Alignment tolerances of IR quadrupoles in the LHC (open access)

Alignment tolerances of IR quadrupoles in the LHC

Luminosity in the LHC will depend critically on the alignment of the triplet quadrupoles. These quadrupoles are closest to the interaction points (IPs), have large gradients and the {beta} functions have their largest values within these quadrupoles. Within a triplet, the cold masses of the Q1 and Q3 quadrupoles will be housed in separate cryostats while Q2a and Q2b will be placed in a single cryostat. The absolute alignments of Q1, Q3 and the Q2a/Q2b pair with respect to the desired axes will be determined during installation. The relative alignment of Q2a and Q2b however will be fixed once they are placed in their common cryostat at Fermilab. In this note, we examine the required relative alignment tolerances of Q2a and Q2b. An early study of some alignment tolerances was done by Weisz [1].
Date: November 5, 1999
Creator: Sen, Tanaji
System: The UNT Digital Library
Analysis of Dry Storage Temperature Limits for Zircaloy-Clad Spent Nuclear Fuel (open access)

Analysis of Dry Storage Temperature Limits for Zircaloy-Clad Spent Nuclear Fuel

Safe interim dry storage of spent nuclear fuel (SNF) must be maintained for a minimum of twenty years according to the Code of Federal Regulations. The most important variable that must be regulated by dry storage licensees in order to meet current safety standards is the temperature of the SNF. The two currently accepted models to define the maximum allowable initial storage temperature for SNF are based on the diffusion controlled cavity growth (DCCG) failure mechanism proposed by Raj and Ashby. These models may not give conservative temperature limits. Some have suggested using a strain-based failure model to predict the maximum allowable temperatures, but we have shown that this is not applicable to the SNF as long as DCCG is the assumed failure mechanism. Although the two accepted models are based on the same fundamental failure theory (DCCG), the researchers who developed the models made different assumptions, including selection of some of the most critical variables in the DCCG failure equation. These inconsistencies are discussed together with recommended modifications to the failure models based on more recent data.
Date: November 5, 1999
Creator: Hayes, T.A.; Kassner, M.D. & Vecchio, K.S.
System: The UNT Digital Library
The CDF TESTCLK module - Providing system level clocking and triggering for Run 2 prototyping crates (open access)

The CDF TESTCLK module - Providing system level clocking and triggering for Run 2 prototyping crates

The TESTCLK module was specifically designed for use in prototyping crates for the Colliding Detector Facility (CDF) Run 2 Experiment at Fermi National Accelerator Laboratory. The TESTCLK Module allows the user to supply system clocks and trigger signals to stand-alone crates. This module has allowed designers of the CDF Run 2 electronics to thoroughly test their modules, despite the lack of a DAQ system supplied clock and trigger interface. This paper will explore the features that were found important to incorporate into the TESTCLK, and describe how they were implemented. The paper will also describe how the TESTCLK module has been used to support the initial implementation of the DAQ system at CDF. This has allowed data taking and testing of CDF Electronic modules before production clock and trigger modules became available.
Date: November 5, 1999
Creator: Stuermer, Theresa Shaw and Walter
System: The UNT Digital Library
The design and PCB layout of the CDF Run 2 calorimetry readout module (open access)

The design and PCB layout of the CDF Run 2 calorimetry readout module

The CDF Calorimetry Readout module, called the ADMEM, has been designed to contain both the analog circuitry which digitizes the phototube charge pulses, and the digital logic which supports the readout of the results through the CDF Run 2 DAQ system. The ADMEM module is a 9Ux400mm VMEbus module, which is housed in a CDF VMEbus VIPA crate. The ADMEM must support near deadtimeless operation, with data being digitized and stored for possible readout every 132ns or 7.6 Mhz. This paper will discuss the implementation of the analog and digital portions of the ADMEM module, and how the board was laid out to avoid the coupling of digital noise into the analog circuitry.
Date: November 5, 1999
Creator: al., Theresa Shaw et
System: The UNT Digital Library
Dynamics of the Inflationary Era (open access)

