2020-7-19Abstracts

ANPA CONFERENCE 2020
JULY 19, 2020

JULY 19th: MORNING SESSIONS
ARE PARALLEL SESSIONS UNTIL 12:30 PM EST

SESSION - XI: Astrophysics

Abstract Number ANPA2020_0050
Author/s Monika Karki, Narayan P. Chapagain
Title Analysis of Total Electron Content Using GPS Observations During 2015 Mw 7.8 Nepal Earthquake
Affiliation/s Amrit Campus, Tribhuvan University
Abstract Abstract not displayed upon Author's request


Abstract Number ANPA2020_0055
Author/s Nishan Lamichhane (1), Aabiskar Bhusal (2)
Title Optical spectroscopy in determining the mass of Messier 87.
Affiliation/s (1) Tribhuvan University
(2) Physics Research Initiative (PRI)
Abstract Abstract hidden upon Author's request


Abstract Number ANPA2020_0057
Author/s Prakash Man Shrestha
Title Study of Variability of Atmospheric Ozone over Jumla in Half Period of 24 Solar Cycle
Affiliation/s Patan Multiple Campus
Abstract This paper reports the variation of total ozone column (TOC) over Jumla (Lat.:29.28o N, Long.:82.16o E and Alt.:2300 m above sea level) from 2008 to 2014 derived from Total Ozone Mapping Spectrometer (TOMS) satellite observations. The trends of monthly, seasonal and annual variations of TOC, solar isolation and clearness index have been analyzed. The result exemplifies that during the whole study period, the maximum value of monthly average TOC is 289.21 ± 10.75 DU in April, while the minimum value is 257.23 ± 11.25 DU on December. The results also show that TOC is highly seasonal dependent with larger TOC in Spring 273.68 ± 14.92 DU and lower in winter season(260.68 ± 15.25 DU). The average annual value of TOC exhibits slightly variable with a maximum in 2010 (277.52 ± 40.64 DU) and minimum in 2008 (267.19 ± 11.11 DU). The average values of solar isolation and clearness index for whole study period are 5.10 ± 0.86 kWh/m2/day and 0.59 ± 0.12 respectively. The average value of TOC during the whole study period is 271.84 ± 14.19 DU, which indicates good amount of stratospheric ozone content over Jumla, Nepal.
Keywords: Total ozone column, solar isolation, clearness index, transmittance, ozone.


Abstract Number ANPA2020_0068
Author/s Ram Krishna Tiwari (1), Prof.Dr.Harihar Paudyal (2)
Title Study of ray path distribution to generate travel time curve for seismic wave produced by 25 April 2015, Gorkha earthquake (Mw 7.8) and its largest aftershock of 12 May 2015 (Mw7.3)
Affiliation/s (1) PhD scholar,Tribhuvan University
(2) Birendra Multiple Campus(Tribhuvan University)
Abstract "A strong Mw7.8 earthquake initiated ∼80km northwest of the Kathmandu on 25 April of 2015 was followed by a series of moderate-to-strong aftershocks, the largest one Mw7.3 occurred 18 day after the main-shock, on 2015 May 12.The seismic phases of main shock and its largest aftershocks were obtained at Kakani seismic station (27.80oN and 85.28oE) using TauPy Model (model ak135).The ak135 velocity model has been augmented with a density and Quality factor model by combining the study of travel times with those of free oscillations. We also compute the arrival times using the same model for both seismic events at respective epicenter distances 0.5962° and 0.7453° from the station. The back-azimuth for both events is computed with gps2Dist Azimuth from functions provided by obspy signal. We found 21 arrivals for mainshocks with first p phase arriving at incident angle 76.93° in 11.706 seconds having ray parameter 1070.003 and phase SKIKSSKIKS as final arrivals in 3268.82 seconds with incident angle 0.0241° having ray parameter 0.7935. Similarly, for the largest aftershock 27 arrivals were collected with the first arrival P phase at incident angle 62.81° in 14.393 seconds having ray parameter 977.071.The final arrivals SKIKSSKIKS seismic phase incidents at 0.030° in 3267.81 seconds with ray parameter 0.9710. For major shocks there are p, P, P phases followed by sP and then s, S, S phase at the beginning while for the largest aftershocks P, p, P, P phases are followed by Pn, P, sP, S, s, S, S, Sn, S. Then after sequences of PcP phase to SKIKSSKIKS phase are same for both events. From this, it can be concluded that with growing depth more and more secondary seismic body wave phases observed which tell about the geometrical and physical properties of discontinuities that they have encountered during their travel through the earth’s interior.
Keywords: seismic phase, ak135, ray parameter.


