Experimental Medium and High Energy Particle Physics

Our particle and nuclear faculty use a wide variety of facilities at many accelerator laboratories. Some of the specific experiments our faculty are associated with include:

Fermilab Experiments (Batavia, Illinois)

The CDF Experiment - M.Schmitt
The Collider Detector at Fermilab (CDF) experiment studies collisions of high-energy protons and anti-protons. Schmitt's group focuses on the precise measurement of electroweak processes (those which involve the W and Z bosons) as well as the search for new phenomena. They maintain a large section of the muon detector called the CMX, and are responsible for offline muon reconstruction as well.

The D0 Experiment - D. Buchholz (Emeritus), H. Schellman
The research of the D0 Experiment is focused on precise studies of the interactions between protons and anti-protons at energies of about 1.8 TeV. The aim is to search for subatomic clues that reveal the character of the building blocks of the universe. Recent work at this experiment has included the search for evidence of possible extra dimensions in the Universe, a search for the fabled Higgs boson in the decay products of top quarks, and a precision measurement of the mass of the W boson.

E815-NuTeV - D. Buchholz (Emeritus), H. Schellman
The NuTeV experiment at Fermilab sends an intense beam of high-energy neutrinos through a target where a very small number of the neutrinos interact with heavy nucleii to produce muons. The ratio of the number of muons produced to the number of neutrinos streaming through provides a very accurate measurement of how neutrinos interact with other particles. NuTeV measurements have revealed significant discrepancies between the observed nucleon-neutrino interaction and that predicted by the Standard Model of Particle Physics.

E835 - J. Rosen (Emeritus), K. Seth
E835 is an experiment which studies charmonium: this is a meson consisting of a charm quark and an anti-charm anti-quark bound together by the strong force. Different combinations of quantum numbers (e.g. spin and angular momentum) of the two bound constituents form different charmonium particle states. The study of the masses, resonance widths, and decay channels of the different states increases what we know about the strong nuclear force and tests many different theories of the strong force.

MINERvA - D. Buchholz (Emeritus), H. Schellman
MINERvA is a neutrino scattering experiment which uses the NuMI beamline at Fermilab. MINERvA seeks to measure low-energy neutrino interactions both in support of neutrino oscillation experiments and also to study the strong dynamics of the nucleon and nucleus that affect these interactions. MINERvA is currently in its final design and prototyping stages. The first detector module will be completed in late 2006 and the plan is to begin taking data in 2009.

CERN Experiments (Geneva, Switzerland)

Compact Muon Spectrometer - B. Gobbi (Emeritus), M. Schmitt, M. Velasco
The Large Hadron Collider (LHC) currently under construction at CERN will collide protons at energies seven times higher than at the Fermilab Tevatron. This machine will open up new frontiers in particle physics, with the prospects of discovering Supersymmetry, or Extra Dimensions, or new Gauge Bosons - whatever Nature has in store. The Compact Muon Spectrometer (CMS) is one of two large detector facilities, and physicists at Northwestern are working on pixel detectors, calorimetry, and the muon systems. Startup for data collection is expected in 2007.

NA48 - M. Velasco
The NA48 experiment is studying charge-parity (CP) violation in Ks and K-beams. These experiments are ultimately aimed at helping us understand the nature of the electroweak force, and in particular, its important role in solving the problem of CP violation in the early Universe: why is there more matter than anti-matter?

CLIC/CTF3 - M. Velasco
The Compact Linear Collider (CLIC ) Study is a site-independent feasibility study aimed at the development of a realistic technology at an affordable cost for an electron-positron Linear Collider in the post-LHC era for physics up to the multi-TeV center-of-mass colliding beam energy range (0.5 to 5 TeV).

Brookhaven Experiments (Brookhaven, New York)

E852 - K. Seth
The E852 experiment searches for exotic mesons -- that is, bound states which are not composed of a quark/anti-quark pair (as a meson is) or of three quarks (as a baryon is). They are composed of various combinations of quarks, anti-quarks and gluons. There are three main types of exotic mesons: glueballs, hybrids, and diquarkonium. A glueball is composed of 2-3 gluons, which the mediators of the strong force. A hybrid is a particle made up of a quark, an anti-quark, and a gluon. Diquarkonium is composed of two quarks and two anti-quarks.

Cornell Synchrotron (Ithaca, New York)

The CLEO Collaboration - K. Seth
The CLEO Collaboration is a team of over 150 physicists from 25 universities who are studying the production and decay of beauty and charm quarks and tau leptons. Using the powerful CLEO III detector, and a large data set of B mesons accumulated with the CLEO II detector, the Collaboration is making some of the most sensitive tests of the Standard Model of Particle Physics, key to understanding the fundamental structure of matter.

DESY Experiments (Hamburg, Germany)

HERA-B - J. Rosen (Emeritus)
HERA-B is a large-aperture high-rate spectrometer built for studying collisions of 920-GeV protons with the nuclei of heavy elements. The experiment is optimized to measure CP-violation in the decay of B mesons into the so-called "golden decay mode". This ambitious goal requires picking each golden-decay event out of a background of 1011 hadronic interactions at a rate of 40 million interactions per second. This required major advances in radiation-hard technologies, the development of a sophisticated first-level trigger, and the construction of the first large integrated multi-level switch-based data acquisition and high-level trigger system.

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August 26, 2013