FUTURE PLANS AT BNL: RHIC-II AND eRHIC. (open access)

FUTURE PLANS AT BNL: RHIC-II AND eRHIC.

The development of future facilities relevant to the study of deep inelastic scattering at BNL is described.
Date: April 16, 2007
Creator: ARONSON,S.
Object Type: Article
System: The UNT Digital Library
Demonstration of Key Elements of a Dual Phase Argon Detection System Suitable for Measurement of Coherent Neutrino-Nucleus Scattering (open access)

Demonstration of Key Elements of a Dual Phase Argon Detection System Suitable for Measurement of Coherent Neutrino-Nucleus Scattering

This feasibility study sought to demonstrate several necessary steps in a research program whose ultimate goal is to detect coherent scattering of reactor antineutrinos in dual-phase noble liquid detectors. By constructing and operating a Argon gas-phase drift and scintillation test-bed, the study confirmed important expectations about sensitivity of these detectors, and thereby met the goals set forth in our original proposal. This work has resulted in a successful Lab-Wide LDRD for design and deployment of a coherent scatter detector at a nuclear reactor, and strong interest by DOE Office of Science. In recent years, researchers at LLNL and elsewhere have converged on a design approach for a new generation of very low noise, low background particle detectors known as two-phase noble liquid/noble gas ionization detectors. This versatile class of detector can be used to detect coherent neutrino scattering-an as yet unmeasured prediction of the Standard Model of particle physics. Using the dual phase technology, our group would be the first to verify the existence of this process. Its (non)detection would (refute)validate central tenets of the Standard Model. The existence of this process is also important in astrophysics, where coherent neutrino scattering is assumed to play an important role in energy …
Date: April 16, 2007
Creator: Adam, B.; Celeste, W.; Christian, H.; Wolfgang, S. & Norman, M.
Object Type: Report
System: The UNT Digital Library
Design and Initial Tests of the Tracker-Converter ofthe Gamma-ray Large Area Space Telescope (open access)

Design and Initial Tests of the Tracker-Converter ofthe Gamma-ray Large Area Space Telescope

The Tracker subsystem of the Large Area Telescope (LAT) science instrument of the Gamma-ray Large Area Space Telescope (GLAST) mission has been completed and tested. It is the central detector subsystem of the LAT and serves both to convert an incident gamma-ray into an electron-positron pair and to track the pair in order to measure the gamma-ray direction. It also provides the principal trigger for the LAT. The Tracker uses silicon strip detectors, read out by custom electronics, to detect charged particles. The detectors and electronics are packaged, along with tungsten converter foils, in 16 modular, high-precision carbon-composite structures. It is the largest silicon-strip detector system ever built for launch into space, and its aggressive design emphasizes very low power consumption, passive cooling, low noise, high efficiency, minimal dead area, and a structure that is highly transparent to charged particles. The test program has demonstrated that the system meets or surpasses all of its performance specifications as well as environmental requirements. It is now installed in the completed LAT, which is being prepared for launch in early 2008.
Date: April 16, 2007
Creator: Atwood, W.B.; Bagagli, R.; Baldini, L.; Bellazzini, R.; Barbiellini, G.; Belli, F. et al.
Object Type: Article
System: The UNT Digital Library
Branching Fraction and Charge Asymmetry Measurements inB to J/psi pi pi Decays (open access)

Branching Fraction and Charge Asymmetry Measurements inB to J/psi pi pi Decays

The authors study the decays B{sup 0} {yields} J/{psi} {pi}{sup +}{pi}{sup -} and B{sup +} {yields} J/{psi} {pi}{sup +}{pi}{sup 0}, including intermediate resonances, using a sample of 382 million B{bar B} pairs recorded by the BABAR detector at the PEP-II e{sup +}e{sup -} B factory. They measure the branching fractions {Beta}(B{sup 0} {yields} J/{psi} {rho}{sup 0}) = (2.7 {+-} 0.3 {+-} 0.17) x 10{sup -5} and {Beta}(B{sup +} {yields} J/{psi} {rho}{sup +}) = (5.0 {+-} 0.7 {+-} 0.31) x 10{sup -5}. The authors also set the following upper limits at the 90% confidence level: {Beta}(B{sup 0} {yields} J/{psi} {pi}{sup +}{pi}{sup -} non-resonant) < 1.2 x 10{sup -5}, {Beta}(B{sup 0} {yields} J/{psi} f{sub 2}) < 4.6 x 10{sup -6}, and {Beta}(B{sup +} {yields} J/{psi} {pi}{sup +}{pi}{sup 0} non-resonant) < 4.4 x 10{sup -6}. They measure the charge asymmetry in charged B decays to J/{psi} {rho} to be -0.11 {+-} 0.12 {+-} 0.08.
Date: April 16, 2007
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Karyotakis, Y.; Lees, J. P.; Poireau, V. et al.
Object Type: Article
System: The UNT Digital Library
A Study of Emittance Measurement at the ILC (open access)

