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Production and Testing Experience with the SRF Cavities for the CEBAF 12 GeV Upgrade
The CEBAF recirculating CW electron linear accelerator at Jefferson Lab is presently undergoing a major upgrade to 12 GeV. This project includes the fabrication, preparation, and testing of 80 new 7-cell SRF cavities, followed by their incorporation into ten new cryomodules for subsequent testing and installation. In order to maximize the cavity Q over the full operable dynamic range in CEBAF (as high as 25 MV/m), the decision was taken to apply a streamlined preparation process that includes a final light temperature-controlled electropolish of the rf surface over the vendor-provided bulk BCP etch. Cavity processing work began at JLab in September 2010 and will continue through December 2011. The excellent performance results are exceeding project requirements and indicate a fabrication and preparation process that is stable and well controlled. The cavity production and performance experience to date will be summarized and lessons learned reported to the community.
Date:
September 1, 2011
Creator:
A. Burrill, G.K. Davis, F. Marhauser, C.E. Reece, A.V. Reilly, M. Stirbet
Object Type:
Article
System:
The UNT Digital Library
The Muon LINAC for the International Design Study of the Neutrino Factory
The first stage of muon acceleration in the Neutrino Factory utilises a superconducting linac to accelerate muons from 244 MeV to 900 MeV. The linac was split into three types of cryomodules with decreasing magnetic fields and increasing amounts of RF voltage but with the design of the superconducting solenoid and RF cavities being the same for all cryomodules. The current status of the muon linac for the International Design Study for the Neutrino Factory will be presented including a final lattice design of the linac and tracking simulations.
Date:
September 1, 2011
Creator:
A. Kurup, C. Bontoiu, Morteza Aslaninejad, J. Pozimski, A. Bogacz, V.S. Morozov, Y.R. Roblin, K.B. Beard
Object Type:
Article
System:
The UNT Digital Library
Effects of the Thickness of Niobium Surface Oxide Layers on Field Emission
Field emission on the inner surfaces of niobium superconducting radio frequency cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results* seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3 nm up to 460 nm. A home-made scanning field emission microscope was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The SFEM experimental results were analyzed in terms of surface morphology and oxide thickness of Nb samples and chemical composition and geographic shape of the emitters. A model based on the classic electromagnetic theory was developed trying to understand the experimental results. Possibly implications for Nb SRF cavity applications from this study will be discussed.
Date:
September 1, 2011
Creator:
A.T. Wu, S. Jin, J.D. Mammosser, R.A. Rimmer, X.Y. Lu, K. Zhao
Object Type:
Article
System:
The UNT Digital Library
Fastest Electropolishing Technique on Niobium for Particle Accelerators
Field emission on the inner surfaces of niobium (Nb) superconducting radio frequency (SRF) cavities is still one of the major obstacles for reaching high accelerating gradients for SRF community. Our previous experimental results [1] seemed to imply that the threshold of field emission was related to the thickness of Nb surface oxide layers. In this contribution, a more detailed study on the influences of the surface oxide layers on the field emission on Nb surfaces will be reported. By anodization technique, the thickness of the surface pentoxide layer was artificially fabricated from 3nm up to 460nm. A home-made scanning field emission microscope (SFEM) was employed to perform the scans on the surfaces. Emitters were characterized using a scanning electron microscope together with an energy dispersive x-ray analyzer. The experimental results could be understood by a simple model calculation based on classic electromagnetic theory as shown in Ref.1. Possibly implications for Nb SRF cavity applications from this study will be discussed.
