118561168
Performance of a silicon microstrip detector in a high radiation environment
The performance of a silicon microstrip detector has been studied in a high rate environment using electron, pion, and proton beams. The pulse height, time response, and leakage current have been studied as a function of particle fluence up to a total integrated flux of about 4 {times} 10{sup 14} protons/cm{sup 2}. 3 figs.
45590013
Indication of pionic-atom anomalies in pion-nucleus elastic scattering.
Elastic cross sections for the scattering of positive and negative pions from /sup 58/Ni were measured at 30 MeV incident pion energy. Statistical errors of +- 3% and normalization errors of +- 6% were achieved. These data appear to confirm the theoretical construct that the physics which explains anomalously small shifts and widths in pionic atoms would be manifested in low energy pion-nucleus elastic scattering. The data show good agreement with the cross sections calculated assuming s and p partial waves are anomalous. Here anomalous refers to partial waves that are calculated from an optical potential which reproduces anomalously small level shifts and widths in pionic atoms. Conventional optical potentials do not agree as well with both the ..pi../sup +/ and ..pi../sup -/ data. Various conventional possibilities such as a larger neutron radius than proton radius in the nuclear density were tried, but these did not result in good agreement with the data.
122872312
Energy dependence of low-energy pion double-charge-exchange on the calcium isotopes
Abstract The forward angle differential cross sections of ( π + , π − ) reactions on the calcium isotopes to the double-isobaric-analog (DIAS) and ground states (GS) were measured between 25 and 65 MeV. These low-energy cross sections are up to an order of magnitude larger than those at resonance energies. The forward-angle excitation functions of 42 Ca, 44 Ca DIAS and 44 Ca GS transitions peak around 50 MeV. The 48 Ca DIAS cross section exhibits a minimum at about 50 MeV and that for the GS has a peak which is shifted to lower energy with a smaller cross section than that of the other nuclei. The observed behaviour is inconsistent with theoretical expectations.
195867607
Nonlinear mode coupling analysis in the Tevatron
Increased demand for higher luminosities from Fermilab proton-antiproton collider requires higher intensities and increased number of bunches. The performance of existing 6/spl times/6 and the proposed 36/spl times/36 collider is often limited by the non-linear effects arising from beam-beam interactions, in particular for high intensity beams. The tune shifts and spread from increased long range interactions combined with higher order multipoles complicates the frequency spectrum of the particle motions. The TEAPOT simulation program is used to generate turn by turn data that could be used in the nonlinear mode spectrum analysis. Bispectral mode analysis is discussed.
26286812
Elastic scattering of 65 MeV positive and negative pions from nickel isotopes.
Angular distributions of elastic differential cross sections were obtained at 65 MeV using positive and negative pions scattered from /sup 58/Ni, /sup 60/Ni, and /sup 64/Ni. The data were compared to predictions using the Michigan State University optical potential. These predictions are not in good agreement with the data. The negative pion cross sections are more poorly described than the positive pion cross sections. The p-italic-wave part of the potential is observed to be especially sensitive to this Coulomb-nuclear interference effect.
46034016
A relational database for magnets and measurement systems at the Fermilab Magnet Test Facility
A magnet measurement system based on relational database technology has been developed for use at the Fermilab Magnet Test Facility (MTF). Results of magnetic field strength and field shape measurements are stored in the database for use in understanding accelerator and beamline operation. In addition to measurement results, the database is used to store measurement history and the commands which prescribe measurement sequences along with supporting parameters that control how each measurement is performed. The system contains more than 200 tables with more than 1500 columns. The design of the tables is documented in the form of diagrams, design documents, as well as through tables which store, within the database itself, descriptions of each table and column.
119187532
Head-on infall of two compact objects: Third post-Newtonian Energy Flux
Head-on infall of two compact objects with arbitrary mass ratio is investigated using the multipolar post-Minkowskian approximation method. At the third post-Newtonian order the energy flux, in addition to the instantaneous contributions, also includes hereditary contributions consisting of the gravitational-wave tails, tails-of-tails, and the tail-squared terms. The results are given both for infall from infinity and also for infall from a finite distance. These analytical expressions should be useful for the comparison with the high accuracy numerical relativity results within the limit in which post-Newtonian approximations are valid.