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AFM-Based Microelectrical Characterization of Grain Boundaries in Cu(In,Ga)Se2 Thin Films (open access)

AFM-Based Microelectrical Characterization of Grain Boundaries in Cu(In,Ga)Se2 Thin Films

We report on a direct measurement of two-dimensional potential distribution on the surface of Cu(In,Ga)Se2 thin films using a nanoscale electrical characterization of scanning Kelvin probe microscopy both in air and in ultra-high vacuum. The potential measurement reveals a higher surface potential or a smaller work function on grain boundaries (GBs) of the film than on the grain surfaces. This demonstrates the existence of a local built-in potential on GBs, and the GB is positively charged. The role of the built-in potential in device performance was further examined and found to be positive, by tuning Ga content or bandgap of the film. With increasing Ga content, the potential drops sharply in a Ga range of 28%-38%. Comparing the change in the built-in potential to the theoretical and experimental photoconversion efficiencies, we conclude that the potential plays a significant role in the device conversion efficiency of NREL's three-stage Cu(In,Ga)Se2 device.
Date: February 1, 2005
Creator: Jiang, C. S.; Noufi, R.; Ramanathan, K.; AbuShama, J. A.; Moutinho, H. R. & Al-Jassim, M. M.
System: The UNT Digital Library
The Rare decay K+ ---> pi+ nu anti-nu at the next-to-next-to-leading order in QCD (open access)

The Rare decay K+ ---> pi+ nu anti-nu at the next-to-next-to-leading order in QCD

The authors calculate the complete next-to-next-to-leading order QCD correction of the charm quark contribution to the branching ratio for the rare decay K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}} in the standard model. The inclusion of these {Omicron}({alpha}{sub s}) contributions leads to a significant reduction of the theoretical uncertainty from {+-} 10.1% down to {+-} 2.4% in the relevant parameter P{sub c}, implying the left over scale uncertainties in {Beta}(K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}) and in the determination of |V{sub td}|, sin 2{beta} and {gamma} from the K {yields} {pi}{nu}{bar {nu}} system to be {+-} 1.3%, {+-} 1.0%, {+-} 0.006 and {+-} 1.2{sup o}, respectively. for the charm quark {ovr MS} mass m{sub c}(m{sub c}) = (1.30 {+-} 0.05) GeV and |V{sub us}| = 0.2248 the next-to-leading order value P{sub c} = 0.37 {+-} 0.06 is modified to P{sub c} = 0.37 {+-} 0.04 at the next-to-next-to-leading order level with the latter error fully dominated by the uncertainty in m{sub c}(m{sub c}). Adding the recently calculated long-distance contributions we find {Beta}(K{sup +} {yields} {pi}{sup +}{nu}{bar {nu}}) = (8.0 {+-} 1.1) x 10{sup -11} with the quoted error almost entirely due to the present uncertainties in m{sub c}(m{sub c}) and the …
Date: August 1, 2005
Creator: Buras, A. J.; Gorbahn, M.; Haisch, U. & Nierste, U.
System: The UNT Digital Library
A Study of anti-p p ---> two neutral pseudoscalar mesons at the chi(c0)(1**3 P0) formation energy (open access)

A Study of anti-p p ---> two neutral pseudoscalar mesons at the chi(c0)(1**3 P0) formation energy

Fermilab experiment E835 has studied reactions {bar p}p {yields} {pi}{sup 0}{pi}{sup 0}, {pi}{sup 0}{eta}, {eta}{eta}, {pi}{sup 0}{eta}' and {eta}{eta}' in the energy region of the {chi}{sub c0}(1{sup 3} P{sub 0}) from 3340 MeV to 3470 MeV. Interference between resonant and continuum production is observed in the {pi}{sup 0}{pi}{sup 0} and {eta}{eta} channels, and the product of the input and output branching fractions is measured. Limits on resonant production are set for the {pi}{sup 0}{eta} and {pi}{sup 0}{eta}' channels. An indication of interference is observed in the {eta}{eta}' channel. The technique for extracting resonance parameters in an environment dominated by continuum production is described.
Date: September 1, 2005
Creator: Andreotti, M.; Bagnasco, S.; Baldini, W.; Bettoni, D.; Borreani, G.; Buzzo, A. et al.
System: The UNT Digital Library
B0(S) mixing, lifetime difference and rare decays at the Tevatron (open access)

