Standoff ultraviolet raman scattering detection of trace levels of explosives. (open access)

Standoff ultraviolet raman scattering detection of trace levels of explosives.

Ultraviolet (UV) Raman scattering with a 244-nm laser is evaluated for standoff detection of explosive compounds. The measured Raman scattering albedo is incorporated into a performance model that focused on standoff detection of trace levels of explosives. This model shows that detection at {approx}100 m would likely require tens of seconds, discouraging application at such ranges, and prohibiting search-mode detection, while leaving open the possibility of short-range point-and-stare detection. UV Raman spectra are also acquired for a number of anticipated background surfaces: tile, concrete, aluminum, cloth, and two different car paints (black and silver). While these spectra contained features in the same spectral range as those for TNT, we do not observe any spectra similar to that of TNT.
Date: October 1, 2011
Creator: Kulp, Thomas J.; Bisson, Scott E. & Reichardt, Thomas A.
Object Type: Report
System: The UNT Digital Library
Transient evolution of a photon gas in the nonlinear QED vacuum (open access)

Transient evolution of a photon gas in the nonlinear QED vacuum

Thermally induced vacuum polarization stemming from QED radiative corrections to the electromagnetic field equations is studied. The physical behavior of thermal radiation, in the nonlinear QED vacuum first described by Heisenberg and Euler, is a problem of some theoretical importance in view of its relation to the cosmic microwave background (CMB), early universe evolution, and Hawking-Unruh radiation. The questions of evolution toward equilibrium, stability, and invariance of thermal radiation under such conditions are of great interest. Our analysis presents novel aspects associated with photon-photon scattering in a photon gas in the framework of quantum kinetic theory. Within the context of the Euler-Heisenberg theory, we show that a homogeneous, isotropic photon gas with arbitrary spectral distribution function evolves toward an equilibrium state with a Bose-Einstein distribution. The transient evolution toward equilibrium of a gas of photons undergoing photon-photon scattering is studied in detail via the Boltzmann transport equation.
Date: October 4, 2011
Creator: Wu, S Q & Hartemann, F V
Object Type: Report
System: The UNT Digital Library
Design Calculations For NIF Convergent Ablator Experiments (open access)

Design Calculations For NIF Convergent Ablator Experiments

The NIF convergent ablation tuning effort is underway. In the early experiments, we have discovered that the design code simulations over-predict the capsule implosion velocity and shock flash rhor, but under-predict the hohlraum x-ray flux measurements. The apparent inconsistency between the x-ray flux and radiography data implies that there are important unexplained aspects of the hohlraum and/or capsule behavior.
Date: October 25, 2011
Creator: Olson, R E; Hicks, D G; Meezan, N B; Callahan, D A; Landen, O L; Jones, O S et al.
Object Type: Article
System: The UNT Digital Library
FINAL REPORT (MILESTONE DATE 9/30/11) FOR SUBCONTRACT NO. B594099 NUMERICAL METHODS FOR LARGE-SCALE DATA FACTORIZATION (open access)

FINAL REPORT (MILESTONE DATE 9/30/11) FOR SUBCONTRACT NO. B594099 NUMERICAL METHODS FOR LARGE-SCALE DATA FACTORIZATION

The following work has been performed by PI Hans De Sterck and graduate student Manda Winlaw for the required tasks 1-5 (as listed in the Statement of Work). Graduate student Manda Winlaw has visited LLNL January 31-March 11, 2011 and May 23-August 19, 2010, working with Van Henson and Mike O'Hara on non-negative matrix factorizations (NMF). She has investigated the dense subgraph clustering algorithm from 'Finding Dense Subgraphs for Sparse Undirected, Directed, and Bipartite Graphs' by Chen and Saad, testing this method on several term-document matrices and adapting it to cluster based on the rank of the subgraphs instead of the density. Manda Winlaw was awarded a first prize in the annual LLNL summer student poster competition for a poster on her NMF research. PI Hans De Sterck has developed a new adaptive algebraic multigrid algorithm for computing a few dominant or minimal singular triplets of sparse rectangular matrices. This work builds on adaptive algebraic multigrid methods that were further developed by the PI and collaborators (including Sanders and Henson) for Markov chains. The method also combines and extends existing multigrid algorithms for the symmetric eigenproblem. The PI has visited LLNL February 22-25, 2011, and has given a CASC seminar …
Date: October 18, 2011
Creator: De Sterck, H
Object Type: Report
System: The UNT Digital Library
The Consortium for Advanced Simulation of Light Water Reactors (open access)