Dynamics of the Inflationary Era

There is very strong circumstantial evidence that there was an inflationary epoch very early in the history of the universe. In this lecture the author describes how we might be able to piece together some understanding of the dynamics during and immediately after the inflationary epoch.
Date: November 5, 1999
Creator: Kolb, Edward W.
System: The UNT Digital Library
Evaluation of Potential Melt-Dilute/Neutron Absorber Systems for DOE SNF Disposal System (open access)

Evaluation of Potential Melt-Dilute/Neutron Absorber Systems for DOE SNF Disposal System

Approximately 50 metric tonnes heavy metal of aluminum-base spent nuclear fuel (Al-SNF) or 30,000 assemblies are being consolidated at the Savannah River Site. The melt-dilute (MD) technology option is being developed to allow ultimate disposal of these fuels in the Monitored Geologic Repository (MGR). Neutron absorbing materials are needed to maintain k{sub eff} less than 0.95 in desired packaging configurations. The aggressive chemical environment in the MGR is expected to lead to the reconfiguration of the contents of the codisposal waste package following waste package failure. This reconfiguration has the potential for increasing the reactivity of the waste package. The reconfiguration and redistribution of materials within the waste package are being investigated in an analytical and experimental program to support the criticality analysis. Further, the incorporation of neutron absorbing materials that will be integral to the MD SNF form is being investigated.
Date: November 5, 1999
Creator: Vinson, D.
System: The UNT Digital Library
HCCI in a CFR engine: experiments and detailed kinetic modeling (open access)

HCCI in a CFR engine: experiments and detailed kinetic modeling

Single cylinder engine experiments and chemical kinetic modeling have been performed to study the effect of variations in fuel, equivalence ratio, and intake charge temperature on the start of combustion and the heat release rate. Neat propane and a fuel blend of 15% dimethyl-ether in methane have been studied. The results demonstrate the role of these parameters on the start of combustion, efficiency, imep, and emissions. Single zone kinetic modeling results show the trends consistent with the experimental results.
Date: November 5, 1999
Creator: Flowers, D; Aceves, S; Smith, R; Torres, J; Girard, J & Dibble, R
System: The UNT Digital Library
Hydrodynamics of Gas-Liquid Counterflow Through Corrugated Parallel Plates (open access)

Hydrodynamics of Gas-Liquid Counterflow Through Corrugated Parallel Plates

Structured packings utilized in today's distillation packed towers consist of stacked units of many vertically oriented parallel corrugated plates. The V-shaped corrugations are oriented at a fixed angle with respect to the vertical direction, and the corrugation angle in adjacent plates are oriented in reverse direction. Points of contact, at the crests of the corrugations, between adjacent plates, form an unconsolidated porous medium with known topology. Modern structured packings have been gaining acceptance in several separation processes, particularly distillation where gas/vapor and liquid flow countercurrently through the packing. In addition, structured packings have been credited with relatively low pressure drop, high efficiency, low holdup, and higher capacity; the packing also can be made corrosion resistive.
Date: November 5, 1999
Creator: de Almeida, V.F.
System: The UNT Digital Library
Ion Beam Sputter Fabrication of Micro-Grooving and Micro-Threading Tools (open access)

