30886954
Experimental investigation of nonlinear dynamics in the Fermilab Tevatron.
The nonlinear dynamics of transverse particle oscillations in the Tevatron is studied experimentally and compared with prediction. Accurate measurements of various phase-space features are obtained. A theoretically expected metastable state of the accelerator, with particles captured on nonlinear resonance islands, is demonstrated experimentally, and stability of the state is investigated.
116033534
EPIC Muon Cooling Simulations using COSY INFINITY
Next gen­er­a­tion mag­net sys­tems need­ed for cool­ing chan­nels in both neu­tri­no fac­to­ries and muon col­lid­ers will be in­no­va­tive and com­pli­cat­ed. De­sign­ing, sim­u­lat­ing and op­ti­miz­ing these sys­tems is a chal­lenge. Using COSY IN­FIN­I­TY, a dif­fer­en­tial al­ge­bra-based code, to sim­u­late com­pli­cat­ed el­e­ments can allow the com­pu­ta­tion and cor­rec­tion of a va­ri­ety of high­er order ef­fects, such as spher­i­cal and chro­mat­ic aber­ra­tions, that are dif­fi­cult to ad­dress with other sim­u­la­tion tools. As an ex­am­ple, a he­li­cal dipole mag­net has been im­ple­ment­ed and sim­u­lat­ed, and the per­for­mance of an epicyclic para­met­ric ion­iza­tion cool­ing sys­tem for muons is stud­ied and com­pared to sim­u­la­tions made using G4Beam­line, a GEAN­T4 toolk­it.
123646626
Nonlinear dynamics experiment in the Tevatron
Results of the continuing analysis of the nonlinear dynamics experiment, E778, are presented. Sixteen special sextupoles introduced nonlinearities in the Tevatron. Smear, which is one of the parameters used to quantify the degree of nonlinearity, was extracted from the data and compared with calculation. Injection efficiency in the presence of nonlinearities was studied. Measurements of the dynamic aperture were performed. The final results in one degree of freedom of the smear, the injection efficiency, and the dynamic aperture are presented. Particles captured on nonlinear resonance islands were directly observed and measurements were taken. The capture efficiency was extracted from the data and compared with prediction. The influence of tune modulation on the stability of these islands was investigated. Plans for future measurements are discussed.<<ETX>>
123216055
Commissioning the LSU synchrotron light source
Abstract The first commercially supplied synchrotron light source to be built in the USA has been installed and commissioned at LSU. The machine was built by MLI/Brobeck on a fixed price basis with a guaranteed performance of 400 mA at 1.2 GeV. The contract called for 200 mA circulating current at 1.2 GeV before the machine was turned over to LSU. Despite some unanticipated delays, this first commissioning phase was completed on schedule, some 15 months after the building was available to start installation. Vacuum conditioning has continued under LSU direction with present best operation above 300 mA at 1.3 GeV. A description of the commissioning process is given, including the conditioning of the vacuum chamber using synchrotron radiation from circulating beam.
15829507
Simulations of a Gas-Filled Helical Muon Beam Cooling Channel
A helical cooling channel (HCC) has been proposed to quickly reduce the six dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of solenoidal, helical dipole, and helical quadrupole current coils to provide focusing and dispersion needed for emittance exchange as the beam follows an equilibrium helical orbit. Inside the coils constituting the HCC examined here, a series of RF cavities filled with dense hydrogen gas acts as the energy absorber for ionization cooling and also suppressed RF breakdown. Two Monte Carlo simulation programs have been developed to compare HCC performance with analytic predictions and to begin the process of optimizing practical designs that could be built in the near future. We discuss the programs, the comparisons with the analytical theory, and the prospects for a HCC design with the capability to reduce the six-dimensional phase space emittance of a muon beam by a factor of over five orders of magnitude in a linear channel less than 100 meters long.
56042523
RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES
Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved, and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Recent studies have shown that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual gas and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A 1.3-GHz RF test cell with replaceable electrodes (e.g. Mo, Cu, Be, W, and Nb) has been built, and a series of detailed experiments is planned at the Argonne Wakefield Accelerator. These experiments will be followed by additional experiments using a second test cell operating at 402.5 MHz.
54066498
OO design and implementation: Java and Java analysis studio
We present an overview of the Java language, Java virtual machine, and the large set of standard libraries and extensions available for Java, and provide a discussion of issues that effect Java performance. This is followed by an introduction to Java Analysis Studio (JAS), a tool written in Java, and in which Java is the language used to perform data analysis. We will also explore how OO techniques have been used to built a system from modular components including visualization, fitting and data-access components that can be used together, or on their own.
2512058
Conformal field theory of a rotating dyon.
A conformal field theory representing a four-dimensional classical solution of heterotic string theory is presented. The low-energy limit of this solution has U(1) electric and magnetic charges, and also nontrivial axion and dilaton fields. The low-energy metric contains mass, NUT, and rotation parameters. We demonstrate that this solution corresponds to part of an extremal limit of the Kerr-Taub-NUT dyon solution. This limit displays interesting ``remnant'' behavior in that asymptotically far away from the dyon the angular momentum vanishes, but far down the infinite throat in the neighborhood of the horizon (described by our CFT) there is a nonzero angular velocity. A further natural generalization of the CFT to include an additional parameter is presented, but the full physical interpretation of its role in the resulting low energy solution is unclear.
32203233
Massive hadron pair production by 800 GeV/c protons on nuclear targets.
We report data on proton-nucleon collisions obtained on Fermilab experiment E711, in which high transverse momentum hadrons are produced near 90[degree] in the proton-nucleon center of mass forming high mass states, using an 800 GeV/[ital c] proton beam on targets of beryllium, aluminum, iron, and tungsten. The data presented cover the mass range from 7 to 15 GeV/[ital c][sup 2], the three dihadron charge states ++, +[minus], and [minus][minus], and parton-parton scattering angles up to cos[theta][sup *]=0.50. We present the differential mass dihadron cross section, as well as the angular and charge dependence of the measurement. The cross section as a function of the parton-parton scattering angle for the three charge states is shown to vary linearly with the value of the atomic weight. While the angular distributions are shown to be independent of the target type, a small dependence on the charge state of the distributions is observed. The data are shown to be in good agreement with extrapolations from previous measurements and phenomenological QCD calculations.
31307451
Double analog state in odd-A nuclei.
Measurements were performed using pion double charge exchange to observe the double isobaric analog state (DIAS) in the odd-[ital A] nuclei [sup 54]V, [sup 59]Co, [sup 115]In, and [sup 197]Au. These results are combined with data for other odd-[ital A] targets and used to investigate the [ital N], [ital Z], and [ital A] dependence of DIAS cross sections.
41594474
Charm production in neutron-nucleon interactions.
Hadronic production of charmed particles in association with muons from their semileptonic decay has been observed in a high-resolution streamer-chamber experiment performed at Fermilab. A miss-distance analysis of the pictures gives a signal of 17.3 +- 4.7 events. Depending on the production model this corresponds to a range of neutron-nucleon cross sections from 8 to 50 ..mu..b, assuming an A/sup 2/3/ dependence.