Experimental Particle Physics

Edward C. Blucher

​Edward C. Blucher

Ph.D., Cornell, 1988.
Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics.

My current research involves studies of oscillations between different flavors of neutrinos. Recent observations of neutrino oscillations raise the exciting possibility of searching for violation of CP symmetry in the neutrino sector. The CP symmetry, which reverses left and right and changes particles into antiparticles, is thought to be necessary for understanding the striking asymmetry in the abundance of matter and antimatter in the Universe. The first step in this search is to detect the last unobserved type of neutrino flavor oscillation. Together with collaborators from France, Spain, Germany, U.K., Japan, Brazil, Russia, and the U.S., we are constructing an experiment to search for this last oscillation using neutrinos from a nuclear power station in northern France. The experiment, called Double Chooz, will begin taking data in 2009 and will run for a few years.

Our group is also completing several studies of CP violation in the neutral kaon system. Professors Wah, Winstein, and I, with a group of physicists from twelve universities, built an experiment called KTeV (Kaons at the TeVatron). The experiment collected data from 1996-2000, and established the existence of a new form of CP violation called direct CP violation. We are completing the analysis of this data sample to make the most precise measurement of direct CP violation along with many other parameters of the neutral kaon system. Our group also used the KTeV data sample to make a new measurement of the u-quark to s-quark coupling, resolving a more than 20 year old puzzle.

Selected Publications:

  • Epsilon'/Epsilon results from KTeV. E. Blucher. In proceedings of 19th International Symposium on Lepton and Photon Interactions at High Energies, Stanford, California, 1999.
  • Observation of Direct CP Violation in KS,L-->pi pi Decays. A. Alavai-Harati et al. Phys. Rev. Lett. 83, 22, 1999.
  • A Determination of the CKM parameter |V(us)|. T. Alexopoulos et al., Phys. Rev. Lett. 3, 181802, 2004.
  • Measurements of K(L) branching fractions and the CP violation parameter |eta+-|. T. Alexopoulos et al., Phys. Rev. D 70, 092006, 2004.
  • Measurements of direct CP violation, CPT symmetry, and other parameters in the neutral kaon system. A. Alavi-Harati et al., Phys. Rev. D 67, 012005, 2003.
  • Report of the APS Neutrino Study Reactor Working Group, E. Abouzaid et al. LBNL-56599, Oct 2004.
  • Status of the Cabibbo angle, E. Blucher et al., hep-ph/0512039, 2005

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Updated 1/2008

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​ Florencia Canelli

Florencia Canelli

Ph.D., University of Rochester, 2003.
Assistant Professor, Dept. of Physics, Enrico Fermi Institute, and the College; Scientist, Fermi National Accelerator Laboratory.
Experimental physics, elementary particles.
Florencia Canelli's homepage

My primary research interest is the field of high energy physics using particle accelerators. The goal of this field is to understand the fundamental constituents of matter and their interactions. I stud particles which do not exist under normal conditions in nature, but can be created in particle accelerators by colliding other particles at almost the speed of light. These particles are a window to understanding the laws that govern our universe as well as how the universe was created. My research focuses on the top quark , the most massive particle known to exist, and the Higgs boson, a particle which is expected to generate mass to other particles. My past research has been conducted at the Tevatron accelerator in Batavia, IL, and continues with higher energies and intensities at the Large Hadron Collider (LHC) in Geneva, Switzerland.

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​James W. Cronin

See Prof. Cronin's entry under Observational Astrophysics & Cosmology.

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Henry J. Frisch​Henry J. Frisch

Ph.D., California, Berkeley, 1971.
Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics.
Henry J. Frisch's homepage

Our group is looking for Supersymmetry, Large Extra Dimensions, heavy right-handed quarks, new gauge bosons corresponding to new symmetries, and other new phenomena related to explaining electro-weak symmetry breaking, flavor, and the mass hierarchy. We have a wealth of new data from the CDF detector at the Tevatron, and are scheduled to continue running (taking data) through FY2009. The advantages of working at the Tevatron are that one can move fast into new and unique data, the groups one works with directly are small, and one should be able to make a topic ones own and finish a thesis quickly. In addition, the Tevatron can explore the lighter supersymmetric mass regions and make precision mass measurements of the W and top, a precision test of the Standard Model, which may prove very difficult at the LHC.

The analyses underway in our group at present with the new data from the ongoing run of CDF are: a search for Supersymmetry via the top quark decaying into a charged Higgs boson; for heavy right-handed quarks (postulated to explain the CKM matrix); searches for new heavy bosons and quarks such as would appear in large-extra-dimensions, and for anomalies in the photon+lepton+X sample, for which the light stop squark would be a good candidate (the stau slepton is another possibility).