The Consortium for Advanced Simulation of Light Water Reactors

The Consortium for Advanced Simulation of Light Water Reactors (CASL) is a DOE Energy Innovation Hub for modeling and simulation of nuclear reactors. It brings together an exceptionally capable team from national labs, industry and academia that will apply existing modeling and simulation capabilities and develop advanced capabilities to create a usable environment for predictive simulation of light water reactors (LWRs). This environment, designated as the Virtual Environment for Reactor Applications (VERA), will incorporate science-based models, state-of-the-art numerical methods, modern computational science and engineering practices, and uncertainty quantification (UQ) and validation against data from operating pressurized water reactors (PWRs). It will couple state-of-the-art fuel performance, neutronics, thermal-hydraulics (T-H), and structural models with existing tools for systems and safety analysis and will be designed for implementation on both today's leadership-class computers and the advanced architecture platforms now under development by the DOE. CASL focuses on a set of challenge problems such as CRUD induced power shift and localized corrosion, grid-to-rod fretting fuel failures, pellet clad interaction, fuel assembly distortion, etc. that encompass the key phenomena limiting the performance of PWRs. It is expected that much of the capability developed will be applicable to other types of reactors. CASL's mission is to …
Date: October 1, 2011
Creator: Szilard, Ronaldo; Zhang, Hongbin; Kothe, Doug & Turinsky, Paul
Object Type: Article
System: The UNT Digital Library
Modeling Personalized Email Prioritization: Classification-based and Regression-based Approaches (open access)

Modeling Personalized Email Prioritization: Classification-based and Regression-based Approaches

Email overload, even after spam filtering, presents a serious productivity challenge for busy professionals and executives. One solution is automated prioritization of incoming emails to ensure the most important are read and processed quickly, while others are processed later as/if time permits in declining priority levels. This paper presents a study of machine learning approaches to email prioritization into discrete levels, comparing ordinal regression versus classier cascades. Given the ordinal nature of discrete email priority levels, SVM ordinal regression would be expected to perform well, but surprisingly a cascade of SVM classifiers significantly outperforms ordinal regression for email prioritization. In contrast, SVM regression performs well -- better than classifiers -- on selected UCI data sets. This unexpected performance inversion is analyzed and results are presented, providing core functionality for email prioritization systems.
Date: October 24, 2011
Creator: Yoo, S.; Yang, Y. & Carbonell, J.
Object Type: Article
System: The UNT Digital Library
Pressure-shear experiments on granular materials. (open access)

Pressure-shear experiments on granular materials.

Pressure-shear experiments were performed on granular tungsten carbide and sand using a newly-refurbished slotted barrel gun. The sample is a thin layer of the granular material sandwiched between driver and anvil plates that remain elastic. Because of the obliquity, impact generates both a longitudinal wave, which compresses the sample, and a shear wave that probes the strength of the sample. Laser velocity interferometry is employed to measure the velocity history of the free surface of the anvil. Since the driver and anvil remain elastic, analysis of the results is, in principal, straightforward. Experiments were performed at pressures up to nearly 2 GPa using titanium plates and at higher pressure using zirconium plates. Those done with the titanium plates produced values of shear stress of 0.1-0.2 GPa, with the value increasing with pressure. On the other hand, those experiments conducted with zirconia anvils display results that may be related to slipping at an interface and shear stresses mostly at 0.1 GPa or less. Recovered samples display much greater particle fracture than is observed in planar loading, suggesting that shearing is a very effective mechanism for comminution of the grains.
Date: October 1, 2011
Creator: Reinhart, William Dodd (Sandia National Laboratories, Albuquerque, NM); Thornhill, Tom Finley, III (, Sandia National Laboratories, Albuquerque, NM); Vogler, Tracy John & Alexander, C. Scott (Sandia National Laboratories, Albuquerque, NM)
Object Type: Report
System: The UNT Digital Library
Minneapolis and Saint Paul, Minnesota: Solar in Action (Brochure) (open access)

Minneapolis and Saint Paul, Minnesota: Solar in Action (Brochure)

This brochure provides an overview of the challenges and successes of Minneapolis, MN, a 2008 Solar America City awardee, on the path toward becoming a solar-powered community. Accomplishments, case studies, key lessons learned, and local resource information are given.
Date: October 1, 2011
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Intra-beam scattering and its application to ERL (open access)

