Tapan Nayak

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Verified

Tapan verified their affiliation via an institutional email.

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• Ph.D.(Michigan State University)
• Professor at European Organization for Nuclear Research

Nuclear and particle physics experiments at high energies, often referred to as High Energy Physics (HEP) experiments, study the constituents of matter and their fundamental interactions. By colliding proton on proton or heavy-ions, such as Au on Au or Pb on Pb at relativistic energies, one creates conditions that were prevalent within a microsecon...

ALICE is a high-energy physics experiment at the CERN Large Hadron Collider (LHC) in Geneva, to study the properties of quark-gluon plasma, formed in heavy-ion collisions. In the upgrade program, a new electromagnetic forward calorimeter (FOCAL) based on silicon and tungsten (Si+W) sampling configuration, has been proposed to address new physics ob...

A wide dynamic range (ratio of maximum detectable signal to noise floor) front end electronics (FEE) readout ASIC ANUINDRA has been developed in 0.35μm standard N-well CMOS technology for the prototype forward calorimeter (FOCAL), a silicon-tungsten (Si-W) electromagnetic (EM) calorimeter, proposed as part of the ALICE upgrade at CERN. It is a 16 c...

A wide swing charge sensitive amplifier (CSA) has been developed, as a part of a front-end electronics (FEE) readout ASIC, for a prototype silicon tungsten (Si-W) based electromagnetic (EM) calorimeter. The CSA, designed in 0.35μm N-well CMOS technology using 5V MOS transistors, has a wide linear operating range of 2.6 pC w.r.t the input charge wit...

A wide swing charge sensitive amplifier (CSA) has been developed, as a part of a front-end electronics (FEE) readout ASIC, for a prototype silicon tungsten (Si-W) based electromagnetic (EM) calorimeter. The CSA, designed in 0.35 $\mu$m N-well CMOS technology using 5V MOS transistors, has a wide linear operating range of 2.6 pC w.r.t the input charg...

We present the research and development work of the first version of a 6*6 array of silicon pad detectors, carried out in India, for the proposed forward calorimeter (FOCAL) as part of the ALICE collaboration upgrade program at CERN. The primary motivation is to develop a large area silicon pad array realizing the challenging requirements of high-e...

We present the research and development work of the first version of a 6×6 array of silicon pad detectors, carried out in India, for the proposed forward calorimeter (FOCAL) as part of the ALICE collaboration upgrade program at CERN. The primary motivation is to develop a large area silicon pad array realizing the challenging requirements of high-e...

The thermodynamic properties of matter created in high-energy heavy-ion collisions have been studied in the framework of the non-extensive Tsallis statistics. The transverse momentum (pT) spectra of identified charged particles (pions, kaons, protons) and all charged particles from the available experimental data of Au-Au collisions at the Relativi...

A silicon–tungsten prototype calorimeter, for the proposed ALICE LS3-upgarde, was fabricated and tested at the CERN-SPS beamline facility in the year 2017. The calorimeter was designed with the help of GEANT4 simulation to perform in a high multiplicity density environment with optimised energy and position resolutions for incident energy up to 200...

Experiments in high energy physics (HEP) operate at the forefront of detector technology, electronics, data acquisition (DAQ), data analysis, and computing. With the advent of high-energy accelerators running at large beam intensities, there is a great demand for radiation-hard high speed protocol for data transmission. Along with the detector data...

Multiplicity and pseudorapidity (η) density (dN ch/dη) distributions of charged hadrons provide key information towards understanding the particle production mechanisms and initial conditions of high-energy heavy-ion collisions. However, detector constraints limit the η-range across which charged particle measurements can be carried out. Extrapolat...

Multiplicity and pseudorapidity ($\eta$) density ($dN_{\rm ch}/d\eta$) distributions of charged hadrons provide key information towards understanding the particle production mechanisms and initial conditions of high-energy heavy-ion collisions. However, detector constraints limit the $\eta$-range across which the charged particle measurements can b...

