Design issues for cryogenic cooling of short periodsuperconducting undulators (open access)

Design issues for cryogenic cooling of short periodsuperconducting undulators

Superconducting insertion devices, which produce periodic magnetic fields, have been built and installed in a number of synchrotron-light source storage-rings. For the most part, these devices have been wigglers, which have relatively long period lengths. This report concerns itself with the special cryogenic issues associated with short period undulators. The motivation for considering the incorporation of superconducting technology in insertion device designs is to achieve higher magnetic fields than can be achieved with more conventional permanent magnet technology. Since the peak field decreases sharply with increased magnet gap to period ratio, the cryogenic design of the magnet system is crucial. In particular, the insulation required for a warm vacuum bore device is impractical for short period undulators. This report describes the issues that are related to a cold bore ({approx}4 K) and an intermediate temperature bore (30 to 70 K) designs. The criteria for the use of small cryocoolers for cooling a short period undulator are presented. The problems associated with connecting small coolers to an undulator at 4.2 K are discussed.
Date: September 15, 2003
Creator: Green, M. A.; Dietderich, D. R.; Marks, S.; Prestemon, S. O. & Schlueter, R. D.
System: The UNT Digital Library
A heat exchanger between forced flow helium gas at 14 to 18 K andliquid hydrogen at 20 K circulated by natural convection (open access)

A heat exchanger between forced flow helium gas at 14 to 18 K andliquid hydrogen at 20 K circulated by natural convection

The Muon Ionization Cooling Experiment (MICE) has three 350-mm long liquid hydrogen absorbers to reduce the momentum of 200 MeV muons in all directions. The muons are then re-accelerated in the longitudinal direction by 200 MHz RF cavities. The result is cooled muons with a reduced emittance. The energy from the muons is taken up by the liquid hydrogen in the absorber. The hydrogen in the MICE absorbers is cooled by natural convection to the walls of the absorber that are in turn cooled by helium gas that enters at 14 K. This report describes the MICE liquid hydrogen absorber and the heat exchanger between the liquid hydrogen and the helium gas that flows through passages in the absorber wall.
Date: September 15, 2003
Creator: Green, M. A.; Ishimoto, S.; Lau, W. & Yang, S.
System: The UNT Digital Library
Focusing solenoids for the MICE cooling channel (open access)

Focusing solenoids for the MICE cooling channel

This report describes a design for focusing solenoids for the low beta sections for the proposed Muon Ionization Cooling Experiment (MICE). There are three focusing solenoid pairs that will be around the muon absorbers for MICE. The two solenoid coils have an inside diameter of 510 mm, a length of 180 mm, and a thickness of 100 mm. A distance of 260 mm separates the two coils in the pair. The coils are designed to operate at opposite polarity, in order to create a gradient field in the low beta sections of the MICE cooling channel. As result, the force pushing the coil pair apart approaches 270 metric tons when the coils operate close to the short sample current for the superconductor. The forces between the coils will be carried by a support structure that is both on the inside and the outside the coils. During some modes of operation for MICE, the coils may operate at the same polarity, which means that the force between the coils pushes them together. The focusing magnet must be designed for both modes of operation. This support structure for the coils will be part of the focusing magnet quench protection system.
Date: September 15, 2003
Creator: Green, M.A.; Baynham, E.; Barr, G.; Lau, W.; Rochford, J.H. & Yang, S.
System: The UNT Digital Library
Supporting integrated design through interlinked tools: The Labs21 toolkit (open access)

Supporting integrated design through interlinked tools: The Labs21 toolkit

The sustainable design of complex building types such as laboratories and hospitals can be particularly challenging, given their inherent complexity of systems, health and safety requirements, long-term flexibility and adaptability needs, energy use intensity, and environmental impacts. Tools such as design guides, energy benchmarking, and LEED rating systems are especially helpful to support sustainable design in such buildings. Furthermore, designers need guidance on how to effectively and appropriately use each tool within the context of an integrated design process involving multiple actors with various objectives. Toward this end, the Laboratories for the 21st Century (Labs21) program has developed an interlinked set of tools -- the Labs21 Toolkit -- to support an integrated design process for sustainable laboratories. Labs21 is a voluntary partnership program sponsored by the U.S. Environmental Protection Agency (EPA) and U.S. Department of Energy (DOE) to improve the environment al performance of U.S. laboratories. In this paper, we present the Labs21 Toolkit, and illustrate how these tools can be used to support sustainable design within an integrated design process. The tool kit includes core information tools, as well as process-related tools, as indicated below: Core information tools: -A Design Guide, which is a compendium of publications on energy …
Date: September 15, 2003
Creator: Mathew, Paul; Bell, Geoffrey; Carlisle, Nancy; Sartor, Dale; van Geet, Otto; Lintner, William et al.
System: The UNT Digital Library
Haplotypes in the APOA1-C3-A4-A5 gene cluster affect plasma lipids in both humans and baboons (open access)

