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Recent results in a search for inorganic scintillators for x- and gamma-ray detection

Description: We present recent results from an ongoing search for inorganic scintillators for gamma ray detection in which we measure the scintillation properties (luminous efficiency, decay time, and emission wavelength) of powdered samples excited by brief x-ray pulses. Recent promising candidates include cerium doped lutetium borate (LuBO{sub 3}) and the lutetium double phosphates K{sub 3}Lu(PO{sub 4}){sub 2} and Rb{sub 3}Lu(PO{sub 4}){sub 2}, which have luminous intensities above 25,000 photons/MeV. In order to find scintillators that are compatible with silicon photodetectors, we have tested over 1,100 samples using a photomultiplier tube with a GaAs:Cs photocathode, which is sensitive to emissions from 200-950 nm. While many samples exhibited strong emissions in the 600-900 nm range, all had decay times that were larger than 10 {mu}s.
Date: October 1997
Creator: Moses, W. W.; Weber, M. J.; Derenzo, S. E.; Perry, D. & Berahl, P.
Partner: UNT Libraries Government Documents Department

Rigid, adjustable support of aligned elements via six struts

Description: At particle accelerators around the world, a great deal of effort is expended on determining precise component locations in space. Much less effort is spent on the design of systems to precisely and solidly locate these components in space, once one has the ability to know where they are. Unfortunately, there are many inadequate ways of adjustably mounting position sensitive beam line hardware, and only a few methods which work well. Traditional jacking screw and shimming support systems are often troublesome, and a drain on manpower and time. Multiple precision stages of adequate capacity for heavy items are expensive. At Lawrence Berkeley National Laboratory's Advanced Light Source, the authors rely almost exclusively on their home-grown, simple, and cost effective six-strut mechanical support systems. This approach meets the seismic requirements, minimizes vibration, and allows easy and precise alignment of a wide variety of accelerator hardware.
Date: October 1, 1997
Creator: Thur, W.; Lauritzen, T.; DeMarco, R.; Baldock, B. & Rex, K.
Partner: UNT Libraries Government Documents Department

Bipolar pulsed reset for AC coupled charge-sensitive preamplifiers

Description: A new type of charge restoration is described for use particularly in germanium gamma-ray spectrometers for accelerator and space physics applications. A bipolar pulsed reset technique is applied to these applications for the first time. This technique overcomes the problems introduced by the need to AC couple detectors and the fact that very large energy depositions occur due to charged particles present in substantial fluxes, particularly in space. The circuit is described and experimental results are presented and discussed.
Date: July 1, 1997
Creator: Landis, D. A.; Madden, N. M. & Goulding, F. S.
Partner: UNT Libraries Government Documents Department

Effectiveness of duct sealing and duct insulation in multi-family buildings. Final report

Description: This research investigated the cost-effectiveness of sealing and insulating the accessible portions of duct systems exposed to unconditioned areas in multifamily housing. Airflow and temperature measurements were performed in 25 apartments served by 10 systems a 9 multi-family properties. The measurements were performed before and after each retrofit, and included apartment airflow (supply and return), duct system temperatures, system fan flow and duct leakage area. The costs for each retrofit were recorded. The data were analyzed and used to develop a prototypical multifamily house. This prototype was used in energy simulations (DOE-2.1E) and air infiltration simulations (COMIS 2.1). The simulations were performed for two climates: New York City and Albany. In each climate, one simulation was performed assuming the basement was tight, and another assuming the basement was leaky. Simulation results and average retrofit costs were used to calculate cost-effectiveness. The results of the analysis indicate that sealing leaks of the accessible ductwork is cost-effective under all conditions simulated (simple payback was between 3 and 4 years). Insulating the accessible ductwork, however, is only cost-effective for buildings with leaky basement, in both climates (simple paybacks were less than 5 years). The simple payback period for insulating the ducts in buildings with tight basements was greater than 10 years, the threshold of cost-effectiveness for this research. 13 refs., 5 figs., 27 tabs.
Date: July 1, 1997
Creator: Karins, N.H.; Tuluca, A. & Modera, M.
Partner: UNT Libraries Government Documents Department

