121334249
Observations of the Scalar Meson f{sub 0} (980) in the photoproduction experiment E687 at Fermilab
Observation of the scalar meson f{sub 0}(980) is reported in the E687 photoproduction experiment at Fermilab. Evidence is given also for the quasi-exclusive associated {phi}(1020)f{sub 0}(980) photoproduction.
62352767
ASPECTS OF SCIENTIFIC VISUALIZATION FOR HEP ANALYSIS AT FERMILAB
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.
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.
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.
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.
135785653
Very-Low-Loss Liquid Helium Transfer with Long Flexible Cryogenic Lines
The four underground areas of LEP, the large electron-positron collider now operating at CERN, are equipped with helium cryogenic plants continuously feeding superconducting magnets over distances of up to 92 m, with differences in elevation reaching 25 m. For this purpose, 500 m of vapour-shielded flexible cryogenic lines, of coaxial corrugated tube construction, have been manufactured in industry and performance tested in the laboratory prior to site installation. Several improvements in design with respect to earlier lines of similar construction, as well as systematic quality-control procedures, made it possible to achieve reproducibly linear heat inleaks of about 30 mW m−1, in self-sustained vapour shielding operation. We describe the main design principles and constructional features of the lines, and report on methods and results of their performance tests.
59027060
ASSESSING RISK IN COSTING HIGH-ENERGY ACCELERATORS:FROM EXISTING PROJECTS TO THE FUTURE LINEAR COLLIDER
High-energy accelerators are large projects funded by public money, developed over the years and constructed via major industrial contracts both in advanced technology and in more conventional domains such as civil engineering and infrastructure, for which they often constitute one-off markets. Assessing their cost, as well as the risk and uncertainty associated with this assessment is therefore an essential part of project preparation and a justified requirement by the funding agencies. Stemming from the experience with large circular colliders at CERN, LEP and LHC, as well as with the Main Injector, the Tevatron Collider Experiments and Accelerator Upgrades, and the NOvA Experiment at Fermilab, we discuss sources of cost variance and derive cost risk assessment methods applicable to the future linear collider, through its two technical approaches for ILC and CLIC. We also address disparities in cost risk assessment imposed by regional differences in regulations, procedures and practices.
120234331
Performances of a preamplifier-silicon photodiode readout system associated with large BGO crystal scintillators
Abstract The characteristics of a hybridized low noise preamplifier are described. Performances of the preamplifier in combination with silicon photodiodes are discussed and results from laboratory tests and test runs with an assembly of large BGO crystals are presented.
73692973
Cooling with Superfluid Helium
The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation.
118067725
Advances in Cryogenics at the Large Hadron Collider
After a decade of intensive R&D in the key technologies of high-field superconducting accelerator magnets and superfluid helium cryogenics, the Large Hadron Collider (LHC) has now fully entered its construction phase, with the adjudication of major procurement contracts to industry. As concerns cryogenic engineering, this R&D program has resulted in significant developments in several fields, among which thermo-hydraulics of two-phase saturated superfluid helium, efficient cycles and machinery for large-capacity refrigeration at 1.8 K, insulation techniques for series-produced cryostats and multi-kilometre long distribution lines, large-current leads using high-temperature superconductors, industrial precision thermometry below 4 K, and novel control techniques applied to strongly non-linear processes. We review the most salient advances in these domains.