Theses Supervised

PhD Students

Sourav Kundu [2014-2020]
After PhD joined CERN, Geneva as a Fellow.
Angular and momentum distribution of vector mesons produced in proton-proton and heavy-ion collisions at LHC energies

List of Publications included in PhD thesis:

Evidence of spin-orbital angular momentum interactions in relativistic heavy-ion collisions, ALICE Collaboration (S. Acharya et al.), Phys. Rev. Lett. 125, 012301 (2020) [Editor’s suggestion].
. Multiplicity dependence of K∗(892)0 and φ(1020) production in pp collisions at 13 TeV, ALICE Collaboration (S. Acharya et al), Phys. Lett. B 78 807, 135501 (2020).
. Production of light flavour hadrons in pp collisions at √s = 7 and √s = 13TeV, ALICE Collaboration (S. Acharya et al.), arxiv:2005.11120 (accepted for publication in Eur. Phys. J. C).
. Study of charged particle multiplicity, average transverse momentum and azimuthal anisotropy in Xe+Xe collisions at √sNN = 5.44 TeV using AMPT model, Sourav Kundu, Dukhishyam Mallick and Bedangadas Mohanty, Eur. Phys. J. A 55, 157 (2019).

Full list of publication during PhD period

Vipul Bairathi [2013-2019]
After PhD joined IISER, Berhampur for a brief period as Postdoctoral fellow and then went to University of Tarapaca in Chile.
Azimuthal Anisotropy of strange and maulti strange hadrons in heavy-ion collisions at RHIC

List of Publications included in PhD thesis:

Bulk Properties of the System Formed in Au+Au Collisions at 14.5 GeV, Phys.Rev. C101 (2020) no.2, 024905.
. Centrality dependence of identified particle elliptic flow in relativistic heavy ion collisions at 7.7–62.4 GeV, Phys.Rev. C93 (2016) no.1, 014907.
. Probing Pb+Pb collisions at 2760 GeV with spectators, Phys.Lett. B754 (2016) 144-150.
. Selecting specific initial configurations using spectator neutrons in U + U collisions, Phys.Rev. C91 (2015) no.5, 054903.
. A Review on 𝜙 Meson Production in Heavy-Ion Collision, Adv.High Energy Phys. 2015 (2015) 197930.

Full list of publication during PhD period

Debadeepti Mishra [2013-2019]

Particle Production Studies in Au+Au and U+U Collisions using the STAR detector at RHIC and Understanding the freeze-out Dynamics

List of Publications included in PhD thesis:

Bulk Properties of the System Formed in Au+Au Collisions at 14.5 GeV, Phys.Rev. C101 (2020) no.2, 024905.
. Freeze-out conditions in proton-proton Collisions at the Highest Energies Available at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider, Phys.Rev. C95 (2017) 014912.
. Freezeout systematics due to the Hadron Spectrum, Phys. Rev. C 96 (2017) 054907.
. Freeze out Parameters in Heavy-ion Collisions at AGS, SPS, RHIC and LHC Energies, Advances in High Energy Physics, 349013 (2015).

Full list of publication during PhD period

Kishora Nayak [2012-2018]
After PhD joined Central China Normal University, China as a postdoctoral fellow.
K* production in high transverse momentum in Pb-Pb collisions and high multiplicity events in pp collisions at LHC [PhD Thesis]

List of Publications included in PhD thesis:

. K∗(892)0 and ϕ(1020) meson production at high transverse momentum in pp and Pb-Pb collisions at 2.76 TeV, Phys.Rev. C95 (2017) no.6, 064606.
. Multiplicity dependence of light-flavor hadron production in pp collisions at s√ = 7 TeV, Phys. Rev. C 99 (2019) 024906.

Full list of publication during PhD period

Md. Rihan Haque [2010-2015]
After PhD he joined Utrecht University, Netherlands as a postdoctoral fellow.
Nuclei production and azimuthal anisotropy of charged particles in heavy ion collisions at RHIC [PhD Thesis]

List of Publications included in PhD thesis:

Elliptic and Triangular flow in asymmetric heavy-ion collisions, Phys. Rev. C 84, 067901 (2011).
Multiplicity, average transverse momentum and azimuthal anisotropy in U+U collisions at √sNN = 200 GeV using AMPT model, Phys. Rev. C 85, 034905 (2012).
Fluctuating initial condition and smoothening effect on elliptic and triangular flow, Phys. Rev. C 86, 037901 (2012).
Even-by-event hydrodynamical simulations for √sNN = 200 GeV Au+Au collisions and the correlation between flow coefficients and initial asymmetry measures, Phys. Rev. C 87, 034907 (2013).
Elliptic flow of light nuclei and identified hadrons, their energy and centrality dependence in STAR, Nuclear Physics A, 931, 915, (2014).
Measurement of elliptic flow of light nuclei at sNN‾‾‾‾√sNN = 200, 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at RHIC, Physical Review C, 94, 034908, (2016).

