Definition and measurement of the beam propagation factor M~2 for chromatic laser beams

The concept of the beam propagation factor M2 is extended for chromatic laser beams. The definition of the beam propagation factor can be generalized with the weighted effective wavelength. Using the new definition of factor M2, the propagation of chromatic beams can be analyzed by the beam propagation factor M2 as same as that of monochromatic beams. A simple method to measure the chromatic beam factor M2 is demonstrated. The chromatic factor M2 is found invariable while the laser beam propagates through the dispersion-free ABCD system.     

Optimization and Comparing a Different Various of Head Part of a Moderator of “Central” Direction for IBR-2 Reactor

The performance of the upstream moderator for neutron beams 1, 4, 5, 6, and 9 extracted from the IBR-2 reactor is simulated towards selecting its optimum configuration. For different moderator options, gain factors with respect to the existing comb-shaped water moderator are computed. Taking into account the technological issues in manufacturing a combined moderator, the scheme with optimal physical characteristics is selected.     

Mixing Time of Markov Chains for the 1–2 Model

Journal of Statistical Physics - A 1–2 model configuration is a subset of edges of a hexagonal lattice satisfying the constraint that each vertex is incident to 1 or 2 edges. We introduce...     

CO2 pressure broadening and shift coefficients for the 1–0 band of HCl and DCl

CO₂ broadened spectra of the 1–0 band of H³⁵Cl and H³⁷Cl, observed near 2886 cm^?1, and the 1–0 band of D³⁵Cl and D³⁷Cl, located near 2089 cm^?1, have been recorded at room temperature and five total pressures between 150 and 700 Torr, using a Bruker IFS125HR Fourier transform spectrometer. Spectra of pure HCl were also recorded. CO₂ broadening and shift coefficients of HCl and DCl have been measured using multi-spectrum non-linear least squares fitting of Voigt profiles. The analysis of the 1–0 band of DCl was complicated by the presence of overlapping CO₂ bands, which were included in the treatment as absorption coefficients calculated taking line-mixing effects into account.     

Synthesis,Structure, and Thermal Properties of the YVO4–BiVO4 Oxides

Physics of the Solid State - The Y0.4Bi0.6VO4 and Y0.6Bi0.4VO4 solid solutions two-phase at xBi = 0.95, 0.90, and 0.80 have been formed by the solid-phase synthesis from the initial Y2O3, Bi2O3,...     

Magnetic hysteretic characterization of the irradiation-induced embrittlement of Fe,Fe–Cu model alloys,and reactor pressure vessel steel

Neutron irradiation is known to cause embrittlement of iron-based materials; in the nuclear industry, this effect can be detrimental for reactor pressure vessel steels. In this paper, we investigate the variations of the magnetic hysteretic behavior due to neutron irradiation, for four materials, i.e. nominally pure Fe, Fe-0.1 wt% Cu and Fe-0.3 wt%Cu model alloys, and a reactor pressure vessel steel, JRQ A533-B. Two parameters related to the magnetization loop shape, i.e. maximum relative differential permeability and peak intensity of local interaction field distribution, are measured as a function of neutron fluence. For all materials both parameters decrease with increasing fluence, due to the irradiation-induced formation of nano-size defects. This decreasing trend in magnetic parameters during embrittlement is noticeable regardless the origin of the embrittlement, which can be only Cu-precipitation (thermal aging of Fe–Cu), only matrix damage (irradiation of pure Fe), or both mechanisms (irradiation of Fe–Cu or steel). The magnetic parameters relatively change up to 40%, which indicates the potential of magnetic characterization to assess irradiation-induced material hardening and embrittlement.     

Fusion,fission, and annihilation of complex waves for the(2+1)-dimensional generalized Calogero–Bogoyavlenskii–Schiff system

With the help of the symbolic computation system, Maple and Riccati equation( ξ= a0+ a1ξ+ a22ξ), expansion method, and a linear variable separation approach, a new family of exact solutions with q = lx + my + nt + Γ(x, y,t) for the(2+1)-dimensional generalized Calogero–Bogoyavlenskii–Schiff system(GCBS) are derived. Based on the derived solitary wave solution, some novel localized excitations such as fusion, fission, and annihilation of complex waves are investigated.     

Monitoring extracted beams of the nuclotron accelerator complex for “energy + transmutation” experiments

A monitoring system for measuring absolute intensity and the space—time structure of extracted beams of Nuclotron based on ionization and activation methods has been created and tested. The monitoring system provides a measurement of the absolute intensity of extracted beams with a precision of 10% and beam position with a precision of 0.5 mm.     

Calculation of the T–P Phase Diagrams for the Halogenomethane Compounds (CCl4 – nBrn,n = 0, 1, 2, 4) Using the Mean Field Theory

Physics of the Solid State - The T–P phase diagrams of the halogenomethane compounds (CCl4 – nBrn, n = 0, 1, 2, 4) are calculated using a mean field model. By...     

