Code 672 observational science branch computer networks

In general, networking increases productivity due to the speed of transmission, easy access to remote computers, ability to share files, and increased availability of peripherals. Two different networks within the Observational Science Branch are described in detail

Angular distribution of photoelectrons at 584A using polarized radiation

Photoelectron angular distributions for Ar, Xe, N2, O2, CO, CO2, and NH3 were obtained at 584 A by observing the photoelectrons at a fixed angle and simply rotating the plane of polarization of a highly polarized photon source. The radiation from a helium dc glow discharge source was polarized (84%) using a reflection type polarizer

Data documentation for the bare soil experiment at the University of Arkansas

The reflectivities of several controlled moisture test plots were investigated. These test plots were of a similar soil texture which was clay loam and were prepared to give a desired initial soil moisture and density profile. Measurements were conducted on the plots as the soil water redistributed for both long term and diurnal cycles. These measurements included reflectivity, gravimetric and volumetric soil moisture, soil moisture potential, and soil temperature

Notes: The Role of the American Corporation in the Economic Development of Latin America:

This note will examine the potential conflict between United States\u27antitrust policy and United States\u27 foreign policy in Latin America. As background, Part II will provide a brief discussion of the United States\u27 foreign policy objective in Latin America. In Part III, the discussion will turn to the most likely context for conflict-the potentials of the American corporation for advancing that foreign policy objective. Part IV will illustrate how the possibility of extra-territorial application of United States\u27 antitrust laws gives rise to the potential for conflict between those laws and the United States\u27 foreign policy in Latin America. Part V will examine the most likely context for conflict and determine whether a conflict actually exists. Finally, Part VI will define the nature of the actual conflict and suggest a resolution

Non-invasive single-bunch matching and emittance monitor

On-line monitoring of beam quality for high brightness beams is only possible using non-invasive instruments. For matching measurements, very few such instruments are available. One candidate is a quadrupole pick-up. Therefore, a new type of quadrupole pick-up has been developed for the 26 GeV Proton Synchrotron (PS) at CERN, and a measurement system consisting of two such pick-ups is now installed in this accelerator. Using the information from these pick-ups, it is possible to determine both injection matching and emittance in the horizontal and vertical planes, for each bunch separately. This paper presents the measurement method and some of the results from the first year of use, as well as comparisons with other measurement methods.Comment: 10 pages, 10 figures; added figure, minor textual additions; To be resubmitted to Phys. Rev. ST-A

New Control Structure of the 200 MHz RF System in the CERN PS

The 200 MHz RF system is an essential tool for the preparation of high-intensity beams in the CERN PS. Presently, six RF cavities are operated to control the longitudinal bunch emittance and rebunching of the beam before the transfer to the SPS. Cavities are selected for the various processes with a dedicated hardware matrix, switching the individual timing pulses and voltage programs per cavity. However, the electronics used for the matrix hardware is obsolete and its reliability cannot be guaranteed due to a lack of spare modules and components. Instead of replacing the old hardware matrix by modern hardware, this note describes a new control structure for the 200MHz RF system so that no dedicated hardware will be required anymore. The implementation of the new control structure is based on two main concepts. Firstly, linked timing trees per blow-up or rebunching are used to handle all related timing and to store one row of the matrix. Secondly, as a reflection of the RF signal generation for the 200 MHz system, where all units always receive the same RF signal, the new implementation features a single global voltage program function. Internal stops in the voltage program function are restarted by timings in the linked trees and assure inherent coherence between timings and voltage programs for the cavities. After a description of the requirements of the present hardware in terms of timing signals and functions, functional s pecification of the new application program is given

Modelling the spread of Wolbachia in spatially heterogeneous environments

The endosymbiont Wolbachia infects a large number of insect species and is capable of rapid spread when introduced into a novel host population. The bacteria spread by manipulating their hosts' reproduction, and their dynamics are influenced by the demographic structure of the host population and patterns of contact between individuals. Reaction–diffusion models of the spatial spread of Wolbachia provide a simple analytical description of their spatial dynamics but do not account for significant details of host population dynamics. We develop a metapopulation model describing the spatial dynamics of Wolbachia in an age-structured host insect population regulated by juvenile density-dependent competition. The model produces similar dynamics to the reaction–diffusion model in the limiting case where the host's habitat quality is spatially homogeneous and Wolbachia has a small effect on host fitness. When habitat quality varies spatially, Wolbachia spread is usually much slower, and the conditions necessary for local invasion are strongly affected by immigration of insects from surrounding regions. Spread is most difficult when variation in habitat quality is spatially correlated. The results show that spatial variation in the density-dependent competition experienced by juvenile host insects can strongly affect the spread of Wolbachia infections, which is important to the use of Wolbachia to control insect vectors of human disease and other pests

Longitudinal Tomographic Reconstruction of LHC-type Bunches in the SPS

Longitudinal tomographic reconstruction on the basis of measured profiles is an important technique to measure the particle density distribution of a bunch in longitudinal phase space. This measurement technique, well established in all circular machines of the PS complex, has been applied to the SPS for the first time. Due to recent improvements of the data acquisition of the signals from the longitudinal pick-ups in the SPS and a new LHC type wall current monitor, the quality of the bunch profiles is now more appropriate for tomography. Longitudinal beam signals from the wall current pick-ups APWL-10 and WC-2 are used as input for the reconstruction algorithm. It is shown that, due to short bunches and long cables in the SPS, the correction of the signal with the transfer function of the transmission system is indispensable. The analysis of the longitudinal distribution of a batch of 48 bunches of an LHC type beam at injection into the SPS, averaged over more than ten cycles, showed that any systematic variation of the bunch parameters along the batch is shadowed by statistical errors due to the quality of the measured bunch profiles. Avoiding the long coaxial cables from the SPS tunnel to the surface is a crucial issue for improving the quality of the bunch profiles suitable for tomographic reconstruction