The thermodynamical properties of matter created in high-energy heavy-ion collisions have been studied in the framework of the non-extensive Tsallis statistics by fitting the transverse momentum spectra (pT) of produced particles. The pT distributions of charged particles and identified pions from the available experimental data of Au-Au collisions...

A silicon-tungsten (Si-W) sampling calorimeter, consisting of 19 alternate layers of silicon pad detectors (individual pad area of 1~cm$^2$) and tungsten absorbers (each of one radiation length), has been constructed for measurement of electromagnetic showers over a large energy range. The signal from each of the silicon pads is readout using an AS...

The ALICE experiment at CERN is preparing for a major upgrade for the third phase of data taking run (Run 3), when the high luminosity phase of the Large Hadron Collider (LHC) starts. The increase in the beam luminosity will result in high interaction rate causing the data acquisition rate to exceed 3 TB/sec. In order to acquire data for all the ev...

The scheme of the data acquisition (DAQ) architecture in High Energy Physics (HEP) experiments consist of data transport from the front-end electronics (FEE) of the online detectors to the readout units (RU), which perform online processing of the data, and then to the data storage for offline analysis. With major upgrades of the Large Hadron Colli...

The scheme of the data acquisition (DAQ) architecture in High Energy Physics (HEP) experiments consist of data transport from the front-end electronics (FEE) of the online detectors to the readout units (RU), which perform online processing of the data, and then to the data storage for offline analysis. With major upgrades of the Large Hadron Colli...

A quadruple GEM detector has been assembled in a standalone configuration and operated using Ar and CO$_2$ gas mixtures in proportions of 70:30 and 90:10. Detailed performance study of the detector has been made by using $^{106}$Ru-Rh $\beta$-source and X-ray spectrum of $^{55}$Fe source. Results of these measurements are presented in terms of gain...

A quadruple GEM detector has been assembled in a standalone configuration and operated using Ar and CO2 gas mixtures in proportions of 70:30 and 90:10. Detailed performance study of the detector has been made by using ¹⁰⁶Ru-Rh β-source and X-ray spectrum of ⁵⁵Fe source. Results of these measurements are presented in terms of gain, efficiency, energ...

The ALICE experiment at CERN is preparing for a major upgrade for the third phase of data taking run (Run 3), when the high luminosity phase of the Large Hadron Collider (LHC) starts. The increase in the beam luminosity will result in high interaction rate causing the data acquisition rate to exceed 3 TB/sec. In order to acquire data for all the ev...

An improved measurement of the HΛ3 lifetime is presented. In this paper, the mesonic decay modes HΛ3→He3 + π− and HΛ3→d+p+π− are used to reconstruct the HΛ3 from Au+Au collision data collected by the STAR collaboration at Relativistic Heavy Ion Collider (RHIC). A minimum χ2 estimation is used to determine the lifetime of τ=142−21+24(stat.)±29(syst....

A large Time Projection Chamber is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019/20, the LHC will deliver Pb beams colliding at an interaction rate of about 50 kHz, which is about a factor of 50 above the present readout rate of the TPC. This will res...

The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high-transverse momentum trigger hadron in p–Pb collisions at sNN=5.02 TeV. Jets are reconstructed from charged-particle tracks using the anti-kT algorithm with resolution parameter R=0.2 and 0.4. A data-driven statistical appro...

Flow harmonics (vn) in the Fourier expansion of the azimuthal distribution of particles are widely used to quantify the anisotropy in particle emission in high-energy heavy-ion collisions. The symmetric cumulants, SC(m,n), are used to measure the correlations between different orders of flow harmonics. These correlations are used to constrain the i...

The azimuthal anisotropy coefficient v2 of prompt D0, D+, D*+, and Ds+ mesons was measured in midcentral (30%–50% centrality class) Pb-Pb collisions at a center-of-mass energy per nucleon pair sNN=5.02 TeV, with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays at midrapidity, |y|<0.8, in the transverse moment...

We present a measurement of azimuthal correlations between inclusive J/ψ and charged hadrons in p–Pb collisions recorded with the ALICE detector at the CERN LHC. The J/ψ are reconstructed at forward (p-going, 2.03<y<3.53) and backward (Pb-going, −4.46<y<−2.96) rapidity via their μ⁺μ⁻ decay channel, while the charged hadrons are reconstructed at mid...