A Study of Emittance Measurement at the ILC

The measurement of the International Linear Collider (ILC) emittance in the ILC beam delivery system (BDS) is simulated. Estimates of statistical and machine-related errors are discussed and the implications for related diagnostics R&D are inferred. A simulation of the extraction of the laser-wire Compton signal is also presented.
Date: April 16, 2007
Creator: Blair, G. A.; Agapov, I. V.; Carter, J.; Deacon, L.; Angal-Kalinin, D. A. K.; Jenner, L. J. et al.
Object Type: Article
System: The UNT Digital Library
Design of the ILC Prototype FONT4 Digital Intra-Train Beam-Based Feedback System (open access)

Design of the ILC Prototype FONT4 Digital Intra-Train Beam-Based Feedback System

We present the design of the FONT4 digital intra-train beam position feedback system prototype and preliminary results of initial beam tests at the Accelerator Test Facility (ATF) at KEK. The feedback system incorporates a fast analogue beam position monitor (BPM) front-end signal processor, a digital feedback board, and a kicker driver amplifier. The short bunchtrain, comprising 3 electron bunches separated by c. 150ns, in the ATF extraction line was used to test components of the prototype feedback system.
Date: April 16, 2007
Creator: Burrows, P.; /Queen Mary, U. of London; Christian, G. B.; Hartin, A. F.; Dabiri Khah, H.; White, G. R. et al.
Object Type: Article
System: The UNT Digital Library
Performance of the FONT3 Fast Analogue Intra-Train Beam-Based Feedback System at ATF (open access)

Performance of the FONT3 Fast Analogue Intra-Train Beam-Based Feedback System at ATF

We report results of beam tests of the FONT3 intra-train position feedback system prototype at the Accelerator Test Facility (ATF) at KEK. The feedback system incorporates a novel beam position monitor (BPM) processor with latency below 5 nanoseconds, and a kicker driver amplifier with similar low latency. The 56 nanosecond-long bunchtrain in the ATF extraction line was used to test the prototype feedback system. The achieved latency of 23ns provides a demonstration of intra-train feedback on very short timescales relevant even for the CLIC Linear Collider design.
Date: April 16, 2007
Creator: Burrows, P.; /Queen Mary, U. of London; Christian, G. B.; Hartin, A. F.; Dabiri Khah, H.; White, G. R. et al.
Object Type: Article
System: The UNT Digital Library
WEATHER RELATED VARIABILITY OF CALORIMETERY PERFORMANCE IN A POORLY CONTROLLED ENVIRONMENT (open access)

WEATHER RELATED VARIABILITY OF CALORIMETERY PERFORMANCE IN A POORLY CONTROLLED ENVIRONMENT

Four Antech airbath calorimeters at the Hanford site were studied for three summers and two winters in a location not well-shielded from outside temperature changes. All calorimeters showed significant increases in variability of standard measurements during hot weather. The increased variability is postulated to be due to a low setting of the Peltier cold face temperature, which doesn't allow the instrument to drain heat fast enough in a hot environment. A higher setting of the Peltier cold face might lead to better performance in environments subjected to a broad range of temperatures.
Date: April 16, 2007
Creator: Cameron, M. A. & Spellman, J. D.
Object Type: Article
System: The UNT Digital Library
WEATHER RELATED VARIABILITY OF CALORIMETERY PERFORMANCE IN A POORLY CONTROLLED ENVIRONMENT (open access)

WEATHER RELATED VARIABILITY OF CALORIMETERY PERFORMANCE IN A POORLY CONTROLLED ENVIRONMENT

Four Antech airbath calorimeters at the Hanford site were studied for three summers and two winters in a location not well-shielded from outside temperature changes. Calorimeters showed significant increases in variability of standard measurements during hot weather. The increased variability is postulated to be due to a low setting of the Peltier cold face temperature, which doesn't allow the instrument to drain heat fast enough in a hot environment. A higher setting of the Peltier cold face might lead to better performance in environments subjected to a broad range of temperatures.
Date: April 16, 2007
Creator: Cameron, M. A. & Spellman, J. D.
Object Type: Article
System: The UNT Digital Library
Effect of pre-equilibrium spin distribution on neutron induced 150Sm cross sections (open access)

Effect of pre-equilibrium spin distribution on neutron induced 150Sm cross sections