In addition, our group is developing picosecond electronics and detectors for the identification of charged particles and the precise measurement of photon momenta. The electronics we are developing, with the Electronics Development Group of the Institute, is more than a factor of 100 faster than typical state-of-the art in HEP. We are also exploring the application of these techniques to medical radiolical applications (PET in particular).

This latter work is a wonderful way to learn cutting-edge instrumentation in a small group. I believe strongly that we train experimentalists and not `high-energy-physicists' or any other label; with a solid grounding in techniques one should be able to move among fields to go where the most interesting questions await.

More details on the beyond-the-Standard Model exploration and the instrumentation development are available on my home page at my home page.

Selected Publications:

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Updated 10/2006

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Young-Kee Kim

​Young-Kee Kim

Ph.D., University of Rochester, 1990.
Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics.
Young-Kee Kim's homepage

My main physics interests are to understand the orgin of mass and the origin of the asymmetry between matter and anti-matter presently observed in our universe. Most of my current research is at the CDF (Collider Detector at Fermilab) experiment, a high energy physics experiment operating at the Tevatron, which brings together an international collaboration of over 800 physicists. Fermilab's Tevatron is currently the world's highest energy accelerator, colliding protons with antiprotons at a center-of-mass energy of 2 trillion volts. My group has played a major role in the detector construction and operation as well as in the data analysis from this experiment. In 1995, we, along with the sister experiment DZero, discovered the sixth and perhaps final quark, called the top quark

Toward understanding the orgin of mass, the emphasis of my research has been the studies of the W boson (carrier of weak force, responsible for radioactive decays) and the top quark, nature's heaviest quark. Through quantum corrections, accurate measurements of the mass of the top quark and the mass of the W boson provide information about the mass of the Higg boson which is responsible for giving masses to elementary particles. My most recent work is in measuring the mass of the top quark. In addition, I am pursuing properties of the bottom quark, in particular its ability to mix into its antiparticle. This is an important measurement for understanding the phenomena of the asymmetry between matter and anti-matter.

Selected Publications:

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Updated 1/2006

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Frank Merritt

​Frank S. Merritt

Ph.D., Cal. Tech., 1976.
Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics.

I am a member of the OPAL collaboration, which has been carrying out high-precision measurements of electroweak physics at the Large Electron Positron accelerator (LEP) at CERN. Measurements near the Z0 resonance (91.2 GeV) over a 5-year period have provided the most precise tests (<0.1%) of the Weinberg-Salam electroweak theory and other physics.

The LEP energy has been substantially increased over the last few years, reaching 200 GeV. This has opened up a number of new research areas, including the most sensitive search for the Higgs boson, the high-precision measurement of the W-boson mass through W+W- pair-production events, and searches for supersymmetric particles and other new physics. Our group is now working on W-mass measurements, Higgs searches, other new-particle searches, precision measurements of the tau lepton, and heavy flavor physics.

I am also a member of the Chicago/ATLAS group, now developing the hadron calorimeter to be used in the ATLAS experiment at CERN's Large Hadron Collider. This will be by far the highest-energy accelerator in the world, and will take us into new physics beyond the Standard Model: supersymmetric particles, technicolor, and/or unexplained new phenomena. The Chicago group's major software effort focused initially on analysis of calorimeter test-beam data, and now on development of the analysis system and code for ATLAS data analysis.

Selected Publications:

  • Precise Determination of the Z Resonance Parameters at LEP: Zedometry. G. Abbiendi et al. Eur. Phys. J. C19, 587, 2001.
  • Search for the Standard Model Higgs Boson in e+e- Collisions at sqrt(s)=192-209 GeV. G. Abbiendi et al. Phys. Lett. B499, 38, 2001.
  • Two Higgs Doublet Model and Model Independent Interpretation of Neutral Higgs Boson Searches. G. Abbiendi et al. Eur. Phys. J. C18, 425, 2001.
  • A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model. CERN-EP-2001-021.
  • Measurement of the Mass and Width of the W Boson in e+e- Collisions at 189 GeV. G. Abbiendi et al. Phys. Lett. B. 507, 29, 2001.
  • A Measurement of the Rate of Charm Production in W Decays. G. Abbiendi et al. Phys. Lett. B490, 71, 2000.
  • Photonic Events with Missing Energy in e+e- Collisions at sqrt(s) = 189 GeV. Eur. Phys. J. C18, 253, 2000.
  • Search for Higgs Bosons and New Particles Decaying into Two Photons at srqt(s) = 183 GeV. The OPAL Collaboration. K. Ackerstaff et al. Phys. Lett. B437, 218, 1998.

