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Physical effects of infrared quark eigenmodes in LQCD

Physical effects of infrared quark eigenmodes in LQCD

Date: October 7, 1999
Creator: A. Duncan, E. Eichten and H. Thacker
Description: A truncated determinant algorithm is used to study the physical effects of the quark eigenmodes associated with eigenvalues below 300 MeV. This initial study focuses on coarse lattices (with O(a{sup 2}) improved gauge action), light internal quark masses and large physical volumes. Four bellweather full QCD processes are discussed: topological charge distributions, the eta prime propagator, string breaking as observed in the static energy and the rho decay into two pions.
Contributing Partner: UNT Libraries Government Documents Department
Experience at Fermilab with high quantum efficiency photo-cathodes for rf electron guns

Experience at Fermilab with high quantum efficiency photo-cathodes for rf electron guns

Date: October 1, 1998
Creator: A. Fry, E. Hahn, W. Hartung, M. Kuchnir, P. Michelato and D. Sertore
Description: As part of the A0 Photo-injector collaboration at Fermi-lab [1, 2] and the TeSLA collaboration [3], a high bright-ness, low emittance electron source has been developed. In the process, a system was constructed for coating molybde-num cathodes with a layer of cæsium telluride (Cs2 Te), a photo-emissive material of high quantum efficiency (QE). The use of Cs2 Te was first investigated at CERN [4] and LANL [5]. The development of the systems for the TeSLA Test Facility Linac and the Fermilab Photo-injector was done in Milano [6]. The system at Fermilab incorporates manipulator arms to transfer a cathode from the preparation chamber into a 1.3 GHz photo-electron RF gun while it re-mains in an ultra-high vacuum (UHV) environment, in or-der to avoid the deleterious effects of residual gases on the QE. A first prototype electron gun has been operated with a photo-cathode for several months [1]. This paper describes preliminary results obtained with the first 2 photo-cathodes and the first gun. Some of the desired parameters for the TeSLA Test Fa-cility beam are given in Table 1. The desired characteristics for the photo-cathodes include (i) high QE, (ii) high current density (>500 A/cm{sup 2} ), (iii) long lifetime, and (iv) ...
Contributing Partner: UNT Libraries Government Documents Department
Fabrication of high-density cantilever arrays and through-wafer interconnects

Fabrication of high-density cantilever arrays and through-wafer interconnects

Date: November 3, 1998
Creator: A. Harley, J.; Abdollahi-Alibeik, S.; Chow, E. M.; Kenney, T. W.; McCarthy, A. M.; McVittie, J. P. et al.
Description: Processes to fabricate dense, dry released microstructures with electrical connections on the opposite side of the wafer are described. A 10 x 10 array of silicon and polysilicon cantilevers with high packing density (5 tips/mm<sup>2</sup>) and high uniformity (<10 µm length variation across the wafer) are demonstrated. The cantilever release process uses a deep SF<sub>6</sub>/C<sub>4</sub>F<sub>8</sub>, plasma etch followed by a HBr plasma etch to accurately release cantilevers. A process for fabricating electrical contacts through the backside of the wafer is also described. Electrodeposited resist, conformal CVD metal deposition and deep SF<sub>6</sub>/C<sub>4</sub>F<sub>8</sub> plasma etching are used to make 30 µm/side square vias each of which has a resistance of 50 m(omega).
Contributing Partner: UNT Libraries Government Documents Department
Results from an FPIX0 chip bump-bonded to an atlas pixel detector

Results from an FPIX0 chip bump-bonded to an atlas pixel detector

Date: October 1, 1998
Creator: A. Mekkaoui, D. Christian, S. Kwan, J Srage and R. Yarema
Description: Results are presented of tests performed on the first pixel detector readout ASIC designed at Fermilab (FPIX0).
Contributing Partner: UNT Libraries Government Documents Department
50x50 GeV Muon Collider Beam Collimation

50x50 GeV Muon Collider Beam Collimation

Date: April 14, 1999
Creator: A.I. Drozhdin, C.J. Johnstone, N.V. Mokhov, A.A. Garen and V.M. Biryukov
Description: A summary of different techniques and systems to scrape beam halo in a 50 x 50 GeV {mu}{sup +}{mu}{sup -} collider is presented. Such systems are installed in a special utility section with optics specifically designed to meet both the requirements of the scraping system and of injection. Results froma realistic Monte Carlo simulation (STRUCT-MARS) show that a system consisting of steel absorbers several meters in length suppresses halo-induced backgrounds in the collider detector by more than three orders of magnitude. The heat load in superconducting magnets near the scraper system can be reduced to tolerable levels by appropriate collimator design and location. This reduction applies to both injection and collider mode of operation. Also discussed is extraction of halo particles using electrostatic deflectors and bent crys-tals, although neither appears to be effective for a muon collider at this energy.
Contributing Partner: UNT Libraries Government Documents Department
Impact of the LHC beam abort kicker prefire on high luminosity insertion and CMS detector performance

