Particle Experiment

Particle physics, also called "high energy physics," is the study of the fundamental particles and their interactions. To explore such particles at the requisite subatomic distance scales requires particles with high energies, and most experiments use particle accelerators to produce them. According to our current understanding, embodied in a model known as the Standard Model, the true elementary particles - the building blocks of matter as we know it - are quarks and leptons. They interact through four types of forces - Strong, Electromagnetic, Weak, and Gravitational (although the gravitational force has not yet been incorporated into the model). Quarks interact strongly -- neutrons, protons, mesons and hyperons are some of the more familiar particles containing them, called hadrons. Leptons are not susceptible to the strong force (we say they have a "strong charge" of zero), and include electrons, muons, tau's, with an associated neutrino for each.

The experimental particle physics group at the University of Cincinnati consists of five faculty members, who conduct several programs at accelerators, in collaborative experiments with other institutions around the world. The group has local facilities to build and test detector concepts. Software is developed both locally and on-site. Faculty, postdoctoral fellows, and students travel frequently to remote accelerator labs to collect and analyze data.

Professor Kinoshita's research interests center on fundamental physics: the form and strength of the interaction forces in nature and the properties of the particles that participate in these interactions. In particular, the so-called Weak Interaction has so far been unique in displaying intriguing violations in particle-antiparticle symmetry that may parallel the dominance of matter over antimatter in the universe. Of the six known quarks, the fourth and fifth (in increasing order of mass), c (charm) and b (beauty), have been especially fruitful subjects of study in this regard. Professor Kinoshita has focused her research on particles containing the b-quark, most recently with the Belle/Belle II experiment at the KEK accelerator facility in Japan. Her election in 2000 as a Fellow of the American Physical Society recognized her highly original work in this field.

Professor Schwartz studies weak interactions of heavy B and D mesons. His studies focus on measurements of quark-antiquark mixing and CP violation. He collaborates on the Belle and Belle II experiments that run at the KEK laboratory in Japan. His group has analyzed B0→π+π- and B0→ρ+ρ- decays, measuring the CKM weak phase φ2, and Bs→Ds(*)Ds(*) decays, measuring the Bs-Bs oscillation parameter ΔΓ. Prof. Schwartz is co-leader of the Heavy Flavors Averaging Group, which is responsible for calculating world averages of fundamental parameters of heavy quark systems. For this group Prof. Schwartz calculates world average values of D0-D0 mixing and CP violation parameters using a global fit to over three dozen measured observables. Prof. Schwartz is also involved in the upgrade of the Belle detector to be used for the future Belle II experiment. This experiment is scheduled to begin taking data in 2016. For this upgrade Prof. Schwartz works on the barrel particle identification system, which uses Cherenkov radiation generated in quartz bars to discriminate among different particle types, e.g., pions and kaons. He has built a small prototype of this type of detector in his laboratory at UC. In 2008 Prof. Schwartz was elected a fellow of the American Physical Society.

Professors Mike Sokoloff and Brian Meadows(retired on May 1, 2016) primarily study the interactions between weak forces that govern decays involving "heavy" quarks with exotic "flavors" (charm and beauty) into those with flavors that are manifest in "ordinary" atomic and nuclear matter. Such interactions take place over tiny distance scales (of order one thousandth of a proton radius) and correspondingly short time periods. They are followed by "long range" strong interactions which produce the decay products observed experimentally. Quantum mechanical interference effects produce time-dependent asymmetries in the decay rates of particles and their corresponding antiparticles. These variations allow measurements of weak interaction phases. A major goal of the research is to understand the extent to which these weak phases can be understood in terms of known physics (the Standard Model of particle physics) and the extent to which new physics (Physics Beyond the Standard Model) is required. The data they analyze presently come from the BaBar experiment at the SLAC National Laboratory, in California, and the LHCb experiment at CERN, in Switzerland. They also study the detailed properties of particles containing heavy quarks.

Professor Randy Johnson's research centers on neutrino interactions. He is presently participating in the MiniBooNE and MicroBooNE experiments at Fermilab and the Daya Bay Neutrino Experiment in China outside of Hong Kong. MiniBooNE is an experiment that is running at Fermilab that was designed to confirm or refute the evidence for a sterile neutrino originally seen by the LSND experiment at Los Alamos. The experiment seemed to refute LSND originally when running with a neutrino beam, but recently seems to confirm the result in antineutrino running (LSND is an antineutrino experiment). Data taking continues with this experiment. MicroBooNE is an experiment at Fermilab that will place a liquid argon time projection chamber in the same beamline as MiniBooNE. There it can both demonstrate the liquid argon technology and follow on MiniBooNE in testing the LSND result. The Daya Bay Neutrino Experiment is located at the Daya Bay Nuclear power plant in China. The experiment uses the plant as an intense source of electron anitneutrinos. In the mountains behind the plant, we have placed an arrange of antineutrino detectors. With these, we will be able to measure the disappearance probability of electron antineutrinos and, from that, the magnitude of the one unmeasured missing angle, θ13, in the neutrino sector.

Professor Alex Sousa's research is focused on searches for new neutrino phenomena and precision measurements of the neutrino properties. He is participating in the NOνA and MINOS+ long-baseline experiments at Fermilab and northern Minnesota. The NOνA experiment will use the World's most powerful neutrino beam in operation, the NuMI beam created at Fermilab, and a 14 kton PVC+liquid scintillator far detector 500 miles away in Ash River, Minnesota, to study neutrino flavor oscillations. NOνA will make precise measurements of the neutrino oscillation parameters Δm232, θ23, and θ13. NOνA is also the only experiment running over the next decade that will be able to determine the spectrum of the masses of the three known neutrinos and one of the few experiments that will look for CP violation in the neutrino sector. Establishing neutrinos violate CP conservation would be a crucial step in resolving the matter-antimatter asymmetry observed in the present Universe, still the major unsolved puzzle in our understanding of Universe evolution. Along with contributions to development of NOνA's simulated data and analyses, Prof. Sousa is leading an effort to expose a NOνA prototype detector to a test beam to precisely calibrate the NOνA detectors. NOνA will start taking data in 2013 and completion of the far detector construction is projected by the end of 2014. MINOS+ will measure the same NuMI beam as NOνA with a 5.4 kton steel/solid scintillator far detector located 2300 ft underground at the Soudan mine, in northern Minnesota. As the MINOS+ physics coordinator, Prof. Sousa will be leading the overall analysis efforts of the experiment, with particular interest on the search for a new fourth neutrino type that does not couple to weak interactions, a sterile neutrino. If no evidence for a sterile neutrino is found, MINOS+ can exclude most of the region of parameter space where a signal was observed by the LSND and MiniBooNE experiments. During NOνA assembly, MINOS+ will further improve its World-leading measurement of Δm232. Furthermore, MINOS+ will search for or constrain exotic phenomena, such as extra-dimensions or new interactions between particles not predicted by the standard model. MINOS+ will resume data taking in the Spring of 2013.