Abstract Number ANPA2020_0094
Author/s Utsav Siwakoti, D. R. Upadhyay, H. K. Neupane
Title A COMPARATIVE STUDY OF PHYSICAL PROPERTIES AROUND NGC7293 NEBULA IN IRIS & AKARI MAP”
Affiliation/s TU
Abstract We study if NGC7293 is an active Star-forming region or not in a comparative manner by using IRIS and AKARI all-sky map. Our selection is a nebular structure at galactic longitude 337.410 degrees and latitude -20.840 degrees at a distance of 200.97pc, 0.5 × 0.5 degrees IRIS, and 0.4 × 0.4 degrees AKARI map of NGC7293 is downloaded from sky view virtual observatory and then processed in the software ALADIN v2.50. The minimum and maximum temperatures from AKARI all-sky map are found to be 19.90 K and 37.46 K respectively. Also, the average temperature via slope of linear plot in the flux is found to be 22.25 K. Similarly, the minimum and maximum temperatures from IRIS all-sky map are found to be 23.99 K and 24.82 K respectively and the average temperature via slope of linear plot in the flux is also found to be 31.38 K. The total mass of the structure is found to be 3.04×1028 kg and 6.46 ×1026 Kg in AKARI and IRIS images. The flux density variation along the major and minor diameters showed a Gaussian-like distribution, suggesting local thermodynamical equilibrium in the isolated structure. The Jeans mass of the dust in the NGC7293 nebular structure in AKARI image is found to 2.29×1033 kg, and in IRIS image is found to be 4.41×1033 kg which is much greater than the total mass, so we have concluded that the structure is not a star-forming region and is in local thermodynamic equilibrium. Key-words: IRAS, AKARI, NGC7293, Infrared Astronomy, Spectral Density.


Abstract Number ANPA2020_0084
Author/s Sujan Prasad Gautam (1), Binil Aryal (1), Ashok Silwal (2), Amrit Sedain (1)
Title Study of Star Formation Rate of Tidal Dwarf Galaxies
Affiliation/s (1) Central Department of Physics, Tribhuvan University, Kirtipur, Nepal
(2) Patan Multiple Campus, Lalitpur, Nepal
Abstract Abstract hidden upon Author's request


Abstract Number ANPA2020_0086
Author/s Suresh Bhattarai
Title All-Nepal Asteroid Search Campaign: Opportunity to Discover Asteroids from Nepal
Affiliation/s NASO
Abstract Abstract hidden upon author's request


Abstract Number ANPA2020_0093
Author/s Usha Joshi (1), Prof. Dr. Khem Narayan Poudyal (2), Prof. Dr. Indra Bahadur Karki (3), Prof. Dr. Narayan Prasad Chapagain (4)
Title Impacts of Sunshine Hour, Ambient Temperature and Relative Humidity on Total Solar Radiation at Mid Hill Region, Nepal
Affiliation/s (1)Patan Multiple Campus, TU, Patan Dhoka, Nepal
(2)Department of Physics, Pulchowk Campus, IOE,TU, Lalitpur, Nepal
(3)Nepal Open University, Nepal
(4)Department of Physics, Amrit Campus, TU, Kathmandu Nepal
Abstract This research work focuses to study the affecting factors like sunshine hour, ambient temperature and relative humidity for the estimation of total solar radiation (TSR) in Mid hill region Kathmandu (lat: 27.70oN, Long: 85.5oE and Alt. 1350m) for years (2010-2015). All those meteorological parameters vary not only seasons to seasons but also local weather conditions as well. Since there is no sufficient reliable measured data of solar radiation at many places of Nepal, empirical models are used to predict the solar radiation potential at various places of Nepal. To find the TSR potential, at Mid Hill location Kathmandu, the modified Angstrom model is used on the basis of sunshine hour, temperature and relative humidity. After using regression technique, the empirical coefficients are found and those coefficients are utilized to predict the TSR. For the validation of this research work statistical tools such as Mean Percentage Error (MPE), Mean Biased Error (MBE), Root Mean Square Error (RMSE) and Coefficient of determination (R2) are analyzed, These values are 3.039, -0.06, 2.75 and 0.728, respectively for the new Model E based on sunshine hour, temperature difference and relative humidity among the five models. Here Model E is better than other models because all the errors are smaller and the value of coefficient of determination is higher compare to other models. Finally, it is concluded that the empirical constants are utilized for predicting TSR at similar geographical location of Nepal. In addition that the solar energy can be utilized to mitigate energy crisis at that location and it also helps to grow more crops using the energy at the modern agriculture farmland.
Keyword: Total solar radiation, meteorological parameters, Statistical tools, empirical constant, mitigate energy


SESSION - XII: Condensed Matter Physics

Abstract Number ANPA2020_0038
Author/s Hem Raj Sharma
Title Quasicrystals with Crystallographic Rotational Symmetry
Affiliation/s The University of Liverpool, UK
Abstract Quasicrystals differ from conventional crystals by possessing long-range order without periodicity. Quasicrystalline phases have been observed not only in metallic alloys [1] but also in liquid crystals, polymers, colloids, perovskites and overlayer structures of single elements and molecules. All of these quasicrystalline phases exhibit orders of rotational symmetry which are forbidden in periodic crystals, such as 5-, 10-, and 12-fold, and their structures are associated with complex aperiodic tilings such as Penrose tilings. This talk will present the first experimental observation of a 4-fold quasicrystalline structure in a physical system. Scanning tunnelling microscopy (STM) shows that fullerenes (C60) deposited on the surface of an icosahedral Al-Pd-Mn quasicrystal selectively adsorb atop specific atomic species, forming a Fibonacci square grid [2] (figure 1). The relative simplicity of such a model system provides an avenue to understanding the unusual properties of quasicrystals with higher order rotational symmetries. This site specific adsorption behaviour offers the potential to create tuneable structures in molecular overlayers, such as array of molecular magnets. The findings also demonstrate that molecules can be used as a chemical probe to identify atomic species on metallic alloy surfaces, a key step in understanding the surface structure of complex systems like quasicrystals. We will also discuss other unique structures of overlayer grown on quasicrystals [3, 4].