Haplotypes in the APOA1-C3-A4-A5 gene cluster affect plasma lipids in both humans and baboons

Genetic studies in non-human primates serve as a potential strategy for identifying genomic intervals where polymorphisms impact upon human disease-related phenotypes. It remains unclear, however, whether independently arising polymorphisms in orthologous regions of non-human primates leads to similar variation in a quantitative trait found in both species. To explore this paradigm, we studied a baboon apolipoprotein gene cluster (APOA1/C3/A4/A5) for which the human gene orthologs have well established roles in influencing plasma HDL-cholesterol and triglyceride concentrations. Our extensive polymorphism analysis of this 68 kb gene cluster in 96 pedigreed baboons identified several haplotype blocks each with limited diversity, consistent with haplotype findings in humans. To determine whether baboons, like humans, also have particular haplotypes associated with lipid phenotypes, we genotyped 634 well characterized baboons using 16 haplotype tagging SNPs. Genetic analysis of single SNPs, as well as haplotypes, revealed an association of APOA5 and APOC3 variants with HDL cholesterol and triglyceride concentrations, respectively. Thus, independent variation in orthologous genomic intervals does associate with similar quantitative lipid traits in both species, supporting the possibility of uncovering human QTL genes in a highly controlled non-human primate model.
Date: September 15, 2003
Creator: Wang, Qian-fei; Liu, Xin; O'Connell, Jeff; Peng, Ze; Krauss, Ronald M.; Rainwater, David L. et al.
System: The UNT Digital Library
The ASTRAL Compendium in 2004 (open access)

The ASTRAL Compendium in 2004

The ASTRAL compendium provides several databases and tools to aid in the analysis of protein structures, particularly through the use of their sequences. Partially derived from the SCOP database of protein structure domains, it includes sequences for each domain and other resources useful for studying these sequences and domain structures. The current release of ASTRAL contains 54,745 domains, more than three times as many as the initial release four years ago. ASTRAL has undergone major transformations in the past two years. In addition to several complete updates each year, ASTRAL is now updated on a weekly basis with preliminary classifications of domains from newly released PDB structures. These classifications are available as a stand-alone database, as well as available integrated into other ASTRAL databases such as representative subsets. To enhance the utility of ASTRAL to structural biologists, all SCOP domains are now made available as PDB-style coordinate files as well as sequences. In addition to sequences and representative subsets based on SCOP domains, sequences and subsets based on PDB chains are newly included in ASTRAL. Several search tools have been added to ASTRAL to facilitate retrieval of data by individual users and automated methods. ASTRAL may be accessed at http://astral.stanford.edu/.
Date: September 15, 2003
Creator: Chandonia, John-Marc; Hon, Gary; Walker, Nigel S.; Lo Conte, Loredana; Koehl, Patrice; Levitt, Michael et al.
System: The UNT Digital Library
Regulation of the transcriptional activator NtrC1: Structural studies of the regulatory and AAA{sup +} ATPase domains (open access)

Regulation of the transcriptional activator NtrC1: Structural studies of the regulatory and AAA{sup +} ATPase domains

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Date: September 15, 2003
Creator: Lee, Seok-Yong; De La Torre, Armando; Yan, Dalai; Kustu, Sydney; Nixon, Tracy B. & Wemmer, David E.
System: The UNT Digital Library
Report on the first VLHC photon stop cryogenic design experiment (open access)

Report on the first VLHC photon stop cryogenic design experiment

As part of Fermilab's study of a Very Large Hadron Collider, a water-cooled photon stop was proposed as a device to intercept the synchrotron radiation emitted by the high-energy proton beams in the high field superconducting magnets with minimal plug-cooling power. Photon stops are radiation absorbers operating at room temperature that protrude into the beam tube at the end of each bending magnet to scrape the synchrotron light emitted by the beam one magnet up-stream. Among the technological challenges regarding photon stops is their cryo-design. The photon stop is water-cooled and operates in a cryogenic environment. A careful cryo-design is therefore essential to enable operation at minimum heat transfer between the room temperature sections and the cryogenic parts. A photon stop cryo-design was developed and a prototype was built. This paper presents the results of the cryogenic experiments conducted on the first VLHC photon stop prototype.
Date: September 15, 2003
Creator: al., Michael Geynisman et
System: The UNT Digital Library
A nonstoichiometric structural model to characterize changes in the nickel hydroxide electrode during cycling (open access)

A nonstoichiometric structural model to characterize changes in the nickel hydroxide electrode during cycling

