Gobinda Majumder

Associate Professor (G)

Experimental High Energy Physics
Tata Institute of Fundamental Research (TIFR)
Mumbai 400 005

As a graduate student I have joined TIFR in Aug 1992 . Though my thesis topic was
"Search for supersymmetric particle in $e^+e^-$ collisions at LEP", I have not done much
on that. My other contributions were R&D for CMS calorimeter,

1. Radiation hardness study of variaout inorganic and organic scintillator crystals
2. R&D on shashlik tile for EM calorimeter
3. Neutral pion rejection, Position and Angular Resolution of $\gamma$ in EM calorimeter
4. Cosmic test setup for CMS outer hadron calorimeter

In March 1998, I went to Syracuse University for my post doctoral work. Some
of my contributions were,
1. Analysis of RICH test beam data
2. Coding of RICH material in the CLEO3 Geant simulation, event display of RICH
3. Alignment of RICH in the CLEO3 detector using Bhabha event, The CLEO RICH Detector
4. Simulation for BTeV EM calorimeter
5. Study of physics potential for the BTeV detector, Workshop on B-physics at the Tevatron
6. CLEO data analysis: $f_{D_S}$ from $D_S^{*+} $ events (incomplete document)

Have returned back to TIFR as a Fellow (D) on 1st December 2000.

Since last 10 years I am/have been working (or tried to work) in the four following experiments,

BELLE

CMS

ILC detector and

INO ICAL

Till 2005-6 I was mainly concentrated on the detector calibration and physics analysis with the BELLE detector.

My BELLE notes are

502 Energy resolution of photons around 400 MeV from $D^{*0} -> D^0 + \gamma$
508 neutrino reconstruction for exclusive semileptonic B decays
515 Improvement of Klong angular resolution and $B \rightarrow J/\psi K_L$ event selection
576 Energy resolution of photon with D* events
618 Effect of pre showering & shower leakage in ECL
620 Observations of $B -> D^{*-} 5\pi}$ and $B^+ -> D^{*-} \pi^+ \pi^+ \pi^+ \pi^-$
641 Uncertainty of track finding efficiency with embedded tracks
670 Proton identification efficiency and fake rate
702 Observation of $B^- \to D^0\,D^-$, $B^- \to D^0\,D^{*-}$ and $B^0 \to D^+\,D^-$
718 Linearity test of ECL detector with Radiative Mupair Event
781 Observation of near-threshold enhancement in the D0\bar{D0}pi0 invariant mass in B -> D0\bar{D0}pi0 K

I was also involved with fabrication, testing and calibration of CMS outer hadron calorimeter(HO) at TIFR. In 2006, I have switched my analysis effort from Belle to CMS and in the same time started developing INO simulation and reconstruction software, and insignificanly contributed towards the R&D on ILC detector.

I have started developing software code in CMSSW framework to monitor and calibrate HO along with the participation of test beam data analysis as well as cosmic muon data collected by the CMS detector. Eventually, developed an algorithm for HO calibration with muon event in pp collision data. Some documents are available as Software code1, code2, validation, twiki, CMS internal note1, note2, note3, note4, note5. In the year 2011, I have coordinated a task force, which has shown the usefulness of HO in Jet/MET measurement and developed algorithms to incorporate HO in CMS physics analysis. At present I am coordinating the prompt feedback group of HCAL system to identify unknown/unforeseen problems in HCAL system and to find solutions to these problems.

In analysis front, I have stated with the Onium procution at LHC, but later on move to Electroweak and QCD physics at LHC. In EW, I am involved with the measurement of W ⁺/W ^- charge asymmetry to identify the best set of Parton Distribution Function (PDF) for LHC as well as tune it at unexplored (x,Q²) range. My main efforts are distributed to choose the best selection criteria by minimising error on asymmetry measurement, decay-in-flight/punch/sail-though background, Charge misidentification from data, pdf uncertainty, muon trigger efficiency/MET calculation in data . In QCD, I am looking for event shape variables , where initially, I was mainly concentrating only on tracker information. But, the using different type of Jets, I have calculated events shape variables and have compared different MC models with data. I am pursuing these studies to make a precise measurement of the strong coupling constant, &alpha_s at TeV scale.