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Spontaneous polarization and piezoelectricity in boron nitride nanotubes (open access)

Spontaneous polarization and piezoelectricity in boron nitride nanotubes

Article on spontaneous polarization and piezoelectricity in boron nitride nanotubes.
Date: June 10, 2003
Creator: Nakhmanson, Serge M.; Calzolari, Arrigo; Meunier, Vincent; Bernholc, Jerry & Buongiorno Nardelli, Marco
System: The UNT Digital Library
Analysis of the b2 correction in the Tevatron (open access)

Analysis of the b2 correction in the Tevatron

Beam loss and emittance dilution during ramping from injection to collision energy is observed in the Tevatron, now in its collider run-II stage. It is well known that the sextupole (b2) components in the superconducting dipole magnets decay during the injection plateau and snap back rapidly at the start of the ramp. These so called dynamic effects, which were originally discovered in the Tevatron, are compensated with the chromaticity correctors, distributed around the ring. Imperfect control of the chromaticity during injection and snapback can contribute to the beam loss. Therefore a thorough investigation of the b2 compensation in the Tevatron was launched, including beam chromaticity measurements and offline magnetic measurements on Tevatron dipoles. This paper reports the status of this investigation. A companion paper describes in detail the results of the magnet measurements. This work was partly conducted as a collaboration between FNAL and CERN.
Date: June 10, 2003
Creator: al., Pierre Bauer et
System: The UNT Digital Library
Gated current integrator for the beam in the RR barrier buckets (open access)

Gated current integrator for the beam in the RR barrier buckets

At the Fermilab Recycler Ring (RR), the antiproton (pbar) beam will be stored azimuthally in different segments created by barrier buckets. The beam in each segment may have widely varying intensities. They have developed a gated integrator system to measure the beam intensity in each of the barrier bucket. Here they discuss the design of the system and the results of beam measurements using the integrator.
Date: June 10, 2003
Creator: Cadorn, A.; Bhat, C. & Crisp, J.
System: The UNT Digital Library
Tune measurement methods of the Tevatron (open access)

Tune measurement methods of the Tevatron

We will discuss several methods for measuring the tunes in the Tevatron. These methods can be separated into three classes: active, passive and hybrid. In the active method, the beam is tickled in order to obtain a frequency response. In the passive method, a Schottky detector which uses a resonant stripline is used to measure the Schottky spectrum of the beam. In the hybrid method, we tickle the beam using kickers, or the Tevatron Electron Lens (TEL) in order to bring the tune signal above the noise floor of the Schottky detectors. An automatic tune fitting algorithm is also under development which allows us to measure the tune without human intervention.
Date: June 10, 2003
Creator: Tan, Cheng-Yang; Zhang, Xiaolong & Lebrun, Paul
System: The UNT Digital Library
Higgs searches at the Tevatron (open access)

Higgs searches at the Tevatron

One of the highest priority physics goals for the upgraded Tevatron experiments, CDF and D0, is the search for the Higgs boson. We present the initial results from both experiments, based on 40-90 pb{sup -1} integrated luminosity, of Higgs searches in several final states, including WH and ZH, H {yields} WW, and doubly-charged Higgs.
Date: June 10, 2003
Creator: Li, Qizhong
System: The UNT Digital Library
Synergia: a hybrid, parallel beam dynamics code with 3D space charge (open access)

Synergia: a hybrid, parallel beam dynamics code with 3D space charge

The authors report on high-dose irradiation studies performed with a 200 MeV proton beam on a 140 Mbit/s pixel-data serializer prototype realized in standard 0.25 micron CMOS technology. The data serializer was implemented recently for the BTeV pixel readout chip developed at Fermilab.
Date: June 10, 2003
Creator: Amundson, James F. & Spentzouris, Panagiotis
System: The UNT Digital Library
Antiproton acceleration in the Fermilab Main Injector using 2.5 MHz (H=28) and 53 MHz (H=588) rf systems (open access)

Antiproton acceleration in the Fermilab Main Injector using 2.5 MHz (H=28) and 53 MHz (H=588) rf systems