Date:
September 1, 2011
Creator:
A.T. Wu, S. Jin, R.A. Rimmer, X.Y. Lu, K. Zhao
Object Type:
Article
System:
The UNT Digital Library
Field Quality Study of the LARP Nb3Sn 3.7m-Long Quadrupole Models of LQ Series
After the successful test of the first long Nb{sub 3}Sn quadrupole magnet (LQS01), the US LHC Accelerator Research Program (LARP) has assembled and tested a new 3.7 m-long Nb{sub 3}Sn quadrupole (LQS02). This magnet has four new coils made of the same conductor as LQS01 coils, and it is using the same support structure. LQS02 was tested at the Fermilab Vertical Magnet Test Facility with the main goal to confirm that the long models can achieve field gradient above 200 T/m, LARP target for 90-mm aperture, as well as to measure the field quality. These long models lack some alignment features and it is important to study the field harmonics. Previous field quality measurements of LQS01 showed higher than expected differences between measured and calculated harmonics compared to the short models (TQS) assembled in a similar structure. These differences could be explained by the use of two different impregnation fixtures during coil fabrication. In this paper, we present a comparison of the field quality measurements between LQS01 and LQS02 as well as a comparison with the short TQS models. If the result supports the coil fabrication hypothesis, another LQS assembly with all coils fabricated in the same fixture will be …
Date:
September 1, 2011
Creator:
AMbrosio, G.; Andreev, N.; Bossert, R.; Chlachidze, G.; DiMarco, J.; Kashikhin, V.V. et al.
Object Type:
Article
System:
The UNT Digital Library
STATUS OF THE DEVELOPMENT OF IN-TANK/AT-TANK SEPARATIONS TECHNOLOGIES FOR FOR HIGH-LEVEL WASTE PROCESSING FOR THE U.S. DEPARTMENT OF ENERGY
Within the U.S. Department of Energy's (DOE) Office of Technology Innovation and Development, the Office of Waste Processing manages a research and development program related to the treatment and disposition of radioactive waste. At the Savannah River (South Carolina) and Hanford (Washington) Sites, approximately 90 million gallons of waste are distributed among 226 storage tanks (grouped or collocated in 'tank farms'). This waste may be considered to contain mixed and stratified high activity and low activity constituent waste liquids, salts and sludges that are collectively managed as high level waste (HLW). A large majority of these wastes and associated facilities are unique to the DOE, meaning many of the programs to treat these materials are 'first-of-a-kind' and unprecedented in scope and complexity. As a result, the technologies required to disposition these wastes must be developed from basic principles, or require significant re-engineering to adapt to DOE's specific applications. Of particular interest recently, the development of In-tank or At-Tank separation processes have the potential to treat waste with high returns on financial investment. The primary objective associated with In-Tank or At-Tank separation processes is to accelerate waste processing. Insertion of the technologies will (1) maximize available tank space to efficiently support …
Date:
September 19, 2011
Creator:
Aaron, G. & Wilmarth, B.
Object Type:
Article
System:
The UNT Digital Library
Detection of the Energetic Pulsar PSR B1509-58 And Its Pulsar Wind Nebula in MSH 15-52 Using the Fermi-Large Area Telescope
None
Date:
September 13, 2011
Creator:
Abdo, A. A.; Ackermann, M.; Ajello, M.; Allafort, A.; Asano, K.; Baldini, L. et al.
Object Type:
Article
System:
The UNT Digital Library
Building Your Congregation Over the Long Haul - Things Learned After 33 Years with One Church
Lecture given Monday, September 19, 2011, 9:00 AM at Abilene Christian University: "There is a lot to consider in leading a church – leadership, growth, community, spiritual formation, outreach. All of us are still learning. Discover lessons learned from both successes and failures in leading a church."
Date:
September 19, 2011
Creator:
Adcox, Jimmy
Object Type:
Sound
System:
The Portal to Texas History
Building Your Congregation Over the Long Haul - Things Learned After 33 Years with One Church
Lecture given Tuesday, September 20, 2011, 8:30 AM at Abilene Christian University: "There is a lot to consider in leading a church – leadership, growth, community, spiritual formation, outreach. All of us are still learning. Discover lessons learned from both successes and failures in leading a church."