Intra-beam scattering and its application to ERL

Treatment of Coulomb collisions within the beam requires consideration of both large and small angle scattering. Such collisions lead to the Touschek effect and Intrabeam Scattering (IBS). The Touschek effect refers to particle loss as a result of a single collision, where only transfer from the transverse direction into longitudinal plays a role. It is important to consider this effect for ERL design to have an appropriate choice of collimation system. The IBS is a diffusion process which leads to changes of beam distribution but does not necessarily result in a beam loss. Evaluation of IBS in ERLs, where beam distribution is non-Gaussian, requires special treatment. Here we describe the IBS and Touschek effects with application to ERLs. In circular accelerators both the Touschek effect and IBS were found important. The generalized formulas for Touschek calculations are available and are already being used in advanced tracking simulations of several ERL-based projects. The IBS (which is diffusion due to multiple Coulomb scattering) is not expected to cause any significant effect on beam distribution in ERLs, unless one considers very long transport of high-brightness beams at low energies. Both large and small-angle Coulomb scattering can contribute to halo formation in future ERLs …
Date: October 16, 2011
Creator: Fedotov, A.
Object Type: Article
System: The UNT Digital Library
Progress toward bridging from atomistic to continuum modeling to predict nuclear waste glass dissolution. (open access)

Progress toward bridging from atomistic to continuum modeling to predict nuclear waste glass dissolution.

This report summarizes research performed for the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Subcontinuum and Upscaling Task. The work conducted focused on developing a roadmap to include molecular scale, mechanistic information in continuum-scale models of nuclear waste glass dissolution. This information is derived from molecular-scale modeling efforts that are validated through comparison with experimental data. In addition to developing a master plan to incorporate a subcontinuum mechanistic understanding of glass dissolution into continuum models, methods were developed to generate constitutive dissolution rate expressions from quantum calculations, force field models were selected to generate multicomponent glass structures and gel layers, classical molecular modeling was used to study diffusion through nanopores analogous to those in the interfacial gel layer, and a micro-continuum model (K{mu}C) was developed to study coupled diffusion and reaction at the glass-gel-solution interface.
Date: October 1, 2011
Creator: Zapol, Peter (Argonne National Laboratory, Argonne, IL); Bourg, Ian (Lawrence Berkeley National Laboratories, Berkeley, CA); Criscenti, Louise Jacqueline; Steefel, Carl I. (Lawrence Berkeley National Laboratories, Berkeley, CA) & Schultz, Peter Andrew
Object Type: Report
System: The UNT Digital Library
Dynamic Analysis of Electrical Power Grid Delivery: Using Prime Mover Engines to Balance Dynamic Wind Turbine Output (open access)

Dynamic Analysis of Electrical Power Grid Delivery: Using Prime Mover Engines to Balance Dynamic Wind Turbine Output

This paper presents an investigation into integrated wind + combustion engine high penetration electrical generation systems. Renewable generation systems are now a reality of electrical transmission. Unfortunately, many of these renewable energy supplies are stochastic and highly dynamic. Conversely, the existing national grid has been designed for steady state operation. The research team has developed an algorithm to investigate the feasibility and relative capability of a reciprocating internal combustion engine to directly integrate with wind generation in a tightly coupled Hybrid Energy System. Utilizing the Idaho National Laboratory developed Phoenix Model Integration Platform, the research team has coupled demand data with wind turbine generation data and the Aspen Custom Modeler reciprocating engine electrical generator model to investigate the capability of reciprocating engine electrical generation to balance stochastic renewable energy.
Date: October 1, 2011
Creator: Grauer, Diana K.
Object Type: Article
System: The UNT Digital Library

NREL Variability and Reserves Analysis for the Western Interconnect

Additional variability and uncertainty increase reserve requirements. In this light, this presentation discusses how use of generation reserves can be optimized for managing variability and uncertainty. Conclusions of this presentation are: (1) Provided a method for calculating additional reserve requirements due to wind and solar production; (2) Method is based on statistical analysis of historical time series data; (3) Reserves are dynamic, produced for each hour; (4) Reserve time series are calculated from and synchronized to simulation data; (5) PROMOD can not model directly, but workarounds exist for regulation and spin; and (6) Other production modeling packages have varying capability for reserves modeling.
Date: October 1, 2011
Creator: Milligan, M. & King, J.
Object Type: Presentation
System: The UNT Digital Library
Study of Multi-Beam Accelerator Driven Thorium Reactor (open access)