During the Run II era at Fermilab, the Recycler stores antiprotons at 8 GeV and the Main Injector accelerates the antiprotons and the protons from 8 GeV to 150 GeV for Tevatron injection. The Recycler injects antiprotons to the Main Injector in 2.5 MHz rf buckets. This report presents an acceleration scheme for the antiprotons that involves a slow ramp with initial 2.5 MHz acceleration and subsequent fast acceleration with 53 MHz rf system. Beam acceleration and rf manipulation with space charge and beam loading effects are simulated using the longitudinal simulation code ESME. Simulation suggests that one can expect about 15% emittance growth for the entire acceleration cycle with beam loading compensations. Preliminary experimental results with proton beam will also be presented.
Date: June 10, 2003
Creator: al., Vincent Wu et
System: The UNT Digital Library
Coupling MM5 with ISOLSM: Development, testing, and applications (open access)

Coupling MM5 with ISOLSM: Development, testing, and applications

Surface water and energy fluxes are tightly coupled with CO2 exchanges between the ecosystem and atmosphere. Other surface-to-atmosphere trace-gas exchanges of interest in climate change research (e.g., N2O, CH4, C18OO, and H218O) are also strongly impacted by surface energy exchanges. Further, land-use change has large effects on the surface energy balance and therefore the exchanges of these trace gases. To investigate these issues at the regional scale we have coupled MM5 (Grell et al. 1995) with ISOLSM (Riley et al. 2002, Riley et al. 2003), a land-surface model based on LSM1 (Bonan 1995).
Date: June 10, 2003
Creator: Riley, W.J.; Cooley, H.S.; He, Y. & Torn, M.S.
System: The UNT Digital Library
Initiation, Growth and Mitigation of UV Laser Induced Damage in Fused Silica (open access)

Initiation, Growth and Mitigation of UV Laser Induced Damage in Fused Silica

Laser damage of large fused silica optics initiates at imperfections. Possible initiation mechanisms are considered. We demonstrate that a model based on nanoparticle explosions is consistent with the observed initiation craters. Possible mechanisms for growth upon subsequent laser irradiation, including material modification and laser intensification, are discussed. Large aperture experiments indicate an exponential increase in damage size with number of laser shots. Physical processes associated with this growth and a qualitative explanation of self-accelerated growth is presented. Rapid growth necessitates damage growth mitigation techniques. Several possible mitigation techniques are mentioned, with special emphasis on CO{sub 2} processing. Analysis of material evaporation, crack healing, and thermally induced stress are presented.
Date: June 10, 2003
Creator: Rubenchik, A M & Feit, M D
System: The UNT Digital Library
Partition of solutes into wet and dry ethers; an LFER analysis (open access)

Partition of solutes into wet and dry ethers; an LFER analysis

Article on the partition of solutes into wet and dry ethers and an LFER analysis.
Date: June 10, 2003
Creator: Abraham, M. H. (Michael H.) & Acree, William E. (William Eugene)
System: The UNT Digital Library
Turbulent boundary layers at very large Reynolds numbers (open access)

Turbulent boundary layers at very large Reynolds numbers

None
Date: June 10, 2003
Creator: Barenblatt, G.I.
System: The UNT Digital Library
Longitudinal emittance measurements in the Fermilab Recycler Ring (open access)

Longitudinal emittance measurements in the Fermilab Recycler Ring

The Recycler Ring (RR) is a new 8Gev antiproton storage ring at Fermilab. Presently, this machine is being commissioned using protons from the Booster. It uses barrier buckets for stacking, un-stacking and storing the beam. At any given time, the RR is capable of storing proton or antiproton beams in multiple segments azimuthally. These segments of the beam may have widely differing longitudinal emittance and beam intensities and bunch lengths. It is highly essential to be able to measure the longitudinal emittance and keep track of the longitudinal dynamics at various stages of the operation of the RR. In this paper, the authors discuss a few methods of longitudinal emittance measurements in barrier buckets and discuss their merits and demerits
Date: June 10, 2003
Creator: Bhat, C. M. & Marriner, John P.
System: The UNT Digital Library
Supersymmetry searches at the Tevatron (open access)

Supersymmetry searches at the Tevatron

For Run II, both CDF and D0 underwent significant improvement of the detectors to enhance their sensitivity to new physics. The detectors are commissioned and are taking data. The Tevatron is operating at a record center of mass energy of 1.96 TeV. Despite earlier difficulties, the luminosity situation is improving and both detectors have accumulated amounts of data comparable or higher than those available in Run I. This is a report on the status and prospects of SUSY searches at CDF and D0 in Run II. Recent SUSY analyses from run I are also reported.
Date: June 10, 2003
Creator: Safonov, A. N.
System: The UNT Digital Library