Lamellar multilayer gratings with very high diffraction efficiency

Description: The authors report here the development of a hard x-ray multilayer grating that has achieved an absolute efficiency of 34% at a wavelength of 1.54{angstrom}. The W-C multilayer itself has a reflectivity of 57% and the grating has a 0th order absolute efficiency of 36%. The origin of this extraordinarily high efficiency is that the short period and highly asymmetric structure of the gratings combined with its deep grooves allows light to interact with a large number of layer pairs. This increases angular separation of the diffraction orders and reduces the multilayer bandwidth to the point where there is little or no order to order overlap in the grating structure, and hence maximum intensity can be diffracted into a selected order. This paper reports on the development of an optimized multilayer grating and some of its unique characteristics.
Date: July 1, 1997
Creator: Martynov, V.V.; Yakshin, A.; Agafonov, Yu.A. & Padmore, H.A.
Partner: UNT Libraries Government Documents Department

Progress towards sub-micron hard x-ray imaging using elliptically bent mirrors

Description: Of the many methods used to focus x-rays, the use of mirrors with an elliptical curvature shows the most promise of providing a sub-micron white light focus. Our group has been developing the techniques of controlled bending of mirror substrates in order to produce the desired elliptical shape. We have been successful in producing surfaces with the required microradian slope error tolerances. Details of the bending techniques used, results from laboratory slope error measurements using a Long Trace Profiler (LTP) and data from the measurement of focus shape using knife edge and imaging methods using x-rays in the 5-12 KeV energy range are presented. The development of a white light focusing opens many possibilities in diffraction and spectroscopic studies.
Date: July 1, 1997
Creator: MacDowell, A.A.; Celestre, R.; Chang, C.H. & Frank, K.
Partner: UNT Libraries Government Documents Department

Energy-Efficiency Options for Insurance Loss Prevention

Description: Energy-efficiency improvements offer the insurance industry two areas of opportunity: reducing ordinary claims and avoiding greenhouse gas emissions that could precipitate natural disaster losses resulting from global climate change. We present three vehicles for taking advantage of this opportunity, including research and development, in- house energy management, and provision of key information to insurance customers and risk managers. The complementary role for renewable energy systems is also introduced.
Date: June 9, 1997
Creator: Mills, E. & Knoepfel, I.
Partner: UNT Libraries Government Documents Department

Calibration of the beam-position monitor system for the SLAC PEP-II B factory

Description: The Beam-Position Monitors (BPM) for the PEP-II B Factory consist of four 1.5-cm diameter button style pickups mounted on the diagonals of the quadrupole vacuum chambers. Before installation of the vacuum chambers in the quadrupole assemblies, the electrical center of the BPMs is measured with respect to the mechanical center in a calibration test stand. In this paper the calibration test stand is described and the precision and accuracy of the calibrations are presented. After installation of the quadrupole assemblies in the PEP-II tunnel, the passive attenuation for each channel of the system is measured to preserve the accuracy of the calibration. Finally, the active electronics includes an onboard calibrator. Results for these portions of the calibration are presented.
Date: June 1, 1997
Creator: Johnson, R.; Smith, S. & Kurita, N.
Partner: UNT Libraries Government Documents Department

A preliminary improved test of the flavor independence of strong interactions

Description: The authors present an improved comparison of the strong couplings of gluons to light (u, d, and s), c, and b quarks, determined from multijet rates in flavor-tagged samples of hadronic Z{sup 0} decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation on the basis of lifetime and decay multiplicity differences among hadrons containing light, c, and b quarks was made using the SLD precision tracking system, yielding tags with high purity and low bias against {ge} 3-jet final states. They find: {alpha}{sub s}{sup uds}/{alpha}{sub s}{sup all} = 0.997 {+-} 0.011(stat) {+-} 0.011(syst) {+-} 0.005(theory), {alpha}{sub s}{sup c}/{alpha}{sub s}{sup all} = 0.984 {+-} 0.042 {+-} 0.053 {+-} 0.022, {alpha}{sub s}{sup b}/{alpha}{sub s}{sup all} = 1.022 {+-} 0.019 {+-} 0.023 {+-} 0.012.
Date: June 1, 1997
Creator: Abe, K.; Abe, K.; Akagi, T. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Symmetry tests in polarized Z{sup 0} decays to b{anti b}g