Full list of publication during PhD period

Sabita Das [2010-2015]
After PhD she joined Central China Normal University, China as a postdoctoral fellow. Assistant Professor of Physics in K.K.S Womens College, Balasore, Odisha
Identified Particle Production and Freeze-out Dynamics Study in STAR at RHIC Beam Energy Scan Program [PhD Thesis]

List of Publications included in PhD thesis:

Bulk Properties of the Medium Produced in Relativistic Heavy-Ion Collisions from the Beam Energy Scan Program, Phys.Rev. C96 (2017) no.4, 044904.
Identfiied Particle Production and freeze-out properties in heavy-ion collisions in RHIC BES program, EPJ Web of Conf. 90 (2015) 08007.
Freeze out Parameters in Heavy-Ion Collisions at AGS, SPS, RHIC, and LHC Energies, Adv. in High Eng. Phys. (2015) 349013.
Cosmic ray test of Mini-drift Thick Gas Electron Multiplier for Transition Radiation Detector, Nucl. Instr. Meth. A 785 (2015) 33-39.
Chemical freeze-out parameters in Beam Energy Scan Program of STAR at RHIC, EPJ Web of Conf. 90 (2015) 10003.
Study of freeze-out dynamics in STAR at RHIC Beam Energy Scan Program, J. Phys. Conf. Ser. 509 (2014) 012066.
Centrality dependence of freeze-out parameters from the beam energy scan at STAR, Nucl. Phys. A 904 (2013) 891c.

Full list of publication during PhD period

Subhash Singha [2009-2014]
After PhD he joined Kent State University, USA (stationed at Brookhaven National Laboratory) as a postdoctoral fellow.
Identified particle production in p+p and Pb+Pb collisions at LHC energies [PhD Thesis]

List of Publications included in PhD thesis:

Studying re-scattering effect in heavy-ion collision through K* production, Int.J.Mod.Phys. E24 (2015) 05, 1550041
Inclusive photon production at forward rapidities in proton-proton collisions at s_√=0.9, 2.76 and 7 TeV, Eur.Phys.J. C75 (2015) 4, 146
K*(892)0 and φ(1020) production in Pb-Pb collisions at √s_NN=2.76 TeV , Phys.Rev. C91 (2015) 2, 024609
Production of K*(892)0 and ϕ(1020) in pp collisions at s_√=7 TeV, Eur.Phys.J. C72 (2012) 2183
Energy dependence of −¯p/p ratio in p+p collisions, Phys.Rev. C82 (2010) 044902

Full list of publication during PhD period

Md. Nasim [2009-2014]
After PhD he joined University of California, Los Angles as a postdoctoral fellow.
Currently Faculty at IISER, Berhampur.Azimuthal Anisotropy Measurements For Identied Particles Produced In Au+Au Collisions At √s_NN = 7.7-200 GeV [PhD Thesis]

List of Publications included in PhD thesis:

Observation of an energy-dependent dierence in elliptic flow between particles and anti-particles in relativistic heavy ion collisions. Physical Review Letters 110 (2013) 142301
Elliptic flow of identified hadrons in Au+Au collisions at √s_NN = 7.7- 62.4 GeV. Physical Review C 88 (2013) 014902
Elliptic flow of phi-meson a sensitive probe for onset of de-confinement transition in high energy heavy-ion collisions. Physical Review C 87 (2013) 01490
Inclusive charged hadron elliptic flow in Au + Au collisions at √s_NN =7.7-39 GeV. Physical Review C 86 (2012) 054908
Longitudinal scaling of observables in heavy-ion collision models. Physical Review C 83 (2011) 054902
Energy dependence of elliptic flow from heavy-ion collision models. Physical Review C 82 (2010) 054908

Full list of publication during PhD period

Ranbir Singh [2008-2014]
After PhD visited Catania University, Italy. Currently Scientist at NISER
Azimuthal Anisotropy Measurements in Pb+Pb Collisions at √sNN = 2.76 TeV and Possibility of Finding Jet-like Events in PMD

