125724255
Acceleration in other diamonds in the Main Ring
123613871
Observations of the transverse and longitudinal nature of the Fermilab linac beam
The installation of nonintercepting beam position monitors (BPMs) in the 200 MeV linac at Fermilab has facilitated several new observations on the character of the linac beam. In particular, two interesting phenomena have been discovered: a high-frequency change in the beam position and a slow variation in the phase-lock loops during a 30 mu s beam pulse. Progress in initiating the Delta -t measurement is being made. The Delta -t procedure adjusts the RF phase and amplitude in each of the accelerating modules of a linac. The procedure uses beam-induced signals from linac BPMs to determine changes in the times of flight of beam bunches when the tuned module is turned off and when it is turned on.<<ETX>>
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.
121242219
Attainment of an MeV-range, DC electron beam for the Fermilab cooler
To prepare a beam generation device for Fermilab's future Recycler Electron Cooling system, an experimental set-up with a simplified beam line has been commissioned at Fermilab. Stable operation was achieved at an electron energy of 3.5 MeV and a DC beam current of up to 0.5 A. The main reason for interruptions of the operation was found to be microsecond long bursts of the cathode current. While the frequency of the interruptions is determined primarily by a flow of secondary ions, the resulting reduction in the duty factor depends on the beam optics, the protection systems, and the tube electric field strength.
118674965
Operation and improvements of the Fermilab 400 MeV Linac
The 400 MeV Fermilab Linac Upgrade commissioning began August 28, 1993. High energy physics collider operation (run 1b) began in November 1993 and ended March 1, 1996. The Linac, operating at 98% reliability, provided 400 MeV H{sup -} beam to the Booster and 66 MeV H{sup -} beam to the Neutron Therapy Facility. During this time, the beam intensity, which initially was administratively set to 35 MA, rose to a peak of 50 mA while losses decreased significantly. This paper discusses the Linac operation and reliability since the Upgrade.
119188644
QCD bulk thermodynamics and conserved charge fluctuations with HISQ fermions
After briefly reviewing recent progress by the HotQCD collaboration in studying the 2+1 flavor QCD equation of state, we will focus on results on fluctuations of conserved charges by the BNL-Bielefeld and HotQCD collaborations. Higher order cumulants of the net-charge distributions are increasingly dominated by a universal scaling behavior, which arises due to a critical point of QCD in the chiral limit. Considering cumulants up to the 6^{th} order, we observe that they generically behave as expected from universal scaling laws, which is quite different from cumulants calculated within the hadron resonance gas model. Taking ratios of these cumulants, we obtain volume independent results that can be compared to the experimental measurements. We will argue that the freeze-out chemical potentials and the freeze-out temperature, usually obtained by a HRG model fit to the measured hadronic yields, can also be obtained in a model independent way from ab-initio lattice QCD calculations by utilizing observables related to conserved charge fluctuations. Further, we will show that the freeze-out strangeness and electric charge chemical potentials can be fixed by imposing strangeness neutrality and isospin asymmetry constraints in the lattice QCD calculations, in order to accommodate conditions met in heavy ion collisions. All results have been obtained with the highly improved staggered quark action (HISQ) and almost physical quark masses on lattices with temporal extent of N_\tau=6,8,10,12. 
After briefly reviewing recent progress by the HotQCD collaboration in studying the 2+1 flavor QCD equation of state, we will focus on results on fluctuations of conserved charges by the BNL-Bielefeld and HotQCD collaborations. Higher order cumulants of the net-charge distributions are increasingly dominated by a universal scaling behavior, which arises due to a critical point of QCD in the chiral limit. Considering cumulants up to the 6(th) order, we observe that they generically behave as expected from universal scaling laws, which is quite different from cumulants calculated within the hadron resonance gas model. Taking ratios of these cumulants, we obtain volume independent results that can be compared to the experimental measurements. We will argue that the freeze-out chemical potentials and the freeze-out temperature, usually obtained by a HRG model fit to the measured hadronic yields, can also be obtained in a model independent way from ab-initio lattice QCD calculations by utilizing observables related to conserved charge fluctuations. Further, we will show that the freeze-out strangeness and electric charge chemical potentials can be fixed by imposing strangeness neutrality and isospin asymmetry constraints in the lattice QCD calculations, in order to accommodate conditions met in heavy ion collisions. All results have been obtained with the highly improved staggered quark action (HISQ) and almost physical quark masses on lattices with temporal extent of N(τ) = 6, 8, 10, 12.
117019402
BFKL versus O (alpha-s**3) corrections to large rapidity dijet production
We examine dijet production at large rapidity intervals at Tevatron energies by comparing an exact ${\cal O}(\alpha_s^3)$ calculation with the BFKL approximation, which resums the leading powers of the rapidity interval $y$ to all orders in $\alpha_s$. We analyze the dependence of the exact ${\cal O}(\alpha_s^3)$ calculation on the jet cone-size as a function of $y$, and use this cross section to define an ``effective rapidity'' $\hat y$ which reduces the error that the large-$y$ approximation induces on the kinematics. Using $\hat y$ in the BFKL resummation, we reexamine jet production at large transverse momenta and the transverse momentum decorrelation of the tagging jets. We find less dramatic, but still significant, effects than found previously using the large-$y$ approximation.
14312972
Partonometry in W + jet production
QCD predicts soft radiation patterns that are particularly simple for W+jet production. We demonstrate how these patterns can be used to distinguish between the parton-level subprocesses probabilistically on an event-by-event basis. As a test of our method we demonstrate correlations between the soft radiation and the radiation inside the outgoing jet. {copyright} {ital 1997} {ital The American Physical Society}
15248842
Transverse momentum distributions in large rapidity dijet production at the Tevatron
In this contribution we examine the transverse momentum distributions in dijet production at large rapidity intervals at the Tevatron, using the BFKL resummation.
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.