B0(S) mixing, lifetime difference and rare decays at the Tevatron

Recent results on B{sub s}{sup 0} mixing, lifetime difference and rare decays obtained by the CDF and D0 collaborations using the data samples collected at the Tevatron Collider in the period 2002-2005 are presented.
Date: May 1, 2005
Creator: Burdin, Sergey
System: The UNT Digital Library
Development of the superconducting 3.9-GHz accelerating cavity at Fermilab (open access)

Development of the superconducting 3.9-GHz accelerating cavity at Fermilab

A superconducting third harmonic 3.9 GHz accelerating cavity was proposed to improve the beam quality in the TTF-like photoinjector [1]. Fermilab has developed, built and tested several prototypes, including two copper 9-cell cavities, one niobium 3-cell cavity, and one 9-cell cavity. The helium vessel and frequency tuner for the 9-cell cavity was built and tested as well. In cold tests, we achieved a peak surface magnetic field of {approx}100mT, well above the 70mT specification. The accelerating gradient was likely limited by thermal breakdown. Studies of the higher order modes in the cavity revealed that the existing cavity design with two HOM couplers will provide sufficient damping of these modes. In this paper we discuss the cavity design, results of the studies and plans for further development.
Date: May 1, 2005
Creator: Arkan, T.; Bauer, P.; Bellantoni, L.; Boffo, C.; Borissov, E.; Carter, H. et al.
System: The UNT Digital Library
Future hadron physics at Fermilab (open access)

Future hadron physics at Fermilab

Today, hadron physics research occurs at Fermilab as parts of broader experimental programs. This is very likely to be the case in the future. Thus, much of this presentation focuses on our vision of that future--a future aimed at making Fermilab the host laboratory for the International Linear Collider (ILC). Given the uncertainties associated with the ILC--the level of needed R&D, the ILC costs, and the timing--Fermilab is also preparing for other program choices. I will describe these latter efforts, efforts focused on a Proton Driver to increase the numbers of protons available for experiments. As examples of the hadron physics which will be coming from Fermilab, I summarize three experiments: MIPP/E907 which is running currently, and MINERvA and Drell-Yan/E906 which are scheduled for future running periods. Hadron physics coming from the Tevatron Collider program will be summarized by Arthur Maciel in another talk at Hadron05.
Date: September 1, 2005
Creator: Appel, Jeffrey A.
System: The UNT Digital Library
Emittance dilution and halo creation during the first milliseconds after injection at the Fermilab Booster (open access)

Emittance dilution and halo creation during the first milliseconds after injection at the Fermilab Booster

During the past year, the Fermilab Booster has been pushed to record intensities in order to satisfy the needs of the Tevatron collider and neutrino programs. This high intensity makes the study of space-charge effects and halo formation highly relevant to optimizing Booster performance. We present measurements of beam width evolution, halo formation, and coherent tune shifts, emphasizing the experimental techniques used and the calibration of the measuring devices. We also use simulations utilizing the 3D space-charge code Synergia to study the physical origins of these effects.
Date: January 1, 2005
Creator: Spentzouris, Panagiotis & Amundson, J.
System: The UNT Digital Library
Top quark mass and properties at the Tevatron (open access)

Top quark mass and properties at the Tevatron

We present recent analyses of top quark properties performed at Run II of the Tevatron. Measurements of the top quark mass, branching ratios and W boson helicity inside top quark decays are covered.
Date: July 1, 2005
Creator: Arguin, Jean-Francois & U., /Toronto
System: The UNT Digital Library
Top physics results at CDF (open access)

Top physics results at CDF

The most recent results on top quark physics at CDF are reported. Measurements of cross-section and mass are presented, and the status of single top quark production searches are discussed. The results obtained from probing various top quark properties are also presented.
Date: May 1, 2005
Creator: Vickey, Trevor
System: The UNT Digital Library
Stability of barrier buckets with short barrier separations (open access)

