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Biographical Sketch
In
2013, I received Highest Academic French Diploma, "Habilitation a
Diriger des Recherches" (H.D.R.) from University of Strasbourg, France.
Title of HDR thesis: "New State of Nuclear Matter : Nearly
Perfect Fluid of Quarks and Gluons in Heavy Ion Collisions at RHIC
Energies"
URL : http://tel.archives-ouvertes.fr/tel-00925262
In 1997,
I received my Ph.D. with Distinction in Nuclear Physique,
University
Louis
Pasteur and National Center for Scientific Research (CNRS), Strasbourg,
France. URL: https://tel.archives-ouvertes.fr/tel-00805800
From 1998-2004, I progressed through the ranks at the
University of Illinois (UIC), Chicago starting as a postdoctoral
through Research Associate Professor. 1998 to 2000, I held a visiting
position at Argonne National Laboratory (ANL),
Illinois. In 2004, I was hired as an Associate Physicist and in 2007 to
Physicisit position in the
PHOBOS research group at BNL.
In
2007, I joined first the
HIRG (Heavy Ion Research Group) group working on ATLAS experiment at LHC and in 2008, I joined PHENIX
group at BNL. Highlights of my work in PHOBOS experiment and PHENIX experiment at RHIC are described below.
As
we know it, the matter is made up from molecules which consist of atoms
which consist of electrons circling around a nucleus which consists of
protons and neutrons which themselves are bound states of quarks and
gluons called partons. Recently, many nuclear physicists
started to question under what conditions the nucleons, or more
generally, the hadrons, lose their identity. QCD lattice Monte Carlo
calculations have given a more explicit and interesting answer to
this question: at temperatures above T = 200 MeV nuclear matter
should melt into a soup of quarks and gluons and, there, the identity
of hadrons should be completely lost, see Ref. H. Satz.
To create and study such a primordial plasma in the laboratory is one
of the great challenges for current experimental physics. Various
estimates (e.g. 1) indicate that the collision of heavy nuclei at very
high energies may indeed produce a terrestrial "little bang," providing
short lived
bubbles of the quark-gluon plasma. As depicted in the phase
diagram (see right figure), several experimental eras, RHIC and
LHC right now and FAIR and NICA in the future, are toward this ultimate
goal, discover and study properties of this new states of nuclear
matter called QGP. My research interests of the Relativistic Heavy Ion
Physics are focused on heavy ion collisions at RHIC energies. My
reaserch on QGP, started at PHOBOS experiment and ongoing at PHENIX experiment at RHIC.
Figure on the right show a diagram of the Relativistic Heavy Ion Collider (RHIC) complex at Brookhaven National Laboratory. The complex is composed of several
accelerator facilities "chained" together to provide beams which are
collided in detectors located inside the RHIC ring. (Courtesy: BNL).
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Highlight of my Work on the PHOBOS Experiment at RHIC
(Brookhaven National Laboratory)
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From
1998-2009, I was involved in the complete PHOBOS multiplicity
sub-detector effort from the initial construction through playing a
leading role in the physics analysis and paper writing. In particular,
I was involved in the construction of PHOBOS silicon detector, wafer
testing, silicon modules and barrel assembly and testing, detector
installation and survey, signal processing and finally managing and
maintaining the silicon multiplicity array during the five PHOBOS
detector running periods. I also co-led the decommissioning of the
silicon
detector after PHOBOS was completed in 2005. The silicon multiplicity
array was clearly the most unique feature of PHOBOS and
crucial for all
of our physics results. In particular, it was used for dN/dη and
d2N/dηdφ (i.e. v1 v2 v3 etc) over a uniquely wide reach of
pseudorapidity (|η|<5.4) and at the lower energies it was also used
for centrality determination. I managed this system for
basically the
entire running of PHOBOS, attending almost daily meetings and being on
call during the entire datataking period for emergencies.
Highlight
of my Physics
Contribution to PHOBOS
I had
a leading role in the data analysis and publication of results on the pseudorapidity
distributions of charged-particles produced in Au+Au, Cu+Cu, d+Au
collisions at several RHIC energies, 19.6, 22.4, 62.4, 130 and 200 GeV,
as well in p+p collisions at 200 and 410 GeV, covering a span of an
order of magnitude in the same
detector, allowing for a reliable systematic study of particle
production as a function of energy in these
collisions. I was the corresponding author on 3 PHOBOS physics
publications and I has played an essential or
leading role in the
analysis for an additional 8 PHOBOS papers. During my time on PHOBOS,
in addition to participating in the dN/dη measurement for almost every
conceivable energy/species combination, I was also co-convenor of the
PHOBOS Multiplicity Working Group as well as serving on the flow physics Internal Review Committee (IRC).
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For
three papers, I was the primary author - performing
the main data analysis, writing the paper and interacting with the
journal editor and referees:
• PRL 102 (2009) 142301 - "System size, energy and
centrality
dependence of pseudorapidity distributions of charged particles in relativistic
heavy
ion collisions".