Study of Multi-Beam Accelerator Driven Thorium Reactor

N/A
Date: October 1, 2011
Creator: H., Ludewig & Aronson, A.
Object Type: Report
System: The UNT Digital Library
Experience With Low-Energy Gold-Gold Operations in RHIC During FY 2010 (open access)

Experience With Low-Energy Gold-Gold Operations in RHIC During FY 2010

During Run-10, RHIC operated at several different Au-Au collision energies, as requested mainly by the STAR collaboration in a quest to search for the critical point in the QGP phase diagram. The center-of-mass energies {radical}s{sub NN} are listed in Table 1, together with the respective start and end dates and the duration of the respective run at each energy. While STAR defines 'low energy' as anything below {radical}s{sub NN} = 39 GeV, we focus in the scope of this paper on energies below the regular RHIC injection energy of {radical}s{sub NN} {approx} 20 GeV, since this energy regime is particularly challenging for stable RHIC operations. Figures 1 and 2 show the evolution of beam intensity and luminosity during the course of the {radical}s{sub NN} = 7.7 GeV and 11.5 GeV run. In the following sections we will recapitulate the modifications during the run that led to significant performance improvements, and summarize what was learned at the various energies for possible application in future runs.
Date: October 7, 2011
Creator: Montag, C.; Satogata, T.; Ahrens, L. A.; Bai, M.; Beebe-Wang, J.; Blacker, I. et al.
Object Type: Report
System: The UNT Digital Library
Accelerating Commercialization of Algal Biofuels Through Partnerships (Brochure) (open access)

Accelerating Commercialization of Algal Biofuels Through Partnerships (Brochure)

This brochure describes National Renewable Energy Laboratory's (NREL's) algal biofuels research capabilities and partnership opportunities. NREL is accelerating algal biofuels commercialization through: (1) Advances in applied biology; (2) Algal strain development; (3) Development of fuel conversion pathways; (4) Techno-economic analysis; and (5) Development of high-throughput lipid analysis methodologies. NREL scientists and engineers are addressing challenges across the algal biofuels value chain, including algal biology, cultivation, harvesting and extraction, and fuel conversion. Through partnerships, NREL can share knowledge and capabilities in the following areas: (1) Algal Biology - A fundamental understanding of algal biology is key to developing cost-effective algal biofuels processes. NREL scientists are experts in the isolation and characterization of microalgal species. They are identifying genes and pathways involved in biofuel production. In addition, they have developed a high-throughput, non-destructive technique for assessing lipid production in microalgae. (2) Cultivation - NREL researchers study algal growth capabilities and perform compositional analysis of algal biomass. Laboratory-scale photobioreactors and 1-m2 open raceway ponds in an on-site greenhouse allow for year-round cultivation of algae under a variety of conditions. A bioenergy-focused algal strain collection is being established at NREL, and our laboratory houses a cryopreservation system for long-term maintenance of algal cultures and …
Date: October 1, 2011
Creator: unknown
Object Type: Report
System: The UNT Digital Library
COMPUTER MODELING OF HIGH-LEVEL WASTE GLASS TEMPERATURES WITHIN DWPF CANISTERS DURING POURING AND COOL DOWN (open access)

COMPUTER MODELING OF HIGH-LEVEL WASTE GLASS TEMPERATURES WITHIN DWPF CANISTERS DURING POURING AND COOL DOWN

This report describes the results of a computer simulation study to predict the temperature of the glass at any location inside a DWPF canister during pouring and subsequent cooling. These simulations are an integral part of a larger research focus aimed at developing methods to predict, evaluate, and ultimately suppress nepheline formation in HLW glasses. That larger research focus is centered on holistically understanding nepheline formation in HLW glass by exploring the fundamental thermal and chemical driving forces for nepheline crystallization with respect to realistic processing conditions. Through experimental work, the goal is to integrate nepheline crystallization potential in HLW glass with processing capability to ultimately optimize waste loading and throughput while maintaining an acceptable product with respect to durability. The results of this study indicated severe temperature gradients and prolonged temperature dwell times exist throughout different locations in the canister and that the time and temperatures that HLW glass is subjected to during processing is a function of pour rate. The simulations indicate that crystallization driving forces are not uniform throughout the glass volume in a DWPF (or DWPF-like) canister and illustrate the importance of considering overall kinetics (chemical and thermal driving forces) of nepheline formation when developing methods …
Date: October 9, 2011
Creator: Amoroso, J.
Object Type: Report
System: The UNT Digital Library
Deep Vadose Zone-Applied Field Research Initiative Fiscal Year 2011 Annual Report (open access)