Stability of barrier buckets with short barrier separations

A barrier bucket with very short or zero rf-barrier separation (relative to the barrier widths) has its synchrotron tune decreasing from a very large value towards the bucket boundary. As a result, chaotic region may form near the bucket center and extends outward under increasing modulation of rf voltage and/or rf phase. Application is made to those barrier buckets used in momentum mining at the Fermilab Recycler Ring.
Date: April 1, 2005
Creator: Ng, K. Y.
System: The UNT Digital Library
Intrabeam scattering formulas for fast numerical evaluation (open access)

Intrabeam scattering formulas for fast numerical evaluation

Expressions for small-angle multiple intrabeam scattering (IBS) emittance growth rates are normally expressed through integrals, which require a numeric evaluation at various locations of the accelerator lattice. In this paper, I demonstrate that the IBS growth rates can be presented in closed-form expressions with the help of the so-called symmetric elliptic integral. This integral can be evaluated numerically by a very efficient recursive method by employing the duplication theorem. Several examples of IBS rates for a smooth-lattice approximation, equal transverse temperatures and plasma temperature relaxation are given.
Date: March 1, 2005
Creator: Nagaitsev, Sergei
System: The UNT Digital Library
Enhanced Adhesion of EVA Laminates to Primed Glass Substrates Subjected to Damp-Heat Exposure (open access)

Enhanced Adhesion of EVA Laminates to Primed Glass Substrates Subjected to Damp-Heat Exposure

We investigated the effectiveness of glass-surface priming to promote enhanced adhesion of EVA laminates during damp-heat exposure at 85 C and 85% relative humidity. The primary objective was to develop advanced encapsulant formulations by incorporation of various primer formulations that exhibit improved adhesion during damp-heat exposure. Several primer formulations were identified that greatly enhanced the EVA adhesion strength, including to the extent that peeling could not be initiated, even for the laminates of the glass substrate/fast-cure EVA15295P/TPE backsheet (a Tedlar/polyester/EVA tri-laminate) that were exposed in a damp-heat test chamber for more than 750 h. The results show that a synergistic increase in the interfacial hydrophobicity, siloxane density, and cross-linking density are the key attributes to the improvement in the EVA adhesion strength.
Date: February 1, 2005
Creator: Pern, F. J. & Jorgensen, G. J.
System: The UNT Digital Library
Top physics results from CDF (open access)

Top physics results from CDF

The top quark is by far the most massive fundamental particle observed so far, and the study of its properties is interesting for several reasons ranging from its possible special role in electroweak symmetry breaking to its sensitivity to physics beyond the Standard Model. They present recent top physics results from CDF based on 160-320 pb{sup -1} of p{bar p} collision data at {radical}s = 1.96 TeV. The t{bar t} cross section and the top mass have been measured in different decay channels and using different methods. they have searched for evidence of single top production, setting upper limits on its production rate. Other results shown in this conference include studies of the polarization of W bosons from top decays, a search for charged Higgs decaying from top, and a search for additional heavy t' quarks.
Date: May 1, 2005
Creator: Gomez, Gervasio
System: The UNT Digital Library
A Measurement of the K0 charge radius and a CP violating asymmetry together with a search for CP violating e1 direct photon emission in the rare decay K(L) ---> pi+ pi- e+ e- (open access)

A Measurement of the K0 charge radius and a CP violating asymmetry together with a search for CP violating e1 direct photon emission in the rare decay K(L) ---> pi+ pi- e+ e-