List of Publications included in PhD thesis:

Selected Experimental Results from Heavy Ion Collisions at LHC. Advances in High Energy Physics 2013 (2013) 761474
Energy dependence of inclusive photon elliptic flow in heavy-ion collision models. Journal of Physics G 39 (2012) 055002
Charged particle anisotropic flow (v2, v3, v4) in Pb-Pb collisions at midrapidity measured by ALICE. Proceedings of Science (CPOD 2013) 054
Identification of jet-like events in forward rapidities using Photon Multiplicity Detector at LHC energies. Proceedings of the DAE Symposium on Nucl. Phys. Vol. 56, 958 (2011)
Elliptic flow measurement of inclusive photons at forward rapidities in heavy-ion collision models. Proceedings of the DAE Symposium on Nucl. Phys. Vol. 56, 1008 (2011)

Full list of publication during PhD period

Chitrasen Jena [2006-2012]
After PhD he joined University of Padua, Italy as a postdoctoral fellow. Currently Faculty at IISER Tirupati
Particle production and elliptic flow of light nuclei in relativistic heavy ion collisions at RHIC [PhD Thesis]

List of Publications included in PhD thesis:

Observation of the antimatter helium-4 nucleus. Nature 473 (2011) 353
Elliptic flow of light nuclei in Au+Au collisions at √sNN = 200 GeV. Nuclear Physics A 862 (2011) 281
Longitudinal scaling of observables in heavy ion collision models. Physical Review C 83 (2011) 054902

Fulllist of publication during PhD period

PhD students whose substantial thesis related work was carried out with me (Not Official Thesis supervisor)

Pawan Kumar Netrakanti [2003-2006]
After PhD he joined Purdue University, USA as a postdoctoral fellow. Currently Scientist at Nuclear Physics Division,Bhabha Atomic Research Centre, Mumbai
Photon production in nucleus-nucleus collisions at forward rapidities at RHIC energies [PhD Thesis]

List of Publications included in PhD thesis which was carried out with me:

Sadhana Dash [2004-2009]
After PhD he joined Tornio University as a INFN postdoctoral fellow. Currently Faculty at Department of Physics, Indian Institute of Technology Bombay, Mumbai
Study of K* Resonance Production in Relativistic Heavy Ion Collisions at RHIC [PhD Thesis]

List of Publications included in PhD thesis which was carried out with me:

K*0 production in Cu+Cu and Au+Au collisions at \sqrt{s_NN} = 62.4 GeV and 200 GeV, Phys.Rev. C84 (2011) 034909

Lokesh Kumar [2004-2009]
After PhD he joined Kent State University, USA (Stationed at BNL) as a postdoctoral fellow. Then joined NISER as Scientific Officer E. Currently Faculty at Department of Physics, Panjab University, Chandigrah
Identified particle production, fluctuations and correlations studies in heavy ion collision at RHIC [PhD Thesis]

List of Publications included in PhD thesis which was carried out with me:

Masters Students Thesis

Roli Esha [2012-2013]
Following her MSc, she joined as a graduate student in University of California, Los Angeles
Glauber modelling of high energy heavy ion collision and a model based study of azimuthal anisotropy of produced particles.

We are using the Glauber Model to understand the initial conditions in heavy-ion collisions and the consequences on the particle production in these collisions. We have carried out as a part of the Masters thesis, both Optical and Monte Carlo Glauber model simulations to estimate initial magnetic eld and angular momentum in heavy-ion collisions. In addition we have obtained initial geometrical features of the collisions as a function of impact parameter such as the number of participating nucleons, number of binary collisions, and eccentricity. Using the number of participating nucleons and binary collisions we are able to describe the charged particle multiplicity distributions in the high{energy heavy{ion collisions. The initial spatial eccentricity is found to be closely related to the experimentally measured momentum anisotropy. We also make a brief note on the eect of event-by-event fluctuations in the number of participating nucleons for a given impact parameter of the collision on multiplicity fluctuations measured in the experiments. Azimuthal anisotropy, or flow of produced particles is sensitive to equation of state and also gives information about the transport coecients. We exploit the centrality dependence of elliptic flow, v2, to extract the Knudsen number and hence obtain the ratio of shear viscosity to entropy density.