Deep Vadose Zone-Applied Field Research Initiative Fiscal Year 2011 Annual Report

This annual report describes the background of the Deep Vadose Zone-Applied Field Research Initiative, and some of the programmatic approaches and transformational technologies in groundwater and deep vadose zone remediation developed during fiscal year 2011. The Department of Energy (DOE) Office of Technology Innovation and Development's (OTID) mission is to transform science into viable solutions for environmental cleanup. In 2010, OTID developed the Impact Plan, Science and Technology to Reduce the Life Cycle Cost of Closure to outline the benefits of research and development of the lifecycle cost of cleanup across the DOE complex. This plan outlines OTID's ability to reduce by $50 billion, the $200 billion life-cycle cost in waste processing, groundwater and soil, nuclear materials, and deactivation and decommissioning. The projected life-cycle costs and return on investment are based on actual savings realized from technology innovation, development, and insertion into remedial strategies and schedules at the Fernald, Mound, and Ashtabula sites. To achieve our goals, OTID developed Applied Field Research Initiatives to facilitate and accelerate collaborative development and implementation of new tools and approaches that reduce risk, cost and time for site closure. The primary mission of the Deep Vadose Zone-Applied Field Research Initiative (DVZ-AFRI) is to protect …
Date: October 1, 2011
Creator: Wellman, Dawn M.; Johnson, Timothy C.; Smith, Ronald M.; Truex, Michael J. & Matthews, Hope E.
Object Type: Report
System: The UNT Digital Library
Energy Systems Sensor Laboratory (Fact Sheet) (open access)

Energy Systems Sensor Laboratory (Fact Sheet)

This fact sheet describes the purpose, lab specifications, applications scenarios, and information on how to partner with NREL's Energy Systems Sensor Laboratory at the Energy Systems Integration Facility. The mission of the Energy Systems Sensor Laboratory at NREL's Energy Systems Integration Facility (ESIF) is to research, develop, test, and evaluate the performance of commercial and developing hydrogen sensor technologies to support the needs of the emerging hydrogen infrastructure. Sensor performance metrics analogous to national and international standards are quantified. Information gained from the sensor testing is provided to the sensor manufacturers to aid in sensor development, to end users to guide sensor selection and deployment, and to committees to support the development of codes and standards. The laboratory also provides support to end-users, including assessment of technologies for applications, information on deployment. Some application scenarios are: (1) Testing and analyzing sensors are over a range of controlled and monitored environmental conditions; (2) Testing the impact of interferants and poisons; (3) Evaluating the life span of sensors with separate dedicated life test fixtures; and (4) Testing of hydrogen sensors for process applications, including responses under high hydrogen concentrations.
Date: October 1, 2011
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Use of Melt Flow Rate Test in Reliability Study of Thermoplastic Encapsulation Materials in Photovoltaic Modules (open access)

Use of Melt Flow Rate Test in Reliability Study of Thermoplastic Encapsulation Materials in Photovoltaic Modules

Use of thermoplastic materials as encapsulants in photovoltaic (PV) modules presents a potential concern in terms of high temperature creep, which should be evaluated before thermoplastics are qualified for use in the field. Historically, the issue of creep has been avoided by using thermosetting polymers as encapsulants, such as crosslinked ethylene-co-vinyl acetate (EVA). Because they lack crosslinked networks, however, thermoplastics may be subject to phase transitions and visco-elastic flow at the temperatures and mechanical stresses encountered by modules in the field, creating the potential for a number of reliability and safety issues. Thermoplastic materials investigated in this study include PV-grade uncured-EVA (without curing agents and therefore not crosslinked); polyvinyl butyral (PVB); thermoplastic polyurethane (TPU); and three polyolefins (PO), which have been proposed for use as PV encapsulation. Two approaches were used to evaluate the performance of these materials as encapsulants: module-level testing and a material-level testing.
Date: October 1, 2011
Creator: Moseley, J.; Miller, D.; Shah, Q.-U.-A. S. J.; Sakurai, K.; Kempe, M.; Tamizhmani, G. et al.
Object Type: Report
System: The UNT Digital Library
Pyrometry simulator (pyrosim) for diagnostic design. (open access)

Pyrometry simulator (pyrosim) for diagnostic design.

