Open Charm measurement in heavy ion and p+p collisions @ SUBATECH Nantes, France

One of the most outstanding new results of the Relativistic Heavy Ion Collider in Brookhaven Laboratory, USA, is the observation of anomalous energy loss of quarks passing through the dense partonic medium (the so called Quark Gluon Plasma or QGP) formed in central Au+Au collisions at sqrt(s)(NN)=200 GeV. This phenomenon, called "jet quenching", allows for a direct measure of the initial density of partons, an important key for the characterization of the QCD phase transition between hadrons and partons. This transition is believed to have taken place in the early universe, 10^6 seconds after the Big Bang.

One of the biggest puzzles of RHIC is the jet quenching of quarks with heavy flavour (charm and beauty added together) which is larger than the theoretical predictions. Or, the flavour dependence of jet quenching is not yet understood.

The proposed PhD Thesis subject concerns the direct measurement of charm and beauty separately within the STAR experiment at RHIC, in order to resolve the puzzle of flavour dependence of jet quenching. This is possible through data analysis of yields and transverse momentum (pT) dependence of open charm, in particular of the D0, D* particles and charmed baryons in Au+Au and p+p collisions at 200 GeV. Azimuthal angular correlations of those particles with high pT electrons is another tool to disengtangle charm and beauty.

The STAR data needed for this Thesis are already taken and are calibrated and ready to be analysed. Furthermore the software codes (c++, root) needed as basis for this analysis are also available. The large number of already existing and well calibrated data which offer a rich source for future papers within short timespan, are a great advantage of the present work.

In addition there is the chance to get partially involved in the upgrade and support of a silicon detector of STAR, which will start in 2010. This allows to enrich the curriculum vitae with hardware as well as software experience. Finally, in the second part of the Thesis there is the possibility of a participation in the open charm analysis of the ALICE experiment at the LHC. Visits to BNL and CERN laboratories in Long Island and in Geneve are foreseen for this work.

Summarizing, the proposed Thesis subject has the advantage to combine: (1) a competitive physics analysis on a subject attracting a great deal of interest today, namely jet quenching and the QCD phase transition (2) the fact that a big number of well calibrated data exists in STAR as well as the codes for their analysis, allowing for fast results and publications. (3) it allows to accumulate expertise in both software and data analysis as well as in hardware, through an implication in the upgrade of a leading edge technology silicon detector. (4) it allows an implication also in a new experiment just starting at the LHC, at a moment (2011-12) in which an improved understanding and calibration of data will be available. The above aspects allow for a rich and competent Thesis, focused on an important problem of contemporary physics, that captures the interest of the community of â~@~XHigh energy nuclear and particle physics".

The applicant should hold a master's degree in physics, preferably in high-energy particle or nuclear physics as well as a diploma in physics.

The position is available starting in 1st october 2009 for an appointment of three years.

SUBATECH is located in Nantes, a city in the western part of France, 400 km west of Paris.

The STAR SUBATECH group is involved in the physics analysis of charm with microvertexing techniques and the upgrade of a silicon strip detector for the future new silicon tracker of STAR.

Applications, including a CV, university records, and the names and field e-mails; of two academic references willing to provide further information on the candidate should be sent by e-mail to the contact below.

Deadline: Friday, May 15, 2009
Contact: Sonia Kabana
Email: kabana@mail.cern.ch
More information: http://www-subatech.in2p3.fr/