arXiv subjects

Debasish Das

Publications and source records attributed to Debasish Das.

45 records · Page 3Linked to original sources

arXiv2012

Quarkonia production at forward rapidities with the ALICE Experiment

Muons from the decay of charmonium resonances are detected in the ALICE Experiment at the Large Hadron Collider(LHC) for pp and Pb-Pb collisions with a muon spectrometer, covering the forward rapidity region 2.5$<$ $y$ $<$4.0. Analysis of the nuclear modification factor ($R_{\rm AA}$) at forward rapidity are presented and compared with mid-rapidity results from electrons in the central barrel covering $|y|<$0.9. The roles of suppression and regeneration mechanisms are discussed, as well as the importance of the results of the forthcoming p-Pb data taking for the estimate of cold nuclear matter effects on quarkonia. Perspectives for the bottomonia measurements are also given. Quarkonia results via muon channel from CMS experiment at LHC are compared with ALICE quarkonia measurements.

nucl-ex↗

arXiv2011

Quarkonia production at forward rapidity in Pb+Pb collisions at $\bf \sqrt{s_{\rm NN}}=2.76$ TeV with the ALICE detector

The study of formation of heavy quarkonia in relativistic heavy ion collisions provides important insight into the properties of the produced high density QCD medium. Lattice QCD studies show sequential suppression of quarkonia states with increasing temperature; which affirms that a full spectroscopy, can provide us a thermometer for the matter produced under extreme conditions in relativistic heavy ion collisions and one of the most direct probes of de-confinement. Muons from the decay of charmonium resonances are detected in ALICE Experiment in p+p and Pb+Pb collisions with a muon spectrometer, covering the forward rapidity region($2.5<y<4$). The analysis of the inclusive J/$ψ$ production in the first Pb+Pb data collected in the fall 2010 at a center of mass energy of $\sqrt{s_{\rm NN}}=2.76$ TeV is discussed. Preliminary results on the nuclear modification factor ($R_{AA}$) and the central to peripheral nuclear modification factor ($R_{CP}$) are presented.

nucl-ex↗

arXiv2011

Performance and First Physics Results of the ALICE Muon Spectrometer

A precise measurement of the heavy-flavor production cross-sections in pp collisions is an essential baseline for the heavy-ion program. In addition it is a crucial test of pQCD models in the new energy regime at LHC. ALICE measures the muons from the decay of charmonium resonances and from the semileptonic decay of heavy-flavored hadrons in its forward (-4.0 $<$ $η$ $<$ -2.5) Muon Spectrometer. We discuss the status of the detector and present results of data taken in pp collisions at $\sqrt{s}$=7 TeV.

nucl-ex↗

arXiv2009

Recent results from STAR experiment in Au+Au collisions at $\sqrt{s_{NN}}$ = 9.2 GeV

Theoretical models suggest that the Quantum Chromo-Dynamics (QCD) phase diagram has a critical point demarcating the order of transition between the two phases: the hadron gas, in which the quarks are confined and the Quark-Gluon Plasma (QGP). The central goal of the experiments with relativistic heavy-ion collisions is to create and study such form of matter called the QGP and understand the QCD phase diagram. The STAR (Solenoidal Tracker At RHIC) detector is pertinent for the RHIC (Relativistic Heavy Ion Collider) energy scan program where we plan to explore this exciting physics possibility using heavy-ion collisions at various center of mass energies. A first test run with Au+Au collisions at $\sqrt{s_{NN}}$ = 9.2 GeV took place in early 2008. We present the recent STAR results from this run of the identified particles (pion, kaon and proton) transverse momentum spectra and ratios. Also we shall present and discuss the results of the azimuthal anisotropy parameters ($v_{1}$, $v_{2}$) along with the pion interferometry measurements. These recent results from Au+Au collisions at $\sqrt{s_{NN}}$ = 9.2 GeV are compared with other SPS and RHIC measurements.

