A lively area of experimental work in the department is High Energy Physics.
This area includes both experiments studying particle physics at accelerators
and experiments studying the new area of astroparticle physics. Eight faculty
members supervise efforts involving roughly forty people (physicists, technical
and clerical staff, graduate and undergraduate students) in a wide spectrum of
elementary particle investigations. These efforts are well supported by the
National Science Foundation, the Department of Energy and the University, and
they have had considerable success in obtaining precious beam time at large
accelerator facilities. At
Professors Eva Halkiadakis, Amit Lath, Steve Schnetzer and Sunil Somalwar
We are members of the Compact Muon Solenoid (CMS) Experiment, one of two
large detector facilities being built for the Large Hadron Collider (LHC) under
construction at the CERN laboratory near
Our group at
In the area of detector hardware and construction, our group has played a
leading role in designing custom, radiation-hard, deep sub micron electronics
for the readout of the CMS pixel detector. We are currently working on an
exciting new proposal that we recently made for building a luminosity monitor
for CMS based on diamond pixel telescopes. This device will measure the
bunch-by-bunch luminosity, intensity of the collisions, to a precision of about
1% while also monitoring the location of the collision point. Both of these are
important inputs needed for many of the physics measurements. The luminosity
monitor utilizes two advanced detector developments that our group has
extensive expertise in, pixels and radiation-hard diamond sensors. We plan to
construct the luminosity monitor at
Professors Douglas Bergman and Gordon Thomson
We are working on the High Resolution Fly's Eye Experiment (HiRes), which has the aim of studying the highest energy cosmic rays. In the energy range of our experiment there are several important physics and astrophysics topics to study.
The transition between cosmic rays of galactic origin to extragalactic occurs here. We observe this transition through composition change: the highest energy galactic cosmic rays should be heavy nuclei (e.g., iron) and extragalactic cosmic rays should be almost all protons.
Interactions between cosmic ray particles and photons of the cosmic microwave background radiation form two energy-loss mechanisms for cosmic rays. Pion production limits protons which have traveled more than 50 Megaparsecs across intergalactic space to an energy lower than about 6*10**19 electron Volts. This produces the so-called GZK cutoff above this energy. Electron-positron pair production is a somewhat weaker energy loss mechanism. It nevertheless produces a dip in the cosmic ray spectrum. Our experiment sees both of these features.
But important questions remain. The origin of the highest energy cosmic rays is a mystery. Known sources should produce cosmic rays no higher in energy than about 10**19 eV, whereas events over 10**20 eV have been seen.
The nature of the sources is not known. Active galactic nuclei, quasistellar objects, and gamma ray bursts are possibilities, and much work is being done searching for anisotropy (both point sources and extended sources) in the cosmic rays.
The HiRes experiment is located atop two desert mountains in west central
Our group consists of two faculty, three postdoctoral research fellows,
three graduate students and several undergraduates, and we are collaborating
with several other universities in the
We are planning a future experiment that will have much greater capabilities
than HiRes. This is called the Telescope Array Experiment (TA). It will also be
Professors Thomas Devlin (Emeritus), Eva Halkiadakis, Amit Lath, Sunil Somalwar, and Terence Watts (Emeritus)
The Tevatron is poised to collect enough data to either find the mechanism that breaks electroweak symmetry -- which makes the W and Z bosons heavy while leaving the photon massless -- or severely constrain most models of this phenomenon. Most such models invoke one or more "Higgs bosons" as well as supersymmetric (SUSY) particles that are heavier partners of known quarks, leptons and bosons. These phenomena have yet to be verified by experiment.
The Rutgers CDF group is deeply involved in searches for such new phenomena, including those for SUSY particles and Higgs bosons. Our group has implemented or improved analysis techniques for many of these searches. Members of our group have worked on identification of tau leptons and b-quark decays for Higgs searches. We have studied low energy electrons and muons that can arise from decays of possible supersymmetric particles. We work closely with theorists to refine our searches and create new analyses as understanding of models of new physics grows.
The CDF experiment offers many other fascinating research topics. Although the top quark has been discovered, its properties (such as mass and couplings to other particles) remain poorly understood. CDF will collect thousands of top quarks and detailed study may well find this heaviest of Standard Model particles is affected by new physics. CDF is also poised to collect a large sample of particles containing b-quarks. In addition to searches for new phenomena, these particles can be used to study b-quark couplings, which may reveal new physics. Several other topics, such as precision measurements of W and Z boson masses and asymmetries, searches for quark substructure in jet events, and many others are available to students willing to work with the CDF Rutgers group.
Students, both undergraduate and graduate, have always been a key part of
the high energy physics effort at
Prof. Devlin is analyzing data from CDF to understand the mechanism responsible for polarization of Lambda hyperons. When this is complete, his research efforts will be devoted to astrophysics.
Professors Mohan Kalelkar and Richard Plano (Emeritus)
We are nearly finished with the analysis of data from an experiment called SLD at the Stanford Linear Collider, studying electron-positron interactions at 91 GeV, the mass of the neutral weak boson Z. A unique feature of our experiment is longitudinal polarization of the electron beam. We have published the world's best measurement of the weak mixing angle, a crucial parameter of the Standard Model, as well as the world's best measurement of the parity-violating coupling of the Z to the s-quark. Our graduate students have written PhD theses on hadron production in Z decays into quarks of different flavors, observing large flavor dependencies that permitted sensitive tests of QCD fragmentation models.
Revised May, 2008