In this paper, I demonstrated that we were seeing
"Npart/2A" or geometric scaling where Npart is the number of nucleon
participant pair
and A is the mass number of the colliding nuclei. The geometry
(Npart/2A) is defined as the fraction of total nuclear volume which
interacts. I showed that CuCu and AuAu pseudorapidity distribution shapes (1/Nch)*dN/dη, at the same energy, were
different for the same value of Npart but that they matched
much better
for the same fractional centrality or even more precisely, the same Npart/2A.
• PRC 72 (2005) 031901 (R) - "Scaling of charged
particle production in d+Au collisions at 200 GeV".
This paper provided a wide variety of scaling
features in the
pseudorapidity distribution and was enthusiastically received by
theorists such as Miklos Gyulassy and
Dima Kharzeev
(actually especially in it's preliminary version at Quark Matter). In this paper,
we found that the longitudinal features of d+Au collisions at 200
GeV are found to be very similar to those seen in p+A collisions at lower energies.
• PRL 93 (2004) 082301 - "Pseudorapidity distribution of
charged
particles in d+Au collisions at 200 GeV".
First results on
this topic. The measured pseudorapidity distribution of primary
charged particles in minimum-bias d +Au was compared to the
predictions of the parton saturation model, as well as microscopic
models.
Finally, I was a member of the IRC for flow physics papers
for a few years. My unique insights
into the performance and analysis of the multiplicity detector (used
for the high η flow measurements) were essential. My "hit merging"
algorithm (was used in multiplicity analysis) was adopted by the
flow group and significantly improved the consistency of their results. The papers involved included:
• PRL 98 (2007) 242302 - "System size,
energy, pseudorapidity and centrality dependence of elliptic flow"
• PRL 97 (2006) 012301 - "Energy
dependence of directed flow over a wide range
of pseudorapidity in Au+Au collisions"
• PRC 72 (2005) 051901 (R) - "Centrality
and pseudorapidity dependence of elliptic flow for charged hadrons in
Au+Au collisions at 200 GeV"
• PRL 94 (2005) 122303 - "Energy
dependence of elliptic flow over a large pseudorapidity range in Au+Au
collisions"
I gave two PHOBOS-based Quark Matter physics talks (QM2004 and
QM2006), one summarizing our multiplicity results and another summarizing (in a different year) our flow results. In
addition to this, I was heavily involved in the discussions and
contributed to several more papers as an active participant.
Highlight of my Work on the PHENIX Experiment at RHIC
(Brookhaven National Laboratory)
I
am an initial member of the PHENIX Silicon Vertex Tracker
(VTX) when we submitted the first proposal in November 2003. At that
time I was a member of PHOBOS and belonged to BNL chemistry department.
I am one of silicon
detector experts of PHOBOS and my knowledge and experience on silicon
detectors becomes
indispensable to the VTX project. VTX detector consists of 4
barrels of silicon detector. The inner two barrels are pixel detectors
and for the outer two barrels we use a novel silicon sensor, which is
called stripixel sensor, developed at BNL. During RHIC Run6
(in 2006), I became acting subsystem manager of stripixel system.
When we submitted a revised proposal to DOE in May 2006, I was named as
the deputy subsystem manager of the stripixel subsystem.
However, I am considered as the principal contact and co-manager
of construction and commissioning of the stripixel detector.
After the VTX project was completed and we moved into the operation
phase of the VTX, I was appointed as the subsystem manager
of the stripixel detector in the Operation Plan for the Silicon Vertex
Detector (VTX) for PHENIX (April 2011).
I have been responsible for essentially every aspect of the
stripixel subsystem except for its read-out electronics, which is the
responsibility of my colleagues from ORNL. We need 224 stripixel
silicon modules assembled in 40 ladders to complete the stripixel
detectors. These 40 ladders are assemble into two layers of barrels. I
have been responsible for all of these elements plus spares. My
responsibility includes (1) Q/A and testing of silicon sensors, (2)
assembly and testing of silicon modules, (3) assembly and testing of
detectoR ladders, and (4) assembly and testing of two layers of
stripxiel barrel. After installation, we started commissioning of the
detector. I lead the commissioning effort of the stripixel system.
During the first part of RUN11 of RHIC (2011), 500 GeV p+p run, the VTX
system was finally integrated in the PHENIX DAQ system.
I led a bunch of graduate students and postdocs during the construction
and the commissioning of the stripixel detector. I should note
that all of the students and postdocs that I lead during the
project has no prior experience to work with delicate and complex
silicon detectors. After working with me for several months, those
students and postdocs became "experts" of the stripixel detector. I
also cares about that the people who worked with me received proper
credit for their contribution. Whenever I made a presentation on the
status of the stripixel detector in VTX meetings or in the
reviews, or when I announced some important achievement, I was very
careful that he mentioned the people, in particular the students
and postdocs, who contributed to the work or the achievement.
Right now, I am in charge of the daily operation (VTX-stripixel
manager) of the stripixel
detector of the VTX in PHENIX experiment. I am also involve in the
heavy flavor data analysis in PHENIX using Silicon Vertex Tracker VTX.
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