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Updated 5/2001

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Piermaria Oddone​

Piermaria Oddone

Ph.D., Princeton, 1970.
Director, Fermi National Accelerator Laboratory, Professor (part-time), Enrico Fermi Institute and Dept. of Physics.
Experimental physics, elementary particles.

Professor Oddone's research has been in experimental particle physics and based primarily on electron-positron colliders at the Stanford Linear Accelerator Center (SLAC). He invented the Asymmetric B-Factory, a new kind of elementary particle collider to study the differences between matter and antimatter, and worked in the development of the PEP II Asymmetric B-Factory at SLAC (a second one was built in Tsukuba, Japan) and the formation of the large international collaboration, BaBar, to exploit its physics opportunities. Together with the Belle detector in Japan, BaBar discovered the violation of matter-antimatter symmetry in the decay of particles containing the b quark. Hundreds of researchers have used the B-Factories over the last decade, developing a precise understanding of the quark model.

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Updated 6/2008

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Mark J. Oreglia​Mark J. Oreglia

Ph.D., Stanford University, 1981.
Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics, gamma-ray astronomy.
Mark J. Oreglia's homepage

I am a member of the ATLAS experiment at CERN, and this will be the main focus of my work for the foreseeable future. My main interest is the search for new physics, particularly alternative models to the minimal Standard Model or minimal supersymmetric SM. This continues my work on searches for SM and exotic Higgs bosons at LEP.

In addition to my ATLAS activities, I am involved in planning and detector R&D for the International Linear Collider (see the GDE site). I am co-spokesperson of the American Linear Collider Physics Group (url) and a member of the CALICE R&D collaboration as well as the SiD detector concept.  To achieve the physics potential of ILC, there is must work to do in order to advance the state of the art for detector systems, particularly the concept of “particle energy flow”.

Selected Publications:

  • S. Dawson and M. Oreglia, “Physics opportunities with a TeV linear collider,” Ann. Rev. Nuci. Part. Sci. 2004 54:269 [arXiv:hep-ph/0403015].
  • M. J. Oreglia et al., “Design Considerations for an International Linear Collider", http://blueox.uoregon.edu/ lc/scope.ps, (2003).
  • The LEP Working Group for Higgs Boson Searches, “Search for Neutral MSSM Higgs Bosons at LEP”, Eur. Phys. J. C 47 (2006) [hep-ex/0602042].
  • G. Abbiendi et al., “Flavor Independent H0A0 Search and two Higgs Doublet Model Interpretation of Neutral Higgs Boson Searches at LEP”, Eur.Phys.J.C40:317-332,2005. [HEP-EX 0408097]
  • G. Abbiendi et al. [OPAL Collaboration], \Search for associated production of massive states decaying into two photons in e+ e- annihilations at s**(1/2) = 88-GeV - 209-GeV," Phys. Lett. B 544 (2002) 44 [arXiv:hep-ex/0207027].
  • G. Abbiendi et al. [OPAL Collaboration],Search for the Standard Model Higgs Boson in e+e- Collisions at SQRT(s) = 192-209 GeV. Phys. Lett. B499, 38, 2001.
  • A Feasibility Study of a Neutrino Source Based on a Muon Storage Ring, N. Holtkamp et al. FERMILAB-PUB-00-108-E.
  • Beam Test of Gammy-ray Large Area Space Telescope Components, W. Atwood et al. Nucl. Instrm. Meth. A446, 444, 2000.

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James Pilcher​James E. Pilcher

Ph.D., Princeton, 1968.
Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics.

My research involves studying nature at the shortest possible distances and highest energy densities. I have been engaged for several years in the preparation of the ATLAS experiment for the CERN Large Hadron Collider. This facility will enable the study of proton-proton collisions at a center of mass energy of 14 TeV or seven times that of earlier work. It will allow us to probe the source of electroweak symmetry breaking, and perhaps to understand why the Higgs boson is as light as the precision electroweak data predicts. The facility also has the potential to produce forms of matter never before observed. These include supersymmetric states, dark matter, heavy gauge bosons, and mini black holes. Some of these experimental signatures could also be associated with extra dimensions.

Our research group is closely involved in the preparation of the calorimeter of the ATLAS detector. This device measures the direction and energy of final state quarks and gluons and hence plays an essential role in the search for final states with apparent missing energy.

My earlier work involved high precision studies of the electroweak interaction using the OPAL experiment at the LEP e+e- collider. We measured the mass of the W boson to a precision of 0.06% to put new constraints on the electroweak theory and its prediction of the Higgs boson mass. We also made precise measurements of the Z boson total width and its decay rates to quarks and leptons. These results provided important additional tests of the theory.