Using the complete KTeV data set of 5241 candidate K{sub L} {yields} {pi}{sup +}{pi}{sup -}e{sup +}e{sup -} decays (including an estimated background of 204 {+-} 14 events), we have measured the coupling g{sub CR} = 0.163 {+-} 0.014 (stat) {+-} 0.023 (syst) of the CP conserving charge radius process and from it determined a K{sup 0} charge radius of <r{sub K{sup 0}}{sup 2}> = (-0.077 {+-} 0.007(stat) {+-} 0.011(syst))fm{sup 2}. We have also determined a first experimental upper limit of 0.04 (90% CL) for the ratio |g{sub E1}|/|g{sub M1}| of the coupling for the E1 direct photon emission process relative to the coupling for M1 direct photon emission process. We also report the measurement of |g{sub M1}| including its associated vector form factor |{bar g}{sub M1}|1 + a{sub 1}/a{sub 2}/(M{sub p}{sup 2} - M{sub K}{sup 2})+2M{sub K}E{sub {gamma}*} where |{bar g}{sub M1}| = 1.11 {+-} 0.12 (stat) {+-} 0.08 (syst) and a{sub 1}/a{sub 2} = (-0.744 {+-} 0.027 (stat) {+-} 0.032 (syst)) GeV{sup 2}/c{sup 2}. In addition, a measurement of the manifestly CP violating asymmetry of magnitude (13.6 {+-} 1.4 (stat) {+-} 1.5 (syst))% in the CP and T odd angle {phi} between the decay planes of the e{sup +}e{sup …
Date: August 1, 2005
Creator: Abouzaid, E.; Arenton, M.; Barker, A. R.; Bellantoni, L.; Bellavance, A.; Blucher, E. et al.
System: The UNT Digital Library
Nature's Greatest Puzzles (open access)

Nature's Greatest Puzzles

It is a pleasure to be part of the SLAC Summer Institute again, not simply because it is one of the great traditions in our field, but because this is a moment of great promise for particle physics. I look forward to exploring many opportunities with you over the course of our two weeks together. My first task in talking about Nature's Greatest Puzzles, the title of this year's Summer Institute, is to deconstruct the premise a little bit.
Date: February 1, 2005
Creator: Quigg, Chris
System: The UNT Digital Library
Absolute calibration of the Auger fluorescence detectors (open access)

Absolute calibration of the Auger fluorescence detectors

Absolute calibration of the Pierre Auger Observatory fluorescence detectors uses a light source at the telescope aperture. The technique accounts for the combined effects of all detector components in a single measurement. The calibrated 2.5 m diameter light source fills the aperture, providing uniform illumination to each pixel. The known flux from the light source and the response of the acquisition system give the required calibration for each pixel. In the lab, light source uniformity is studied using CCD images and the intensity is measured relative to NIST-calibrated photodiodes. Overall uncertainties are presently 12%, and are dominated by systematics.
Date: July 1, 2005
Creator: Bauleo, P.; Brack, J.; Garrard, L.; Harton, J.; Knapik, R.; Meyhandan, R. et al.
System: The UNT Digital Library
Simulations of an acceleration scheme for producing high intensity and low emittance antiproton beam for Fermilab collider operation (open access)

Simulations of an acceleration scheme for producing high intensity and low emittance antiproton beam for Fermilab collider operation

During Fermilab collider operation, the Main Injector (MI) provides high intensity and low emittance proton and antiproton beams for the Tevatron. The present coalescing scheme for antiprotons in the Main Injector yields about a factor of two increase in the longitudinal emittance and a factor of 5% to 20% decrease in intensity before injection to the Tevatron. In order to maximize the integrated luminosity delivered to the collider experiments, it is important to minimize the emittance growth and maximize the intensity of the MI beam. To this end, a new scheme using a combination of 2.5 MHz and 53 MHz accelerations has been developed and tested. This paper describes the full simulation of the new acceleration scheme, taking account of space charge, 2.5 MHz and 53 MHz beam loading, and the effect of residual 53 MHz rf voltage during 2.5 MHz acceleration and rf manipulations. The simulations show the longitudinal emittance growth at the 10% level with no beam loss. The experimental test of the new scheme is reported in another PAC05 paper.
Date: May 1, 2005
Creator: Wu, Vincent; Bhat, C. M. & MacLachlan, J. A.
System: The UNT Digital Library
Fermilab Recycler damper requirements and design (open access)