Impact of the LHC beam abort kicker prefire on high luminosity insertion and CMS detector performance

Date: April 13, 1999
Creator: A.I. Drozhdin, N.V. Mokhov and M. Huhtinen
Description: The effect of possible accidental beam loss in LHC on the IP5 insertion elements and CMS detector is studied via realistic Monte Carlo simulations. Such beam loss could be the consequence of an unsynchronized abort or � in worst case � an accidental prefire of one of the abort kicker modules. Simulations with the STRUCT code show that this beam losses would take place in the IP5 inner and outer triplets. MARS simulations of the hadronic and electro-magnetic cascades induced in such an event indicate severe heating of the inner triplet quadrupoles. In order to protect the IP5 elements, two methods are proposed: a set of shadow collimators in the outer triplet and a prefired module compensation using a special module charged with an opposite voltage (antikicker). The remnants of the accidental beam loss entering the experimental hall have been used as input for FLUKA simulations in the CMS detector. It is shown that it is vital to take measures to reliably protect the expensive CMS tracker components.
Contributing Partner: UNT Libraries Government Documents Department
On possible use of bent crystal to improve Tevatron beam scraping

On possible use of bent crystal to improve Tevatron beam scraping

Date: April 8, 1999
Creator: A.I. Drozhdin, N.V. Mokhov and V.M. Biryukov
Description: A possibility to improve the Tevatron beam halo scraping using a bent channeling crystal instead of a thin scattering primary collimator is studied. To evaluate the efficiency of the system, realistic simulations have been performed using the CATCH and STRUCT Monte Carlo codes. It is shown that the scraping efficiency can be increased and the accelerator-related backgrounds in the CDF and DØ collider detectors can be reduced by about one order of magnitude. Results on scraping efficiency versus thickness of amorphous layer of the crystal, crystal alignment and its length are presented.
Contributing Partner: UNT Libraries Government Documents Department
Radiation environment resulting from Main Injector beam extraction to the NuMI beam line

Radiation environment resulting from Main Injector beam extraction to the NuMI beam line

Date: April 29, 1999
Creator: A.I. Drozhdin, P.W. Lucas, N.V. Mokhov, C.D. Moore and S.I. Striganov
Description: A 120 GeV Main Injector proton beam will be delivered to the NuMI beam line at Fermilab at the rate of 3.7x 10{sup 20} per year. Realistic Monte Carlo simulations have been performed to examine the radiation environment in the beam extraction system and NuMI beam line elements. A complete 3-D model of the 160 meter extraction region has been implemented utilizing the computer code MARS. The model includes a description of the field of the electrostatic septa and POISSON calculated field maps of the Lambertson magnets and the other lattice components in the area. The beam element alignment and the source term have been simulated using the code STRUCT. Results on beam losses in the system, energy deposition in the core elements and residual dose rates on the components are presented.
Contributing Partner: UNT Libraries Government Documents Department
Advanced Emissions Control Development Program

Advanced Emissions Control Development Program

Date: April 1, 1998
Creator: A.P.Evans; Redinger, K.E. & Holmes, M.J.
Description: The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).
Contributing Partner: UNT Libraries Government Documents Department
Roles and Delegation of Authority (R/DA) System

Roles and Delegation of Authority (R/DA) System

Date: October 21, 1999
Creator: ABBOTT,JOHN P.; HUTCHINS,JAMES C. & SCHOCH,DAVID G.
Description: The processes of defining managerial roles and providing for delegation of authority are essential to any enterprise. At most large organizations, these processes are defined in policy manuals and through sets of standard operating procedures for many, if not all, business and administrative functions. Many of these staff-initiated, administrative functions require the routing of documents for approval to one or more levels of management. These employee-oriented, back office types of workflows tend to require more flexibility in determining to whom these documents should go to, while, at the same time, providing the responsible parties with the flexibility to delegate their approval authority or allow others to review their work. Although this practice is commonplace in manual, paper-based processes that exist in many organizations, it is difficult to provide the same flexibility in the more structured, electronic-based, workflow systems.
Contributing Partner: UNT Libraries Government Documents Department