Abstract Number ANPA2020_0035
Author/s Gyanendra Dhakal, Md. Mofazzel Hosen (1), Ayana Ghosh (2, 3), Christopher Lane (3, 4),
Karolina Gornicka (5), Michal J. Winiarski (5), Klauss Dimitri (1), Firoza Kabir (1), Christopher Sims (1), Sabin Regmi (1)
Luis Persaud (1), Yangyang Liu (1), Dariusz Kaczorowski (6), Jian-Xin Zhu (3, 4), Tomasz Klimczuk (5), Madhab Neupane (1)
Title Observation of distinct topological superconducting state in CaBi2
Affiliation/s (1) Department of Physics, University of Central Florida, Orlando, Florida 32816, USA
(2) Department of Materials Science and Engineering and Institute of Materials Science
University of Connecticut, Storrs, Connecticut 06269, USA, Department of Physics, University
(3) Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
(4) Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
(5) Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Narutowicza 11/12, 80-233 Gdansk, Poland
(6) Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wroclaw, Poland
Abstract The discovery of topological insulator phase has ignited massive research interests in novel quantum materials. Topological insulators with superconductivity further invigo- rate the importance of materials providing the platform to study the interplay between these two unique states. However, the candidates of such materials are rare. Here, we report a systematic angle-resolved photoemission spectroscopy (ARPES) study of a superconducting material CaBi2 [Tc = 2 K], corroborated by the first-principles calculations. Our study reveals the presence of Dirac state in this compound. System- atic topological analysis based on symmetry indicator shows the presence of distinct topological indices as opposed to the previously studied topological superconducting materials. Furthermore, our transport measurements show the presence of large mag- netoresistance in this compound. Our results indicate that CaBi2 could potentially provide a new material platform to study the interplay between superconductivity and topology.


Abstract Number ANPA2020_0044
Author/s Luis Persaud, Christopher Sims, Gyanendra Dhakal, Firoza Kabir, Klauss Dimitri
Sabin Regmi, Md Mofazzel Hosen, Yangyang Liu, Madhab Neupane
Title Application of Edge Detection Techniques to the Analysis of Spectroscopic Data
Affiliation/s Department of Physics, University of Central Florida
Abstract Edge detection and similar image analysis techniques are commonly used in computer vision but have not been fully realized for the purpose of ARPES data analysis. Without applying any Image analysis, the interpretation of ARPES data is left to the eyes of researchers and can be tricky and unreliable due to many sources of noise and distortion from the experimental processes, as a result, some of the finer, defining, details required to classify a material can be missed. By applying edge detection techniques, we are able to highlight key features such as distinct, clustered bands and other fine details that may otherwise have been obscured by noise and other experimental artefacts. Here we show the implementations of various image processing techniques applied to ARPES data and how they not only aid the interpretation of results, but can also be looked upon as stepping stones for better data processing techniques and potential automation of the classification of quantum materials through analysis of ARPES data.


Abstract Number ANPA2020_0075
Author/s "Sabin Regmi 1, Md Mofazzel Hosen 1, Barun Ghosh 2, Bahadur Singh3,4
Gyanendra Dhakal 1, Christopher Sims 1, Baokai Wang 3, Firoza Kabir 1, Klauss Dimitri 1, Yangyang Liu 1
Amit Agarwal 2, Hsin Lin 5, Dariusz Kaczorowski 6, Arun Bansil 4, and Madhab Neupane 1 "
Title Temperature Dependent Electronic Structure in a Higher Order Topological Insulator Candidate EuIn2As2
Affiliation/s 1 Department of Physics, University of Central Florida, Orlando, Florida 32816, USA 2 Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India 3 Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA 4 SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center for 2D Materials Information Functional Devices and Systems of Guangdong Province, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China 5 Institute of Physics, Academia Sinica, Taipei 11529, Taiwan 6 Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-950 Wroclaw, Poland
Abstract It has been well known that interplay between topology and magnetism in topological materials can give rise to various magnetic topological states. The study of the topological materials with intrinsic magnetism is thus very desirable. Here, using the high-resolution angle-resolved photoemission spectroscopy (ARPES) combined with the first-principles calculations, we report a systematic study on the electronic band topology across the magnetic phase transition in EuIn2As2 which possesses an antiferromagnetic ground state below 16 K. Antiferromagnetic EuIn2As2 has been predicted to host both the Axion insulator and higher order topological insulator (HOTI) phase. Our experimental results show the clear signature of the evolution of the topological state across the magnetic transition. Our theoretical calculation of the parity invariant Z4 topological invariant indicates the axion insulating phase (Z4 = 2). Our study thus provides a platform to further study the interplay of topological and magnetism in this material.


