55851079
Progress Update on the Development of the $^{3}$He Linac for PET Isotope Production
In 1995, Fermilab and SAIC formed a collaboration with partners from the University of Washington (UW) and the Biomedical Research Foundation of Northwest Louisiana (BRF) to explore an innovative approach to the production of radioisotopes. The accelerator system that is being developed accelerates 3He to 10.5 MeV and then delivers this beam to the target to produce the short lived radioisotopes of interest to the PET community (18F, 15O, 13N, 11C). Research is being conducted to investigate the contribution that this promising approach can make to clinical and research PET. The accelerator system has several very interesting aspects. These innovations include multiple RFQ accelerators configured in series, a gas stripper jet to doubly charge the low energy (1 MeV) 3He beam, and an isochronous matching section to manipulate the transverse and maintain the longitudinal profile of the beam (without the use of an RF buncher) in the charge doubler transition section between RFQ’s. This paper updates the progress of the PET 3He RFQ accelerator, the current status of the design, and some of the interesting ongoing research.
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.
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.
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.
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>>
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.
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.
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.
16845888
Review of BFKL
I describe the underlying physics behind the BFKL resummation and discuss some of the recent ideas and results in this field. On the theoretical side I consider the formalism in the next-to-leading logarithmic (NLL) approximation and the interpretation of the large corrections. On the phenomenological side I discuss several experiments that attempt to observe the BFKL effects in the high energy limit.
5511493
Common features of deconfining and chiral critical points in QCD and the three state Potts model in an external field
In the presented study we investigated the second order endpoints of the lines of first order phase transitions which emerge for the QCD in the heavy and light quark mass regime and for the three-dimensional three state Potts model with an external field. We located the endpoints with Binder cumulants and constructed the energy-like and ordering-field-like observables. The joint probability distributions of these scaling fields and the values of the Binder cumulant confirm that all three endpoints belong to the universality class of the 3-dimensional Ising model.