Ion Beam Sputter Fabrication of Micro-Grooving and Micro-Threading Tools

This paper presents techniques for fabricating microscopic, nonplanar features in a variety of materials. Micro-grooving and micro-threading tools having cutting dimensions of 10-30{micro}m are made by focused ion beam sputtering and used in ultra-precision machining. Tool fabrication involves directing a 20 keV gallium beam at polished cylindrical punches made of cobalt M42 high-speed steel or C2 tungsten carbide. This creates cutting edges having radii of curvature less than 0.4 {micro}m, and rake features similar to conventional lathe tools. Clearance for minimizing frictional drag of a tool results from the sputter yield dependence on ion herd target incidence angle. Numerically controlled, ultra-precision machining with micro-grooving tools results in a close matching between tool width and feature size. Microtools controllably machine 13 {micro}m wide, 4 {micro}m deep, helical grooves in polymethyl methacrylate and 6061-T6 Al cylindrical substrates. Micro-grooving tools also fabricate sinusoidal waveform features in polished metal substrates.
Date: November 5, 1999
Creator: Adams,David P.; Vasile,M. J. & Krishnan,A. S. M.
System: The UNT Digital Library
Measures to implement the Chemical Weapons Convention (open access)

Measures to implement the Chemical Weapons Convention

This seminar is another excellent opportunity for those involved in preventing chemical weapons production and use to learn from each other about how the Chemical Weapons Convention (CWC) can become a foundation of arms control in Africa and around the world. The author is grateful to the staff of the Organization for the Prohibition of Chemical Weapons (OPCW) for inviting him to address this distinguished seminar. The views expressed in this paper are those of the authors alone, and do not represent the position of the government of the US nor or of any other institution. In 1993, as the process of CWC ratification was beginning, concerns arose that the complexity of integrating the treaty with national law would cause each nation to implement the Convention without regard to what other nations were doing, thereby causing inconsistencies among States Parties in how the Convention would be carried out. As a result the Manual for National Implementation of the Chemical Weapons Convention was prepared and presented it to each national delegation at the December 1993 meeting of the Preparatory Commission in The Hague. During its preparation, the Manual was reviewed by the Committee of Legal Experts on National Implementation of the …
Date: November 5, 1999
Creator: Tanzman, E. & Kellman, B.
System: The UNT Digital Library
Micromilling of Metal Alloys with Focused Ion Beam-Fabricated Tools (open access)

Micromilling of Metal Alloys with Focused Ion Beam-Fabricated Tools

This work combines focused ion beam sputtering and ultra-precision machining as a first step in fabricating microstructure in metals and alloys. Specifically, {approx}25{micro}m diameter micro-end mills are made from cobalt M42 high-speed steel and C2 micrograin tungsten carbide tool blanks by ion beam sputtering. A 20 keV focused gallium beam defines tool cutting edges having radii of curvature < 0.1{micro}m. Micro-end mills having 2, 4 and 5 cutting edges successfully machine small trenches in 6061-T4 aluminum, brass, 4340 steel and polymethyl methacrylate. Machined trench widths are approximately equal to the tool diameters and surface roughnesses (rms) are {approx}150 nm or less. Microtools are robust and operate for more than 6 hours without fracture. Results from ultra-precision machining aluminum at feed rates as high as 50 mm/minute are included.
Date: November 5, 1999
Creator: ADAMS,DAVID P.; VASILE,M.J.; BENAVIDES,GILBERT L. & CAMPBELL,ANN N.
System: The UNT Digital Library
The NLC Injector System (open access)

The NLC Injector System

The Next Linear Collider (NW) Injector System is designed to produce low emittance, 10 GeV electron and positron beams at 120 hertz for injection into the NLC main linacs. Each beam consists of a train of 9.5 bunches spaced by 2.8 ns; each bunch has a population of 1.15 x 10{sup 10} particles. At injection into the main linacs, the horizontal and vertical emittances are specified to be {gamma}{var_epsilon}{sub x} = 3 x 10{sup -6} m-rad and {gamma}{var_epsilon}{sub y} = 3 x 10{sup -8} m-rad and the bunch length is 100 {micro}m. Electron polarization of greater than 80% is required. Electron and positron beams are generated in separate accelerator complexes each of which contain the source, damping ring systems, L-band, S-band, and X-band linacs, bunch length compressors, and collimation regions. The need for low technical risk, reliable injector subsystems is a major consideration in the design effort. This paper presents an overview of the NLC injector systems.
Date: November 5, 1999
Creator: Bharadwaj, V.; Clendenin, J. E.; Emma, P.; Frisch, J.; Jobe, R.; Kotseroglou, T. et al.
System: The UNT Digital Library
Photon Beam Diagnostics for VISA FEL (open access)

