Pb-Glass Detector Efficiency Testing at the University of Illinios Tagged Photon Facility

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

The H_2O Jet Target

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

A Calibration of the K600 FPP from 120 to 200 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Report on CE-19: 16-O(p,n)16-F(0-) in the IUCF Cooler

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

A Measurement of the Spin Transfer Observable D_NN' for p+p Elastic Scattering at T_p = 200MeV

This research was sponsored by the National Science Fooundation Grant NSF PHY-931478

A Coincidence Measurement of D_NN' for p+p Elastic Scattering at T_p = 200 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Evaluation of Absolute Cross Sections for the p(n,d)γ Reaction at T_n = 138 Mev

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Cooler Target Development

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

The Physics of Cluster Mergers

Clusters of galaxies generally form by the gravitational merger of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. Some of the basic physical properties of mergers will be discussed, with an emphasis on simple analytic arguments rather than numerical simulations. Semi-analytic estimates of merger rates are reviewed, and a simple treatment of the kinematics of binary mergers is given. Mergers drive shocks into the intracluster medium, and these shocks heat the gas and should also accelerate nonthermal relativistic particles. X-ray observations of shocks can be used to determine the geometry and kinematics of the merger. Many clusters contain cooling flow cores; the hydrodynamical interactions of these cores with the hotter, less dense gas during mergers are discussed. As a result of particle acceleration in shocks, clusters of galaxies should contain very large populations of relativistic electrons and ions. Electrons with Lorentz factors gamma~300 (energies E = gamma m_e c^2 ~ 150 MeV) are expected to be particularly common. Observations and models for the radio, extreme ultraviolet, hard X-ray, and gamma-ray emission from nonthermal particles accelerated in these mergers are described.Comment: 38 pages with 9 embedded Postscript figures. To appear in Merging Processes in Clusters of Galaxies, edited by L. Feretti, I. M. Gioia, and G. Giovannini (Dordrecht: Kluwer), in press (2001

Observation of {sup 135}Xe with the PNNL ARSA System

The automated radioxenon sampler-analyzer (ARSA) developed by PNNL and with funding and support form the DOE NN-20 CTBT research and development program, observed 9.1-hr {sup 135}Xe in a sample of New York City air obtained on April 4th, 1997. The report below briefly describes the ARSA system and the first ever reported measurement of the short-lived {sup 135}Xe from an automated radioxenon system