Abstract Number ANPA2020_0049
Author/s Mohan Bhattarai
Title A review of relaxor ferroelectric materials for energy storage applications
Affiliation/s University of Puerto Rico, Rio Piedras Campus, San Juan, PR, USA
Abstract Abstract not displayed upon Author's request


Abstract Number ANPA2020_0022
Author/s Bishnu Pokhrel
Title DENSITY FUNCTIONAL THEORY STUDY ON ELECTRONIC PROPERTIES OF METHANE HYDRATE
Affiliation/s M. Sc. Physics, Prithvi Narayan Campus, Pokhara, Nepal
Abstract " Gas hydrates are solid compounds with water cage like structure where gas molecules as guest molecule enclosed inside water molecules. There is no any chemical bonding between the water molecules and the guest molecules but they are connected by hydrogen bonding. they are ice like compounds and typically form under high pressure and low temperature in permafrost region and shallow marine environment such as in seabed sediments along continental margin. Methane hydrate is an example of gas hydrate in which methane gas acts as guest.The energy stored in methane hydrate reserves is twice more than the energy in the reserves of other hydrocarbon sources. As methane is also a greenhouse gas and it is difficult to utilize it properly. Even a small quantity of methane gas would cause severe effect in environment. The electronic properties of methane hydrate analogous with ice. This is true because the amount of water in hydrate structure is high. The electronic properties of methane hydrate such as the HOMO-LUMO gap, bond length, electron transfer, B.E. per atom and charge distribution, are derived using a functional B3LYP of DFT. Many properties of methane hydrate are almost identical to the properties of ice, and both ice and methane hydrate do not appear to be good conductors of electricity whereas their properties seem to be bad conductors. "


Abstract Number ANPA2020_0001
Author/s Aabiskar Subedi
Title STUDY THE MECHANOCHEMISTRY OF SILICON CARBIDE NANORIBBON (SiCNRs) BY USING FIRST PRINCIPLE
Affiliation/s PrithiviNaryan Campus
Abstract " STUDY THE MECHANOCHEMISTRY OF SILICON CARBIDE NANORIBBON (SiCNRs) BY USING FIRST PRINCIPLE Mechanochemistry deals with the behavior of molecule under applied stress. Constrained Geometries Simulate External Forces method is used in order to study the behavior of Silicon Carbide Nanoribbon (SiCNR) to find their behavior under external stress. This approach is based on the scan of potential energy due to change in nanoribbon geometry. Thus, applied stress is the negative gradient of change in energy. A hybrid density functional B3LYP as implemented in Gaussian09 suites of program is used for energy scan of the nanoribbon under study. Method comprise constrained geometry optimization of the stretched nanoribbon along with their energy scan. The change in successive energies along with their change in length helps in determining the externally applied force. Finally this work calculates their Young modulus and force-extension curves. The study also includes some fundamental electronic properties that undergoes in nanosystem with the application of external force. "


SESSION - XIII: Nuclear Physics

Abstract Number ANPA2020_0002
Author/s Abishek Karki
Title EMC ratios in Lighter Nuclei
Affiliation/s Mississippi State University
Abstract At Jefferson Lab we recently conducted an experiment where an electron beam traveling almost at the speed of light was made to collide with several nuclear targets such as Deuterium, Beryllium, Carbon, and Boron. The aim of this experiment was to study how quarks, which are fundamental particles that make up protons and neutrons, are changed when they are bound up inside a nucleus such as Carbon compared to free protons and neutrons that are not held inside nuclei. In the experiment the electrons that scatter off from the target nucleus are detected with a set of particle detectors attached to magnets that allow us to select electrons that are scattered at a fixed angle while carrying a fixed fraction of the electrons beam's energy. Knowing the energy and angle of the scattered electrons we can reconstruct the distribution of energy of the quarks inside the nucleus (called its structure function). We can then compare the structure functions of Be, C and B to those from Deuterium (an isotope of Hydrogen which we consider to be an almost free proton and neutron) to figure out how the quark distributions change when they are held together inside nuclei by the strong nuclear force. One of the goals of this experiment is to verify if the changes to the quark distributions are caused by the protons and neutrons that are closest to each other rather than all of the protons and neutrons in the nucleus.


Abstract Number ANPA2020_0037
Author/s Hem Bhatt
Title Charge Symmetry Violation in Quark Distributions Using SIDIS
Affiliation/s Mississippi State University
Abstract " In modern physics, symmetry principles play a critical role in the study and formulation of the fundamental laws of physics. Charge symmetry is one such symmetry principle which says that the strong force which holds protons and neutrons inside nuclei is the same for protons and neutrons. Protons and neutrons are made up of quarks and the charge symmetry principle restated in terms of these underlying quarks which states that the distributions of up quarks in the protons is the same as the distribution of the down quark in the neutrons and vice-versa. Since the mass of the proton and neutron, as well as the up and down quark, differ by about 1% it is expected that charge symmetry is violated at the 1% level.  However, experimental data collected so far can only verify charge symmetry to < ±10%. Yet, charge symmetry has been universally assumed as a bedrock principle in studying the distributions of quarks inside protons and neutrons.
Jefferson Lab experiment E12-09-002 was the first experiment to try to remedy the situation by precisely measuring the charge symmetry violation with an uncertainty of 1%.  In this experiment, electrons traveling almost at the speed of light collided with a target made of liquefied deuterium. The scattered electrons produced in the collision along with another type of charged particle known as pions (made up of a quark and an anti-quark) were detected simultaneously in a set of detectors attached to magnets that allow us to select electrons that are scattered at a fixed angle while carrying a fixed fraction of the electron beam's energy. The experiment alternately detected positive or negative pions which help us extract the distribution of up or down quarks in the deuterium nucleus. By taking this special ratio of the positive pions to the negative pions produced in the electron-deuterium collisions we can look for charge symmetry violation with higher precision than ever before. We will show preliminary results from the experiment and talk about the current progress in data analysis. "