Signal estimates are crucial to the design of time-resolved pyrometry measurements. These estimates affect fundamental design decisions, including the optical relay (fiber versus open beam), spectral range (visible or infrared), and amplification needs (possibly at the expense of time resolution). The pyrosim program makes such estimates, allowing the collected power, photon flux, and measured signal to be determined in a broad range of pyrometry measurements. Geometrical collection limits can be applied; sample emissivity, transfer efficiency, and detector sensitivity may also be specified, either as constants or functions of wavelength.
Date: October 1, 2011
Creator: Dolan, Daniel H., III
Object Type: Report
System: The UNT Digital Library
Research and Development of Non-Spectroscopic MEMS-Based Sensor Arrays for Targeted Gas Detection (open access)

Research and Development of Non-Spectroscopic MEMS-Based Sensor Arrays for Targeted Gas Detection

The ability to monitor the integrity of gas volumes is of interest to the stockpile surveillance community. Specifically, the leak detection of noble gases, at relevant concentration ranges and distinguished from other chemical species that may be simultaneously present, is particularly challenging. Aside from the laboratory-based method of gas chromatography-mass spectrometry (GC-MS), where samples may be collected by solid-phase microextraction (SPME) or cryofocusing, the other major approaches for gas-phase detection employ lasers typically operating in the mid-infrared wavelength region. While mass spectrometry can readily detect noble gases - the helium leak detector is an obvious example - laser-based methods such as infrared (IR) or Raman spectroscopy are completely insensitive to them as their monatomic nature precludes a non-zero dipole moment or changes in polarizability upon excitation. Therefore, noble gases can only be detected by one of two methods: (1) atomic emission spectroscopies which require the generation of plasmas through laser-induced breakdown, electrical arcing, or similar means; (2) non-spectroscopic methods which measure one or more physical properties (e.g., mass, thermal conductivity, density). In this report, we present our progress during Fiscal Year 2011 (FY11) in the research and development of a non-spectroscopic method for noble gas detection. During Fiscal Year 2010 …
Date: October 24, 2011
Creator: Loui, A & McCall, S K
Object Type: Report
System: The UNT Digital Library
Preliminary Results of a RANS Simulation for a Floating Point Absorber Wave Energy System Under Extreme Wave Conditions (open access)

Preliminary Results of a RANS Simulation for a Floating Point Absorber Wave Energy System Under Extreme Wave Conditions

This paper presents the results of a preliminary study on the hydrodynamics of a moored floating-point absorber (FPA) wave energy system under extreme wave conditions.
Date: October 1, 2011
Creator: Yu, Y. & Li, Y.
Object Type: Article
System: The UNT Digital Library
Extreme Performance Scalable Operating Systems Final Progress Report (July 1, 2008 - October 31, 2011) (open access)

Extreme Performance Scalable Operating Systems Final Progress Report (July 1, 2008 - October 31, 2011)

This is the final progress report for the FastOS (Phase 2) (FastOS-2) project with Argonne National Laboratory and the University of Oregon (UO). The project started at UO on July 1, 2008 and ran until April 30, 2010, at which time a six-month no-cost extension began. The FastOS-2 work at UO delivered excellent results in all research work areas: * scalable parallel monitoring * kernel-level performance measurement * parallel I/0 system measurement * large-scale and hybrid application performance measurement * onlne scalable performance data reduction and analysis * binary instrumentation
Date: October 31, 2011
Creator: Malony, Allen D. & Shende, Sameer
Object Type: Report
System: The UNT Digital Library
Comparison of Carbon and Hi-Z Primary Collimators for the LHC Phase II Collimation System (open access)

Comparison of Carbon and Hi-Z Primary Collimators for the LHC Phase II Collimation System

A current issue with the LHC collimation system is single-diffractive, off-energy protons from the primary collimators that pass completely through the secondary collimation system and are absorbed immediately downbeam in the cold magnets of the dispersion suppressor section. Simulations suggest that the high impact rate could result in quenching of these magnets. We have studied replacing the 60 cm primary graphite collimators, which remove halo mainly by inelastic strong interactions, with 5.25 mm tungsten, which remove halo mainly by multiple coulomb scattering and thereby reduce the rate of single-diffractive interactions that cause losses in the dispersion suppressor.
Date: October 31, 2011
Creator: Keller, Lewis; /SLAC; Markiewicz, Thomas; /SLAC; Smith, Jeffrey; /SLAC et al.
Object Type: Article
System: The UNT Digital Library