Welcome to my website:

Rachid Nouicer


Physicist at Brookhaven National Laboratory
Adjunct Professor at Stony Brook University    
          New York, U.S.A.         

E-mail : 
nouicer@bnl.gov
             
 



   Research Interests

• Experimental Nuclear Physics
• Relativistic Heavy-Ion Physics
• Detector Development


  





 

PHOBOS Experiment at RHIC:
Multipilicty Silicon Pad Detecor 



PHENIX Experiment at RHIC:
Silicon Vertex Tracker



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.  


Research Interests

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).

 

     
      Highlight of my Work on the PHOBOS Experiment at RHIC (Brookhaven National Laboratory)


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).


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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