Prompt {gamma}-ray production cross section measurements were made as a function of incident neutron energy (En = 1 to 35 MeV) on an enriched (95.6%) {sup 150}Sm sample. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the Los Alamos Neutron Science Center (LANSCE) facility. The prompt-reaction {gamma} rays were detected with the large-scale Compton-suppressed Germanium Array for Neutron Induced Excitations (GEANIE). Above E{sub n} {approx} 8 MeV the pre-equilibrium reaction process dominates the inelastic reaction. The spin distribution transferred in pre-equilibrium neutron-induced reactions was calculated using the quantum mechanical theory of Feshbach, Kerman, and Koonin (FKK). These preequilibrium spin distributions were incorporated into the Hauser-Feshbach statistical reaction code GNASH and the {gamma}-ray production cross sections were calculated and compared with experimental data. Neutron inelastic scattering populates 150Sm excited states either by (1) forming the compound nucleus {sup 151}Sm* and decaying by neutron emission, or (2) by the incoming neutron transferring energy to create a particle-hole pair, and thus initiating the pre-equilibrium process. These two processes produce rather different spin distributions: the momentum transfer via the pre-equilibrium process tends to be smaller than in the compound reaction. This difference in the spin population has …
Date: April 16, 2007
Creator: Dashdorj, D.; Kawano, T.; Mitchell, G. E.; Becker, J. A.; Agvaanluvsan, U.; Chadwick, M. et al.
Object Type: Article
System: The UNT Digital Library
Direct Extraction of One-loop Integral Coefficients (open access)

Direct Extraction of One-loop Integral Coefficients

We present a general procedure for obtaining the coefficients of the scalar bubble and triangle integral functions of one-loop amplitudes. Coefficients are extracted by considering two-particle and triple unitarity cuts of the corresponding bubble and triangle integral functions. After choosing a specific parameterization of the cut loop momentum we can uniquely identify the coefficients of the desired integral functions simply by examining the behavior of the cut integrand as the unconstrained parameters of the cut loop momentum approach infinity. In this way we can produce compact forms for scalar integral coefficients. Applications of this method are presented for both QCD and electroweak processes, including an alternative form for the recently computed three-mass triangle coefficient in the six-photon amplitude A{sub 6}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup -}, 6{sup +}). The direct nature of this extraction procedure allows for a very straightforward automation of the procedure.
Date: April 16, 2007
Creator: Forde, Darren
Object Type: Article
System: The UNT Digital Library
In situ Investigation of the Silver-CTAB system (open access)

In situ Investigation of the Silver-CTAB system

Recent research has shown that biologically inspired approaches to materials synthesis and self-assembly, hold promise of unprecedented atomic level control of structure and interfaces. In particular, the use of organic molecules to control the production of inorganic technological materials has the potential for controlling grain structure to enhance material strength; controlling facet expression for enhanced catalytic activity; and controlling the shape of nanostructured materials to optimize optical, electrical and magnetic properties. In this work, we use organic molecules to modify silver crystal shapes towards understanding the metal-organic interactions that lead to nanoparticle shape control. Using in situ electrochemical AFM (EC-AFM) as an in situ probe, we study the influence of a cationic surfactant cetyltrimethylamminobromide (CTAB) on Ag growth during electrochemical deposition on Ag(100). The results show that the organic surfactant promotes the growth of steps on the (100) surface and changes the surface evolution from island nucleation to step flow growth. Overall, this leads to a smoother, faster growing (100) surface, which may promote plate-formation.
Date: April 16, 2007
Creator: Gray, J J; Orme, C A; Du, D & Srolovitz, D
Object Type: Article
System: The UNT Digital Library
Strings on AdS2 and the high-energy limit of noncritical M-theory (open access)

Strings on AdS2 and the high-energy limit of noncritical M-theory

Abstract. Noncritical M-theory in 2+1 dimensions has been defined as a double-scaling limit of a nonrelativistic Fermi liquid on a flat two-dimensional plane. Here we study this noncritical M-theory in the limit of high energies, analogous to the alpha' --> infinity limit of string theory. In the related case of two-dimensional Type 0A strings, it has been argued that the conformal alpha' --> infinity limit leads to AdS_2 with a propagating fermion whose mass is set by the value of the RR flux. Here we provide evidence that in the high-energy limit, the natural ground state of noncritical M-theory similarly describes the AdS_2 x S1 spacetime, with a massless propagating fermion. We argue that the spacetime effective theory in this background is captured by a topological higher-spin extension of conformal Chern-Simons gravity in 2+1 dimensions, consistently coupled to a massless Dirac field. Intriguingly, the two-dimensional plane populated by the original nonrelativistic fermions is essentially the twistor space associated with the symmetry group of the AdS_2 x S1 spacetime; thus, at least in the high-energy limit, noncritical M-theory can be nonperturbatively described as a"Fermi liquid on twistor space.''
Date: April 16, 2007
Creator: Horava, Petr; Horava, Petr & Keeler, Cynthia A.
Object Type: Article
System: The UNT Digital Library
GRBs from the First Stars (open access)