Abstract Number ANPA2020_0018
Author/s Bhawin Dhital, Geoffrey A Krafft
Title Two-Energy Storage Ring Cooler for Future Electron-Ion Collider (EIC)
Affiliation/s Old Dominion University, Jefferson Lab
Abstract Abstract not displayed at Author's request


Abstract Number ANPA2020_0011
Author/s Anita Mishra
Title Radiological assessment of Bagh Bhairav in Kirtipur, Nepal by in-situ gamma ray spectrometry
Affiliation/s Central Department of Physics, Tribhuvan University
Abstract The results of in-situ radiological survey of Bagh Bhairav complex in Kirtipur, Nepal using portable gamma ray spectrometer (backpack) equipped with GPS and data logger unit is presented. The aim of the study is to assess external exposure by evaluating and mapping external absorbed dose rates and radionuclides activity concentrations in the study area. The measured absorbed dose rate in air was found in the range of 100.330 nGy/h to 170.506 nGy/h with average value 128.661 ± 14.637 nGy/h. The activity concentrations of the gamma radionuclides 238U, 232Th and 40K were found 85.340 ± 21.423 Bq/kg, 74.326 ± 13.899 Bq/kg and 978.901 ± 161.189 Bq/kg respectively. The absorbed dose rate in air was compared with the terrestrial data. The statistical analysis showed positive and linear correlation between them. The absorbed dose rate was also calculated from the activity concentrations of gamma radionuclides and was compared with the measured absorbed dose rate in air. The calculated absorbed dose rate from terrestrial data and measured absorbed dose rate in air was found nearly equal which showed that gamma radiation in air was from natural terrestrial radiation. The Annual Effective Dose (AED) was calculated from the average of measured absorbed dose rate and was compared with the study of other places in different parts of the world. The outdoor AED and Excess Lifetime Cancer Risk (ELCR) is calculated 0.157 mSv/y and 0.519 × 10-3 respectively, which is higher than the world average value. Higher air absorbed dose rate is measured due to high activity concentrations of gamma radionuclides 238U, 232Th and 40K in soils and rocks. The primordial radionuclides in the earth crusts and building materials produces gamma radiation and contribute dose which is hazardous for the human health. So far no radiological data is available for studied area and the most area in Nepal, the data will be baseline data for Nepal.
Key Words: Absorbed dose rate, Activity concentration, AED, ELCR, In-situ radiological survey, Nepal


Abstract Number ANPA2020_0059
Author/s Pratiksha Shahi (1), B.B. Chand (2), Aimandu Shrestha (3)
Title STATUS OF RADIATION FACILITY in Province No. 5 of Nepal.
Affiliation/s (1) Chief consultant radiologist, Bheri hospital, Nepalgunj.
(2) Lecturer Of Physics , Nepalgunj
(3) Consultant radiologist, National Trauma center Kathmandu.
Abstract The use of ionizing radiation in medicine, energy production, industry, and research bring enormous benefits to people when it is used safely. However, the potential radiation risk must be assessed and controlled [1]. This study was done to know about the actual status of radiation protection in the hospitals and diagnostic centres in province 5 of Nepal, specially to know about the radiation leakage in different places near radiographic area. In total, 14 hospitals with diagnostic radiology facility and different radiography centres were randomly chosen for this study. Questionnaire for radiation workers were used and radiation exposures of the radiation equipment were measured with dosimeter in and outside the room. To calculate equivalent dose level H(mSv/min) we measured dose rate level in each area D(mSv/min) in an exposition at higher kV, mAs [2].
Keywords: Radiation, Dosimeter, Equivalent dose


Abstract Number ANPA2020_0071
Author/s Rasmita Timalsina
Title Study of Longitudinal Dynamics of a Simple Linear Proton Accelerator Using MatLab
Affiliation/s Tribhuvan University
Abstract This paper presents the study of longitudinal beam dynamics of a linear accelerator, and simulation results for a model linear accelerator (LINAC) using Matlab. The study part the transition energy, particle acceleration, the transit time factor, RF factor, and momentum compaction are discuss. For the simulation, the model LINAC is build using a unit cells, and the unit cell consists of Quadrupole doublet and acceleration cavity. Model LINAC’s basic setup is present, and the simulation is on basis of the single particle analysis. The robustness of the model LINAC is test by varying different parameters, like, initial arrival phase, input energy. And the criteria to measure the robustness of the model LINAC are to check the kinetic energy at the end of the LINAC and the transverse stability of the transfer matrices of the each cell. The paper also presents the theoretical analysis of Phase stability at both below and above transition energy. stability of small and larger amplitude oscillations is present and simulation result for different particles each starting with different amplitude is see, where the large amplitude oscillation falls outside of the separatrix.