Selected Publications:

  • Measurement of the Mass and Width of the W Boson, G. Abbiendi et al., Euro. Phys. Journal C45, 307 (2006).
  • Precision Electroweak Measurements on the Z Resonance, The LEP Collaborations, Phys. Reports 427, 5 (2006).
  • Design of the front-end analog electronics for the ATLAS tile calorimeter, K. Anderson et al., Nucl. Instr. and Meth. A551, 469 (2005).
  • Search for the Standard Model Higgs Boson with the OPAL Detector at LEP, G. Abbiendi et al., Euro. Phys. Journal C26, 479 (2003).
  • Precise Determination of the Z Resonance Parameters at LEP: Zedometry. G. Abbiendi et al. Eur. Phys. J. C19, 587, 2001.
  • Search for the Standard Model Higgs Boson in e+e- Collisions at sqrt(s)=192-209 GeV. G. Abbiendi et al. Phys. Lett. B499, 38, 2001.
  • Two Higgs Doublet Model and Model Independent Interpretation of Neutral Higgs Boson Searches. G. Abbiendi et al. Eur. Phys. J. C18, 425, 2001.
  • Results from a New Combined Test of an Electromagnetic Liquid Argon Calorimeter with a Hadronic Scintillating-Tile Calorimeter, S. Akhmadaliev et al., Nucl. Instr. and Meth. A449, 461 (2000).
  • A Measurement of the Rate of Charm Production in W Decays. G. Abbiendi et al. Phys. Lett. B490, 71, 2000.

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Updated 8/2007

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Melvyn Shochet

​Melvyn J. Shochet

Ph.D., Princeton, 1972.
Elaine M. and Samuel D. Kersten, Jr. Distinguished Service Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics.
Melvyn J. Shochet's homepage

My research involves interactions between elementary particles at the highest manmade energies. For many years, this has been carried out with the Collider Detector at Fermilab (CDF), a massive detector that we built to study collisions between 1000 GeV protons and 1000 GeV antiprotons. With the large accumulated data sample, we have studied the strong and electroweak interactions and searched for new phenomena. Our most important result is the discovery of the top quark and the determination of its mass. Our latest top-quark mass measurement, which employs a new technique for significantly reducing the major systematic uncertainty, is (173.4 +/- 2.8) GeV, by far the most precise measurement of the mass of any quark. From this value, one can calculate the top quark's Yukawa coupling constant, the strength of its interaction with the Higgs Boson, the source of an elementary particle's mass. The Yukawa coupling constant for the top quark is 0.996 +/- 0.016, consistent with 1. This coupling to the source of mass is strong, unlike that of any other elementary particle, making it plausible that the top quark plays a special role in physics.

My group is now working on the ATLAS experiment at the CERN Large Hadron Collider (LHC), which will produce collisions 7 times more energetic than those at Fermilab. Our focus is an upgrade to the trigger, which selects interesting collisions in real time for later study. Hadron collider experiments can efficiently and quickly select events that contain electrons, muons, or generic hadron jets. However it is much more difficult to identify heavy elementary particles, the bottom quark and tau lepton, because of very large backgrounds. The new phenomena that should appear at the LHC will likely be characterized by the creation of heavy particles. This makes triggering on bottom quarks and tau leptons a priority. We are designing a set of trigger electronics boards that can identify these objects more than an order of magnitude faster than can otherwise be done. This device is based on the very successful Silicon Vertex Trigger (SVT) that we and our Italian colleagues built for CDF.

Selected Publications:

  • Evidence for Top Quark Production in pbar-p Collisions at SQRT(s) = 1.8 TeV. The CDF Collaboration. Phys. Rev. Lett. 73, 225, 1994; also Phys. Rev. D 50, 2966, 1994.
  • Observation of Top Quark Production in pbar-p Collisions with the CDF Detector at Fermilab. The CDF Collaboration. Phys. Rev. Lett. 74, 2626, 1995.
  • Search for Long-Lived Parents of Z Bosons in p-pbar Collisions at SQRT(s) = 1.8 TeV. The CDF Collaboration. Phys. Rev. D 58, 051102, 1998.
  • The Top Quark. In The Particle Century, ed. by G. Fraser, Institute of Physics Publishing, 1998.
  • Measurement of the t-tbar Production Cross Section in p-pbar Collisions at SQRT(s) = 1.96 TeV Using Kinematic Fitting of b-tagged Lepton + Jet Events. The CDF Collaboration. Phys. Rev. D 71, 072005 (2005).
  • Precision Top Quark Mass Measurement in the Lepton + Jets Topology in p-pbar Collisions at SQRT(s) = 1.96 TeV, the CDF Collaboration, Phys. Rev. Lett. 96, 022004 (2006).
  • Measurement of the B0s-B0sbar Oscillation Frequency, the CDF Collaboration, submitted to Phys. Rev. Lett. (June, 2006), hep-ex/0606027.