Description: Angular asymmetries have been measured in polarized Z{sup 0} decays to b{anti b}g collected by the SLD experiment at the SLC. A high purity b{anti b}g event sample is selected utilizing lifetime information given by the SLD CCD pixel vertex detector and the stable micron-size SLC beams, and the b- and {anti b}-jets are identified using lifetime information and momentum-weighted track charge. The forward-backward asymmetry is observed in the b-jet polar angle distribution, and the parity-violation parameter is measured to test the Standard Model. Two angular correlations between the three-jet plane and the Z{sup 0} polarization are studied. The CP-even and T-odd angular asymmetry, and the CP-odd and T-odd angular asymmetry are sensitive to physics beyond the Standard Model. The authors measure the expectation values of these quantities to be consistent with zero and set limits on the correlations.
Date: June 1, 1997
Creator: Abe, K.; Abe, K.; Akagi, T. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Directory and survey of particle physicists

Description: In order to develop a clearer understanding of the demographics of the U.S. particle physics workforce, the US Department of Energy, the National Science Foundation, and the Division of Particles and Fields of the American Physical Society commissioned a survey and census of particle physicists employed in the United States. This survey and census were conducted in 1995, with an update of the census in April 1997. The agencies and the scientific community were represented for the 1995 efforts by Dr. Robert Woods (DOE), Dr. William Chinowsky (NSF), and Prof. Uriel Nauenberg (DPF); for the current census, by Dr. Robert Diebold (DOE), Dr. Marvin Goldberg (NSF), and Dr. Patricia Rankin (NSF). The survey/census were carried out with the assistance of the Particle Data Group at Lawrence Berkeley National Laboratory. In order to obtain an accurate study of the current workforce and of future needs, we requested that all HEP physicists fill out and return the 1995 survey. There were 2494 respondents. For the 1997 census, a representative of each university and laboratory was asked to provide information on all persons at that institution who spend at least 50% of their research time on particle physics. In some cases this includes accelerator physicists. The total number of physicists in the 1997 census is 3492 from 155 institutions in the United States. The full survey questionnaires are shown. The primary one was addressed to individual particle physicists, while the secondary one was addressed to principal investigators and sought information about people leaving the field. There are many possible tables and plots from this survey, with a variety of correlations. Those chosen are representative of a cross-section of the demographic results. It should be emphasized that this survey was a snapshot in time, and does not have the same capabilities as would a ...
Date: April 1, 1997
Partner: UNT Libraries Government Documents Department

Decision making through use of interoperable simulation software

Description: Many building simulation computer programs, originally developed on mainframe computers for research purposes, can now run on the powerful workstation and personal computers that are available to most architectural and engineering firms. Major efforts have been underway during the last decade to compile these programs on personal computers and make them available to a wider range of building professionals. However, even with the addition of user-friendly front- and back-ends, their use is still limited to a small number of specialized consultants. Considering the tremendous benefits of informed decisions that these programs can support, it is critical to address and resolve the issues that are associated with their limited acceptance. In this paper, the authors report on their research and development efforts to better understand decision-making and develop computer tools that will facilitate the use of simulation software during the building design process. They present a brief analysis of decision-making and then describe how they try to address it in building design through the development of the Building Design Advisor (BDA). Moreover, the authors elaborate on the major issues that they have encountered, discuss lessons learned, and offer recommendations for short- and long-term developments in this area.
Date: March 1997
Creator: Papamichael, K.; La Porta, J. & Chauvet, H.
Partner: UNT Libraries Government Documents Department