nucl-ex↗

arXiv2008

$Υ$ production in p+p and Au+Au collisions in STAR

The study of quarkonium production in relativistic heavy ion collisions provides insight into the properties of the produced medium. The lattice studies show a sequential suppression of quarkonia states when compared to normal nuclear matter; which further affirms that a full spectroscopy including bottomonium can provide us a better thermometer for the matter produced under extreme conditions in relativistic heavy ion collisions. With the completion of the STAR Electromagnetic Calorimeter and with the increased luminosity provided by RHIC in Run 6 and 7, the study of $Υ$ production via the di-electron channel becomes possible. We present the results on $Υ$ measurements in p+p collisions (from Run 6) along with the first results from Au+Au collisions (in Run 7) at $\sqrt{s_{\rm{NN}}} = 200$ GeV from the STAR experiment.

nucl-ex↗

arXiv2007

Full Spectrum Diffused and Beamed Solar Energy Application Using Optical Fibre

Existing solar energy application systems use small fraction of full spectrum of solar energy. So attempts are made to show how full spectrum solar energy can be used for diffused and beamed form of incident solar energy. Luminescent Solar Concentrator (LSC) principle with optical fibre in diffused sun light and dielectric mirror separation technique with optical fibre in beamed form are discussed. Comparison of both the cases are done. Keywords: full spectrum, solar photonics, diffused solar energy, beamed solar energy, LSC, dielectric mirror, optical fibre, Photo-Voltaic

physics.optics↗

arXiv2007

Identical Meson Interferometry in STAR Experiment

The influence of Bose-Einstein statistics on multi-particle production characterized for various systems and energies by the STAR collaboration provides interesting information about the space-time dynamics of relativistic heavy-ion collisions at RHIC. We present the centrality and transverse mass dependence measurements of the two-pion interferometry in Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 62.4 GeV and Cu+Cu collisions at $\sqrt{s_{\rm{NN}}}$ = 62.4 GeV and 200 GeV. We compare the new data with previous STAR measurements from p+p, d+Au and Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 200 GeV. In all systems and centralities, HBT radii decrease with transverse mass in a similar manner, which is qualitatively consistent with collective flow.The scaling of the apparent freeze-out volume with the number of participants and charged particle multiplicity is studied. Measurements of Au+Au collisions at same centralities and different energies yield different freeze-out volumes, which mean that $N_{part}$ is not a suitable scaling variable. The multiplicity scaling of the measured HBT radii is found to be independent of colliding system and collision energy.

nucl-ex↗

arXiv2005

Opto-Electronics in Large Array Gas Detector Systems

Large array gas detector systems are used in particle and nuclear physics experiments involving high-energy nucleon-nucleon and heavy-ion collisions. We have observed that in large array gas detector systems the momentary discharges inside the detector cells result in slowdown of High Voltage conditioning and possible hindrances in signal processing. We have explored the opto-electronic devices like the opto-coupler, optical fibre and signal processing circuit, which provide successful monitoring procedures and preventive measures to overcome the challenges produced in such complex detector systems.

physics.ins-det↗

arXiv2005

Preliminary Results on Direct Photon-Photon HBT Measurements in $\sqrt{s_{\rm{NN}}}$ = 62.4 GeV and 200 GeV Au+Au Collisions at RHIC

We present the preliminary results on direct photon interferometry measurements in Au+Au collisions at $\sqrt{s_{\rm{NN}}}$ = 62.4 and 200 GeV using the STAR (Solenoidal Tracker at RHIC) detector. Photons are reconstructed via $e^+/e^-$ conversions in STAR Time Projection Chamber(TPC) and energy deposited by photons in STAR Barrel Electromagnetic Calorimeter(BEMC). The two-photon correlations are measured using (1) both photons measured using BEMC; (2) one photon from conversions and the other measured with BEMC. Both the methodologies and the possible constraints in the correlation function measurements are discussed.

nucl-ex↗