Date:
September 20, 2011
Creator:
Adcox, Jimmy
Object Type:
Sound
System:
The Portal to Texas History
A Compact X-Band Linac for an X-Ray FEL
With the growing demand for FEL light sources, cost issues are being reevaluated. To make the machines more compact, higher frequency room temperature linacs are being considered, specifically ones using C-band (5.7 GHz) rf technology, for which 40 MV/m gradients are achievable. In this paper, we show that an X-band (11.4 GHz) linac using the technology developed for NLC/GLC can provide an even lower cost solution. In particular, stable operation is possible at gradients of 100 MV/m for single bunch operation and 70 MV/m for multibunch operation. The concern, of course, is whether the stronger wakefields will lead to unacceptable emittance dilution. However, we show that the small emittances produced in a 250 MeV, low bunch charge, LCLS-like S-band injector and bunch compressor can be preserved in a multi-GeV X-band linac with reasonable alignment tolerances. The successful lasing and operation of the LCLS [1] has generated world-wide interest in X-ray FELs. The demand for access to such a light source by researchers eager to harness the capabilities of this new tool far exceeds the numbers that can be accommodated, spurring plans for additional facilities. Along with cost, spatial considerations become increasingly important for a hard X-ray machine driven by a …
Date:
September 12, 2011
Creator:
Adolphsen, Chris; Huang, Zhirong; Bane, Karl L. F.; Li, Zenghai; Zhou, Feng; Wang, Faya et al.
Object Type:
Article
System:
The UNT Digital Library
Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info)
Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography-mass spectrometry (GC-MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally"unresolved complex mixture" by separating components by GC retention time, tR, and mass-to-charge ratio, m/Q, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved based on tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally-relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.
Date:
September 5, 2011
Creator:
Aerosol Dynamics Inc.,; Aerodyne Research, Inc.,; Tofwerk AG, Thun, Switzerland; Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H. et al.
Object Type:
Article
System:
The UNT Digital Library
LIPSS Free-Electron Laser Searches for Dark Matter
A variety of Dark Matter particle candidates have been hypothesized by physics Beyond the Standard Model (BSM) in the very light (10{sup -6} - 10{sup -3} eV) range. In the past decade several international groups have conducted laboratory experiments designed to either produce such particles or extend the boundaries in parameter space. The LIght Pseudo-scalar and Scalar Search (LIPSS) Collaboration, using the 'Light Shining through a Wall' (LSW) technique, passes the high average power photon beam from Jefferson Lab's Free-Electron Laser through a magnetic field upstream from a mirror and optical beam dump. Light Neutral Bosons (LNBs), generated by coupling of photons with the magnetic field, pass through the mirror ('the Wall') into an identical magnetic field where they revert to detectable photons by the same coupling process. While no evidence of LNBs was evident, new scalar coupling boundaries were established. New constraints were also determined for hypothetical para-photons and for millicharged fermions. We will describe our experimental setup and results for LNBs, para-photons, and milli-charged fermions. Plans for chameleon particle searches are underway.
Date:
September 1, 2011
Creator:
Afanaciev, Andrei; Beard, Kevin; Biallas, George; Boyce, James R; Minarni, M; Ramdon, R et al.
Object Type:
Article
System:
The UNT Digital Library
Finding Enough - Sabbath Keeping in the 21st Century
Lecture given Monday, September 19, 2011, 9:00 AM at Abilene Christian University: "Is everyday a whirlwind of activity? Are you so busy working for God that you no longer feel near God? It must be time for Sabbath. Join us as we explore the why and how of contemporary Sabbath keeping."
Date:
September 19, 2011
Creator:
Agnell, Cynthia
Object Type:
Sound
System:
The Portal to Texas History
Cosmic Ray Interactions in Shielding Materials
This document provides a detailed study of materials used to shield against the hadronic particles from cosmic ray showers at Earth’s surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during transport for the MAJORANA collaboration. The materials suitable for cosmic-ray shield design are materials such as lead and iron that will stop the primary protons, and materials like polyethylene, borated polyethylene, concrete and water that will stop the induced neutrons. The interaction of the different cosmic-ray components at ground level (protons, neutrons, muons) with their wide energy range (from kilo-electron volts to giga-electron volts) is a complex calculation. Monte Carlo calculations have proven to be a suitable tool for the simulation of nucleon transport, including hadron interactions and radioactive isotope production. The industry standard Monte Carlo simulation tool, Geant4, was used for this study. The result of this study is the assertion that activation at Earth’s surface is a result of the neutronic and protonic components of the cosmic-ray shower. The best material to shield against these cosmic-ray components is iron, which has the best combination of primary shielding and minimal secondary neutron production.
