Congratulations to Gian-Michele Innocenti for receiving a 2014 Infinite Kilometer Award of the MIT School of Science for his outstanding contributions to MIT’s mission and community!
Gian Michele has been working on the L1 trigger upgrade and heavy flavor meson analyses in heavy ion collisions in the CMS collaboration.
Congratulations to Alex Barbieri for winning the Henry Kendall Teaching Award for his great work as a teaching assistant of the Vibrations and Waves course and ” for going out of his way to help students “.
Congratulations to Doga Gulhan for winning Deutsch Award for Excellence in Experimental Physics ” for the excellence that characterizes her detector and analysis work and everything she does, leading to the most sophisticated CMS heavy ion analysis to date “.
Doga presents a study of dijet events in pPb collisions, making good use of the analog pointer.
The third Heavy Ion Jet Workshop was held recently in Lisbon, sponsored by MIT and Instituto Superior Tecnico. Over three days, more than twenty five theoretical and experimental physicists gathered and discussed recent results in jet physics and the modifications observed when jets propagate through the strongly coupled medium created in the high energy collisions of nuclear matter, or Quark Gluon Plasma (QGP). Of particular interest at this workshop were new experimental results recently presented at the Quark Matter conference in Darmstadt, new background subtraction techniques for a many particle environment, and the introduction of several Monte Carlo generators modeling heavy ion collisions.
Our measurement of the fragmentation function in PbPb and pp collsions is submitted to arXiv:1406.0932and for publication in Physical Review C. This paper is the second PbPb/pp fragmentation function measurement from CMS, and the first paper to observe a significant modification in PbPb collisions when compared to pp. The evolution of this difference is further explored as function of both the the collision centrality, and for the first time, jet momentum.
Here we see relative to proton-proton systems, dijet imbalance is recoved in central PbPb systems by low momentum particles distributed through large angles.
The Quark Matter conference returned to its birthplace, Darmstadt, in its 24th edition. Results from proton-Lead collisions at the LHC continued to generate interest, with contributions from MIT and CMS at the forefront. The most intriguing results from the previous Quark Matter conference concerned energy loss in the hot dense medium formed in heavy ion collisions. This conference continued in that vein, and MIT presented exciting new results exploring the origin of this energy loss in proton-Lead and Lead-Lead collisions.
A comparison between dijet eta distributions in data and in NLO calculations are shown.
Our paper on first event activity dependent jet measurements in pPb collisions is submitted to arXiv:1401.4433. The dijet transverse momentum ratio is found to be independent of event activity in pPb collisions. This confirms that the dijet transverse momentum imbalance enhancement in central PbPb collisions is not originating from initial-state effects. It also shows that any final state effect on jets in pPb collisions is small, justifying the usefulness of jets in studying initial state effects.
Victoria Zhukova was one of the winners of the 2014 MIT School of Science “Infinite Kilometer” awards, recognizing her contributions to MITs mission in education and research. Congratulations, Victoria!
An event display of a heavy ion collision containing two reconstructed jets with unequal energies.
At the start of July, MIT and Universite Pierre and Marie Curie jointly organized a workshop on Jets which took place in Paris. About twenty high energy and heavy ion theoretical and experimental physicists were in attendance discussing the challenges and new opportunities of doing jet measurements and predictions in heavy ion collisions. A jet is the experimental signature of a quark or gluon that is scattered off at very high momentum perpendicular to the direction of motion of the colliding particles, the beampipe, and into our detector. However a single quark or gluon can not freely propagate through the vacuum to reach our detector but will transform into more quarks and gluons sharing the original momentum, in a process called fragmentation. It will also pull particles from the vacuum to create a collimated spray of color neutral particles that exist for timescales observable by our detectors, in a process called hadronization. This spray of particles is what we call a jet and it carries exactly the energy and momentum of the initial parton, so by reconstructing the jet in our detector we can infer these kinematic properties of the partons that we can’t directly observe.
Congratulations to Frank on his successful thesis defense on “Detailed Characterization of Jets in Heavy Ion Collisions Using Jet Fragmentation Functions”. In the fall Frank will continue his studies in Boston at the Gordon Conwell Theological Seminary.