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Updated 10/2006

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Yau W. Wah

​Yau W. Wah

Ph.D., Yale, 1983.
Professor, Dept. of Physics, Enrico Fermi Institute, and the College.
Experimental physics, particle physics.
Yau W. Wah's homepage

My current research primarily focuses on the measurement of the branching ratio of a very special rare kaon decay, a k-long particle decays into a neutral pion and two neutrinos (so called the "golden" mode). This decay mode provides the cleanest and best answer to the question of CP violation in elementary particle physics that the theoretical calculation (prediction) within the so called Standard Model is unambiguous and precise. Therefore no matter what the measurement result is, standard or non-standard; it will be most fascinating.

The experimental pursuit of this measurement started in 1990 with a Chicago undergraduate, Greg Graham who wrote a senior thesis on the first measurement of this decay mode using data from a dedicated rare kaon decay (Experiment E799 at Fermilab, proposed in 1988, data taking in 1990-91). Since then, follow up experiment KTeV/E799-II (proposed 1993, data taking 1996-97 and 1999-2000) improved the limit with basically the same technique. The KTeV detector had the highest sensitivities for many decay modes that the current knowledge about neutral kaon decays are mostly from KTeV results.

Experiment E391a at KEK (Japan High Energy Accelerator Laboratory) is designed and built to measure the "golden" mode. Our group joined E391a in 2001, and is responsible to build the front-plug and back-plug calorimeters. This experiment is a pilot to get within reach of Standard Model sensitivity and also provides comprehensive background checks and understanding. Data taking will start in early 2004, and we expect many results by end of 2004. This experiment is an important step to a possible new experiment at JPARC (Japan Physics and Accelerator Research Complex, aka JHF) in 2006. This new accelerator is expected to be online in 2006. Currently a letter of intent to measure a thousand "golden" mode events has been submitted, and a formal proposal will follow soon.

Much R&D on detector technology has been done and will continue for the JPARC experiment, and our group here in Chicago has a large involvement. We have develop many new techniques for the purpose.

My other interest includes experiment to study nonlinear phenomena, and we have so far a very active participation of dedicated undergraduates. Below is a partial listing of papers published as Chicago PhD thesis, undergraduate senior thesis, and the "golden" mode.

Selected Publications:

  • A Search for the Decay K-long to Neutral Pion and two Neutrinos, G. Graham et al., Phys. Lett. B295, 169, 1992.
  • A Measurement of the Branching Ratio of Neutral Pion to Electron Positron pair from the Neutral Pions Produced by K-long decays to three Neutral Pions in Flight, K.S. McFarland et al., Phys. Rev. Lett. 71, 31, 1993.
  • A Limit on the Branching Ratio of K-long to Neutral Pion and Electron Positron pair. D.A. Harris et al., Phys. Rev. Lett. 71, 3918, 1993.
  • A Limit on the Lepton-Family Number Violating Process Neutral Pions decays to Muon and Electron, P. Krolak et al., Phys. Rev. Lett. B320, 407, 1994.
  • Search for Lepton-Family Violating Decays K-long to Neutral Pion and Muon and Electron, K. Arisaka et al., Phys. Lett. B 432, 230, 1998.
  • Search for the Decay Decay K-long to Neutral Pion and two Neutrinos, J. Adams et al.,Phys. Rev. Lett. B 447, 240, 1999.
  • Measurement of the Branching Ratio of Neutral Pion to Electron Positron pair using K-long to three Neutral Pions Decays in Flight, A.Alavi-Harati et al. Phys. Rev. Lett. 83, 922, 1999.
  • Search for the Decay K-long to Neutral Pion and two Neutrinos using Neutral Pion Electron Dalitz Decay, A.Alavi-Harati et al. Phys. Rev. D61 072006-072010, 2000.
  • First Observation of the Decay K-long to Neutral Pion and Electron Positron Pair and Gamma. A. Alavi-Harati et al., Phys. Rev. Lett. 87, 021801, 2001.
  • Measurement of the Branching Ratio and Form Factor of Muonic Dalitz Decay of K-long, A. Alavi-Harati et al., Phys. Rev. Lett. 87, 071801, 2001.

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Updated 3/2003

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​Bruce D. Winstein

See Prof. Winstein's entry under Observational Astrophysics & Cosmology.

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