Date:
September 8, 2011
Creator:
Aguayo Navarrete, Estanislao; Kouzes, Richard T.; Ankney, Austin S.; Orrell, John L.; Berguson, Timothy J. & Troy, Meredith D.
Object Type:
Report
System:
The UNT Digital Library
Recommendations for a Static Cosmic Ray Shield for Enriched Germanium Detectors
This document provides a detailed study of cost and materials that could be used to shield the detector material of the international Tonne-scale germanium neutrinoless double-beta decay experiment from hadronic particles from cosmic ray showers at the Earth's surface. This work was motivated by the need for a shield that minimizes activation of the enriched germanium during storage; in particular, when the detector material is being worked on at the detector manufacturer's facility. This work considers two options for shielding the detector material from cosmic ray particles. One option is to use a pre-existing structure already located near the detector manufacturer, such as Canberra Industries in Meriden, Connecticut. The other option is to build a shield onsite at a detector manufacturer's site. This paper presents a cost and efficiency analysis of such construction.
Date:
September 21, 2011
Creator:
Aguayo Navarrete, Estanislao; Orrell, John L.; Ankney, Austin S. & Berguson, Timothy J.
Object Type:
Report
System:
The UNT Digital Library
Highly Efficient Small Form Factor LED Retrofit Lamp: FInal Report
This report summarizes work to develop a high efficiency LED-based MR16 lamp downlight at OSRAM SYLVANIA under US Department of Energy contract DE-EE0000611. A new multichip LED package, electronic driver, and reflector optic were developed for these lamps. At steady-state, the lamp luminous flux was 409 lumens (lm), luminous efficacy of 87 lumens per watt (LPW), CRI (Ra) of 87, and R9 of 85 at a correlated color temperature (CCT) of 3285K. The LED alone achieved 120 lumens per watt efficacy and 600 lumen flux output at 25 C. The driver had 90% electrical conversion efficiency while maintaining excellent power quality with power factor >0.90 at a power of only 5 watts. Compared to similar existing MR16 lamps using LED sources, these lamps had much higher efficacy and color quality. The objective of this work was to demonstrate a LED-based MR16 retrofit lamp for replacement of 35W halogen MR16 lamps having (1) luminous flux of 500 lumens, (2) luminous efficacy of 100 lumens per watt, (3) beam angle less than 40{sup o} and center beam candlepower of at least 1000 candelas, and (4) excellent color quality.
Date:
September 11, 2011
Creator:
Allen, Steven; Palmer, Fred & Li, Ming
Object Type:
Report
System:
The UNT Digital Library
Demonstration of a 17 cm robust carbon fiber deformable mirror for adaptive optics
Carbon-fiber reinforced polymer (CFRP) composite is an attractive material for fabrication of optics due to its high stiffness-to-weight ratio, robustness, zero coefficient of thermal expansion (CTE), and the ability to replicate multiple optics from the same mandrel. We use 8 and 17 cm prototype CFRP thin-shell deformable mirrors to show that residual CTE variation may be addressed with mounted actuators for a variety of mirror sizes. We present measurements of surface quality at a range of temperatures characteristic of mountaintop observatories. For the 8 cm piece, the figure error of the Al-coated reflective surface under best actuator correction is {approx}43 nm RMS. The 8 cm mirror has a low surface error internal to the outer ring of actuators (17 nm RMS at 20 C and 33 nm RMS at -5 C). Surface roughness is low (< 3 nm P-V) at a variety of temperatures. We present new figure quality measurements of the larger 17 cm mirror, showing that the intra-actuator figure error internal to the outer ring of actuators (38 nm RMS surface with one-third the actuator density of the 8 cm mirror) does not scale sharply with mirror diameter.
Date:
September 12, 2011
Creator:
Ammons, S. M.; Hart, M.; Coughenour, B.; Romeo, R.; Martin, R. & Rademacher, M.