The production of Z⁰ bosons at large rapidities in Pb–Pb collisions at sNN=5.02TeV is reported. Z⁰ candidates are reconstructed in the dimuon decay channel (Z⁰→μ⁺μ⁻), based on muons selected with pseudo-rapidity −4.0<η<−2.5 and pT>20GeV/c. The invariant yield and the nuclear modification factor, RAA, are presented as a function of rapidity and coll...

The transversity distribution, which describes transversely polarized quarks in transversely polarized nucleons, is a fundamental component of the spin structure of the nucleon, and is only loosely constrained by global fits to existing semi-inclusive deep inelastic scattering (SIDIS) data. In transversely polarized p↑+p collisions it can be access...

First results on the longitudinal asymmetry and its effect on the pseudorapidity distributions in Pb–Pb collisions at sNN = 2.76 TeV at the Large Hadron Collider are obtained with the ALICE detector. The longitudinal asymmetry arises because of an unequal number of participating nucleons from the two colliding nuclei, and is estimated for each even...

The production of the charm-strange baryon Ξc⁰ is measured for the first time at the LHC via its semileptonic decay into eΞ−+νe in pp collisions at s=7 TeV with the ALICE detector. The transverse momentum (pT) differential cross section multiplied by the branching ratio is presented in the interval 1<pT<8 GeV/c at mid-rapidity, |y|<0.5. The transve...

An invariant differential cross section measurement of inclusive π0 and η meson production at mid-rapidity in pp collisions at s=8 TeV was carried out by the ALICE experiment at the LHC. The spectra of π0 and η mesons were measured in transverse momentum ranges of 0.3<pT<35 GeV/c and 0.5<pT<35 GeV/c, respectively. Next-to-leading order perturbative...

Invariant differential yields of deuterons and antideuterons in pp collisions at s = 0.9, 2.76 and 7 TeV and the yields of tritons, He3 nuclei, and their antinuclei at s = 7 TeV have been measured with the ALICE detector at the CERN Large Hadron Collider. The measurements cover a wide transverse momentum (pT) range in the rapidity interval |y|<0.5,...

The correlations between event-by-event fluctuations of anisotropic flow harmonic amplitudes have been measured in Pb-Pb collisions at sNN=2.76 TeV with the ALICE detector at the Large Hadron Collider. The results are reported in terms of multiparticle correlation observables dubbed symmetric cumulants. These observables are robust against biases o...

Rapidity-odd directed-flow measurements at midrapidity are presented for Λ, Λ¯, K±, Ks0, and ϕ at sNN=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV in Au+Au collisions recorded by the Solenoidal Tracker detector at the Relativistic Heavy Ion Collider. These measurements greatly expand the scope of data available to constrain models with differin...

We report the first measurements of transverse single-spin asymmetries for inclusive jet and jet+π± production at midrapidity from transversely polarized proton-proton collisions at s=500 GeV. The data were collected in 2011 with the STAR detector sampled from 23 pb−1 integrated luminosity with an average beam polarization of 53%. Asymmetries are r...

The first estimation of the isothermal compressibility (kT) of matter is presented for a wide range of collision energies from √sNN = 7.7 GeV to 2.76 TeV. kT is estimated with the help of event-byevent charged particle multiplicity fluctuations from experiment. Dynamical fluctuations are extracted by removing the statistical fluctuations obtained f...

We present the results of three-dimensional femtoscopic analyses for charged and neutral kaons recorded by ALICE in Pb-Pb collisions at sNN=2.76 TeV. Femtoscopy is used to measure the space-time characteristics of particle production from the effects of quantum statistics and final-state interactions in two-particle correlations. Kaon femtoscopy is...

We report a precise measurement of the J/ψ elliptic flow in Pb-Pb collisions at sNN=5.02 TeV with the ALICE detector at the LHC. The J/ψ mesons are reconstructed at midrapidity (|y|<0.9) in the dielectron decay channel and at forward rapidity (2.5<y<4.0) in the dimuon channel, both down to zero transverse momentum. At forward rapidity, the elliptic...