Recently, at RHIC, Beam Energy Scan (BES) program has been undertaken to study the phase diagram of strong interaction. At higher beam energy, the transition from Quark-Gluon phase to Hadron gas phase is a cross-over and at large baryonic chemical potential, it is expected to show first order phase transition, which, in principle, should then be associated with cluster formation. In this work, we use one such cluster based model available to understand the v2 pt data from RHIC BES.

Evan John Philip [2013-2014]
Following his MSc, he joined as a graduate student in State University of Stony Brook, New York
Hydrodynamics and momentum distribution of produced hadrons in high energy heavy-ion collisions.

The transverse momentum distribution of hadrons produced in heavy ion collisions over a wide range of centre-of-mass energy (9 GeV to 2760 GeV) has been compared to the random walk model, which is based on the assumption that a nucleus-nucleus (A-A) collision is the superposition of isotropically decaying thermal sources at a given freeze out temperature. The freeze out temperature in A-A collisions is fixed from the inverse slope of the transverse momentum spectra of hadrons in nucleon-nucleon (p-p) collision. Successive collisions, like in case of nucleon-nucleus (p-A) collision, leads to gain in transverse momentum, as the nucleons are assumed to propagate in the nucleus following a random walk pattern. The average transverse rapidity shift per collision is determined from the p-A collision data. Using this information, we obtain a parameter free result for the transverse momentum distribution of produced hadrons in A-A collision.

It is observed that the random walk model is able to explain the transverse momentum spectra of produced particles, especially the lighter pions, at lower energies. However, it fails to explain the transverse momentum distribution of hadrons at higher energies. This indicates the presence of additional physical effects, like a collective phenomena, which cannot be accounted for by the initial state collision broadening of transverse momentum of produced hadrons, which is the basis of random walk model. In support of this later phenomena we, present a model inspired by hydrodynamic modelling of A-A collisions. This model, called blast wave model, satisfactorily explains the transverse momentum distribution of produced hadrons in A-A collisions across all the beam energies studied.

The blast wave model is a phenomenological hydrodynamics-inspired model. The application of hydrodynamics to matter created in high energy heavy-ion collisions is then studied. The time in the evolution history of heavy-ion collisions where hydrodynamics is applicable is alluded to, followed by a brief discussion on relativistic formulation of hydrodynamics. Then hydrodynamics equations are set up in 1+1 dimensions and their solutions using Bjorken initial conditions is presented. An essential input to solving these calculations is the equation of state of the matter under consideration. A discussion follows on a range of possible equations of state, starting with a simple ideal gas equation of state, proceeding to MIT Bag Model approach and QCD based calculation using lattice gauge theory. The effect of different choices of equation of state on the time evolution of the energy density of the system is presented. The derivation of the hydrodynamic equations in a more realistic 2+1 dimensions in then discussed. Solutions to these equations can provide both momentum and azimuthal angle distribution of produced hadrons in the heavy-ion collisions. Finally, the 1+1 dimensional hydrodynamic calculations are used to convert the fluid matter to particles (Cooper-Frye algorithm) and the momentum distributions of pions and protons produced in heavy-ion collisions is looked at. The slope of pion momentum distribution is seen to be larger compared to that of protons, proving that the mass dependence of the slope of transverse momentum distribution of particles produced in heavy-ion collisions is a consequence of hydrodynamics-like behaviour of the medium formed in the collisions.

Arabinda Behera [2014-2015]
Following his MSc, he joined as a graduate student in State University of Stony Brook, New York
K*0 Resonance Production and Elliptic Flow at STAR

This thesis presents the study of K*0 resonance production and elliptic flow with the aim of probing the characteristics of the medium created in ultra-relativistic nucleus-nucleus collisions. K*0 has average lifetime ~4 fm/c which is comparable to the hadronic cascade time of the fireball (~10 fm/c). So, K*0 can decay within the hadronic phase and the daughter particles can interact with the medium particles which will shape the final K*0 yield. These interactions are called in-medium effects and categorised as Re-scattering and Regeneration. First the production of resonances in heavy ion collisions and their properties like mass, width and lifetime obtained from the invariant mass distribution of the daughter particles is studied. The shape of the invariant mass distribution following a Breit-Wigner function is derived using Quantum Scattering and Phase shift. After getting a detailed idea about resonances and their properties, a simulation of collision of heavy nuclei (Au-Au) at √sNN = 200GeV is done using AMPT model. The simulated data is analysed to obtain the invariant mass distribution which gives the yield, mass and width of K*0 produced in the simulation. The reconstructed K*0 yield is observed to decrease with the increase in hadronic cascade time. To explain this behaviour a theoretical model was developed which demonstrated the effect of in-medium effects like Re-scattering and Regeneration on the K*0 yield.