Photon Beam Diagnostics for VISA FEL

The VISA (Visible to Infrared SASE Amplifier) project is designed to be a SASE-FEL driven to saturation in the sub-micron wavelength region. Its goal is to test various aspects of the existing theory of Self-Amplified Spontaneous Emission, as well as numerical codes. Measurements include: angular and spectral distribution of the FEL light at the exit and inside of the undulator; electron beam micro-bunching using CTR; single-shot time resolved measurements of the pulse profile, using auto-correlation technique and FROG algorithm. The diagnostics are designed to provide maximum information on the physics of the SASE-FEL process, to ensure a close comparison of the experimental results with theory and simulations.
Date: November 5, 1999
Creator: Murokh, A.; Pellegrini, C.; Rosenzweig, J.; Frigola, P.; Musumeci, P.; Tremaine, A. et al.
System: The UNT Digital Library
Protocols and standard crate configuration for a typical CDF Run 2 readout crate (open access)

Protocols and standard crate configuration for a typical CDF Run 2 readout crate

This paper describes a standard for the readout and the trigger interface of a VMEbus based crate to be used by the front-end and trigger electronics of the CDF Run 2 experiment. Hereafter, this crate will be referred to as the CDF Readout Crate. The goal is to standardize the implementation of functions that are common among all systems (i.e. power distribution, timing signals, DAQ functions) while allowing some flexibility with other functions (e.g. cooling, rear transition modules, J3 backplanes, etc.). This allows designers of cards that satisfy this standard to have access to a common well defined crate system with interfaces to the trigger and DAQ system, allowing them to concentrate their efforts on the functions they need. This paper lists the mechanical specifications, readout scheme, backplane and signal distribution specifications of the CDF Readout Crate. The paper will also go into some detail on the TRigger And Clock + Event Readout (TRACER) module, a common CDF crate module which provides the crate interface to the system clock and the trigger system.
Date: November 5, 1999
Creator: al., Theresa Shaw et
System: The UNT Digital Library
Recent Developments in the Design of the NLC Positron Source (open access)

Recent Developments in the Design of the NLC Positron Source

Recent developments in the design of the Next Linear Collider (NLC) positron source based on updated beam parameters are described. The unpolarized NLC positron source [1,2] consists of a dedicated 6.2 GeV S-band electron accelerator, a high-Z positron production target, a capture system and an L-band positron linac. The 1998 failure of the SLC target, which is currently under investigation, may lead to a variation of the target design. Progress towards a polarized positron source is also presented. A moderately polarized positron beam colliding with a highly polarized electron beam results in an effective polarization large enough to explore new physics at NLC. One of the schemes towards a polarized positron source incorporates a polarized electron source, a 50 MeV electron accelerator, a thin target for positron production and a new capture system optimized for high-energy, small angular-divergence positrons. The yield for such a process, checked using the EGS4 code, is of the order of 10{sup -3}. The EGS4 code has being enhanced to include the effect of polarization in bremsstrahlung and pair-production process.
Date: November 5, 1999
Creator: Kotseroglou, T.; Bharadwaj, V.; Clendenin, J. E.; Ecklund, S,; Frisch, J.; Krejcik, P. et al.
System: The UNT Digital Library
Single top and top properties at CDF (open access)

Single top and top properties at CDF

Recent CDF results with 110 pb{sup -1} of data on top quark production and decay properties are presented. Limits are placed on single top quark production in the W* and W-gluon channels. A measurement of the polarization of the intermediate W boson in top decay, a search for resonances in the mass of the t{bar t} system, and the transverse momentum of top quarks in t{bar t} events are presented.
Date: November 5, 1999
Creator: Koehn, P.
System: The UNT Digital Library
Single top production and top properties at the Tevatron (open access)