The azimuthal anisotropic flow of identified and unidentified charged particles has been systematically studied in Cu+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV for harmonics $n=$ 1-4 in the pseudorapidity range $|\eta|<1$. The directed flow in Cu+Au collisions is compared with the rapidity-odd and, for the first time, the rapidity-even componen...

We present the charged-particle multiplicity distributions over a wide pseudorapidity range (\(-\,3.4<\eta <5.0\)) for pp collisions at \(\sqrt{s}= 0.9, 7\), and 8 TeV at the LHC. Results are based on information from the Silicon Pixel Detector and the Forward Multiplicity Detector of ALICE, extending the pseudorapidity coverage of the earlier publ...

In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-depend...

Results on the production of ⁴He and He‾4 nuclei in Pb–Pb collisions at sNN=2.76TeV in the rapidity range |y|<1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0–10% central events are found to be dN/dyHe4=(0.8±0.4(stat)±0.3(syst))×10−6 and dN/dyHe‾4=(1.1±0.4(stat)±0.2(syst))×10−6, respectively. This...

The STAR Collaboration reports on the photoproduction of π+π- pairs in gold-gold collisions at a center-of-mass energy of 200 GeV/nucleon-pair. These pion pairs are produced when a nearly real photon emitted by one ion scatters from the other ion. We fit the π+π- invariant-mass spectrum with a combination of ρ0 and ω resonances and a direct π+π- co...

We report measurements of the inclusive J/ψ yield and average transverse momentum as a function of charged-particle pseudorapidity density dNch/dη in p–Pb collisions at sNN=5.02TeV with ALICE at the LHC. The observables are normalised to their corresponding averages in non-single diffractive events. An increase of the normalised J/ψ yield with norm...

This letter presents the first measurement of jet mass in Pb–Pb and p–Pb collisions at sNN=2.76 TeV and sNN=5.02 TeV, respectively. Both the jet energy and the jet mass are expected to be sensitive to jet quenching in the hot Quantum Chromodynamics (QCD) matter created in nuclear collisions at collider energies. Jets are reconstructed from charged...

With ever increasing particle beam energies and interaction rates in modern High Energy Physics (HEP) experiments in the present and future accelerator facilities, there has always been the demand for robust Data Acquisition (DAQ) schemes which perform in the harsh radiation environment and handle high data volume. The scheme is required to be flex...

The transversity distribution, which describes transversely polarized quarks in transversely polarized nucleons, is a fundamental component of the spin structure of the nucleon, and is only loosely constrained by global fits to existing semi-inclusive deep inelastic scattering (SIDIS) data. In transversely polarized $p^\uparrow+p$ collisions it can...

Phase measurement is required in electronic applications where a synchronous relationship between the signals needs to be preserved. Traditional electronic systems used for time measurement are designed using a classical mixed-signal approach. With the advent of reconfigurable hardware such as field-programmable gate arrays (FPGAs), it is more adva...

We present measurements of bulk properties of the matter produced in Au+Au collisions at sNN=7.7,11.5,19.6,27, and 39 GeV using identified hadrons (π±, K±, p, and p¯) from the STAR experiment in the Beam Energy Scan (BES) Program at the Relativistic Heavy Ion Collider (RHIC). Midrapidity (|y|<0.1) results for multiplicity densities dN/dy, average t...

The transverse momentum (\(p_\mathrm{T} \)) spectra and elliptic flow coefficient (\(v_{2}\)) of deuterons and anti-deuterons at mid-rapidity (\(|y|<0.5\)) are measured with the ALICE detector at the LHC in Pb–Pb collisions at \(\sqrt{s_{\mathrm {NN}}}\) = 2.76 TeV. The measurement of the \(p_\mathrm{T} \) spectra of (anti-)deuterons is done up to...

In two-particle angular correlation measurements, jets give rise to a near-side peak, formed by particles associated to a higher-pT trigger particle. Measurements of these correlations as a function of pseudorapidity (Δη) and azimuthal (Δφ) differences are used to extract the centrality and pT dependence of the shape of the near-side peak in the pT...