Abstract Number ANPA2020_0102
Author/s Suyog Shrestha
Title Taking High Energy Physics to Higher Altitudes
Affiliation/s Ohio State University, USA
Abstract Several phenomena observed in nature are not explained by the current theories in fundamental physics. For example, why is there such a large asymmetry between matter and anti-matter? What is the nature of dark matter? How does the Higgs boson interact with itself? These unanswered questions form the basis of my research interests. In this talk, I will briefly discuss my research on the ATLAS experiment at CERN's Large Hadron Collider, but the crux of the talk will focus on how fundamental research can inspire the next generation of scientists, especially in the context of Nepal, what has been done so far, and what some near- to mid-term goals are.


Abstract Number ANPA2020_0092
Author/s Umesh Silwal
Title Structure of 75Ge nuclei from beta-decay spectroscopy
Affiliation/s University of Wyoming, USA
Abstract In this measurement, a pure 75Cu beam was developed at the Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National Lab (ORNL), and detailed β-decay studies of A = 75 decay chain was performed to understand the structure of corresponding daughter nuclei. Presented here is the case for 75Ga beta decay. Data on γ ray emission following β-decay, including βγ and γγ coincidences, were recorded, and the gated γγ spectra were analyzed to identify the statistically significant coincidences in cascades. The decay scheme developed from this work has been able to significantly increase both the number of energy levels and transitions. Finally, shell model-calculations are used for comparison to the observed level density.


Abstract Number ANPA2020_0081
Author/s Shambhu Ghimire
Title Particle Accelerator Technology Enables Ultrafast X-ray Science
Affiliation/s SLAC National Accelerator Laboratory, Menlo Park, California, USA
Abstract Constructed in the sixties and seventies Stanford Linear Accelerator Center (SLAC) was the biggest particle accelerator of its kind at the time. Quickly after construction, it had enabled many important high-energy particle physics experiments, including the discovery of quarks for the first time. It uses a 3.2-kilometer-long linear accelerator, which can accelerate particles to relativistic speeds, such as electrons reaching the energy in the access of 50 GeV. When the laboratory’s mission was re-defined in the years of 2,000, this giant accelerator has been repurposed to make the most powerful x-ray machine in the world, called the Linac Coherent Light Source (LCLS). The first intense flashes of x rays were recorded in the summer of 2009, and since then SLAC has been a leading institute in ultrafast x-ray science. Key features of the LCLS include very high x-ray photon flux (10^12 x-ray photons per shot) and very short pulses (10 to 100 femtoseconds, where 1 fs = 10^-15 s). Therefore, it has enabled unprecedented imaging capabilities, as well as a new way to probe ultrafast processes in materials with element specificity. This talk provides a brief overview of the LCLS intended for wide range of research areas.


Abstract Number ANPA2020_0103
Author/s Medani Sangroula
Title The Electron-Ion Collider (EIC)
Affiliation/s Brookhaven National Laboratory, USA
Abstract The proposed Electron-Ion Collider (EIC) at Brookhaven National Laboratory (BNL) is designed to collide spin-polarized beams of electrons with ions producing a peak luminosity of 1034 cm-2 sec-1, which will open a new frontier for research in nuclear physics and quantum chromodynamics by answering profound questions about nucleons, and how they are assembled to form the nuclei of atoms. The existing Relativistic Heavy Ion Collider (RHIC) will be reconfigured to EIC, also called eRHIC, by adding a brand-new electron storage ring with an energy range from 5 to 18 GeV. In this talk, I will present key features of EIC, how the currently operating RHIC will transform into EIC, and my current research on the feasibility of using the existing RHIC stripline Beam Position Monitors (BPMs) for the EIC hadron ring.


SESSION - XIV: Condensed Matter Physics

Abstract Number ANPA2020_0067
Author/s Ram Babu Ray, Dr. Gopi Chandra Kaphle
Title Electronic structure, Magnetic properties of and Strain effect of quaternary Heusler compoundsZrRhTiIn and ZrRhTiAl by first principle study
Affiliation/s TU, Nepal
Abstract Abstract hidden upon Author's request


