCPs, include ${}^4$He, ${}^6$Li, ${}^9$Be ¹⁰B, ¹²C, ¹⁴N, ¹⁶O, ¹⁹F ²⁰Ne, ²³Na ²⁴Mg, ²⁶Al, ²⁸Si, ³⁰P ³²S, ³⁵Cl, ⁴⁰Ar, ³⁹K and ⁴⁰Ca. Using Coulomb potential and proximity potential, the overall potential has been investigated. In estimating potential, deformations and angle of orientation were taken into account. Using cold valley plots, the driving potential at its lowest level is determined. Using WKB integral, the penetration probability is evaluated. When the fission fragment combinations include equal or close to the magic number of protons or neutrons, the minimal driving potential, maximum penetration probability, and maximum logT${}_{1/2}$ are observed. Therefore, ¹³⁸Ba+⁴He+¹¹¹Ru are the most likely fission fragment combination when ²⁵³Cf undergoes LCP followed ternary fission. Therefore, ${}^4$He particle-emission coupled with two likely fission fragments are the most likely fission fragments if the nuclei ²⁵³Cf undergo LCP-accompanied ternary fission. The significance of this finding may thus be seen in the ternary fission half-lives.

Natural gamma radiation exposure to humans can possess significant health risks when exposed either externally or internally. Though risks are not established at low doses, the exposure levels are set based on conservative approach. In this work, 22 bore-well rock samples were collected from the agricultural area of Dharmapuri district, Tamil Nadu to evaluate the radiation exposure to humans living in that area using a gamma-ray spectrometer. The results shows that, the activity concentration of ²³⁸U ranges from MDA to 87±2 Bq kg⁻¹ with an average value of 25 Bq kg⁻¹, and for ²³²Th it ranges from MDA to 10±2 Bq kg⁻¹, and for the ⁴⁰K it ranges from 167±9 to 669±10 Bq kg⁻¹ with the mean value of 310 Bq kg⁻¹. The various radiological parameters are calculated and compared with the world-recommended limit to assess the radiation hazards. To identify the relation among the natural radioisotopes, Pearson correlation analysis was performed between the radiological variables. It reveales that radionuclides ²³⁸U and ²³²Th strongly correlated with each other and radiological parameters. This implies that ²³⁸U and ²³²Th originated from the same source and ⁴⁰K was derived from different sources.

In this study, we have theoretically presented a prepare-and-measure based SARG04 protocol over free-space. It has been shown that the highest secret key rate is achievable even under free-space losses with a maximum noise tolerance.

In this study, ethylene propylene diene monomer (EPDM)-lead monoxide (PbO)-magnetite (Fe₃O₄) composite was prepared and changes in its properties with different gamma irradiation doses (50, 100, 200, 300, 500, and 1000 kGy) were investigated. Characterizations of irradiated EPDM-metal oxide composites were performed by X-ray Diffractometer (XRD), Field Emission Scanning Electron Microscope (FESEM) and Universal Testing Machine (UTM). It was observed that the synthesized sample shows an amorphous nature beyond the 500 kGy irradiation dose. The FESEM morphographs of irradiated samples show an increase in fracture size with an increase in irradiation dose. The mechanical tests have shown that prepared samples retain their mechanical strength up to ∼100 kGy. In addition, the effect of thermal and electrical properties on irradiation dose has also been studied. The synthesized samples show good thermal stability up to ∼500 kGy. The AC conductivity of the synthesized EPDM-metal oxide composites has been observed to increase slightly with an increase in irradiation dose. It was observed that synthesized EPDM-metal oxide composites are relatively good radiation resistant candidates and can be used for radioactive waste disposal management applications.

The ionosphere is a region of the upper atmosphere where free electrons and ions are created by solar radiation. An effort is made to study the solar radiation influence on the earth's ionosphere's total electron content (TEC) across the low latitude Indian subcontinent from January to October 2022. TEC readings were obtained using GNSS receivers over Bengaluru (13.021 °N, 77.570 °E) and Hyderabad (17.417 °N, 78.551 °E). Ionospheric TEC variations are studied by measuring the degree to which satellite-sent GPS signals are disrupted. The results were compared with geomagnetic measurements such as disturbed storm time (Dst) index and planetary K-index (Kp) and analyzed with TEC anomalies during geomagnetic storms, and the results may be used to estimate the magnetic field of the Earth. The study revealed that ionospheric storms had an advantageous impact in January, March, and April of 2022, but a negative effect in July 2022.

In inverse kinematics, we explored Coulomb fission cross-sections and time scales. Heavier projectiles such as ²³⁸U, ¹³²Xe, and ²⁰⁸Pb on lighter targets such as ¹⁶O ²⁶Mg, ²⁷Al, ³²S, ³⁵Cl, ${}^{40,48}$Ca, ⁴⁵Sc, ${}^{48,50}$Ti, ${}^{56,58}$Fe, ⁶⁴Ni, ⁸⁹Y, ³⁰Si and ⁶⁵Zn were looked into. The photofission cross-sections and the number of equivalent photons impinge on the target nuclei are important parameters in cross-section assessment. The anticipated cross-sections increases with increase in atomic number of target nuclei. We also explored the time scale of projectile nuclei at various transition levels. The estimated time scales accord well with the available experimental value, which is in the order of picoseconds. In addition, we predicted time scales of ¹⁶⁵Ho nuclei in the transition state from $19/2^{+}\to 15/2^{+}$ to $29/2^{+}\to 25/2^{+}$ for which experimental time scales are not available in literature. As a result, Coulomb fission is one of the causes that has severely hampered in the formation of compound nuclei. Prediction of time scales, in particular, would aid in understanding the structure of various energy levels.

Quantum point contacts (QPC) are the building blocks of quantum dot qubits and semiconducting quantum electrical metrology circuits. QPCs also make highly sensitive electrical amplifiers with the potential to operate in the quantum-limited regime. Though the inherent operational bandwidth of QPCs can eclipse the THz regime, the impedance mismatch with the external circuitry limits the operational frequency to a few kHz. Lumped-element impedance-matching circuits are successful only up to a few hundreds of MHz in frequency. QPCs are characterised by a complex impedance consisting of quantized resistance, capacitance, and inductance elements. Characterising the complex admittance at higher frequencies and understanding the coupling of QPC to other circuit elements and electromagnetic environments will provide valuable insight into its sensing and backaction properties. In this work, we couple a QPC galvanically to a superconducting stub tuner impedance matching circuit realised in a coplanar waveguide architecture to enhance the operation frequency into the GHz regime and investigate the electrical amplification and complex admittance characteristics. The device, operating at ∼ $1.96GHz,$ exhibits a conductance sensitivity of $2.92\times {10}^{-5}{(e}^2/h)/\sqrt{Hz}$ with a bandwidth of $13MHz$. Besides, the RF reflected power unambiguously reveals the complex admittance characteristics of the QPC, shining more light on the behaviour of quantum tunnel junctions at higher operational frequencies.