Fermilab Recycler damper requirements and design

The design of transverse dampers for the Fermilab Recycler storage ring is described. An observed instability and analysis of subsequent measurements where used to identify the requirements. The digital approach being implemented is presented.
Date: May 1, 2005
Creator: Crisp, J.; Hu, M.; Tupikov, V. & /Fermilab
System: The UNT Digital Library
Search for a strongly decaying neutral charmed pentaquark (open access)

Search for a strongly decaying neutral charmed pentaquark

We present a search for a charmed pentaquark decaying strongly to D{sup (*)}-p. Finding no evidence for such a state, we set limits on the cross section times branching ratio relative to D*{sup -} and D{sup -} under particular assumptions about the production mechanism.
Date: June 1, 2005
Creator: Link, J. M.; Yager, P. M.; /UC, Davis; Anjos, J. C.; Bediaga, I.; Castromonte, C. et al.
System: The UNT Digital Library
Modeling heavy ion ionization loss in the MARS15 code (open access)

Modeling heavy ion ionization loss in the MARS15 code

The needs of various accelerator and space projects stimulated recent developments to the MARS Monte Carlo code. One of the essential parts of those is heavy ion ionization energy loss. This paper describes an implementation of several corrections to dE/dx in order to take into account the deviations from the Bethe theory at low and high energies as well as the effect of a finite nuclear size at ultrarelativistic energies. Special attention is paid to the transition energy region where the onset of the effect of a finite nuclear size is observed. Comparisons with experimental data and NIST data are presented.
Date: May 1, 2005
Creator: Rakhno, I. L.; Mokhov, N. V. & Striganov, S. I.
System: The UNT Digital Library
Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project: Data Analysis Overview; Preprint (open access)

Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project: Data Analysis Overview; Preprint

Paper for the 2005 National Hydrogen Association conference provides an overview of the U.S. Department of Energy's Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project.
Date: March 1, 2005
Creator: Welch, C.; Wipke, K.; Gronich, S. & Garbak, J.
System: The UNT Digital Library
The Improbability scale (open access)

The Improbability scale

The Improbability Scale (IS) is proposed as a way of communicating to the general public the improbability (and by implication, the probability) of events predicted as the result of scientific research. Through the use of the Improbability Scale, the public will be able to evaluate more easily the relative risks of predicted events and draw proper conclusions when asked to support governmental and public policy decisions arising from that research.
Date: March 1, 2005
Creator: Ritchie, David J.
System: The UNT Digital Library
Searches for non-SM Higgs at Tevatron (open access)

Searches for non-SM Higgs at Tevatron

We sent the non-standard model Higgs boson searches at both D0 and CDF experiments. We concentrate on three topics, reported by D0 and CDF recently: the searches for the minimal supersymmetric Higgs boson using p{bar p} {yields} hb{bar b} {yields} b{bar b}b{bar b} and p{bar p} {yields} hX {yields} {tau}{tau}X, and for long-lived doubly charged Higgs boson.
Date: May 1, 2005
Creator: Tomoto, Makoto
System: The UNT Digital Library
Measurement of the cross section for t anti-t production in p anti-p collisions using the kinematics of lepton + jets events (open access)

Measurement of the cross section for t anti-t production in p anti-p collisions using the kinematics of lepton + jets events

The authors present a measurement of the top pair production cross section in p{bar p} collisions at {radical}s = 1.96 TeV. We collect a data sample with an integrated luminosity of 194 {+-} 11 pb{sup -1} with the CDF II detector at the Fermilab Tevatron. We use an artificial neural network technique to discriminate between top pair production and background processes in a sample of 519 lepton + jets events, which have one isolated energetic charged lepton, large missing transverse energy and at least three energetic jets. We measure the top pair production cross section to be {sigma}{sub t{bar t}} = 6.6 {+-} 1.1 {+-} 1.5 pb, where the first uncertainty is statistical and the second is systematic.
Date: April 1, 2005
Creator: Acosta, D.; Adelman, J.; Affolder, Anthony A.; Akimoto, T.; Albrow, M. G.; Ambrose, D. et al.
System: The UNT Digital Library