Abstract Number ANPA2020_0096
Author/s Youbraj Paudel, Gopi Chandra Kaphle
Title A FIRST-PRINCIPLES STUDY OF STRUCTURAL, ELECTRONIC AND MAGNETIC PROPERTIES OF CHROMIUM BASED BINARY ALLOYS
Affiliation/s Tribhuvan University, Nepal
Abstract The structural, electronic and magnetic properties of CrX(X=As, Sb, Se) have been investigated using Tight Binding Linear Muffin-Tin Orbital Atomic Sphere Approxi- mation (TB-LMTO-ASA) within the frame work of Density Functional Theory (DFT) and Generalized Gradient Approximation (GGA). Energy minimization calculation have been performed to obtain the most stable structure for each of three binary system, as these compound vary their structural and magnetic properties of state at different temperature range. In addition electronic properties such as band structure and fatband structure, and magnetic properties such as density of state and partial density of state of CrX binary alloys have been investigated. Furthermore, Charge Density, Charge Distributions and Hartree potentials are observed for these compounds. Specially, total energy minimization has been performed to calculate equilibrium in- plane a0 , out-of-plane c0 and volume V0 , structural lattice parameter of CrX binary alloys. From theoretical study, we obtained the value of a 0 , c 0 and V0 for CrAs(ZB), CrSb(NiAs) and CrSe(NiAs) equal to (a 0 =5.65Å, v 0 =180.36Å3 ), (a 0 =4.02Å, c 0 =5.89Å and V 0 =95.18 Å3 ) and (a 0 =3.61Å, c 0 =5.04Å and v 0 =65.68 Å3 ) respectively . The calculation band structure with fatbands and DOS reveal the supportive properties . From the calculation CrAs system exhibit stable half-metal ferromagnetic with magnetic moment (3.00 μ B) phase at ground state indicating that it can be used in magneto-optical, GMR and spinotronics properties. Similarly the study of CrSb and CrSe reveal that the stable structure is hexagonal (NiAs) and exhibits the metallic property with ferromagnetic properties having magnetic moment(2.35 μ B) and anti- ferromagetic respectively. The calculation charge distribution, Hatree potential and ELF plots supports that the charge is maximum at the core of the atom and minimum at the interstitial space. Our results are in good agreement with the previous experimental and theoretical findings.
Keywords: First principles , Half metal, Spinotronic, Magnetic prerties, Chaege distribution.


Abstract Number ANPA2020_0078
Author/s Sanjeev Kunwar
Title STUDY OF SURFACE MODELLING OF CARBON DIOXIDE CRYSTAL
Affiliation/s Prithivi Narayan Campus , M.Sc. Physics
Abstract Surface modelling is a mathematical technique for representing solid-appearing objects. Solid carbondioxide has a phase diagram rich in polymorphs, which exhibit great diversity in intermolecular interactions, chemical bonding and crystal structures.At atmospheric pressure, the dry ice crystal structure doesnot however,resemble network covalent silica,but some high-pressure solid carbondioxide phases have network covalent structures. In this reasearch determine the surface properties of carbondioxide crystal. The surface properties such as surafce energy,electronic band gap and energy required to cleaving are found and analyzed. Moreover,interlayer separation,structural stability are also found by using DFT implementing Quantum Esspresso .


Abstract Number ANPA2020_0079
Author/s Saran Lamichhane
Title Electric field effect on electronic properties of H2O adsorbed MoS2/Graphene heterostructures
Affiliation/s Central Department of Physics, Tribhuvan University, Nepal
Abstract The zero-band gap problem of graphene and band gapped MoS2 have motivated to search heterostructure as a functional material to achieve the desired properties in practical applications. In this study, the first- principles calculations with density functional theory are employed to investigate the geometries, energetics of MoS2/graphene and graphene/MoS2 heterostructures, taking each component on basal plane. Changes in hydrophilic properties are investigated by the adsorption of water on the basal plane of heterostructure. Electrons transfer from graphene to MoS2 during the formation of heterostructure. Interaction of water molecule towards MoS2 side is significantly higher. Hydrophilic nature can be continuously tuned by external electric field, and may have potential applications in sensing. The electronic properties of studied materials are observed to be sensitive to liquid environment.
Keywords: Heterostructure, DFT, Adsorption & External electric field


Abstract Number ANPA2020_0080
Author/s Shambhu Bhandari Sharma, Rajendra Adhikari, Keshab Raj Sigdel, Ramchandra Bhatta
Title First Principle Study of strain and electric field induced electronic properties and Optical properties of two dimensional heterolayers of planar SiC , SnC and GeC.
Affiliation/s Kathmandu University
Abstract Abstract hidden upon Author's request


Abstract Number ANPA2020_0083
Author/s Sita Kandel, G. C. Kaphle N. P. Adhikari
Title Structural, Electronic and Magnetic properties of Co/Mn based quaternary Heusler alloy
Affiliation/s Associate Professor, Central Department of Physics Tribhuvan University, Kirtipur, Kathmandu, Nepal Professor Central Department of Physics Tribhuvan University Kirtipur, Kathmandu, Nepal
Abstract " Structural, Electronic and Magnetic properties of Co/Mn based quaternary Heusler alloy Sita Kandel*, G. C. Kaphle, and N. P. Adhikari Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal *Email: kandel.s211@gmail.com The zero-gap (gapless) semiconductor in Heusler alloy have created a much interest, because of their extraordinary electronic property. These gapless materials have numerous practical applications in electronic devices, such as photo detector, photo generator, electromagnetic sensor and so on. Moreover, the gapless semiconductor with magnetism could have wide application in novel spintronic devices. The gapless property is observed in Co-Mn based quaternary Heusler alloy CoMnVAl employing first-principles calculations through density functional theory (DFT) based on Tight Binding Linear Muffin-Tin Orbital within Atomic Sphere Approximation (TB-LMTO-ASA) with local density approximation (LDA) and exchange correlation. We here observed density of state(DOS) and band structure of optimized CoMnVAl. The structure of CoMnVAl is found to be FCC with lattice parameters 5.66 A 0 (10.68 a. u.), which fairly agree with experimental value 5.80 A 0 (10.95 a. u.) [1]. From the spin polarized band structure and DOS, CoMnVAl is found to have zero-gap energy bands of indirect type at Fermi level. Which is in clear agreement with the previously calculated theoretical and experimental results [2]. The highest energy gap between valance band (VB) at L point and conduction band (CB) at the same point implies that the highest energy is required when an electron hole pair is created by transferring the electron from VB to CB at the same point L. While, the lowest (zero) value of indirect gap between CB and VB respectively at X and G designate the smallest energy required for electron hole pair at these points. By the analysis of fat band and partial DOS, the major contribution to energy bands and DOS near Fermi level is found from d orbital electron of cobalt (Co), manganese (Mn) and vanadium (V) and little from s and p orbital electron of aluminum (Al). The symmetric nature of DOS in majority and minority spin channel reveals that there is no magnetic moment either in parent CoMnVAl or in individual atomic cite. The absence of magnetic moment in 24 valance electron quaternary Heusler alloy CoMnVAl strongly support the Slater Pauling rule [3] . Finally, the complex type of bonding (i. e. mixture of covalent, metallic and some how ionic) is ascertained between atoms in CoMnVAl.
References:
1. S. Idrissia, H. Labrimb, S. Zitic, L. Bahmada, Physics Letters A, 126453 (2020)
2. S Rumugan, U. Devrajan, M. S. Esaki, S. Singh, R. Thiyagarajan et al. JMMM, 442, 460-467 (2017).
3. L. Pauling, Phys. Rev. 54, 899 (1938)


