28671836
Alignment and Steering for Injection and Multi-Turn Operation of the University of Maryland Electron Ring (UMER)
The injection line and main lattice for the University of Maryland Electron Ring (UMER) has been completed. The electron beam has completed more than three full turns of the ring. Beam steering and matching in the injection line are achieved with six quadrupole magnets and several small steering dipole magnets. The dipole component of an offset quadrupole and a pulsed dipole are combined to achieve the 10 degree bend required from the injection line into the ring. The pulsed dipole is designed to operate with a short pulse (2 kV, - 30 A, 100 ns flat top duration) for injection superimposed on a long pulse (300 V, 15 A, 20e-6 s duration) for multiple beam passes. The beam is controlled in the recirculating ring with a regular lattice of 35 dipole and 72 quadrupole magnets. Initial experimental results of the beam transport and control are presented.
119603668
Tomography as a diagnostic tool for phase space mapping of intense particle beams
A technique is described for the tomographic mapping of transverse phase space in beams with space charge. Most prior studies where performed at high energy where space charge was negligible and therefore not considered in the analysis. The tomographic reconstruction process is compared with results of simulations using the particle-in-cell code WARP. The new tomographic technique is tested for beams with different intensities (both emittance and space-charge dominated), and with different initial distributions. Effects of various errors in the data collection process on the reconstructed phase space are discussed. It is shown that the crucial factor is not necessarily the number of projections but the range of angles over which the projections are taken. This study also includes a number of experimental results on tomographic phase space mapping performed on the University of Maryland Electron Ring.
126136900
Threshold Measurement of the Reaction $\bar{p} p \to \bar{\ell}$ambda $\lambda$ at {LEAR}
122841402
Energy analyzer experiments for the University of Maryland electron ring
The University of Maryland electron ring (UMER) experiment, currently under construction, will be used to investigate the dynamics of space charge dominated low energy (10 keV) electron beams. One point of interest is the energy distribution in the beam. We use an energy analyzer of cylindrical geometry to determine the longitudinal energy of the electron beam. The data can be resolved temporally, which gives an indication of the axial energy distribution in the beamlets. We also have the capability of scanning the beam in the transverse direction so that a lateral distribution of the longitudinal energy may be determined. We present results of energy spread measurements from the injector region of UMER under various conditions. Later efforts will include the effects of bending on the energy spread in the beam.
29456018
Electromagnetic excitation of the delta resonance in nuclei.
Inclusive cross sections for the proton and nuclear targets of A = 4, 9, 12, and 16 were measured for 537 and 730 MeV electrons scattered at 37.1 deg. Systematic features of the continuum scattering data are compared with other electron scattering data and with photoabsorption measurements. A model calculation based on the isobar-hole formalism is compared with the data in the delta resonance region.
9813062
Space-charge-dominated phenomena in the UMER source region
For space-charge-dominated beams, details of the beam distribution as it emerges from the source region can strongly influence beam evolution well downstream. This occurs because collective space-charge modes, excited as the beam is born, can remain undamped for many focusing periods. Nevertheless, traditional studies of the source region in particle beam systems have emphasized the behavior of averaged beam characteristics such as total current, rms beam size, or emittance, rather than the details of the full beam distribution function that are necessary to predict the excitation of any collective space-charge modes. Simulations of the source region using the particle-in-cell WARP code along with detailed comparisons to experimental measurements of the beam in the University of Maryland Electron Ring (UMER) are therefore being employed to understand the complex behavior that has been observed in the source region, including a surprising sensitivity of the beam evolution to details of the transverse velocity distribution.
122467530
Measurement of the KL--> mu+mu-gamma Branching Ratio and Form Factor From KTeV
118474620
Studies of single top quark production at the Tevatron
In this paper we present several measurements of single top quark production from the CDF and D0 experiments at the Tevatron. The various analyses utilize integrated luminosity ranging from 2.1 to 4.8 fb{sup -1}. The results include the observation of single top production with a combined cross section of 2.76{sub -0.47}{sup +0.58} pb for a top quark mass of 170 GeV/c{sup 2}, as well as measurements of top quark polarization and first evidence for t-channel production.
119115234
Z Boson Asymmetry Measurements at the Tevatron
We present measurements of the forward-backward asymmetry (A_fb) in dilepton pair decays of Z bosons produced in ppbar collisions using the full Tevatron dataset. The CDF experiment extracts a value for the effective weak mixing angle parameter sin^{2}\theta^{l}_{eff} of 0.2315 +/- 0.0010 from the A_fb distribution of dimuon events in 9.2 fb^{-1} of integrated luminosity. From dielectron events in 9.7 fb^{-1} of data, the D0 experiment finds sin^{2}\theta^{l}_{eff} = 0.23106 +/- 0.00053, the world's most precise measurement of sin^{2}\theta^{l}_{eff} from hadron colliders and with light quark couplings.
108516447
Carbon fiber grounding in the D0 Run IIb silicon detector design
Abstract Carbon fiber support structures have become common elements of silicon detector designs. While the use of carbon fiber solves a variety of mechanical problems, it presents a challenging set of electrical concerns. Well-designed coupling and grounding schemes are essential for producing low-noise environments within the detectors. General principles involved in grounding systems with carbon fiber structures are described, as well as specific applications to the D0 Run IIb silicon detector.