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.
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.
56333052
Benchmarking/Crosschecking DFS in the ILC Main Linac
In an effort to compare beam dynamics and create a ''benchmark'' for Dispersion Free Steering (DFS) a comparison was made between different ILC simulation programs while performing DFS. This study consisted of three parts. First, 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.
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.
43442717
Recent results from Fermilab E687
Recent analyses from Fermilab fixed target photoproduction experiment 687 are summarized. Emphasis is placed on strong interaction studies performed on high statistics samples of Charm decays and light quark states. In particular, semi-leptonic measurements of form factors in Cabibbo suppressed modes are described. A Dalitz analysis of the D{sub s}{sup +}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup +} has been performed and can be linked to recent results on scalar states decaying to {pi}{sup +}{pi}{sup -}. In addition, Charm-Anticharm asymmetries in high energy photoproduction have been measured. Finally, photoproduction of light quark states, such as the vector meson {rho}(1700) or the f{sub 0}(980) are discussed.
121144688
Cryogenic benches for superfluid helium testing of full-scale prototype superconducting magnetsfor the CERN LHC project
Abstract The Large Hadron Collider (LHC) project at CERN will make massive use ofhigh-field superconducting magnets, operating below 1.9 K in pressurized superfluid helium. Reception testing of these magnets requires dedicated cryogenic facilities, consisting of an array of single-magnet test benches fed from a common large-capacity refrigeration system. Following installation and commissioning of general. cryogenic infrastructure, we have designed and constructed two such cryogenic benches, and are operating the first one for tests of 10-m long LHC prototype dipole cryomagnets supplied by European industry. We describe system architecture, cryogenic process and constructional features of these benches in the following, and report on test results in a companion paper.
56249291
EXERGY ANALYSIS OF THE CRYOGENIC HELIUM DISTRIBUTION SYSTEM FOR THE LARGE HADRON COLLIDER (LHC)
The Large Hadron Collider (LHC) at CERN features the world’s largest helium cryogenic system, spreading over the 26.7 km circumference of the superconducting accelerator. With a total equivalent capacity of 145 kW at 4.5 K including 18 kW at 1.8 K, the LHC refrigerators produce an unprecedented exergetic load, which must be distributed efficiently to the magnets in the tunnel over the 3.3 km length of each of the eight independent sectors of the machine. We recall the main features of the LHC cryogenic helium distribution system at different temperature levels and present its exergy analysis, thus enabling to qualify second‐principle efficiency and identify main remaining sources of irreversibility.
107929768
Measurement and analysis of thermal performance of LHC prototype cryostats
The heat inleaks into the cryostats represent a significant fraction of the total heat loads to the Large Hadron Collider (LHC). In view of the large size of this machine and the high thermodynamic cost of low-temperature refrigeration, it is essential to maintain the heat inleaks within budgeted values. Following experimental validation of thermal design of critical components (e.g. multilayer reflective insulation, support posts, cold valves), thermal performance assessment of complete cryomagnets has been undertaken. Thermo-mechanical and cryogenic behaviour was measured on full-scale prototype units.
120725124
Application of liquid helium cryoplants at CERN
In 1992, the liquid-helium cooling capacity installed at CERN was nearly tripled, passing from 6.8 to 19.7 kW/4.5 K (entropy equivalent*). Further tripling is expected in 1993. While the 6.8 kW available in 1991 were produced by 14 plants of moderate size (500 W/4.5 K average), two of the four plants added in 1992 have unit capacities of 6 kW/4.5 K. Four plants of 12 kW/4.5 K, upgradable to 18 kW/4.5 K in a later phase, are presently being installed. Most of the smaller plants are associated with particle physics experiments, cooling superconducting magnets of particle detectors and high-gradient focusing magnets of colliding-beam experiments. Six plants provide liquid helium for development laboratories and test facilities. The recently acquired multi-kW plants will be integral parts of the collider itself. Their present function is to cool superconducting RF cavities designed to increase the beam energy of the Large Electron Positron collider LEP from 50 to above 90 GeV. In the future, the same and additional plants will be available for the cooling of the superconducting magnet ring of the planned Large Hadron Collider LHC. To this end, they will be equipped with complementary 1.8 K final stages.
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.