Single top production and top properties at the Tevatron

We summarize recent measurements made at the Tevatron Collider using top event candidates. Cross section and mass measurements are discussed in a separate contribution to these Proceedings. Here we report on studies of the top P<sub>T</sub> distribution in t{anti t} production and studies of single top production. Properties of top decays examined are: BF(t {yields} Wb)/BF(t {yields} Wq), helicity amplitudes of W's from top decays and correlations of t{anti t} decay products. Searches for new physics in rare top decays and a search for a state X {yields} t{anti t} are also reported.
Date: November 5, 1999
Creator: Barbaro-Galtieri, Angela
System: The UNT Digital Library
SMQIE: A charge integrator and encoder chip for the CDF Run II Shower Max Detector (open access)

SMQIE: A charge integrator and encoder chip for the CDF Run II Shower Max Detector

The Technical Design Report for the CDF II Detector calls for the development of an imbedded two-dimensional position sensitive detector sandwiched inside the electromagnetic calorimeter and placed at the shower maximum. The purpose of this detector is to aid in the identification of electrons and photons, to separate photons from {pi}{sup 0}s, and to help identify electromagnetic showers. This detector is called the Shower Max. In order to achieve CDF's goals for resolution, timing, power and economy, as well as to fit into the available space, a full-custom integrated circuit was required for the project - the SMQIE. The SMQIE has been fabricated in a 1.2{micro}m CMOS process using vertical NPN transistors in critical areas. It operates without deadtime. Its QIEs have eight ranges and an overall dynamic range of 13 bits. Its FADCs have a 5-bit resolution with a nominal LSB of 31.25 mV. Its Level 1 Trigger delays are 42 beam crossings or approximately 5.5 {micro}s. Its data buffers hold up to four events, each of which can consist of four time slices. Finally, the chip accepts a maximum input charge up to 150 pC with a minimum resolution of 15 fC.
Date: November 5, 1999
Creator: al., J. Hoff et
System: The UNT Digital Library
System architecture and hardware design of the CDF XFT online track processor (open access)

System architecture and hardware design of the CDF XFT online track processor

A trigger track processor is being designed for CDF Run 2. This processor identifies high momentum (P{sub T} &gt; 1.5 GeV/c) charged tracks in the new central outer tracking chamber for the CDF II detector. The design of the track processor, called the eXtremely Fast Tracker (XFT), is highly parallel and handle an input rate of 183 Gbits/sec and output rate of 44 Gbits/sec. The XFT is pipelined and reports the results for a new event every 132ns. The XFT uses three stages, hit classification, segment finding, and segment linking. The pattern recognition algorithms for the three stages are implemented in Programmable Logic Devices (PLDs) which allow for in-situ modification of the algorithm at any time. The PLDs reside on three different types of modules. Prototypes of each of these modules have been designed and built, and are working. An overview of the hardware design and the system architecture are presented.
Date: November 5, 1999
Creator: al., Scott Holm et
System: The UNT Digital Library
Tungsten Z-Pinch Long Implosions on the Saturn Generator (open access)

Tungsten Z-Pinch Long Implosions on the Saturn Generator

Recent success on the Saturn and Z accelerators at Sandia National Laboratories have demonstrated the ability to scale z-pinch parameters to increasingly larger current pulsed power facilities. Next generation machines will require even larger currents (&gt;20 MA), placing further demands on pulsed power technology. To this end, experiments have been carried out on Saturn operating in a long pulse mode, investigating the potential of lower voltages and longer implosion times while still maintaining pinch fidelity. High wire number, 25 mm diameter tungsten arrays were imploded with implosion times ranging from 130 to 240 ns. The results were comparable to those observed in the Saturn short pulse mode, with risetimes on the order of 4.5 to 6.5 ns. Experimental data will be presented, along with two dimensional radiation magnetohydrodynamic simulations used to explain and reproduce the experiment.
Date: November 5, 1999
Creator: Douglas, Melissa R.; Deeney, Christopher; Spielman, Rick B.; Coverdale, Christine A.; Roderick, N. F. & Haines, M. G.
System: The UNT Digital Library
An updated measurement of sin (2{Beta}) at CDF (open access)