Abstract Number ANPA2020_0087
Author/s Suresh Paudyal, Dr. Gopi chandra kaphle
Title Study of Electronic and magnetic properties of manganese based binary alloy.
Affiliation/s Central department of physics, TU
Abstract electronic and magnetic properties of manganese based binary alloys


Abstract Number ANPA2020_0089
Author/s Tarani Prasad Yadav (1) , Dr. Gopi Chandra Kaphle (1), Dr. Anurag Srivastava (2)
Title Structural Stability and Magnetic Moment of CuO at Different Morphologies: Ab-initio Approach
Affiliation/s 1. Central Department of Physics, Tribhuvan University, Kirtipur, Kathamandu, Nepal
2. AMR Group, CNT Lab, ABV – IIITM, Gwalior, India
Abstract We investigate bining energy, band structure and density of states of different morphologies of CuO as nanocluster, nanotube, nanoribbon, nanosheet and bulk. We apply exchange correlation functional SGGA+U in Density Functional Theory (DFT) based Ab-initio Approach for the investigations of their structural st abilities and analyzed magnetic moments. They are optimized and analyzed before their calculations. We observe the antiferromagnetic and p-type semiconducting behavior with band gap 2.22 eV in bulk where as the n-type semiconducting behavior with band gap 2.2 eV in chiral (2,1) CuO nanotube but half metallic ferromagnetic feature in chiral (3,1) CuO nanotube . The other forms as cluster, zigzag (7,0) and armchair (7,7) in nanoribbon, and zigzag (7,0) and armchair (7,7) in nanosheet show metallic and ferromagnetic behaviors respectively. The structural stability conformed through their binding energy estimations. The magnetic behavior is found by the calculations of magnetic moment and spin polarization. The magnetic moments of half metallic clusture (CuO)4, half metallic chiral (3,1) nanotube, full metallic zigzag (7,0) and armchair (7,7) nanoribbons, and half metallic zigzag (7,0) and armchair (7,7) nanosheets are 0.03, 0.66, 0.41, 0.84, 0.76, and 1.29 mB respectively. They may be applied in applications as battery, solar cell, diode rectifier, storage media, sensor etc.
Key words: morphologies of CuO, SGGA+U, structural stability, DOS, semiconducting, magnetic moment, metallic ferromagnetic
Acknowledgments: NAST Nepal is acknowledged for the partial support .


Abstract Number ANPA2020_0091
Author/s Thakur Bhandari
Title A FIRST-PRINCIPLES STUDY OF ELECTRONIC AND MAGNETIC PROPERTIES OF VANADIUM BASED BINARY ALLOYS VAs, VSb AND VTe.
Affiliation/s Tribhuvan University
Abstract " https://drive.google.com/file/d/1tm4-SjCC4nMotYTX-jKwupBvd8vDUkhU/view?usp=sharing "


Abstract Number ANPA2020_0095
Author/s Yogendra Limbu,Niraj Shah, Gopi Chandra Kaphle
Title COMAPARATIVE STUDY OF FUNCTIONALIZED MXENE(Ti2N, AND Ti2C)
Affiliation/s Tribhuvan University
Abstract In our work, we investigate systematically the evolution of structural and electronic prop- erties of graphene-like titanium carbide and nitride MXenes (Ti2N, and Ti2C) with different functional groups (F, O, H, and OH) using density functional calculation with PEB func- tional. We found that, the structure of pristine MXene posses same hexagonal symmetry as parent bulk MAX phase. In case of terminated derivatives, the terminated species are distributed randomly on surface of pristine sheet with preferred location in the sites of va- cant space between Ti atoms in pristine sheet. In contrast of electronic properties, We found that, all the studied MXene are metallic with large conductivity except Ti2CO2, It is ex- pected to be semiconducting. Similarly for magnetic properties, without termination it show magnetic nature but with termination magnetism is completely destroyed. Now, currently we are studying vacancy defect in Ti2N and Ti2C separately.