113925183
Factors Affecting H- Beam Performance in the Fermilab Linac
119968235
Direct current surface plasma source with high emission current density
A surface plasma source for long-time dc operation with efficient production of negative ions and high emission current density has been designed and tested. Several modifications of the discharge system, beam extraction, cesium supply, and source design have been tested for long-time operation. The emission current density of H− ions has been increased to j=1 A/cm2 in the dc mode of operation with a discharge voltage, Ud=80 V; a discharge current, Id=0.9 A and a discharge power, P=70 W. Corresponding efficiency of the current density production S=j/P=15 A/cm2 kW is much higher than in modern positive ion sources. Source features determining an operational lifetime will be discussed.
25489712
The AGS Fast Kicker Magnet System
A new fast extraction system from the AGS will be implemented to improve the neutrino beam and to serve for ISABELLE injection. The fast kicker for the system is of an open C-type design with a field strength of 1.25 kG at 2650 amperes. The pulser system is a mismatched, discharge type PFN which is capable of delivering a pulse of 3000 amperes peak current at 30 kV d.c., with a 2.7 ¿sec pulse width, 170 nsec rise time, and flat top ripple within ± 1%. It also serves as a prototype for an ISA injection magnet, and is to be operated in UHV in the 10-11 Torr range. Special measures to achieve this goal are also discussed.
54638822
Performance of the Fermilab's 4.3 MeV electron cooler
A 4.3 MeV DC electron beam is used to cool longitudinally an antiproton beam in the Fermilab's Recycler ring. Cooling capabilities of the electron beam are characterized by the drag rate that was measured at various conditions. Fitting the results with a formula for non-magnetized cooling gives electron parameters that agree within a factor of 2 with independently measured electron beam properties.
723137
Status of the Fermilab electron cooling project
The first stage of the Fermilab Electron Cooling R&D program is now complete: technology necessary to generate hundreds of milliamps of electron beam current at MeV energies has been demonstrated. Conceptual design studies show that with an electron beam current of 200 mA and with a cooling section of 20 m electron cooling in the Fermilab Recycler ring can provide antiproton stacking rates suitable for the Tevatron upgrades beyond Run II luminosity goals. A prototype of such an electron cooling system is now being built at Fermilab as part of the continuing R&D program. This paper describes the electron cooling system design as well as the status of the Fermilab electron cooling R&D program.
122794487
Status of the Fermilab electron cooling project
Abstract A prototype of a 4.3-MeV electron cooling system has been assembled at Fermilab as part of the on-going R&D program in high-energy electron cooling. This electron cooler prototype will not demonstrate the actual cooling but it would allow to determine if the electron beam properties are suitable for antiproton beam cooling. An electron beam is accelerated by a 5-MV Pelletron (Van de Graaff type) accelerator and transported to a prototype cooling section. The cooling would take place in a 20-m long solenoid flanked on both sides by supply and return beam-lines—a total of 60 m of transport channel. This paper describes the status of the electron cooling R&D program.
117111536
THE DENSITY OF STATES METHOD AT FINITE CHEMICAL POTENTIAL.
We study the density of states method to explore the phase diagram of the chiral transition on the temperature and quark chemical potential plane. Four quark flavors are used in the analysis. Though the method is quite expensive small lattices show an indication for a triple-point connecting three different phases on the phase diagram.
1697339
Virtual next-to-leading corrections to the impact factors in the high-energy limit
We compute the virtual next-to-leading corrections to the impact factors or offshell coefficient functions in the high-energy limit. When combined with the known real corrections, these results will provide the complete NLO corrections to the impact factors, which are necessary to use the BFKL resummation at NLL for jet production at both lepton-hadron and hadron-hadron colliders.
13924287
Next-to-leading corrections to the Higgs boson transverse momentum spectrum in gluon fusion
We present a fully analytic calculation of the Higgs boson transverse momentum and rapidity distributions, for nonzero Higgs p⊥, at next-to-leading order in the infinite-top-mass approximation. We separate the cross section into a part that contains the dominant soft, virtual, collinear, and small-p⊥-enhanced contributions, and the remainder, which is organized by the contributions due to different parton helicities. We use this cross section to investigate analytically the small-p⊥ limit and compare with the expectation from the resummation of large logarithms of the type ln mH/p⊥. We also compute numerically the cross section at moderate p⊥ where a fixed-order calculation is reliable. We find a K-factor that varies from ≈ 1.6−1.8, and a reduction in the scale dependence, as compared to leading order. Our analysis suggests that the contribution of current parton distributions to the total uncertainty on this cross section at the LHC is probably less than that due to uncalculated higher orders.
17264957
An Effective Higgsless Theory: Satisfying Electroweak Constraints and a Heavy Top Quark
The main challenge faced by Higgsless models of electroweak symmetry breaking is to reconcile the experimental constraints imposed by the precision electroweak data and the top quark phenomenology with the unitarity constraints imposed by longitudinal gauge boson scattering amplitudes. In this paper we expand on previous work, giving details of how delocalized fermions can be used to adjust the S parameter to zero, while keeping the T and U parameters naturally suppressed. We also show that it is possible to obtain the top quark mass, without affecting the delay of unitarity violation of the W{sup +}W{sup -}{yields}W{sup +}W{sup -} scattering amplitude, by separating the mass scales of the fermion sector (1/R{sub f}) from that of the gauge sector (1/R{sub g}). The fermion sector scale 1/R{sub f} is only weakly constrained by unitarity of the tt{yields}W{sup +}W{sup -} scattering amplitude; thus the ratio R{sub g}/R{sub f} can be quite large, and the top mass can be achieved easily. Anomalous right-handed couplings involving the third generation quarks also avoid constraints from experimental data if 1/R{sub f} is sufficiently large.
5933086
Virtual next-to-leading corrections to the Lipatov vertex
We compute the virtual next-to-leading corrections to the Lipatov vertex in the helicity-amplitude formalism. These agree with previous results by Fadin and collaborators, in the conventional dimensional-regularization scheme. We discuss the choice of reggeization scale in order to minimize its impact on the next-toleading-logarithmic corrections to the BFKL equation.