Object Type:
Article
System:
The UNT Digital Library
Microarcsecond relative astrometry from the ground with a diffractive pupil
The practical use of astrometry to detect exoplanets via the reflex motion of the parent star depends critically on the elimination of systematic floors in imaging systems. In the diffractive pupil technique proposed for space-based detection of exo-earths, extended diffraction spikes generated by a dotted primary mirror are referenced against a wide-field grid of background stars to calibrate changing optical distortion and achieve microarcsecond astrometric precision on bright targets (Guyon et al. 2010). We describe applications of this concept to ground-based uncrowded astrometry using a diffractive, monopupil telescope and a wide-field camera to image as many as {approx}4000 background reference stars. Final relative astrometric precision is limited by differential tip/tilt jitter caused by high altitude layers of turbulence. A diffractive 3-meter telescope is capable of reaching {approx}35 {micro}as relative astrometric error per coordinate perpendicular to the zenith vector in three hours on a bright target star (I < 10) in fields of moderate stellar density ({approx}40 stars arcmin{sup -2} with I < 23). Smaller diffractive apertures (D < 1 m) can achieve 100-200 {micro}as performance with the same stellar density and exposure time and a large telescope (6.5-10 m) could achieve as low as 10 {micro}as, nearly an order of …
Date:
September 8, 2011
Creator:
Ammons, S. Mark; Bendek, Eduardo A. & Guyon, Olivier
Object Type:
Article
System:
The UNT Digital Library
NEPHELINE NUCLEATION AND CRYSTAL GROWTH IN WASTE GLASSES: INTERIM REPORT
None
Date:
September 14, 2011
Creator:
Amoroso, J.
Object Type:
Report
System:
The UNT Digital Library
ADDITIVE TESTING FOR IMPROVED SULFUR RETENTION: PRELIMINARY REPORT
The Savannah River National Laboratory is collaborating with Alfred University to evaluate the potential for additives in borosilicate glass to improve sulfur retention. This preliminary report provides further background on the incorporation of sulfur in glass and outlines the experiments that are being performed by the collaborators. A simulated waste glass composition has been selected for the experimental studies. The first phase of experimental work will evaluate the impacts of BaO, PbO, and V{sub 2}O{sub 5} at concentrations of 1.0, 2.0, and 5.0 wt % on sulfate retention in simulated high level waste borosilicate glass. The second phase of experimental work will evaluate the effects of time at the melt temperature on sulfur retention. The resulting samples will be characterized to determine the amount of sulfur remaining as well as to identify the formation of any crystalline phases. The results will be used to guide the future selection of frits and glass forming chemicals in vitrifying Department of Energy wastes containing high sulfur concentrations.
Date:
September 7, 2011
Creator:
Amoroso, J. & Fox, K.
Object Type:
Report
System:
The UNT Digital Library
Deaf Ministry Classes - Bible Knowledge for the deaf Christian
Lecture given Monday, September 19, 2011, 10:00 AM at Abilene Christian University: "Special topics and methods for enhancing general Bible knowledge for the Deaf. Special emphasis on the Old Testament."
Date:
September 19, 2011
Creator:
Anderson, Bob
Object Type:
Sound
System:
The Portal to Texas History
Talking Back to God - Discovering Help
Lecture given Tuesday, September 20, 2011, 8:30 AM at Abilene Christian University: "Learn how to pour out your heart to God through the Psalms. Powerful yet practical benefits can come through reading, singing, praying and memorizing the Psalms."
Date:
September 20, 2011
Creator:
Anderson, Lynn
Object Type:
Sound
System:
The Portal to Texas History
Talking Back to God - Learning the Language
Lecture given Monday, September 19, 2011, 9:00 AM at Abilene Christian University: "Learn how to pour out your heart to God through the Psalms. Powerful yet practical benefits can come through reading, singing, praying and memorizing the Psalms."
Date:
September 19, 2011
Creator:
Anderson, Lynn
Object Type:
Sound
System:
The Portal to Texas History
Talking Back to God - Wonder
Lecture given Wednesday, September 21, 2011, 9:00 AM at Abilene Christian University: "Learn how to pour out your heart to God through the Psalms. Powerful yet practical benefits can come through reading, singing, praying and memorizing the Psalms."
Date:
September 21, 2011
Creator:
Anderson, Lynn
Object Type:
Sound
System:
The Portal to Texas History