39316948
A Betatron Tune Fitting Package for the Tevatron 21.4 MHz Schottky
The Fermilab Tevatron is equipped with two independent Schottky monitors for measurement of betatron tunes, one operating at 21.4 MHz and the other at 1.7 GHz. A new front-end and related data acquisition for the 21.4 MHz resonator has been installed and commissioned during the FY04 Collider RunII. Sophisticated fitting strategies are required to analyze the spectra. Optimization of this fitting package allows us to report tune and chromaticity measurements at almost 1 Hz.
1161525
Recent studies of dispersion matched steering for the ILC bunch compressor and main linac
The dispersion matched steering (DMS) method is studied in detail in the context of a curved main linac. In the absence of cavity tilts (rotations in the YZ plane), DMS provides a unique and stable solution with negligible emittance growth. If cavity tilts are about 300 murad, the algorithm is not very robust. The emittance growth through the entire linac for positrons is about 5 nm, if the system is strictly static and statistical averaging can be used to improve beam position measurements. This growth is mostly eliminated if the dispersion and its derivative at injection can be adjusted. If anticipated ground motion, beam and klystron jitter, beam position measurement resolution are introduced (i.e. dynamical case), the emittance preservation goal is currently not achieved by DMS alone. Mitigation strategies are outlined.
116622236
Beam simulation tools for GEANT4 (and neutrino source applications)
Geant4 is a tool kit developed by a collaboration of physicists and computer professionals in the High Energy Physics field for simulation of the passage of particles through matter. The motivation for the development of the Beam Tools is to extend the Geant4 applications to accelerator physics. Although there are many computer programs for beam physics simulations, Geant4 is ideal to model a beam going through material or a system with a beam line integrated to a complex detector. There are many examples in the current international High Energy Physics programs, such as studies related to a future Neutrino Factory, a Linear Collider, and a very Large Hadron Collider.
33125511
Beam-Beam Effects in the Tevatron Run II
Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams are significant sources of beam loss and lifetime limitations in the Tevatron Collider Run II (2001-present). We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in high energy physics (HEP) operation, predict the performance for planned luminosity upgrades and discuss ways to improve it.
62352767
ASPECTS OF SCIENTIFIC VISUALIZATION FOR HEP ANALYSIS AT FERMILAB
16599712
Comparison of tracking codes for the International Linear Collider
In an effort to compare beam dynamics and create a "benchmark" for Dispersion Free Steering (DFS) a comparison was made between different International Linear Collider (ILC) simulation programs while performing DFS. This study consisted of three parts. Firstly, a simple betatron oscillation was tracked through each code. Secondly, a set of component misalignments and corrector settings generated from one program was read into the others to confirm similar emittance dilution. Thirdly, given the same set of component misalignments, DFS was performed independently in each program and the resulting emittance dilution was compared. Performance was found to agree exceptionally well in all three studies.
114128621
Conclusions from Procuring, Installing and Commissioning Six Large-Scale Helium Refrigerators at CERN
Between 1990 and 1994 CERN procured, installed and commissioned six large-scale helium cryoplants for its programme of superconducting acceleration cavities in the electron-positron collider LEP. Two European suppliers were selected to each provide one plant of 6 kW and two plants of 12 kW equivalent cooling power at 4.5 K. All installations are now commissioned and operational, some have been running continuously for several years. The concepts applied to specification, tendering, sharing of responsibilities for infrastructure and controls, installation, and commissioning are presented. Conclusions are drawn from the experiences during the different phases of this project and applied to acquisition of plant upgrades and additional plants required for LHC, CERN’s new project for a proton-proton collider in the LEP tunnel using superconducting magnets.
108030818
Helium Cryogenics at the Lep Experimental Areas
LEP, the large electron-positron collider built at CERN, is now starting to operate. Its four experimental areas, installed in large caverns down to 150 m below ground, are equipped with two types of superconducting magnet, namely large detector solenoids and “low-beta” focusing quadrupoles, operated from common ancillary cryogenic systems. The large size, geographical dispersion, underground implantation and operating environment of LEP have set unusual constraints and dictated specific choices for the four helium cryogenic plants, distribution systems, magnet cryostats, and process operation, particularly as concerns operational flexibility, reliability, safety, remote control and automation. After describing the main design features of the cryogenic systems, we report on their installation, commissioning and first experience of operation.
115884934
Operational experience with the LEP low-beta superconducting quadrupoles
118873811
Experimental investigation of accidental loss of insulation vacuum in an LHC prototype dipole cryostat
A sudden loss of insulation vacuum in an accelerator cryomagnet system be it due to a helium leak from a cryogenic circuit or leak from atmosphere has consequences for the cold mass as well as for the vacuum enclosure. The vacuum enclosure for the LHC dipole cryostat is made of carbon steel to reduce costs and to provide magnetic shielding. In the case of a loss of insulation vacuum the vacuum enclosure will be cooled rapidly but must not reach temperatures low enough to cause embrittlement of the wall material. Helium gas at room temperature was admitted into the insulation space of a modified prototype cryomagnet, the cold mass of which had been previously cooled to 80 K. The evolution of temperature with time of the cold mass and of the vacuum enclosure has been measured and the corresponding heat influx estimated from a simple model.
117780885
Cryogenics for particle accelerators and detectors