The second part involves experimental data analysis of U-U collision data of STAR at center of mass energy of 193 GeV (√sNN = 193GeV) for 9.98 million events for K*0 study. Various experimental variables like transverse momentum, pseudorapidity, vertex position etc. and their distributions are obtained from the data. The invariant mass distribution of K*0 is obtained which gives the actual yield, mass and width of K*0 produced in the experiment. Finally the Elliptic flow (v2)of K*0 is studied, which is a very important property of the resonance and gives the experiiii mental measurement of the momentum anisotropies produced in the collective flow of the particle. The event planes are constructed and corrected and used to obtain the v2 of K*0 . The plot of v2 as a function of pT for minimum-bias is obtained. The non-zero value of v2 confirms the presence of anisotropy in collective flow of K*0 . The elliptic flow of K*0 is then compared with that of F which is also a meson resonance like K*0 with mass close to K*0 . The plot shows that v2 of both the particles are quite similar as expected which confirms the efficiency of the analysis. To show the centrality dependance, v2 vs pT is plotted for different centralities. Comparison of the plots shows that v2 increases with increase in centrality. This confirms the presence of different degree of anisotropies for different centralities.

Himangshu Neog [2015-2016]
Following his MSc, he joined as a graduate student inTexas A&M University,College Station, TX
φ(1020) and K∗0(892) production in proton-proton collisions at √s = 7 TeV

This thesis presented the differential yield (d2N/dydpT), mean pT and pT-integrated (dN/dy) yield of φ(1020) and K∗0 (892) at midrapidity(| y |< 0.5) in pp collisions at √s = 7 TeV is presented in this work. The measured pT spectra for both the resonances are com- pared with QCD-based event generator, PYTHIA 6.4. Invariant mass and width values for each transverse momentum bin from the two data sets (experimental mea- surement and event generator) are compared in each case.

Sumanya Sekhar Sahoo [2015-2016]
Following his MSc, trying to pursue a career in bio-physics
Study of gaseous detectors for high energy physics experiments

Gas filled detectors are one of the oldest and most widely used radiation detectors and are based on the effects produced when a charged particle passes through a gas. Many ionization mechanisms arise in gases and over the years these have been studied and exploited in the detectors. In this particular work, we have studied a few aspects of these different phenomena. We have described the principles of operation of the gas ionization chamber focusing on the most relevant mechanisms involved in the detection process. This knowledge is necessary to understand, simulate and optimize the performance of the proposed or any existing detection system. The simulation procedure is nowadays widely utilized in designing such detectors. Starting with the basic principle of operation of gas detectors, we first discuss the different regions of operation of gas detectors. Following which, the production of primary and secondary electrons, transport of charged particle in gases, the electron multiplication process, development of the induced signal, the required characteristics of the gas mixture have been described. Then we illustrate the basic features of some gas detectors. We also give a brief idea about the simulation and present some calculation utilizing various computer programmes.

Amit Nanda [2016-2017]
Following his MSc, he is joined Accelerators Validating Antimatter physics project, Stefan Mayer Institute for Sub Atomic Physics, Vienna, Austria.
Measurement of φ(1020) meson production in pp collisions at √s = 13 TeV

The production of φ meson in pp collisions at √s = 13 TeV was measured by the ALICE experi- ment at the LHC in the year 2015. The integrated yield dN/dy and the transverse momentum spectra in the mid-rapidity region, |y| <0.5 and 0.4< pT <10 GeV/c are calculated and have been compared to PYTHIA8 model predictions. Further, the multiplicity dependence of dN/dy and the transverse momentum spectra has been measured. The different multiplicity classes were chosen using V0M as the multiplicity estimator. The dN/dy and ⟨pT ⟩ values as a function of dNch/dη have been calculated. Finally, the ratio φ/K for different systems have been presented.

