[en] An overview of the current bellows module design and performance parameters is presented. Performance requirements based on external chamber design constraints, and operational needs are discussed. Parameters include beam impedance of the RF shield, and electrical resistance of the shield gap joint. Also discussed is the analysis of the high-current thermal management, and structural and cyclic behavior of the bellows and RF shield. Experiments of the tribology and electrical resistance of the shield sliding joint are summarized, and their results presented. Existing and new design options are discussed in light of the analyses and experiments. The final design is presented as the optimal compromise between the varying parameters

[en] The Beam-Position Monitors (BPM) for the PEP-II B Factory consist of four 1.5-cm diameter button style pickups mounted on the diagonals of the quadrupole vacuum chambers. Before installation of the vacuum chambers in the quadrupole assemblies, the electrical center of the BPMs is measured with respect to the mechanical center in a calibration test stand. In this paper the calibration test stand is described and the precision and accuracy of the calibrations are presented. After installation of the quadrupole assemblies in the PEP-II tunnel, the passive attenuation for each channel of the system is measured to preserve the accuracy of the calibration. Finally, the active electronics includes an onboard calibrator. Results for these portions of the calibration are presented

[en] The Isotope Hydrology Section has been testing a newly available automated precipitation sampler to obtain short term isotopic data on precipitation and a laser spectroscopy analyzer for water vapour isotope analysis. The reliability of model based future climate scenarios described in the Intergovernmental Panel on Climate Change (IPCC) assessment report depends on how these models can simulate the observed present day climate - both globally and at the regional level. It is well known that the climate models fail to simulate the observed precipitation field in the tropics and there are wide variations between models for the simulated global field. Recently, to reduce these model uncertainties, a high resolution climate model was developed and a more realistic scheme incorporated into the model. These developments may contribute to improving the reproducibility of present day climate, though an accurate simulation of the present day climate field does not guarantee a precise future prediction. One of the most important things for future prediction is whether the current climate model can reproduce key climate processes both in the present and the past.

[en] Due to the beamline space constrictions and the modular design of the vacuum system, a conventional bellows can not be used everywhere in the PEP-II High-Energy Ring (HER) arcs. A zero-length ''Flex Flange'' was developed which actually performs better than a more standard bellows. The Flex Flange fits the space available while still preserving the modularity of the system. Furthermore, the design provides for an accurate match-up between adjoining octagonal copper chambers despite the large fabrication and assembly tolerances and high operational loads. Beam chamber continuity is ensured by an integral RF seal ring which is easy to install and fault-tolerant. Heating from synchrotron radiation and higher-order mode trapping is managed to ensure a robust connection despite the 3,000 mA beam current of the PEP-II HER. The Flex Flange concept is versatile and adaptable to many applications, yet economical both in space needed and cost

[en] Attainment of high luminosity in storage ring colliders necessitates increasing stored currents and reducing bunch lengths. Consequently, intense beam fields will scatter more power into higher order modes from beam line sources such as collimators, masks and tapers. This power penetrates into sensitive components such as a bellows, causing undesirable heating and limits machine performance. To overcome this limitation we propose incorporating ceramic absorbers in the vicinity of the bellows to damp beam induced modes while preserving a matched impedance to the beam. This is accomplished with an absorber configuration which damps TE dipole and quadrupole traveling waves while preserving TM monopole propagation. A scattering parameter analysis is presented utilizing properties of commercial grade ceramics and indicates a feasible solution

[en] The authors use MAFIA to analyze the PEP-II button-type beam position monitors (BPMs). Employing proper termination of the BPM into a coaxial cable, the output signal at the BPM can be determined. Thus the issues of sensitivity and power output can be addressed quantitatively, including all transient effects and wakefields. Besides this first quantitative analysis of a true BPM 3D structure, they find that internal resonant modes are a major source of high value narrow-band impedances. These are evaluated and methods are presented to suppress these parasitic resonances below the tolerable limit of multibunch instabilities

[en] The beam position monitor (BPM) was designed to provide a robust UHV feedthru and a reliable electromagnetic sensor. Stringent resolution requirements at low beam currents, bunch parameters, along with mechanical and chamber requirements produced challenges in the electrical, thermal, and structural design of the BPM's. Numerical modeling and experimental analyses were used to optimize the design. The higher order modes (HOM's) and beam impedance were modeled using MAFIA. Measurements agreed with the calculated 1 Ω transfer impedance at the 952 MHz signal processing frequency, and the first two HOM's found in MAFIA. Tests and analysis both showed the button signal power approaching 40 W. Temperature and stress distributions were analyzed using this power loading with ANSYS. An electronic grade CuNi was selected for the BPM to reliably weld into the copper chambers. Pin seal and compressive joints were considered for the insulator vacuum seals. Both glassy ceramic-to-metal and ceramic-to-metal seals were evaluated

[en] We have performed low-temperature specific heat and electrical resistivity measurements on a single-crystalline Ce₂CoIn₈. We observed a distinct jump at 0.47 K in specific heat, providing clear evidence of bulk superconductivity. H_c2(0) is 1.1 T for H||a and 0.9 T for H||c, respectively. The unknown steps observed resistivity, T_a1 and T_a2, shifted to low-temperature with increasing field and exhibits large anisotropy by field directions

[en] We use MAFIA to analyze the PEP-II button-type beam position monitor (BPM). Employing proper termination of the BPM into a coaxial cable, the output signal at the BPM is determined. Thus the issues of signal sensitivity and power output can be addressed quantitatively, including all transient effects and wakefields. Besides this first quantitative analysis of a true BPM 3D structure, we find that internal resonant modes are a major source of high value narrow-band impedances. The effects of these resonances on coupled-bunch instabilities are discussed. An estimate of the power dissipation in the ceramic vacuum seal under high current operation is given. (author)

[en] The authors use MAFIA to analyze the PEP-II button-type beam position monitor (BPM). Employing proper termination of the BPM into a coaxial cable, the output signal at the BPM is determined. Thus the issues of signal sensitivity and power output can be addressed quantitatively, including all transient effects and wakefields. Besides this first quantitative analysis of a true BPM 3D structure, they find that internal resonant modes are a major-source of high value narrow-band impedances. The effects of these resonances on coupled-bunch instabilities are discussed. An estimate of the power dissipation in the ceramic vacuum seal under high current operation is given