Effect of gamma irradiation on the structural,thermal and optical properties of Makrofol BL 2–4

Makrofol BL 2–4 is an extrusion film based on Makrolon polycarbonate. It comprises excellent die-cutting performance combined with high light transmission and moderate light scattering properties. It is a class of polymeric solid state nuclear track detectors which has many applications in various radiation detection fields. In the present work, Makrofol samples were irradiated using different gamma doses ranging from 10 to 350 kGy. The structural modifications in the gamma-irradiated Makrofol samples have been studied as a function of dose using different characterization techniques such as X-ray diffraction, intrinsic viscosity, Fourier transform infrared spectroscopy, thermogravimetric analysis, refractive index and color difference studies. The gamma irradiation in the dose range 20–200 kGy led to a more compact structure of Makrofol polymer, which resulted in an improvement in its thermal stability with an enhancement in its structural and optical properties.     

A comprehensive model to predict the microwave spectrum of propyne in the region 17–70 GHz for the ground and v10 = 1, 2, 3, 4, 5 vibrational states

A comprehensive model for predicting rotational frequency components in various v₁₀ vibrational levels of propyne was developed. A number of components of the rotational spectra in the ground and v₁₀ = 1, 2, 3, 4 excited vibrational states of propyne in the frequency range 17–70 GHz have been obtained. Molecular constants for these vibrationally excited states have been determined from more than 100 observed rotational transitions. From these experimentally observed components and a model based upon first principals for C_3v molecules, rotational constants have been expressed in a form which enables one to predict rotational components for vibrational levels for propyne up to v₁₀ = 5. The model also appears to be useful in predicting rotational components in more highly excited vibrational levels but data were not available for comparison with the theory. Experimentally measured frequencies are presented and compared with those calculated using the results of basic perturbation theory.     

Rotational components of the v8 = 1, 2, and 3 and ground vibrational levels of CH3C15N for the frequency range 17–75 GHz

The microwave spectrum of methyl cyanide CH₃C¹⁵N was studied for the v₈ = 3 vibrational state in the frequency range of 17 to 75 GHz. In addition, some rotational components for the ground, v₈ = 1 and 2 were remeasured and these results compared to those found in the literature. The frequencies of 42 components were measured and these frequencies were used to produce a constant set which can be used to predict overall frequencies of spectral components in the ground, v₈ = 1, 2 up to an accuracy of 100 KHz and those for v₈ = 3, 4 up to an accuracy of 150 KHz. Previously obtained experimental data, available from the literature, and our own data for the ground, v₈ = 1 and 2, and the new data for v₈ = 3 are presented and compared with the frequencies obtained from a comprehensive equation derived from perturbation techniques.     

Elasticity of the B2 phase and the effect of the B1–B2 phase transition on the elasticity of MgO

A study of the high-pressure anisotropy of MgO was conducted using first-principles calculations based on density functional theory within the generalized gradient approximations. The pressure dependence of the elastic stiffness coefficients and the anisotropy parameters, in both B1 and B2 phases, shows that for high-hydrostatic compression the easiest deformation is the shear along (100) plane and the the material's response to deformation and to shearing strains is quite the same. According to the calculations of the velocities of propagation of elastic waves, we deduced that MgO develop an elastic anisotropy, especially, in the B1 phase. We present the B2 phase elastic properties which are not already studied under high pressure.     

Design and development of the 6–18 MeV electron beam system for medical and other applications

A system for the electron and photon therapy has been designed and developed at SAMEER, IITB, Mumbai. All the components of the system such as the 270° beam bending electromagnet, trim coils, magnet chamber, electron scattering foil, slits, applicators, etc., were designed and fabricated indigenously. The electrons of 6, 8, 9, 12, 15 and 18?MeV energies were provided by a linear accelerator, indigenously designed and made at SAMEER, IITB campus, Mumbai. The electron beam from the LINAC enters the magnet chamber horizontally, and after deflection and focusing in the 270° bending magnet, comes out of the exit port, and travels a straight path vertically down. After passing through the beryllium and tantalum scattering foils, the electron beam gets scattered and turns into a solid cone shape such that the diameter increases with the travel distance. The simulation results indicate that at the exit port of the 270° beam bending magnet, the electron beam has a divergence angle of ≤ 3?mrad and diameter ～2–3?mm, and remains constant over 6–18?MeV. Normally, 6–18?MeV electrons are used for the electron therapy of skin and malignant cancer near the skin surface. On a plane at a distance of 100?cm from the scattering foils, the size of the electron beam could be varied from 10?cm?×?10?cm to 25?cm?×?25?cm using suitable applicators and slits. Different types of applicators were therefore designed and fabricated to provide required beam profile and dose of electrons to a patient. The 6?MeV cyclic electron accelerator called Race-Track Microtron of S. P. Pune University, Pune, was extensively used for studying the performances of the scattering foils, electron beam uniformity and radiation dose measurement. Different types of thermoluminescent dosimetry dosimeters were developed to measure dose in the range of 1–10kGy.