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.
124025480
Beam simulation tools for GEANT4 (BT-v1.0) user's guide
122661128
A first approach to mechanical construction and cooling of a composite 3D silicon vertex detector
Abstract This paper presents first results on mechanical and cooling studies for a 3D silicon vertex detector designed for B physics at a hadron collider. Prototype modules were built from raw silicon wafers. One module was instrumented with resistors to simulate readout electronics. Both module movement and temperature variations were recorded. A cooling method utilizing simple air/helium flow was investigated, but proved inadequate because of too large temperature anisotropies.
116611232
B Physics working group summary
Calculations of the B{sub c} spectrum of energy levels, transitions between levels, and weak decays of the ground state, as well as their production and observation at hadron colliders, are summarized. Also, recent experimental B Physics results from the CDF and D0 Tevatron experiments are reviewed and future prospects are discussed.
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.
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.
121687747
A full-scale thermal model of a prototype dipole cryomagnet for theCERN LHC project
Abstract The design, construction and thermal performance of an LHC Cryostat Thermal Model are described. In place of an LHC prototype dipole cold mass a standard- cryostat houses a cold mass with the same overall dimensions, cold surface area, thermal insulation and support systems. The Cryostat Thermal Model is connected to suitably dimensioned end boxes fixing the required temperature levels, by means of saturated helium baths at 1.9 K and 4.2 K, and controlled flows of gaseous helium at 50 to 75 K. Comprehensive instrumentation and fully automatic process control and data acquisition allow precise calorimetric measurements to be performed at all temperature levels.
118732852
Advanced Technology from and for Basic Science: Superconductivity and Superfluid Helium at the Large Hadron Collider
122883842
SUPERFLUID HELIUM AS A TECHNICAL COOLANT
The characteristics of superfluid helium as a technical coolant, which derive from its specific transport properties, are presented with particular reference to the working area in the phase diagram (saturated or pressurised helium II). We then review the principles and scaling laws of heat transport by equivalent conduction and by forced convection in pressurised helium II, thus revealing intrinsic limitations as well as technological shortcomings of these cooling methods. Once properly implemented, two-phase flow of saturated helium II presents overwhelming advantages over the previous solutions, which dictated its choice for cooling below 1.9 K the long strings of superconducting magnets in the Large Hadron Collider (LHC), a 26.7 km circumference particle collider now under construction at CERN, the European Laboratory for Particle Physics near Geneva (Switzerland). We report on recent results from the ongoing research and development programme conducted on thermohydraulics of two-phase saturated helium II flows, and on the validation of design choices for the LHC cooling system.
55760121
Economics of Large Helium Cryogenic Systems : experience from Recent Projects at CERN
Large projects based on applied superconductivity, such as particle accelerators, tokamaks or SMES, require powerful and complex helium cryogenic systems, the cost of which represents a significant, if not dominant fraction of the total capital and operational expenditure. It is therefore important to establish guidelines and scaling laws for costing such systems, based on synthetic estimators of their size and performance. Although such data has already been published for many years, the experience recently gathered at CERN with the LEP and LHC projects, which have de facto turned the laboratory into a major world cryogenic center, can be exploited to update this information and broaden the range of application of the scaling laws. We report on the economics of 4.5 K and 1.8 K refrigeration, cryogen distribution and storage systems, and indicate paths towards their cost-to-performance optimisation.
121495790
Ionization loss in BGO
Abstract We report on a precise measurement of the energy loss through ionization by pions in bismuth germanate performed at several values of the incident particles momentum with a prototype of the L3 electromagnetic calorimeter. The experimental results are in good agreement with theoretical predictions showing the relativistic rise modified by density effect.