Electrochromic lithium nickel oxide thin film by pulsed laser deposition

Description: * Thin films of lithium nickel oxide were deposited by pulsed laser deposition (PLD) from targets of pressed LiNiO{sub 2} powder with layered structure. The composition, structure and surface air sensitivity of these films were analyzed using a variety of techniques, such as nuclear reaction analysis, Rutherford backscattering spectrometry (RBS), x-ray diffraction, infrared spectroscopy, and atomic force microscopy. Optical properties were measured using a combination of variable angle spectroscopic ellipsometry and IP spectroradiometry. Crystalline structure, surface morphology and chemical composition of Li{sub x}Ni{sub 1-x}O thin films depend strongly on deposition oxygen pressure, temperature as well as substrate target distance. The films produced at temperatures lower than 600 degrees C spontaneously absorb CO{sub 2} and H{sub 2}O at their surface once they are exposed to the air. The films deposited at 600 degrees C proved to be stable in air over a long period. Even when deposited at room temperature the PLD films are denser and more stable than sputtered films. RBS determined that the best electrochromic films had the stoichiometric composition L{sub 0.5}Ni{sub 0.5}O when deposited at 60 mTorr O{sub 2} pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0 V to 3.4 V versus lithium and long cyclic life stability in a liquid electrolyte half cell. Electrochemical formatting which is used to develop electrochromism in other films and nickel oxide films is not needed for these stoichiometric films. The optical transmission range is almost 70% at 550 nm for 120 nm thick films.
Date: October 1996
Creator: Wen, S. J.; von Rottkay, K. & Rubin, M.
Partner: UNT Libraries Government Documents Department

Energy effectiveness of duct sealing and insulation in two multifamily buildings

Description: Energy losses from forced air distribution systems have a significant impact on the energy efficiency of buildings. Little work has been done to quantify these losses in apartment buildings. In this paper the authors will discuss field measurements made on four forced air heating systems to evaluate the duct system energy losses to unconditioned basements. The apartments were heated by natural gas furnaces located in the basements. The systems had bare sheet metal ductwork exposed to the basement conditions. The pre-retrofit measurements were made on the systems after sealing large easily visible leaks. The post-retrofit measurements were made after wrapping the ducts in foil backed glass fiber insulation and additional leak sealing. Only the sections of duct exposed to the basement were retrofitted because only these sections were accessible. This study examines the potential energy savings for this type of limited retrofit. The energy losses were separated into leakage and conduction terms. Leakage measurements were made using register flowhood techniques. Conduction losses were estimated by measuring temperatures in the plenums and at the registers. Analysis of the measurements has shown typical reduction in leakage flow due to duct sealing of about 40%. The reduction in leakage translated into a reduction in energy consumption of about 10%.
Date: August 1996
Creator: Walker, I. S.; Modera, M. P.; Tuluca, A. & Graham, I.
Partner: UNT Libraries Government Documents Department

Solar heat gain coefficient of complex fenestrations with a venetian blind for differing slat tilt angles

Description: Measured bidirectional transmittances and reflectances of a buff-colored venetian blind together with a layer calculation scheme developed in previous publications are utilized to produce directional-hemispherical properties for the venetian blind layer and solar heat gain coefficients for the blind in combination with clear double glazing. Results are presented for three blind slat tilt angles and for the blind mounted either interior to the double glazing or between the glass panes. Implications of the results for solar heat gain calculations are discussed in the context of sun positions for St. Louis, MO.
Date: August 1996
Creator: Klems, J. H. & Warner, J. L.
Partner: UNT Libraries Government Documents Department

