Dhiman Chakraborty _________________________________________________________________ Address: Department of Physics, Northern Illinois University, DeKalb, IL 60115, USA. Phone: 1-630-452-6368 e-mail: dhiman@fnal.gov www: http://www-d0.fnal.gov/~dhiman/ \vskip 0.2cm The online version of this CV on my web-page has some useful live links. _________________________________________________________________ BIO-DATA Born July 7, 1966. Indian citizen. Permanent resident of the USA. _________________________________________________________________ EDUCATION Ph.D., Physics, State University of New York at Stony Brook (1994). B.Tech., Engineering Physics, Indian Inst. of Technology, Mumbai (1988). _________________________________________________________________ EXPERIENCE Assistant Professor of Physics, Northern Illinois University January 2001 - Present Teaching: I have taught the following courses at the NIU Physics department: * Analytical Mechanics 1 (PHYS 300): Core course for junior undergraduate Physics majors; Fall '01. * Analytical Mechanics 2 (PHYS 400): Core course for senior undergraduate Physics majors; Spring '02, Spring '03. * Classical Mechanics (PHYS 500): Core course for all gradute students of Physics; Fall '02; Fall '03, Fall '04, Fall '05, Fall '06. * Introduction to Elementary Particle Physics (PHYS 584): Elective for physics graduate students; Spring '01, Spring '06. * Techniques in Experimental High Energy Physics (PHYS 690B), Elective ``special topics'' course for physics graduate students; Spring '05. Research: I am actively involved in the following projects: * The International Linear Collider (ILC): In the new millenium, a worldwide consensus has emerged that after the Large Hadron Collider (LHC), the next High Energy Particle collider should be an international linear $e^+ e^-$ machine with a center-of-mass energy reach of 500 GeV to 1 TeV. A high-energy, high-luminosity $e^+ e^-$ collider is essential for precision studies of many processes within the Standard Model (SM) as well as some beyond the SM that may be discovered at the LHC. To fully exploit the physics potential of the ILC, detectors must employ novel technologies and algorithms that yield unprecedented resolution in position and energy-momenta measurements of particles and jets. A large part of NICADD's efforts is invested in calorimetry for the ILC, which will play a key role in acheiving such ambitious goals as jet energy resolution of $\sigma(E)\approx 0.30 Unknown LaTeX command \sqrt E $ ($E$ in GeV) by using the ``particle-flow'' algorithms (PFA, also known as energy-flow algorithms or EFA). These algorithms seek to achive the best possible jet energy resolution by limiting the use of calorimeters to the measurement of neutral particle energies, employing the magnetized tracker for more precise momentum measurement of the charged particles in a jet. This requires fine 3D granularity in the calorimeter for the neutral clusters to be separated from the charged clusters so the latter can be substituted by track momentum measurements. I am in charge of NICADD's detector software efforts, i.e., simulation and algorithm development. Our team had developed a GEANT4-based detector simulation program, called LCDG4 that allows run-time specification of detector geometry. It served for more than two years as the standard simulation tool for the American Linear Collider Physics Group (ALCPG), a consortium of 50+ universities and 7 national or industrial laboratories across North America. We also provide large samples of simulated data for various physical processes under several detector configurations. These form the basis of testing reconstruction algorithms for ALCPG. Over the past 2 years we have developed another important program, called DigiSim, for fast parametric simulation of the processes between the energy deposition in the detector volume and signal recording. DigiSim offers a flexible means for simulating such phenomena as random fluctuations, noise, non-linearities, cross-talk etc. In essence, it enables the user to model the transfer function in the through an easy and intuitive interface. Thus, it is a very useful tool for detector design and algorithm tuning. DigiSim is implemented in both Java and C++. The former has been adopted as a part of the standard simulation chain in America, while the latter is being tried in Europe. Since its formation in 2001, our group has been playing a prominent role in the development of PFA's as well. Several clustering algorithms have been developed, and extensively tested. In close collaboration with colleagues at other institutions, we have identified the specific challenges in achieving the ambitious performance goal. Finding ways to overcome those challenges by careful optimization of detector design and algorithm parameters is one of our highest priorities at the moment. I am also involved in NICADD's detector hardware development efforts that are primarily focused on using plastic scintillator as the active medium for the ILC hadron calorimeter. Very