An updated measurement of sin (2{Beta}) at CDF

We report an updated direct measurement of the Standard Model CP violation parameter sin(2{beta}) using the CDF Detector at Fermilab. We use the entire Run-I data sample of 110 pb{sup -1} of proton-antiproton collisions at {radical}s = 1.8 TeV. In this analysis, we have combined three tagging methods: a same-side tag, a soft-lepton tag, and a jet-charge tag, and also added events that have less precise lifetime information because they are not fully contained within the acceptance of the SVX. The signal sample consists of {approx} 400 B {yields} J/{psi} K{sub S}{sup 0} events. A maximum likelihood fitting method is used to measure sin(2{beta}) = 0.79{sub -0.44}{sup +0.41} (stat.+syst.). We calculate a 93% Feldman-Cousins confidence interval of 0 &lt; sin(2{beta}) &lt; 1. This measurement is the best direct indication for CP violation in the neutral B meson sector to date. The sin(2{beta}) value is consistent with the Standard Model prediction of large CP symmetry violation in the b quark system.
Date: November 5, 1999
Creator: Bedeschi, Franco
System: The UNT Digital Library
Brittle-Ductile Relaxation Kinetics of Strained AlGaN/GaN (open access)

Brittle-Ductile Relaxation Kinetics of Strained AlGaN/GaN

The authors have directly measured the stress evolution during metal organic chemical vapor deposition of AlGaN/GaN heterostructures on sapphire. In situ stress measurements were correlated with ex situ microstructural analysis to directly determine a critical thickness for cracking and the subsequent relaxation kinetics of tensile-strained Al{sub x}Ga{sub 1{minus}x}N on GaN. Cracks appear to initiate the formation of misfit dislocations at the AlGaN/GaN interface, which account for the majority of the strain relaxation.
Date: October 5, 1999
Creator: CHASON, E.; FLORO, JERROLD A.; FOLLSTAEDT, DAVID M.; HAN, JUNG; HEARNE, SEAN JOSEPH; LEE, STEPHEN R. et al.
System: The UNT Digital Library
Database system for management of health physics and industrial hygiene records. (open access)

Database system for management of health physics and industrial hygiene records.

This paper provides an overview of the Worker Protection System (WPS), a client/server, Windows-based database management system for essential radiological protection and industrial hygiene. Seven operational modules handle records for external dosimetry, bioassay/internal dosimetry, sealed sources, routine radiological surveys, lasers, workplace exposure, and respirators. WPS utilizes the latest hardware and software technologies to provide ready electronic access to a consolidated source of worker protection.
Date: October 5, 1999
Creator: Murdoch, B. T.; Blomquist, J. A.; Cooke, R. H.; Davis, J. T.; Davis, T. M.; Dolecek, E. H. et al.
System: The UNT Digital Library
Effect of shadowing on initial conditions, transverse energy and hard probes in ultrarelativistic heavy ion collisions (open access)

Effect of shadowing on initial conditions, transverse energy and hard probes in ultrarelativistic heavy ion collisions

The effect of shadowing on the early state of ultrarelativistic heavy ion collisions is investigated along with transverse energy and hard process production, specifically Drell-Yan, J/psi, and Upsilon production. We choose several parton distributions and parameterizations of nuclear shadowing, as well as the spatial dependence of shadowing, to study the influence of shadowing on relevant observables. Results are presented for Au+Au collisions at sqrt(s{sub NN}) = 200 GeV and Pb+Pb collisions at sqrt(s{sub NN}) =5.5 TeV.
Date: October 5, 1999
Creator: Emel'yanov, V.; Khodinov, A.; Klein, S.R. & Vogt, R.
System: The UNT Digital Library