Stable bootstrap-current driven equilibria for low aspect ratio tokamaks

Description: Low aspect ratio tokamaks can potentially provide a high ratio of plasma pressure to magnetic pressure {beta} and high plasma current I at a modest size, ultimately leading to a high power density compact fusion power plant. For the concept to be economically feasible, bootstrap current must be a major component of the plasma current. A high value of the Troyon factor {beta}{sub N} and strong shaping are required to allow simultaneous operation at high {beta} and high bootstrap current fraction. Ideal magnetohydrodynamic stability of a range of equilibria at aspect ratio 1.4 is systematically explored by varying the pressure profile and shape. The pressure and current profiles are constrained in such a way as to assure complete bootstrap current alignment. Both {beta}{sub N} and {beta} are defined in terms of the vacuum toroidal field. Equilibria with {beta}{sub N} {ge} 8 and {beta} - 35% to 55% exist which are stable to n = {infinity} ballooning modes, and stable to n = 0, 1,2,3 kink modes with a conducting wall. The dependence of {beta} and {beta}{sub N} with respect to aspect ratio is also considered.
Date: August 1, 1996
Creator: Miller, R.L.; Lin-Liu, Y.R.; Turnbull, A.D.; Chan, V.S.; Pearlstein, L.D.; Sauter, O. et al.
Partner: UNT Libraries Government Documents Department

You Won`t Find These Leaks with a Blower Door: The Latest in "Leaking Electricity" in Homes

Description: Leaking electricity is the energy consumed by appliances when they are switched off or not performing their principal functions. Field measurements in Florida, California, and Japan show that leaking electricity represents 50 to 100 Watts in typical homes, corresponding to about 5 GW of total electricity demand in the United States. There are three strategies to reduce leaking electricity: eliminate leakage entirely, eliminate constant leakage and replace with intermittent charge plus storage, and improve efficiency of conversion. These options are constrained by the low value of energy savings-less than $5 per saved Watt. Some technical and lifestyle solutions are proposed. 13 refs., 1 fig., 2 tabs.
Date: August 1996
Creator: Rainer, L.; Greenberg, S. & Meier, A.
Partner: UNT Libraries Government Documents Department

Measurement of the B{sup +} and B{sup 0} lifetimes with topological vertexing at SLD

Description: The lifetimes of the B{sup +} (B{sub u}) and B{sup 0} (B{sub d}) mesons have been measured using a sample of 150,000 hadronic Z{sup 0} decays collected by the SLD experiment at the SLC between 1993 and 1995. The analysis reconstructs the decay length and charge of the B meson using a novel topological technique. This method results in a high statistics sample of 6,033 (3,665) charged (neutral) vertices. The ratio of B{sup +}:B{sup 0} decays in the charged (neutral) sample is 1.8:1 (1:2.3).
Date: July 1, 1996
Creator: Abe, K.; Abe, K.; Abt, I. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Muon muon collider: Feasibility study

Description: A feasibility study is presented of a 2 + 2 TeV muon collider with a luminosity of L = 10{sup 35} cm{sup {minus}2} s{sup {minus}1}. The resulting design is not optimized for performance, and certainly not for cost; however, it does suffice--the authors believe--to allow them to make a credible case, that a muon collider is a serious possibility for particle physics and, therefore, worthy of R and D support so that the reality of, and interest in, a muon collider can be better assayed. The goal of this support would be to completely assess the physics potential and to evaluate the cost and development of the necessary technology. The muon collider complex consists of components which first produce copious pions, then capture the pions and the resulting muons from their decay; this is followed by an ionization cooling channel to reduce the longitudinal and transverse emittance of the muon beam. The next stage is to accelerate the muons and, finally, inject them into a collider ring which has a small beta function at the colliding point. This is the first attempt at a point design and it will require further study and optimization. Experimental work will be needed to verify the validity of diverse crucial elements in the design.
Date: June 18, 1996
Partner: UNT Libraries Government Documents Department

