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S. K. Biswas

Publications and source records attributed to S. K. Biswas.

9 recordsLinked to original sources
arXiv2022

An iterative method based FLC-SLM system design for forming multiple complex structures simultaneously in 3D volume with tissue

Complex structure formation and fast focusing of light inside or through turbid media is a challenging task due to refractive index heterogeneity, random light scattering and speckle noise formation. Here, we have proposed a weighted-mutation assisted genetic algorithm (WMA-GA) with an R-squared metric based fitness function that advances the contrast, resolution, focuses light tightly and does fast convergence for both simple and complex structure formation through the scattering media. As a compatible system with the binary WMA-GA, we have presented a fast, cost-effective, and robust iterative wavefront shaping system design with an affordable ferroelectric liquid crystal (FLC) based binary-phase spatial light modulator (SLM). The proposed wavefront shaping system design has been used to construct multiple complex hetero-structures simultaneously in 3D volume by an optimized single phase-mask. The WMA-GA and the prototype system have been validated with 120, 220, 450, and 600 grit ground glass diffusers along with 323, 588, and 852 μm thick fresh chicken tissues including fluorescence in it. We have demonstrated the robustness of the proposed method to control the photon-in and photon-out from a localized fluorescent dye embedded in the tissue. The detailed results show that the proposed class of algorithm-backed integrated system converges fast with higher contrast and advances the resolution.

physics.optics↗
arXiv2022

Thermo-acoustics and its detection in a premixed flame

A new optical technique based on light-matter interaction is devised in-house to detect thermo-acoustic disturbances generated after ignition and during propagation of a premixed flame front in a half open channel. The technique involves passing a polarized laser light through a medium whose density or refractive index varies due to the passage of acoustic waves and/or flame front and then capturing the leaked depolarised light through an analyser by a photo-detector. The technique is applied to combustor involving premixed flame propagation and tulip inversion. The thermo-acoustic signals and the flame front are distinguished by comparing the oscilloscope signal with high speed photography of the flow-field. Acoustic waves are found to intercept the flame propagation at various axial locations and time instants.

physics.flu-dyn↗
arXiv2012

Production of J/$Ψ$-Particles at RHIC and LHC energies: An Alternative `Psi'-chology

We attempt here to understand successfully some crucial aspects of $J/Ψ$-production in some high energy nuclear collisions in the light of a non-standard framework outlined in the text. It is found that the results arrived at with this main working approach here is fairly in good agreement with both the measured data and the results obtained on the basis of some other models of the `standard' variety. Impact and implications of this comparative study have also been precisely highlighted in the end.

hep-ph↗
arXiv2011

On Production of `Soft' Particles in Au+Au and Pb+Pb Collisions at High Energies

Production of low-$p_T$ (soft) hadronic particles in high energy collisions constitutes a significant corner of special interests and problems, as the perturbative quantum chromodynamics (pQCD) does not work in this region. We have probed here into the nature of the light particle production in two symmetric nuclear collisions at two neighbouring energies with the help of two non-standard models. The results are found to be in good agreement with data. Despite this, as the models applied here are not intended to provide deep insights into the actual physical processes involved in such collisions, the phenomenological bounds and constraints which cannot be remedied for the present continue to exist.

hep-ph↗
arXiv2010

Understanding the Characteristics of Multiple Production of Light Hadrons in Cu + Cu Interactions at Various RHIC Energies: A Model-based Analysis

Experiments involving copper-copper collisions at the RHIC-BNL (USA) at energies $\sqrt{s_{NN}}$ = 22.5, 62 and 200 GeV have produced a vast amount of high-precision data which are to be analysed in the light of various competing models in the domain of multiparicle production scenario. We have chosen to analyse here the measured data on the $p_T$ -spectra of various light and non-strange secondaries at various energies mentioned above, some of their very important ratio-behaviours at the various centralities of the collisions and the nuclear modification factors $R_{AA}$ and $R_{CP}$ in the light of a version of the Sequential Chain Model (SCM). The agreements between the measured data and model-based results are generally found to be modestly satisfactory. Besides, our obtained results have also been compared with results based upon two approaches with strong standard model flavour, of which one is purely pQCD-oriented and is forwarded by Vitev.

hep-ph↗
arXiv2010

On the Nature of the Rapidity-Spectra at RHIC and Some Other Energies

On the basis of the Grand Combinational Model (GCM) outlined and somewhat detailed in the text, we have attempted to capture here the several interesting assorted characteristics of the rapidity-spectra of the major varieties of secondaries produced in diverse nuclear reactions at various energies, though the main thrust of our work lies on addressing the data-trends from RHIC-BNL experiments. Obviously the core of the present approach is purely phenomenological. Still, the method and the model address the features of the data modestly well. And the method appears to have the rich potentiality, if the systematic sets of data for rapidity-studies at gradually increasing energies were available.

hep-ph↗
arXiv2009

Paradigm Shifts and a Possible Resolution of the PAMELA-Paradox in Astroparticle Physics

Very recently, PAMELA Collaboration has formally reported two sets of data on positron and antiproton flux measurements done at very high energies and with unprecedented accuracy. The reports reveal a puzzle of great topical interest and importance : it is decisively found that there is a sharp smooth rise of the positron fraction, whereas for antiproton production no such rises occur; rather the fraction either flattens, or shows signs of falling off gradually with increasing energies. The present work is just an attempt to decipher the riddle with the help of a host of radically new ideas about the particle-structure, the multiparticle-production mechanisms and the concept of nucleon break-downs into the constituent partons. The application of these ideas found remarkable successes in the past; exactly similar or more striking are the findings by the present study.

astro-ph.HE↗
arXiv2009

Analysing $j/Ψ$ Production in Various RHIC Interactions with a Version of Sequential Chain Model (SCM)

We have attempted to develop here tentatively a model for $J/Ψ$ production in p+p, d+Au, Cu + Cu and Au + Au collisions at RHIC energies on the basic ansatz that the results of nucleus-nucleus collisions could be arrived at from the nucleon-nucleon (p + p)-interactions with induction of some additional specific features of high energy nuclear collisions. Based on the proposed new and somewhat unfamiliar model, we have tried (i) to capture the properties of invariant $p_T$ -spectra for $J/Ψ$ meson production; (ii) to study the nature of centrality dependence of the $p_T$ -spectra; (iii) to understand the rapidity distributions; (iv) to obtain the characteristics of the average transverse momentum $< p_T >$ and the values of $< p_T^2 >$ as well and (v) to trace the nature of nuclear modification factor. The alternative approach adopted here describes the data-sets on the above-mentioned various observables in a fairly satisfactory manner. And, finally, the nature of $J/Ψ$-production at Large Hadron Collider(LHC)-energies deduced on the basis of our chosen model has been presented in a predictive way against the RHIC-yields, both calculated for the most central collisions and on the same model.

hep-ph↗