The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a pT region inaccessible by direct jet identification. In these measurements pseudorapidity (Δη) and azimuthal (Δφ) differences are used to extract the shape of the near-side peak formed by particles associated with a higher pT trigger particle (1<pT,t...

We present the first ever measurements of femtoscopic correlations between the KS0 and K± particles. The analysis was performed on the data from Pb-Pb collisions at sNN=2.76 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding via the a0(980) resonance. The extracted kao...

We present the first estimation of isothermal compressibility (\kT) of matter formed in relativistic nuclear collisions (\sNN=7.7 GeV to 2.76 TeV) using experimental observables. \kT is connected to the equation of state (EOS) of matter and along with the speed of sound help to determine the softest point of the phase transition and location of the...

We present the first estimates of isothermal compressibility (\kT) of hadronic matter formed in relativistic nuclear collisions ($\sqrt{s_{\rm NN}} = 7.7$ GeV to 2.76~TeV) using experimentally observed quantities. \kT~is related to the fluctuation in particle multiplicity, temperature, and volume of the system formed in the collisions. Multiplicity...

We report the first measurements of transverse single-spin asymmetries for inclusive jet and jet + $\pi^{\pm}$ production at midrapidity from transversely polarized proton-proton collisions at $\sqrt{s} = 500$ GeV. The data were collected in 2011 with the STAR detector sampled from 23 pb$^{-1}$ integrated luminosity with an average beam polarizatio...

Rapidity-odd directed flow measurements at midrapidity are presented for $\Lambda$, $\bar{\Lambda}$, $K^\pm$, $K^0_s$ and $\phi$ at $\sqrt{s_{NN}} =$ 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4 and 200 GeV in Au+Au collisions recorded by the STAR detector at the Relativistic Heavy Ion Collider. These measurements greatly expand the scope of data available...

The STAR Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum hadron trigger, in central and peripheral Au+Au collisions at sNN=200 GeV. Charged jets are reconstructed with the anti-kT algorithm for jet radii R between 0.2 and 0.5 and with low infrared cutoff of tra...

We report the first dijet transverse momentum asymmetry measurements from Au+Au and pp collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2 GeV/c display a significantly higher momentum imbalance in heavy-ion collisions than in the pp reference. When reexamined with correlated sof...

The extreme energy densities generated by ultra-relativistic collisions between heavy atomic nuclei produce a state of matter that behaves surprisingly like a fluid, with exceptionally high temperature and low viscosity. Non-central collisions have angular momenta of the order of 1,000h, and the resulting fluid may have a strong vortical structure...

The second and the third order anisotropic flow, and , are mostly determined by the corresponding initial spatial anisotropy coefficients, and , in the initial density distribution. In addition to their dependence on the same order initial anisotropy coefficient, higher order anisotropic flow, ( ), can also have a significant contribution from lowe...

The production cross sections for prompt charmed mesons \(\mathrm{D^0}\), \(\mathrm{D^+}\), \(\mathrm{D^{*+}}\) and \(\mathrm{D_s^+}\) were measured at mid-rapidity in proton–proton collisions at a centre-of-mass energy \(\sqrt{s}=7~{\mathrm {TeV}}\) with the ALICE detector at the Large Hadron Collider (LHC). D mesons were reconstructed from their...

Two-particle angular correlations were measured in pp collisions at s=7 TeV for pions, kaons, protons, and lambdas, for all particle/anti-particle combinations in the pair. Data for mesons exhibit an expected peak dominated by effects associated with mini-jets and are well reproduced by general purpose Monte Carlo generators. However, for baryon–ba...

We report measurements of the nuclear modification factor, $R_{ \mathrm{CP}}$, for charged hadrons as well as identified $\pi^{+(-)}$, $K^{+(-)}$, and $p(\overline{p})$ for Au+Au collision energies of $\sqrt{s_{_{ \mathrm{NN}}}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV. We observe a clear high-$p_{\mathrm{T}}$ net suppression in central colli...