small cell sizes ($<10$ cm$^2$) can be realized at a reasonable cost without sacrificing hermeticity, thanks to the newly emerging Silicon Photomultipliers (SiPM). Our group has carried out extensive characterization of SiPMs from different sources, and studied many variants of scintillator cell designs, to establish this as a viable option for the ILC HCal. We are playing a key role in the continued R&D toward a conceptual design based on this option. We have successfully tested some of our detector elements with test beams of single particles at DESY and Fermilab, and are presently preparing for another long series of beam tests at CERN and Fermilab. Our efforts on simulation and algorithm development, as well as those on hardware R&D have steadily attracted favorable peer reviews and strong federal funding over and above our base grant. Since June, 2002, I have been serving as a co-leader of the ALCPG's Calorimetry working group, which coordinates research and development activities of about a dozen university and laboratory groups. These R&D include design and prototyping of several different technologies for the electromagnetic and the hadron calorimeters, as well as PFA/EFA's. During 2002-2003 I served a member of the Linear Collider R&D proposal coordination committee that oversaw the joint submission of grant proposals by all university groups to the US federal funding agencies.% (NSF and DOE). I have recently co-authored, by invitation, the new section on Photon Detectors in the upcoming 2006 edition of the Particle Data Group's Review of Particle Physics, which serves as the standard sourcebook to the entire particle physics community worldwide. * Studies of proton-antiproton collisions with the D\O\ detector at the Tevatron (Fermilab): Since 1991, D\O\ has been one of the two detector experiments operating at the Tevatron, the world's highest energy particle collider. Currently, nearly 700 physicists representing some 84 institutions from 21 countries around the world are participating in the project. From June 2001 to July 2005, I served as a co-convenor of the \tau identification group of the D\O\ collaboration. As the heaviest lepton, \tau's are of special interest to any mass- or flavor-dependent coupling. Many popular Higgs and SUSY processes involve \tau leptons in their decays. To identify hadronically decaying \tau's, I implemented a multivariate pattern-recognition algorithm based on artificial neural networks. During my tenure as a co-convenor, the group implemented a completely new set of algorithms (a different algorithm for each major \tau decay mode) both offline and at the software trigger (level 3), as well as several improvements in the hardware trigger definitions (levels 1 and 2), and made the first observation of $Z\rightarrow \tau \tau$ events at D\O. Several searches of Higgs bosons beyond the SM have been completed and submitted for publication. My student Mikhail Arov and I have recently completed the first measurement of top-antitop pair-production cross section using the $t\bar t \rightarrow \tau+$jets final state at the Tevatron. The result is consistent with the SM predictions. We are now updating the analysis to span cover a much larger data sample, which will significantly reduce the statistical uncertainty. This investigation is not only an important test of the SM, but also a big step toward the search for certain scenarios beyond the SM that predict large enhancements of this final state. For example, if a charged Higgs exists and is lighter than the top quark, then the branching fraction for $t\bar t \rightarrow \tau+$jets would be greater than that predicted in the SM. We expect to complete such a search for the charged Higgs within a year. I am the principal investigator of the NIU High Energy Physics group's base research grant awarded by the National Science Foundation (NSF). Overlapping with NICADD, the group presently consists of 4 faculty members, 4 research scientists, 6 graduate and 2 undergraduate students. In addition to the above-mentioned activities, a large part of our group's efforts are directed toward searches for new phenomena at D\O. Members of the group also play key roles in the administration and operations (muon triggers, calorimetry) at D\O. Research Scientist, State University of New York at Stony Brook. May 1997 - January 2001 * Search for charged Higgs boson at D\O: A charged Higgs pair is an integral feature of most models beyond the Standard Model (SM), including a large class of supersymmetric (SUSY) theories. I carried out a search for charged Higgs bosons in decays of pair-produced top quarks at D\O. This study probed previously unexplored regions of the [$M(H^+),\tan\beta$] parameter space, and led to an upper limit on the branching fraction of top decay to charged Higgs, based on the degree of agreement between the expected cross section for top pair production and the number of events observed in lepton+jets final states. The limits are the most stringent ones to date. I also supervised a