111241112
Linearization of the Fermilab recycler high level RF
In studying the recycler high level RF, it was found that at 89 kHz, the lowest frequency required by the system, some nonlinearities in magnitude and phase were discovered. The visible evidence of this was that beam injected in a barrier bucket had a definite slope at the top. Using a network analyzer, the S-parameter S/sub 21/ was realized for the overall system and from mathematical modeling a second order numerator and denominator transfer function was found. The inverse of this transfer function gives our linearization transfer function. The linearization transfer function was realized in hardware by summing a high pass, band pass and low pass filter together. The resulting magnitude and phase plots, along with actual beam response will be shown.
55311799
A new flying wire system for the Tevatron
A new flying wire system replaces an older system to enhance the analysis of beam emittance, improve reliability, and support future upgrades to the Tevatron. New VME data acquisition and timing modules allow for more bunches to be sampled more precisely. A LabVIEW application, running on a Macintosh computer, controls the data acquisition and wire motion. The application also analyzes and stores the data as well as handles local and remote commands. The new system flies three wires and fits profiles of 72 bunches to a gaussian function in a total of three seconds. A new console application allows remote operator control and display from any control console. This paper discusses the hardware and software setup, capabilities, and measurement results of the new flying wire system.
109094861
Modification of Linac 7651 driver to operate at 425 MHz
6190198
Narrowband beam loading compensation in the Fermilab Main Injector accelerating cavities
A narrowband beam loading compensation system was installed for the Main Injector accelerating cavities. This feedback operates solely on the fundamental resonant mode of the cavity. This paper describes modifications to the high level radiofrequency system required to make the system operational. These modifications decreased the effect of steady-state beam loading by a factor of 10 and improved the reliability of paraphasing for coalescing.
73632693
Antiproton acceleration in the Fermilab Main Injector using 2.5 MHz (H=28) and 53 MHz (H=588) RF systems
During the Run II era at Fermilab, the Recycler stores antiprotons at 8 GeV and the Main Injector accelerates the antiprotons and the protons from 8 GeV to 150 GeV for Tevatron injection. The Recycler injects antiprotons to the Main Injector in 2.5 MHz rf buckets. This report presents an acceleration scheme for the antiprotons that involves a slow ramp with initial 2.5 MHz acceleration and subsequent fast acceleration with 53 MHz rf system. Beam acceleration and rf manipulation with space charge and beam loading effects are simulated using the longitudinal simulation code ESME. Simulation suggests that one can expect about 15% emittance growth for the entire acceleration cycle with beam loading compensations. Preliminary experimental results with proton beam will also be presented.
119710134
Bound for entropy and viscosity ratio of strange quark matter
Abstract High energy density (ϵ) and temperature (T) links general relativity and hydrodynamics leading to a lower bound for the ratio of shear viscosity ( η ) and entropy density ( s ). We get the interesting result that the bound is saturated in the simple model for quark matter that we use for strange stars at the surface for T ∼ 80 MeV . At this T we have the possibility of cosmic separation of phases. At the surface of the star where the pressure is zero—the density ϵ has a fixed value for all stars of various masses with correspondingly varying central energy density ϵ c . Inside the star where this density is higher, the ratio of η / s is larger and are like the known results found for perturbative QCD. This serves as a check of our calculation. The deconfined quarks at the surface of the strange star at T = 80 MeV seem to constitute the most perfect interacting fluid permitted by nature.
119382272
Is SAX J1808.4-3658 a strange star?
The possibility of strange stars is one of the most important issues in the study of compact objects. Here we use the observations of the newly discovered millisecond x-ray pulsar SAX J1808.4-3658 to constrain the radius of the compact star. Comparing the mass-radius relation of SAX J1808.4-3658 with theoretical models for both neutron stars and strange stars, we argue that a strange star model could be more consistent with SAX J1808.4-3658, and suggest that it is a likely strange star candidate. Our results are useful in constraining microscopic chiral symmetry restoration parameters in the quantum chromodynamics (QCD) modeling of strange matter.