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.
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.
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.
119863690
RMS envelope matching of electron beams from 'zero' current to extreme space charge in a fixed lattice of short magnets
We present detailed calculations of RMS-envelope matching over a broad range of beam intensities for the University of Maryland Electron Ring (UMER). Containment of beams from zero current to extreme space charge, all without changing the strength of external focusing in the periodic lattice, is possible thanks to the high density of quadrupoles in UMER. In turn, the small-aspect ratio of the UMER magnets results in gradient or field profiles that are ``all edges,'' thus requiring special treatment when constructing accurate hard-edge models. Further, the results of matching calculations, for both symmetric and asymmetric FODO (alternating gradient) schemes, are compared with calculations from simple general expressions valid in the uniform-focusing approximation of the periodic lattice. Finally, some aspects of the source-to-FODO matching calculation/optimization problem are discussed, together with sensitivity studies of the matching solutions under realistic conditions. The examples from the UMER project, which include experimental results, emphasize the practical aspects of beam envelope matching.
111239993
MODELING AND EXPERIMENTS ON INJECTION INTO UNIVERSITY OF MARYLAND ELECTRON RING
The University of Maryland Electron Ring (UMER) is built as a low‐cost testbed for intense beam physics for benefit of larger ion accelerators. The beam intensity is designed to be variable, spanning the entire range from low current operation to highly space‐charge‐dominated transport. The ring has been closed and multi‐turn commissioning has begun. One of the biggest challenges of multi‐turn operation of UMER is correctly operating the Y‐shaped injection/recirculation section, which is specially designed for UMER multi‐turn operation. It is a challenge because the system requires several quadrupoles and dipoles in a very stringent space, resulting in mechanical, electrical, and beam control complexities. Also, the Earth’s magnetic field and the image charge effects have to be investigated because they are strong enough to impact the beam centroid motion. This paper presents both simulation and experimental study of the beam centroid motion in the injection region to address above issues.
123447930
Evidence for a strongly bound kaonic system K ppn in the 4 He(stopped K ,n) reaction
We measured a neutron energy spectrum by means of time-of-flight (TOF) from the 4 He(K − stopped ,n) reaction by stopping negative kaons in a super-fluid helium target. A distinct peak was observed in the neutron spectrum, indicating the formation of a strongly bound kaonic system, K − ppn, with the binding energy and width, BKppn = 173 ± 4 MeV and Kppn . 25 MeV, respectively.
36812204
Injector Electronics for Multi-Turn Operation of the University of Maryland Electron Ring
Progress is described toward the development of pulse generators required for injection and extraction of the University of Maryland Electron Ring (UMER). The geometry, described elsewhere, employs a fast ironless dipole at the junction of a Y-shaped section of the ring. The dipole as developed has an inductance of 600nH. The required +21 A long pulse generator for multi-turn operation is installed. The first prototype pulse generator, providing –42 A for deflection of the beam in the opposite sense, has been installed on the beam line and tested. Successful multiple beam laps have been observed.