graduate student in an alternative search using $H^+\rightarrow \tau\nu$ decays. Both results were published in Phys. Rev. Lett. Participating SUSY/Higgs workshop at Fermilab in March, 2000, I extended the search for charged Higgs to estimate the reach of the Tevatron experiments in Run 2 and beyond, and wrote the corresponding section of the report. * Studies of the top quark: For 4 years (1996-2000), I served first as a co-leader of a subgroup, and later as the leader of the \it top physics working group at D\O. The topics studied by this group included, in addition to refinement of pair-production cross section and mass measurements, tests of the SM through top-antitop spin correlation, polarization of the $W$ boson in top decay, and measurement of $|V_tb|$, as well as non-SM processes, such as top decay via its SUSY partner, via charged Higgs, or via flavor changing neutral currents (FCNC), and pair-production through decays of a heavier boson ($Z^\prime$). I supervised a Ph.D. student in her search for $Z^\prime\rightarrow t \bar t$. Analyses coordinated by this group resulted in 8 publications in refereed journals and 6 Ph.D. theses. I have co-authored an invited article on the present status and future prospects of top quark physics at the Tevatron, LHC, and ILC. This article, titled Review of Top Quark Physics (\texttt hep-ph/0303092) was published in the 2003 issue of the Annual Review of Nuclear and Particle Science. * Alignment of the D\O\ detector: The ability to isolate secondary decay vertices of $b$ quarks is crucial for the suppression of background in a number of physics analyses, including those involving top quarks and neutral Higgs bosons which are expected to decay predominantly to $b\bar b$ (unless $M_H^0 > 130$ GeV). The D\O\ silicon microstrip tracker (SMT) is designed to provide impact parameter resolutions of 10-20 \mum. This cannot be achieved, however, unless its position with respect to the global coordinate system, as well as its internal geometry, are measured with a precision of a few microns. I designed and implemented the infrastructure for the offline program to calculate and correct misalignments of the entire D\O\ detector. For the SMT, I calculated the precisions required in the measurement of various degrees of freedom, wrote the first version of the code for measurement of both global and local misalignments, and to apply the necessary ``corrections'' to the nominal design specifications of the geometry system. Much of that code was subsequently adopted for alignment of other subdetector components as well. Post-doctoral Research Associate, State University of New York at Stony Brook. July 1995 - May 1997 * Run 2 Software: D\O's migration from FORTRAN to C++ involved a complete rebuilding of its entire software system to be based on object-oriented concepts. I contributed to the analysis and design of the D\O\ Run 2 software framework (the infrastructure that provides easy connectivity between all the components needed for data access and analysis e.g. packages of analysis code, event data, calibration data, control parameters, etc.), and wrote the first prototype of it. I also authored \tt mc_analyze, the standard software package used at D\O\ for the analysis of Monte Carlo information, either in stand-alone mode to study event kinematics at the parton-level, or to estimate signal efficiency and background rejection of reconstruction algorithms. * Forward Preshower Detector: I participated in the design and trigger studies for the Forward Preshower Detector (FPS), an important component of the D\O\ detector upgrade. These studies were a part of the Technical Design Report for the FPS. * Run 1 Software: I coordinated, and authored a large part of, the calorimeter section of D0FIX, a program that reprocessed the entire D\O\ data set from Run 1 in order to improve event reconstruction. The resultant improvements were critical to several physics analyses, including the study of single top production, the study of $W \rightarrow \tau\nu$, and searches for New Phenomena. From 1995 to 1998 I served as the ``czar'' of the D\O\ calorimeter reconstruction software for Run 1. Post-doctoral Research Associate, University of Iowa. September 1994 - June 1995 Studies of electron-proton collisions with the ZEUS detector at HERA (DESY): As a member of the ZEUS collaboration at DESY, I worked with the group studying photoproduction of vector mesons ($ep \rightarrow epV$). I designed the software trigger for $J/ \psi \rightarrow e^+e^-$, that was used in the 1995 run, which included a new Beam Pipe Calorimeter and a Forward Presampler. This helped extend the measurement of inclusive $J/ \psi$ photoproduction cross section to previously unexplored regions of small $Q^2$ at large $W$, where competing calculations for the proton structure functions disagreed. I also contributed to the simulation and beam test of the Beam Pipe Calorimeter, designed to study electrons scattered at very small angles. Graduate Research Assistant, State University of New York at Stony