115981537
Longitudinal Emittance from the Fermilab 400 MeV Linac
The measurements which characterize the longitudinal emittance of the Fermilab 400 MeV Linac beam are presented. These measurements are made by determining the momentum spread and the bunch length of the beam using wall-current monitors, bunch length detectors and a spectrometer.
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>>
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.
113925183
Factors Affecting H- Beam Performance in the Fermilab Linac
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.
118113223
Testing the Strong and Weak Interactions
15032603
Mueller-navelet jets at hadron colliders
We critically examine the definition of dijet cross sections at large rapidity intervals in hadron-hadron collisions, taking proper account of the various cuts applied in a realistic experimental setup. We argue that the dependence of the cross section on the precise definition of the parton momentum fractions and the presence of an upper bound on the momentum transfer cannot be neglected, and we provide the relevant modifications to the analytical formulae by Mueller and Navelet. We also point out that the choice of equal transverse momentum cuts on the tagging jets can spoil the possibility of a clean extraction of signals of BFKL physics.
53607643
Intrinsic Charm Parton Distribution Functions from CTEQ-TEA Global Analysis
Sayipjamal Dulat, 2, ∗ Tie-Jiun Hou, Jun Gao, Joey Huston, Jon Pumplin, Carl Schmidt, Daniel Stump, and C.–P. Yuan † 1 School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 China 2 Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 U.S.A. 3 Institute of Physics, Academia Sinica, Taipei, Taiwan 115 4 Department of Physics, Southern Methodist University, Dallas, TX 75275-0181, U.S.A.
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.
16115905
Flavor and quark mass dependence of QCD thermodynamics
We calculate the transition temperature in 2 and 3-flavor QCD using improved gauge and staggered fermion actions on lattices with temporal extent Nτ = 4. We find Tc = 173 (8) MeV and 154 (8) MeV for nf = 2 and 3, respectively. In the case of 3-flavor QCD we present evidence that the chiral critical point, i.e. the second order endpoint of the line of first order chiral phase transitions, belongs to the universality class of the 3d Ising model.