Rohith Saradhy [2016-2017]
Following his MSc, he joined University of Minnesota, USA as a graduate student.
Study of Particle Interaction in Matter, Gas based Detector Development and Simulation

We have studied the interaction of radiation with matter as well as the simulation and development of gaseous detectors: Resistive Plate Chamber(RPC) and Propor- tional Counter. In the first part we deal with the study of charged particle interaction mainly using the Bethe-Bloch equation. After which, we developed and characterised a 15×15 cm2 bakelite RPC. Leakage current, efficiency, and noise rate have been studied. This was followed by the simulation of the same geometry using Geant4 for different charged particles. The effect of gas composition as well as the gap length were studied for protons of different energies. We extended the study of interaction of radiation by including the interactions of neutral particles like photons and neutrons. We designed, simulated and developed a double windowed proportional counter for the study of 17.5 keV X-rays for ongoing research purposes. The counter was tested in the X-ray diffractometer facility in the Institute of Physics, Bhubaneswar.

Somadutta Bhatta [2017-2018]
Following his MSc, joined University of Stony Brook, USA as a graduate student.
Probing Particle Production in Au+Au collisions at 200 GeV using spectators

Events in heavy ion collisions are categorized into centralities, usually based on charged particle multiplicity. But, there are event-by-event fluctuations in the initial event conditions for a given centrality. The access to these variations are limited and it is very difficult to select particular events with definite initial configuration. The categorization of events into centralities allows us to obtain centrality averaged values only. A study done recently demonstrated that by performing a further binning over spectator neutrons count in addition to the standard centrality binning based on charged particle multiplicity, it is possible to probe the fireball with different initial state conditions. This study was done for Pb+Pb collision at √sNN= 2.76 TeV using a multiphase transport model (AMPT). This thesis explores a similar approach in probing initial state using the actual experimental data from Au+Au collision at √sNN= 200 GeV through the spectator neutron number (measured by the Zero Degree Calorimeter (ZDC)) in the STAR detector. We find that in the data collected from STAR detector for Au+Au collisions at 200 GeV, this novel method of binning gives us a better handle at selecting events with specific initial conditions. The initial states that can be accessed by this new procedure cannot be accessed even by finer centrality definition (by multiplicity). This new procedure of choosing initial conditions strongly breaks some previously postulated scaling relations between v2/ε2 vs (1/S)*dNch/deta and acoustic scaling relation for centrality (by multiplicity) averaged values. The proposed study in this thesis allows for access to new initial conditions in heavy-ion collisions that can be studied in detail in future.

Ganesh Parida [2018-2019]

Following his MSc, set to University of Wisconsin-Madison, USA. HBT correlations with π+ and Λ0 baryons in heavy-ion collisions and Spin Alignment of Vector Meson (K∗0) in p-Pb collisions

This thesis is organised into two parts. In the first half, we study the Hanbury- Brown-Twiss (HBT) interference of pions using Therminator and Pythia event gen- erators for Au-Au collisions at √sNN = 200 GeV and pp collisions at √s = 900 GeV, respectively. We investigate the dependence of HBT radii and chaoticity on pair transverse momenta (kT ) for Au-Au and pp systems. The results from the model are compared with the corresponding experimental data. Further, we use the existing framework of Therminator to investigate HBT correlation for fermions by using Λ0 baryon pairs in Au-Au collisions at √sN N = 200 GeV. In the second part we look into the spin alignment of vector meson (K∗0) in minimum bias p-Pb collisions at √sN N =5.02 TeV with data recorded by ALICE at LHC. Our aim is to see if the spin density matrix element ρ00 for K∗0 deviates from its ”no alignment” value of 1. 3 Value of ρ00 for different pT bin is obtained by measuring the angular distribution of the decay daughters of K∗0 with respect to the normal of the production plane.

Viraj Thakkar [2018-2019]

Following his MSc, set to join New York University Center for Data Science, USA for pursuing MS in Data Science. Machine Learning Applications in High Energy Physics and Dark Matter Search

The purpose of this work is to use Machine Learning to improve the results in Experimental High Energy Physics (ALICE-LHC) and Dark Matter Search (Super- CDMS) experiments. The first part describes the analysis where we have used super- vised Machine Learning algorithm called Boosted Decision Trees (BDT) to improve the significance of resonance particle K∗0. The second part describes the analysis on SuperCDMS data where we have done Fiducial Volume optimization and classified Electron Recoils and Nuclear Recoils events by using BDT algorithm for classification.

