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.
36506128
Experimental Test of a New Antiproton Acceleration Scheme in the Fermilab Main Injector
In an effort to provide higher intensity and lower emittance antiproton beam to the Tevatron collider for high luminosity operation, a new Main Injector (MI) antiproton acceleration scheme has been developed [1-4]. In this scheme, beam is accelerated from 8 to 27 GeV using the 2.5 MHz rf system and from 27 to 150 GeV using the 53 MHz rf system. This paper reports the experimental results of beam study. Simulation results are reported in a different PAC’ 05 paper [5]. Experiments are conducted with proton beam from the Booster. Acceleration efficiency, emittance growth and beam harmonic transfer between 2.5 MHz (h=28) and 53 MHz (h=588) buckets have been studied. Beam study shows that one can achieve an overall acceleration efficiency of about 100%, longitudinal emittance growth less than 20% and negligible transverse emittance growth.
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.
109094861
Modification of Linac 7651 driver to operate at 425 MHz
110039324
Improving the linearity of ferrite loaded cavities using feedback
A simple beam loading compensation system was installed for the Fermilab Main Injector Coalescing Cavities. This paper describes the design and implementation of the feedback system. These modifications improved the linear dynamic range of operation of the ferrite loaded cavity.
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.
121156151
Thermodynamics of massless quarks and gluons Finite-size hadron formation and phase transition to the quark-gluon plasma state☆
Abstract The free energy F of massless quarks and gluons confined in a spherical bag has been calculated by computing the discrete allowed states and taking appropriately weighted sums. The behaviour of F as a function of the bag radius R shows a unique solution R upto a transition temperature T s beyond which the model shows a first-order phase transition to QGP ( R =∞). We also find a limiting temperature T c > T s beyond which hadrons cannot exist.
11411115
Newtonian and general relativistic contribution of gravity to surface tension of strange stars
Surface tension (S ) is due to the inward force experienced by particles at the surface and usually gravitation does not play an important role in this force. But in compact stars the gravitational force on the particles is very large and S is found to depend not only on the interactions in the strange quark matter, but also on the structure of the star, i.e. on its mass and radius. Indeed, it has been claimed recently that 511 keV photons observed by the space probe INTEGRAL from the galactic bulge may be due to e + e − annihilation, and their source may be the positron cloud outside of an antiquark star. Such stars, if they exist, may also go a long way towards explaining away the antibaryon deficit of the universe. For that to happen S must be high enough to allow for survival of quark/antiquark stars born in early stages of the formation of the universe. High value of S may also assist explanation of delayed γ-ray burst after a supernova explosion, as conversion from normal matter to strange matter takes place. The possibility of some implications from formation of surface waves are also discussed.
18781228
Mean-field baryon magnetic moments and sumrules
New developments have spurred interest in magnetic moments (μ's) of baryons. The measurement of some of the decuplet μ's and the findings of new sumrules from various methods are partly responsible for this renewed interest. Our model, inspired by large colour approximation, is a relativistic self-consistent mean-field description with a modified Richardson potential and is used to describe the μ's and masses of all baryons with up (u), down (d) and strange (s) quarks. We have also checked the validity of the Franklin sumrule (referred to as CGSR in the literature) and sumrules of Luty, March-Russell and White. We found that our result for sumrules matches better with experiment than the non-relativistic quark model prediction. We have also seen that quark magnetic moments depend on the baryon to which they belong while the naive quark model expects them to be constant.
119254246
Strange star equation of state fits the refined mass measurement of 12 pulsars and predicts their radii
There are three categories of stars whose masses have been found accurately in recent times: (1) two for which Shapiro delay is used which is possible due to GR light bending as the partner is heavy : PSR J1614-2230 and PSR J1903+0327 (2) six eclipsing stars for which numerical Roche Lobe geometry is used and (3) 3 stars for which spectroscopic methods are used and in fact for these three the mass and radii both are estimated. Motivated by large color (N_c) expansion using a modified Richardson potential, along with density dependent quark masses thereby allowing chiral symmetry restoration, we get compact strange stars fitting all the observed masses.
14551482
DENSITY DEPENDENT STRONG COUPLING CONSTANT OF QCD DERIVED FROM COMPACT STAR DATA
Since 1996 there is major influx of X-ray and γ-ray data from binary stars, one or both of which are compact objects that are difficult to explain as neutron stars since they contain a mass M in too small a radius R. The suggestion has been put forward that these are strange quark stars (SS) explainable in a simple model with chiral symmetry restoration (CSR) for the quarks and the M, R and other properties like QPOs (quasi-periodic oscillations) in their X-ray power spectrum. It would be nice if this astrophysical data could shed some light on fundamental properties of quarks obeying QCD. One can relate the strong coupling constant of QCD, αs to the quark mass through the Dyson–Schwinger gap equation using the real time formalism of Dolan and Jackiw. This enables us to obtain the density dependence of αs from the simple CSR referred to above. This way fundamental physics, difficult to extract from other models like for example lattice QCD, can be constrained from present-day compact star data and may be put back to modeling the dense quark phase of early universe.