202681335
Steady State and Transient Current Lead Analysis
A mathematical model of the gas-cooled, resistive portion of a binary current lead has been developed. An analytical solution of the time-dependent differential equations for the resistive portion of the forced flow cooled current lead is presented which allows one to calculate the evolution of the temperature profile and voltage drop. A comparison of analytical with numerical calculations and a comparison of the calculations with experimental data are given.
122705766
Construction experience with MQXB quadrupole magnets built at Fermilab for the LHC interaction regions
Fermilab is building eighteen full length cold masses for the LHC Interaction Region inner triplets. One prototype and several production assemblies have been completed. This paper summarizes the construction details. Topics include coil fabrication, ground insulation, collaring, instrumentation, electrical testing, and final assembly. In-process measurements are presented and explained. Problems encountered during construction and their solutions are discussed.
157115
Field quality measurements of the LQXB inner triplet quadrupoles for LHC
As a part of the USLHC program, Fermilab is building half of the inner triplet quadrupole magnets for the LHC. Two identical quadrupoles (MQXB) with a dipole corrector between them in a single cryogenic unit (LQXB) comprise the Q2 optical element of the final focus triplets in the interaction regions. The 5.5 m long MQXB have a 70 mm aperture and operate in superfluid helium at 1.9 K with a peak field gradient of 215 T/m. Manufacturing of the 18 magnets is in an advanced stage. A program of magnetic field quality measurements of the magnets is performed at room temperature during magnet fabrication as well as at superfluid helium temperature during the cold qualification of each magnet. Results of the measurements are summarized in this paper.
124796127
$Z \gamma$ production in $\bar{p} p$ collisions $S^{(1/2)}$ = 1.8-TeV and limits on anomalous $Z Z \gamma$ and $Z \gamma \gamma$ couplings
We present a study of Zγ+X production in p¯p collisions at √s=1.8TeV from 97 (87)pb−1 of data collected in the eeγ (μμγ) decay channel with the D0 detector at Fermilab. The event yield and kinematic characteristics are consistent with the standard model predictions. We obtain limits on anomalous ZZγ and Zγγ couplings for form factor scales Λ=500GeV and Λ=750GeV. Combining this analysis with our previous results yields 95% C.L. limits |hZ30|<0.36, |hZ40|<0.05, |hγ30|<0.37, and |hγ40|<0.05 for a form factor scale Λ=750GeV.
55615786
TEST RESULTS OF SHORT MODEL QUADRUPOLES FOR THE LHC LOW-BETA INSERTIONS
A quadrupole is being developed for the LHC low- insertions by Fermilab and LBNL. A series of short model magnets is being built to optimize the design and refine assembly methods. This paper presents results of two short model magnet tests performed in normal and superfluid helium, summarizing the quench and mechanical performance of the short model magnets. Results on quench protection heater studies are also presented.
34116764
Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands
Recent advancements in the critical current density of conductors, coupled with a large effective filament size, have drawn attention to the problem of magneto-thermal instabilities. At low magnetic fields, the quench current of such high strands is significantly lower than their critical current because of the above-mentioned instabilities. An adiabatic model to calculate the minimum current at which a strand can quench due to magneto-thermal instabilities is developed. The model is based on an dasiaintegralpsila approach already used elsewhere . The main difference with respect to the previous model is the addition of the self-field effect that allows to describe premature quenches of non-magnetized strands and to better calculate the quench current of strongly magnetized strands. The model is in good agreement with experimental results at 4.2 K obtained at Fermilab using virgin Modified Jelly Roll (MJR) strands with a low residual resistivity ratio (RRR) of the stabilizing copper. The prediction of the model at 1.9 K and the results of the tests carried out at CERN, at 4.2 K and 1.9 K, on a 0.8 mm Rod Re-Stack Process (RRP) strand with a low RRR value are discussed. At 1.9 K the test revealed an unexpected strand performance at low fields that might be a sign of a new stability regime.
40861122
Separating the dyon system.
The relation between the ''dyon'' system studied by D'Hoker and Vinet and its spin-0 counterpart described earlier by McIntosh and Cisneros and by Zwanziger can be made manifest by using suitable variables, introduced before by Biedenharn and by McIntosh and Berrondo in the relativistic Kepler problem. This leads to a simple determination of the spectra.