Diptanil Roy [2018-2019]
Following his MSc, joined Rutgers University, New Jersey, USA. Feasibility study of fluctuations of net-proton, net-charge, and net-kaon multiplicity distributions in the CBM experiment

Fluctuations of conserved quantities are sensitive observables to probe the sig- nature of QCD phase transition and critical point in heavy-ion collisions. With the UrQMD model, we have studied the centrality and energy dependence of various order cumulants (up to fourth order) of net-proton, net-charge and net-kaon multi- plicity distributions in Au+Au collisions at lab energies of 4, 6, 8, and 10 AGeV. We further calculated the cumulants after UrQMD events were passed through the CBM detector setup and probed different methods to get back the real cumulants from the data from the detctors. Furthermore, we studied the second order mixed cumulants of the above net-particle distributions as they are also related to quantities which are sensitive to the QCD phase transition. To correct for detector inefficiencies, we used two different methods : binomial acceptance and unfolding, and showed that cumulants of unfolded distributions have better agreement with the real cumulants from UrQMD. Finally, to correct for the mixed cumulants, we introduced unfolding for two-dimensional distributions and successfully corrected for detector inefficiencies.

Tanmay Pani [2019-2020]
Following his MSc, joine Rutgers University, New Jersey, USA. Study of Au-3He collisions @ 200 GeV

The thesis included two set of studies of Au-He 200 GeV collisions. The first one is the work on STAR data, taken in 2014, where we have done centrality determination and found transverse momentum spectra for pions. In the second part, we have compared AMPT simulations, with and without modified 3He distribution. We see that the Pearson correlator and eccentricities are lower when we use modified 3He nuclear profile. We have also discussed our future plans for both parts.

Soumik Chandra [2019-2020]
Following his MSc, joined one of the Purdue University in USA. Construction and Simulation of Glass Resistive Plate Chamber for μ detection

A Resistive Plate Chamber (RPC) is a gaseous particle detector that consists of two resistive plates with a sensitive gas gap in between. The plates are maintained at high potential difference, hence they act as high resistivity electrodes. Radiations are detected by charges induced in external conducting readout strips. The RPC provides an effective way to obtain high time resolution and temporal resolution of the particles that passing through the detectors. These detectors can be constructed in required dimensions at relatively lower cost and are currently used as triggers for muon detectors in the CMS experiments. The RPC constructed in this project is designated to be used at the CBM experiments at FAIR. Low resistance glass plate used here has lower bulk resistivity (1010 Ω cm) in order to reach high rate capacity. The series of experiments carried out are aimed to study the properties of the detector made of low resistivity glass with different surface resistivity and different composition of the gas mixture. We look at properties like efficiency, optimal operation voltage, multiplicity, rate capacity and noise rate. A detection of muons using RPC detector has been simulated using Garfield++.

Aman Dimri [2020-2021]

Aranya Giri [2020-2021]

Integrated MSc-PhD Students who did Master's thesis project

Rik Bhattacharyya [2017-2019]
Following his MSc, he is going to join as a graduate student in Texas A&M University,College Station, TX to work in SuperCDMS experiment. Study of 32Si background for CDMS II and neutron detector for dark matter search experiments

The first part of this thesis is focussed on 32Si background analysis in Cryogenic Dark Matter Search (CDMS) experiment. 32Si is an important background in low-mass dark matter search experiments that use Si detectors. To estimate this background, both simulation of low-energy beta decay spectrum and charge energy spectrum from CDMS II data is required. In direct dark matter search experiments, neutron is an important background as it can mimic WIMPs signals. To understand the neutron background, neutron detector is studied at NISER as second part of the thesis.

Some Selected Semester (6th) Projects

Diptanil Roy [2017]
Current pursuing MSc at NISER. Sixth semester project was on:
Study of spin polarisation in simulated high energy pp and heavy ion collisions. Presentation in the School

Maneesha ushama Pradeep [2013]
Following her MSc, she joined as a graduate student in University of Illinois at Chicago. Sixth semester project was on:
Shear viscosity of a hadron gas. Presentation in the School

Srijit Paul [2013]
Following his MSc, he joined as a graduate student with Prof. Constantia Alexandrou at The Cyprus Institute and Prof. Dirk Pleiter at the University of Regensburg ( also at the Forchungszentrum Juelich). Sixth semester project was on:
Solving 1+1 Dimension Hydrodynamics Equations and Studying its applications

BedangadasMohanty

Theses Supervised

PhD Students

PhD students whose substantial thesis related work was carried out with me (Not Official Thesis supervisor)

Masters Students Thesis

Integrated MSc-PhD Students who did Master's thesis project

Some Selected Semester (6th) Projects

Bedangadas
Mohanty