125438498
Top quark mass measurements
The top quark, with its extraordinarily large mass (nearly that of a gold atom), plays a significant role in the phenomenology of EWSB in the Standard Model. In particular, the top quark mass when combined with the W mass constrains the mass of the as yet unobserved Higgs boson. Thus, a precise determination of the mass of the top quark is a principal goal of the CDF and D0 experiments. With the data collected thus far in Runs 1 and 2 of the Tevatron, CDF and D0 have measured the top quark mass in both the lepton+jets and dilepton decay channels using a variety of complementary experimental techniques. The author presents an overview of the most recent of the measurements.
119530771
Acceleration in the linear non-scaling fixed-field alternating-gradient accelerator EMMA
In a fixed-field alternating-gradient (FFAG) accelerator, eliminating pulsed magnet operation permits rapid acceleration to synchrotron energies, but with a much higher beam-pulse repetition rate. Conceived in the 1950s, FFAGs are enjoying renewed interest, fuelled by the need to rapidly accelerate unstable muons for future high-energy physics colliders. Until now a ‘scaling’ principle has been applied to avoid beam blow-up and loss. Removing this restriction produces a new breed of FFAG, a non-scaling variant, allowing powerful advances in machine characteristics. We report on the first non-scaling FFAG, in which orbits are compacted to within 10 mm in radius over an electron momentum range of 12–18 MeV/c. In this strictly linear-gradient FFAG, unstable beam regions are crossed, but acceleration via a novel serpentine channel is so rapid that no significant beam disruption is observed. This result has significant implications for future particle accelerators, particularly muon and high-intensity proton accelerators.
111000899
Operational experience and performance of the CDFII silicon detector
The CDFII silicon detector consists of 8 layers of double-sided silicon micro-strip sensors totaling 722,432 readout channels, making it one of the largest silicon detectors in present use by an HEP experiment. After nearly 2 years of data taking, we report on our experience operating the complex device. The performance of the CDFII silicon detector is presented and its effect on physics analyses is discussed. The CDFII silicon detector has begun to show measurable effects of radiation damage. These results and their impact on the expected lifetime of the detector are briefly reviewed.
55284518
High current, high frequency ECRIS development program for LHC havy ion beam application
A research program with the aim of producing pulsed currents with hitherto unequalled intensity of Pb 27+ , with length and repetition rate compatible with those desired by CERN (1 mAe / 400 μs / 10 Hz in the context of future heavy ion collisions at LHC) is organised in a collaboration between CERN/GSI/CEA-Grenoble and IN2P3-ISNGrenoble. Two main experimental programs will be carried out : (i) tests with the LNS-Catania team on the SERSE superconducting source with a 28 GHz gyrotron, (ii) tests on a nonsuperconducting source (new source at Grenoble) with a 28 GHz gyrotron. For this purpose CEA/DRFMC has borrowed from CEA a 28 GHz 10 kW gyrotron transmitter. The project includes also the construction of a source body, by ISNG, with conventional coils and permanent magnets for working at the frequency of about 28 GHz and biased up to 60 kV. This source called PHOENIX will run on a test bench at ISN. PHOENIX is an improvement of the present ECR4-14.5 GHz/CERN source, having a mirror ratio R=2 at 14.5 GHz, and R=1.7 at 28 GHz (possibly reaching 2.1 T on the axis of the source), and with a plasma volume up to 2.5 larger. Experiments at 28 GHz will be performed on the SERSE source in Catania at INFN/LNS where both the axial and the hexapolar fields will be varied so that the mirror ratio is continuously varied up to R=1.6 ; the SERSE source will be also operated at lower magnetic fields such as those which can be produced by conventional magnets (less than 2 T axial field at injection far from the 28 GHz High-B mode).
29994289
Acceleration and stacking of α particles in the CERN Linac, PS and ISR
The CERN Intersecting Storage Rings (ISR) have been successfully operated with sufficient α particles for experiments at total center of mass energies up to 120 GeV. Initially, the small beam currents obtainable from the (old) Linac hampered machine studies with the PS so that conclusive experiments similar to those done with deuterons were not possible. Recent attempts to increase the intensity by stripping a He+ beam at 520 keV succeeded and gave 10 mA of α particles from the Linac. Multiturn injection and acceleration in the PS produced 2×10<sup>11</sup> particles/pulse and stacking in the ISR resulted in a maximum stored beam intensity of 4.2 A at 52 GeV. After further acceleration by phase displacement in the ISR, luminosities of 4×10<sup>28</sup>cm<sup>-2</sup>s<sup>-1</sup> for α-α and 9×10<sup>29</sup>cm<sup>-2</sup>s<sup>-1</sup> for α-p experiments were obtained.
115909941
Possible cosmological origin of the ultra high energy cosmic rays
118703681
Top Quark and Electroweak Mass
We describe a class of models of electroweak symmetry breaking that involve strong dynamics and top quark condensation. A new scheme based upon a seesaw mechanism appears particularly promising. Various implications for the first-stage muon collider are discussed.
120690224
{QCD} Prediction for the Structure Functions of the Photon
We compute the unpolarized deep inelastic structure functions of the photon in an asymptotically free gauge theory, including mass effects. We show that when the momentum squared of the struck photon is small relative to the contributing quark mass, m, the free quark model prediction is obtained to O(1/ln(Q2/m2)) and (g2ln(Q2/m2)). For the light quark contribution the perturbation expansion does not converge. For large momentum squared of the struck photon the free quark model result is renormalized by a finite amount computable in QCD. For forseeable experimental ranges ofQ2 this renormalization is small.