Brook. August 1988 - September 1994 Studies of proton-antiproton collisions with the D\O\ detector at the Tevatron (Fermilab): I conducted my thesis research under the direction of Prof. Roderich J. Engelmann. My doctoral dissertation presented a search for the top quark in the lepton+jets final states using the D\O\ detector. My analysis exploited distinctive topological characteristics of the signal, and led to the improvement of the lower limit for the mass of the top quark from 91 GeV to 131 GeV. The analysis techniques that I developed for enhancement of signal, and for the modeling and estimation of backgrounds, played a key role in the discovery of the top quark in March, 1995. I also made substantial contributions to the calorimeter reconstruction software and electron identification, developed the online monitoring software for the central drift chamber (CDC) and had the primary responsibility for certifying its data integrity. _________________________________________________________________ RESEARCH GRANTS Since FY2002, I have been a PI or Co-PI on federal research grant awards totaling nearly $2 million. Proposals requesting another $2 million over FY2007-08 are in preparation (parts submitted). Proposals funded: \vskip 0.2cm 1. ``Searches for new phenomena at high-energy particle colliders'', base grant for NIU's High Energy Physics program (PI, $775,000, NSF, FY2006-09), 2. ``Development of particle-flow algorithms and simulation software for the ILC detector(s)'', (PI, $55,000, DOE/NSF, FY2006), 3. ``Development of extruded scintillator and tracking calorimetry'': (PI, $145,000, DOE Advanced Detector Research Program, FY2003-05), 4. ``Development of particle-flow algorithms, simulation, and other software for the LC detector'', (PI, $44,000, DOE, FY2004), 5. ``Development of new hadronic calorimeter technology'', (PI, $45,000, DOE Advanced Detector Research Program, FY2002), 6. ``Design and prototyping of a scintillator-based hadron calorimeter for the ILC detector(s)'', (Co-PI, $47,500, DOE+NSF, FY2006), 7. ``Beam test of a scintillator-based tailcatcher/muon tracker for ILC detector(s)'', (Co-PI, $45,500, DOE+NSF, FY2006). 8. ``Design and prototyping of a scintillator-based hadron calorimeter for the ILC detector(s)'', (Co-PI, $31,500, DOE+NSF, FY2004), 9. ``Searches for new phenomena at high-energy particle colliders'', base grant for NIU's High Energy Physics program (Co-PI, $639,000, NSF, Unknown LaTeX command \mbox FY2003-05 ), 10. ``Design and prototyping of a scintillator-based digital hadron calorimeter'', (Co-PI, $61,000, DOE, FY2003), Proposals submitted or in preparation: \vskip 0.2cm 1. ``Development of particle-flow algorithms and simulation, software for ILC detector(s)'', (PI, $376,000, DOE+NSF, FY2007-08), 2. ``Design and prototyping of a scintillator-based hadron calorimeter for the ILC detector(s)'', (Co-PI, $1,220,000, DOE+NSF, FY2007-08), 3. ``Design and prototyping of a scintillator-based tailcatcher/muon tracker for the ILC detector(s)'', (Co-PI, $330,000, DOE+NSF, FY2007-08), _________________________________________________________________ ACADEMIC HONORS * President's merit list, Govt. of India, 1984. * National merit scholarship, Govt. of India, 1982. _________________________________________________________________ COMMITTEE MEMBERHSIPS * Fermilab Director's ILC-HEP task force, * The US ILC detector R&D proposal coordination committee, * Reviewer for DOE's Advanced Detector Research program, * The NSF review panel for Information Technology Research - Information Management, * Several editorial boards and review committes at D\O, chaired 2 of them, * NIU physics department undergraduate curriculum committee, * NIU physics department colloquium committee (chair). _________________________________________________________________ STUDENTS * Jeremy McCormick (MS completed), * Mikhail Arov (Ph.D in progress), * Diego Menezes (Ph.D in progress). _________________________________________________________________ CONFERENCE ORGANIZATION I have participated in the organization of several international conferences and workshops either as a session convener, member of the local organizing committee, or of the international advisory committee. These include International Linear Collider workshops, IEEE Nuclear Science Symposium, Calor, Workshop on Hadronic Shower Simulation, and Charged Higgs 2006. _________________________________________________________________ SYNERGISTIC ACTIVITIES * Co-leader, Calorimetry working group of the American Linear Collider Physics Group (2002-present), * Research Coordinator of Calorimetry, University Consortium for Linear Collider Research and Development (UCLC, 2002-2003), * Co-convenor, \tau id group, D\O\ collaboration (2001-2005), * Leader, top working group, D\O\ collaboration (1997-2000), * Coordinator, calorimeter software, D\O\ collaboration (1995-1998). _________________________________________________________________ OUTREACH Volunteer, ``Ask-a-scientist'' open-house program at Fermilab (2000-present). _________________________________________________________________ OTHER * Member, CAlorimetry for LInear Collider with Electrons collaboration, * Member, American Physical Society, * Visiting scientist, Center for Particle Physics at Marseille, France (2004). _________________________________________________________________ CONFERENCE TALKS (past 10 yrs) * Studies of the top quark at hadron colliders, Workshop on Top Quark at the LHC, Grenoble, France, Oct, 2006 (Invited). * Search for charged Higgs boson at D\O, Charged Higgs Conference, Uppsala, Sweden, Sep, 2006 (Invited). * Particle-Flow Algorithm Development at NIU, Linear Collider Workshop, Vancouver, Canada, Jul, 2006. * Scintillator Hadron Calorimeter R&D in America, ibid. * A Scintillator-based Hadron Calorimeter for the ILC Detector(s), XII International Conference on Calorimetry in High Energy Physics (Calor06), Chicago, Illinois, Jun 2006. * The case for a Scintillator-based Hadron Calorimeter for the SiD detector, ILC Physics and Detector Workshop (ALCPG2005), Snowmass, Colorado, Aug, 2005. * Particle-Flow Algorithm Development at NIU, ibid. * Studies of silicon photodetectors for hadron calorimetry at the next electron-positron linear collider, 4th International Conference on New Developments in Photodetection (Beaune'05), Beaune, France, Jun, 2005. * Electroweak results from the Tevatron, The 20th International Workshop on Weak Interactions and Neutrinos (WIN'05), Delphi, Greece, Jun, 2005. * CALICE Tail-catcher/Muon Tracker Status and Plans, ILC Workshop, Stanford, California, Mar, 2005. * The Hadron Calorimeter: Analog or Digital?, Workshop on ILC Detectors with Gaseous Tracking, (ILCD'05) Paris, France, Jan, 2005 (Invited). * Toward Realistic Particle-Flow Algorithms, ibid. * Requirements for a worldwide ILC Detector Simulation Program The 3rd Linear Collider Simulation Workshop (LCSW'04), ANL, Illinois, Jun 2004. * Summary of American ILC Calorimetry efforts, The 4th International Conference on Linear Colliders, Paris, France, Apr, 2004. * LCDG4: a GEANT4-based ILC detector simulation program, ALCPG'04 Workshop Stanford, California, Jan, 2004. * New results from the Tevatron, The 6th workshop of the Asian Consortium for Future Accelerators, Mumbai, India. Dec, 2003 (Invited). * Summary of American ILC Calorimetry efforts, ibid. * Calorimetry summary, The 4th workshop of the American Linear Collider Physics Group, Cornell U., Jul, 2003. * Particle Flow Algorithms and Calorimetric Reconstruction, The 2nd LC Detector Simulation Workshop (LCSW'03) Stanford, California, May, 2003. * Status of the LC simulation software development, The 3rd workshop of the American Linear Collider Physics Group, UT, Arlington, Jan, 2003. * Summary of the American Calorimetry efforts, The 3rd ECFA-DESY workshop on the ILC, Prague, Czech Republic. Nov, 2002. * Calorimetry summary, The 2nd workshop of the American Linear Collider Physics Group, U of California, Santa Cruz, Jul, 2002. * Latest top and W/Z results from the Tevatron, XVIII Recontres de Moriond, Les Arcs, France, Mar, 2002. * Workshop Summary, The 1st LC Detector Simulation Workshop (LCDsoft) NIU, Illinois, Nov, 2002. * Digital hadron calorimetry, The 1st workshop of the American Linear Collider Physics Group, U. of Chicago, Jan, 2002. * Top Quark pair production cross section at Tevatron, Thinkshop2, Fermilab, Illinois, Nov, 2000 (Invited). * Particle Identification at D\O\ using Neural Networks, VII International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT 2000), Fermilab, Batavia, Illinois, Oct, 2000. * Studies of the top quark at D\O, 30th International Conference on High Energy Physics, Osaka, Japan, Jul-Aug, 2000. * Search for charged Higgs in the decay of top quark pairs at the Tevatron, SUSY 99, Fermilab, Batavia, Illinois, Jun, 1999. * Charged Higgs and spin correlations in $p\bar p \rightarrow t \bar t$, XIII symposium on Hadron Collider Physics, Mumbai, India, Jan, 1999. * New results from the Tevatron, X symposium on High Energy Physics Chandigarh, India, Dec, 1998 (Invited). * Search for a charged Higgs boson in the decay of top quark pairs, Joint Theoretical and Experimental Seminar, Fermilab, Illinois, USA, Dec, 1998. * Measurements of top quark production cross section and mass at D\O., DESY seminar, Hamburg, Germany, Jun, 1997. * Top quark: new results from the Tevatron, Beyond Standard Model V, Balholm, Norway, May, 1997. * Measurement of top production cross section at D\O., XI symposium on Hadron Collider Physics, Padova, Italy, Jun, 1996. * Top Physics at the Tevatron, 4th workshop on High Energy Physics Phenomenology, Calcutta, India, Jan, 1996. \vskip -0.4cm In addition, I have given seminars and colloquia at many universities and research laboratories in Asia, Europe and the USA. _________________________________________________________________ PUBLICATIONS See accompanying list. _________________________________________________________________ REFERENCES Available on request. _________________________________________________________________