Model calibration and symmetry restoration of the advanced light source

Description: The symmetry of the ALS magnetic lattice is crucial in suppressing nonlinear structural resonances. Breaking the symmetry of the lattice can lead to a reduction in the dynamic aperture. The degree of symmetry breaking can be determined by fitting a magnetic lattice model to the measured orbit response matrix. This reveals a large beating of the vertical beta-function caused mainly by gradient errors in the QD quadrupole magnets. When the quadrupole field strengths are adjusted to compensate for the gradient errors, the symmetry of the lattice is restored. The new lattice has a larger dynamic aperture and an improved injection efficiency.
Date: June 10, 1996
Creator: Robin, D.; Portmann, G.; Nishimura, H. & Safranek, J.
Partner: UNT Libraries Government Documents Department

High-resolution VUV spectroscopy: New results from the Advanced Light Source

Description: Third-generation synchrotron light sources are providing photon beams of unprecedented brightness for researchers in atomic and molecular physics. Beamline 9.0.1, an undulator beamline at the Advanced Light Source (ALS), produces a beam in the vacuum-ultraviolet (VUV) region of the spectrum with exceptional flux and spectral resolution. Exciting new results from experiments in atomic and molecular VUV spectroscopy of doubly excited autoionizing states of helium, hollow lithium, and photoelectron spectroscopy of small molecules using Beamline 9.0.1 at the ALS are reported.
Date: June 1, 1996
Creator: Schlachter, F. & Bozek, J.
Partner: UNT Libraries Government Documents Department

Element-specific soft x-ray magneto-optic rotation studies of magnetic films and multilayers

Description: Tunable multilayer linear polarizers extend magneto-optic rotation techniques that directly sense polarization changes into the 50--1,000 eV range. The resonant response at atomic core levels yields element-specific magnetic signals that can be much larger than the analogous signal in the visible. A tunable multilayer polarimeter is described, and examples of its use in early Kerr rotation hysteresis studies of Fe films and Fe/Cr multilayers are given.
Date: May 1, 1996
Creator: Kortright, J.B. & Rice, M.
Partner: UNT Libraries Government Documents Department

Guidelines for sustainable building design: Recommendations from the Presidio of San Francisco energy efficiency design charrette

Description: In 1994, the Bay Chapter of the Association of Energy Engineers{reg_sign} organized a two-day design charrette for energy-efficient redevelopment of buildings by the National Park Services (NPS) at the Presidio of San Francisco. This event brought together engineers, researchers, architects, government officials, and students in a participatory environment to apply their experience to create guidelines for the sustainable redesign of Presidio buildings. The venue for the charrette was a representative barracks building located at the Main Post of the Presidio. Examination of this building allowed for the development of design recommendations, both for the building and for the remainder of the facilities. The charrette was organized into a committee structure consisting of: steering, measurement and monitoring, modeling, building envelope and historic preservation (architectural), HVAC and controls, lighting, and presentation. Prior to the charrette itself, the modeling and measurement/monitoring committees developed substantial baseline data for the other committees during the charrette. An integrated design approach was initiated through interaction between the committees during the charrette. Later, committee reports were cross-referenced to emphasize whole building design and systems integration.
Date: May 1996
Creator: Brown, K.; Sartor, D. & Greenberg, S.
Partner: UNT Libraries Government Documents Department

Photoelectron emission microscopy and its application to the study of polymer surfaces

Description: The X-ray Photoelectron Emission Microscopy (X-PEEM) at the Advanced Light Source (ALS) has a spatial resolution of 0.2 microns at an accelerating voltage of 12kV. The tunability of the photon energy is used to provide chemical state information using near edge X-ray absorption fine structure (NEXAFS) spectroscopy on the sub-micrometer scale. The homogeneity of thin films of polymer blends was studied for various film thicknesses. The polystyrene/polyvinylmethylether film of 194 {angstrom} showed protrusions of 2-3{mu}m diameter with an enriched polystyrene content while the polystyrene/polystyreneacrylonitrile 504 {angstrom} thick films showed 5-6 {mu}m segregated regions without any topological structure.
Date: May 1, 1996
Creator: Cossy-Favre, A.; Diaz, J.; Anders, S. & Padmore, H.A.
Partner: UNT Libraries Government Documents Department