Experimental capacities and mass changes are recorded using an electrochemical quartz crystal microbalance during the first 9 charge and discharge cycles of nickel hydroxide thin films cycled in 3.0 weight percent (wt%) potassium hydroxide electrolyte. For the first time, the film capacities have been corrected for the oxygen evolution side reaction, and the data used as input into the point defect-containing structural model to track the changes that occur during short-term cycling. Variations in capacity and mass during formation and charge/discharge cycling are related to changes in the point defect parameters, thus providing a structural origin for the unique experimental variations observed here and often reported in the literature, but previously unexplained. Proton-, potassium-, and water-content vary in the active material during charge/discharge cycling. The observed capacity loss, or ''capacity fade'', is explained by incomplete incorporation of potassium ions in (or near) the nickel vacancy during charge, as additional protons are then allowed to occupy the vacant lattice site. The increase in water content during reduction parallels the expansion of the electrode that is well known during cycling. This result confirms the origin of the swelling phenomenon as being caused by water incorporation. The model and methodology developed in this …
Date: September 15, 2003
Creator: Srinivasan, Venkat; Bahne, C. Cornilsen & Weidner, John W.
System: The UNT Digital Library
The National Ignition Facility High-Energy Ultraviolet Laser System (open access)

The National Ignition Facility High-Energy Ultraviolet Laser System

The National Ignition Facility (NIF), currently under construction at the Lawrence Livermore National Laboratory, is a stadium-sized facility containing a 192-beam, 1 .&Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for nearly 100 experimental diagnostics. When completed, NIF will be the world's largest and most energetic laser experimental system, providing an international center to study inertial confinement fusion and the physics of matter at extreme energy densities and pressures. NIF's 192 energetic laser beams will compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. Other NIF experiments will allow the study of physical processes at temperatures approaching 10{sup 8} K and 10{sup 11} Bar, conditions that exist naturally only in the interior of stars, planets and in nuclear weapons. NIF is now entering the first phases of its laser commissioning program. The first four beams of the NIF laser system have generated 106 kilojoules of infrared light and over 10 kJ at the third harmonic (351 nm). NIF's target experimental systems are also being installed in preparation for experiments to begin in late 2003. This paper provides a detailed look the NIF laser systems, …
Date: September 15, 2003
Creator: Moses, E I
System: The UNT Digital Library
DPAL: A New Class of Lasers for CW Power Beaming at Ideal Photovoltaic Cell Wavelengths (open access)

DPAL: A New Class of Lasers for CW Power Beaming at Ideal Photovoltaic Cell Wavelengths

The new class of diode pumped alkali vapor lasers (DPALs) offers high efficiency cw laser beams at wavelengths which efficiently couple to photovoltaic (PV) cells: silicon cells at 895 nm (cesium), and GaAs cells at 795 nm (rubidium) and at 770 nm (potassium). DPAL electrical efficiencies of 25-30% are projected, enabling PV cell efficiencies {approx}40% (Si) and {approx}60% (GaAs). Near-diffraction-limited DPAL device power scaling into the multi-kilowatt regime from a single aperture is projected.
Date: September 15, 2003
Creator: Krupke, W F; Beach, R J; Payne, S A; Kanz, V K & Early, J T
System: The UNT Digital Library
Computational Science at Brookhaven National Laboratory: Three Selected Topics. (open access)

Computational Science at Brookhaven National Laboratory: Three Selected Topics.

We present an overview of computational science at Brookhaven National Laboratory (BNL), with selections from three areas: fluids, nanoscience, and biology. The work at BNL in each of these areas is itself very broad, and we select a few topics for presentation within each of them.
Date: September 15, 2003
Creator: Davenport, J. W.; Deng, Y.; Glimm, J. & Samulyak, R.
System: The UNT Digital Library
LHC detector upgrades (open access)

LHC detector upgrades

The LHC detectors are well into their construction phase. The LHC schedule shows first beam to ATLAS and CMS in 2007. Because the LHC accelerator has begun to plan for a ten fold increase in LHC design luminosity (the SLHC or super LHC) it is none too soon to begin to think about the upgrades which will be required of the present LHC detectors. In particular, the tracking systems of ATLAS and CMS will need to be completely rebuilt. Given the time needed to do the R & D, make prototypes, and construct the new detectors and given the accelerator schedule for the SLHC, work needs to begin rather soon.
Date: September 15, 2003
Creator: Green, Dan
System: The UNT Digital Library
Aspects of diffraction at the Tevatron (open access)

Aspects of diffraction at the Tevatron

Results on soft and hard diffraction obtained by the CDF Collaboration at the Fermilab Tevatron {bar p}p Collider are reviewed with emphasis on aspects of the data that point to the underlying QCD mechanism for diffraction. The results are interpreted in terms of a phenomenological approach in which diffraction is due to an exchange of low-x partons subject to color constraints.
Date: September 15, 2003
Creator: Goulianos, K.
System: The UNT Digital Library