Coalescing at 8 GeV in the Fermilab Main Injector

For Project X, it is planned to inject a beam of 3 10**11 particles per bunch into the Main Injector. To prepare for this by studying the effects of higher intensity bunches in the Main Injector it is necessary to perform coalescing at 8 GeV. The results of a series of experiments and simulations of 8 GeV coalescing are presented. To increase the coalescing efficiency adiabatic reduction of the 53 MHz RF is required, resulting in ~70% coalescing efficiency of 5 initial bunches. Data using wall current monitors has been taken to compare previous work and new simulations for 53 MHz RF reduction, bunch rotations and coalescing, good agreement between experiment and simulation was found. Possible schemes to increase the coalescing efficiency and generate even higher intensity bunches are discussed. These require improving the timing resolution of the low level RF and/or tuning the adiabatic voltage reduction of the 53 MHz.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012) 20-25 May 2012, New Orleans, Louisian

Randomly Broken Nuclei and Disordered Systems

Similarities between models of fragmenting nuclei and disordered systems in condensed matter suggest corresponding methods. Several theoretical models of fragmentation investigated in this fashion show marked differences, indicating possible new methods for distinguishing models using yield data. Applying nuclear methods to disordered systems also yields interesting results.Comment: 10 pages, 4 figure

Processing and Transmission of Information

Contains research objectives and reports on two research projects.National Aeronautics and Space Administration under Grant NsG-334Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E)National Science Foundation (Grant GP-2495)National Aeronautics and Space Administration (Grant NsG-496

The transformative potential of reflective diaries for elite English cricketers

The sport of cricket has a history of its players suffering from mental health issues. The psychological study of cricket and, in particular, the attendant demands of participating at an elite level has not previously received rigorous academic attention. This study explored ten elite male cricketers’ experiences of keeping a daily reflective diary for one month during the competitive season. The aim was to assess how valuable qualitative diaries are in this field. Participants were interviewed regarding their appraisal of the methodology as a self‐help tool that could assist coping with performance pressures and wider life challenges. Three outcomes were revealed: first, that diary keeping was an effective opportunity to reflect upon the past and enhance one’s self (both as an individual and a performer); second, that diary keeping acted as a form of release that allowed participants to progress; and third, that diary keeping allowed participants to discover personal patterns of success that increased the likeliness of optimum performance

Various Models for Pion Probability Distributions from Heavy-Ion Collisions

Various models for pion multiplicity distributions produced in relativistic heavy ion collisions are discussed. The models include a relativistic hydrodynamic model, a thermodynamic description, an emitting source pion laser model, and a description which generates a negative binomial description. The approach developed can be used to discuss other cases which will be mentioned. The pion probability distributions for these various cases are compared. Comparison of the pion laser model and Bose-Einstein condensation in a laser trap and with the thermal model are made. The thermal model and hydrodynamic model are also used to illustrate why the number of pions never diverges and why the Bose-Einstein correction effects are relatively small. The pion emission strength $\eta$ of a Poisson emitter and a critical density $\eta_c$ are connected in a thermal model by $\eta/n_c = e^{-m/T} < 1$, and this fact reduces any Bose-Einstein correction effects in the number and number fluctuation of pions. Fluctuations can be much larger than Poisson in the pion laser model and for a negative binomial description. The clan representation of the negative binomial distribution due to Van Hove and Giovannini is discussed using the present description. Applications to CERN/NA44 and CERN/NA49 data are discussed in terms of the relativistic hydrodynamic model.Comment: 12 pages, incl. 3 figures and 4 tables. You can also download a PostScript file of the manuscript from http://p2hp2.lanl.gov/people/schlei/eprint.htm

Off-diagonal parton distributions and their evolution

We construct off-diagonal parton distributions defined on the interval 0 < X < 1 starting from the off-forward distributions defined by Ji. We emphasize the particular role played by the symmetry relations in the "ERBL-like" region. We find the evolution equations for the off-diagonal distributions which conserve these symmetries. We present numerical results of the evolution, and verify that the analytic asymptotic forms of the parton distributions are reproduced. We also compare the constructed off-diagonal distributions with the non-forward distributions defined by Radyushkin and comment on the singularity structure of the basic amplitude written in terms of the off-diagonal distributions.Comment: 22 pages, Latex, 6 ps figures. Improved presentation after discussions with X.Ji and A.Radyushki

Relativistic Structure, Stability and Gravitational Collapse of Charged Neutron Stars

Charged stars have the potential of becoming charged black holes or even naked singularities. It is presented a set of numerical solutions of the Tolman-Oppenheimer-Volkov equations that represents spherical charged compact stars in hydrostatic equilibrium. The stellar models obtained are evolved forward in time integrating the Einstein-Maxwell field equations. It is assumed an equation of state of a neutron gas at zero temperature. The charge distribution is taken as been proportional to the rest mass density distribution. The set of solutions present an unstable branch, even with charge to mass ratios arbitrarily close to the extremum case. It is performed a direct check of the stability of the solutions under strong perturbations, and for different values of the charge to mass ratio. The stars that are in the stable branch oscillates and do not collapse, while models in the unstable branch collapse directly to form black holes. Stars with a charge greater or equal than the extreme value explode. When a charged star is suddenly discharged, it don't necessarily collapse to form a black hole. A non-linear effect that gives rise to the formation of an external shell of matter (see Ghezzi and Letelier 2005), is negligible in the present simulations. The results are in agreement with the third law of black hole thermodynamics and with the cosmic censorship conjecture.Comment: 27 pages, 14 figures, 4 tables, paper accepte

Crab cavities for linear colliders

Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.Comment: 3 pages. To be published in proceedings of LINAC 2008, Victoria, Canad

A simple theorem to generate exact black hole solutions

Under certain conditions imposed on the energy-momentum tensor, a theorem that characterizes a two-parameter family of static and spherically symmetric solutions to Einstein's field equations (black holes), is proved. A discussion on the asymptotics, regularity, and the energy conditions is provided. Examples that include the best known exact solutions within these symmetries are considered. A trivial extension of the theorem includes the cosmological constant {\it ab-initio}, providing then a three-parameter family of solutions.Comment: 14 pages; RevTex; no figures; typos corrected; references adde