GRBs from the First Stars

We present an estimate of the Gamma Ray Bursts which should be expected from metal-free, elusive first generation of stars known as PopulationIII (PopIII). We derive the GRB rate from these stars from the Stellar Formation Rate obtained in several Reionization scenarios available in the literature. In all of the analyzed models we find that GRBs from PopIII are subdominant with respect to the ''standard'' (PopII) ones up to z {approx} 10.
Date: April 16, 2007
Creator: Iocco, Fabio & /Naples U. /KIPAC, Menlo Park
Object Type: Article
System: The UNT Digital Library
Mitigation of Emittance Dilution Due to Transverse Mode Coupling in the L-Band Linacs of the ILC (open access)

Mitigation of Emittance Dilution Due to Transverse Mode Coupling in the L-Band Linacs of the ILC

The main L-band linacs of the ILC accelerate 2820 bunches from a center of mass of 10 GeV to 500 GeV (and in the proposed later upgrade, to 1 TeV). The emittance of the vertical plane is approximately 400 times less than that of the horizontal plane. Provided the vertical and horizontal mode dipole frequencies are degenerate then the motion in each plane is not coupled. However, in reality the frequency degeneracy is split and the eigenmodes are shifted due to inevitable manufacturing errors introduced in fabricating 20,000 cavities. This gives rise to a transverse coupling in the horizontal-vertical motion and can readily lead to a dilution in the emittance in the vertical plane. We investigate means to ameliorate this effect dilution by splitting the horizontal-vertical tune of the lattice.
Date: April 16, 2007
Creator: Jones, R. M. & Miller, R. H.
Object Type: Article
System: The UNT Digital Library
Single Spin Asymmetries of Identified Hadrons in P +P at Square Root S = 62.4 and 200 Gev. (open access)

Single Spin Asymmetries of Identified Hadrons in P +P at Square Root S = 62.4 and 200 Gev.

Measurements of x{sub F}-dependent single spin asymmetries of identified charged hadrons, {pi}{sup {+-}}, K{sup {+-}}, p, and {bar p}, from transversely polarized proton collisions at {radical}s = 200 and 62.4 GeV at RHIC are presented. The energy and flavor dependent asymmetry measurements bring new insight into the fundamental mechanisms of transverse spin asymmetries and Quantum Chromodynamical description of hadronic structure.
Date: April 16, 2007
Creator: Lee, J. H.; Videbaek, F. & Collaboration), (for the Brahms
Object Type: Article
System: The UNT Digital Library
Initial Search for 9-keV XTR from a 28-GeV Beam at SPPS (open access)

Initial Search for 9-keV XTR from a 28-GeV Beam at SPPS

The potential to use x-ray transition radiation (XTR) as a beam diagnostic and coherent XTR (CXTR) as a gain diagnostic in an x-ray FEL was proposed previously. At that time we noted that the unique configuration of the SLAC Sub-picosecond Photon Source (SPPS) with its known x-ray wiggler source, a special three-element x-ray monochromator, x-ray transport line, and experimental end station with x-ray detectors made it an ideal location for an XTR feasibility experiment. Estimates of the XTR compared to the SPPS source strength were done, and initial experiments were performed in September 2005. Complementary measurements on optical transition radiation (OTR) far-field images from a 7-GeV beam are also discussed.
Date: April 16, 2007
Creator: Lumpkin, A. H.; Hastings, J. B. & Rule, D.W.
Object Type: Article
System: The UNT Digital Library
Identifying Dark Matter Burners in the Galactic Center (open access)

Identifying Dark Matter Burners in the Galactic Center

If the supermassive black hole (SMBH) at the center of our Galaxy grew adiabatically, then a dense ''spike'' of dark matter is expected to have formed around it. Assuming that dark matter is composed primarily of weakly interacting massive particles (WIMPs), a star orbiting close enough to the SMBH can capture WIMPs at an extremely high rate. The stellar luminosity due to annihilation of captured WIMPs in the stellar core may be comparable to or even exceed the luminosity of the star due to thermonuclear burning. The model thus predicts the existence of unusual stars, i.e. ''WIMP burners'', in the vicinity of an adiabatically grown SMBH. We find that the most efficient WIMP burners are stars with degenerate electron cores, e.g. white dwarfs (WD) or degenerate cores with envelopes. If found, such stars would provide evidence for the existence of particle dark matter and could possibly be used to establish its density profile. In our previous paper we computed the luminosity from WIMP burning for a range of dark matter spike density profiles, degenerate core masses, and distances from the SMBH. Here we compare our results with the observed stars closest to the Galactic center and find that they could …
Date: April 16, 2007
Creator: Moskalenko, Igor V. & Wai, Lawrence L.
Object Type: Report
System: The UNT Digital Library
The Use Of Scanning Probe Microscopy To Investigate Crystal-Fluid Interfaces (open access)

The Use Of Scanning Probe Microscopy To Investigate Crystal-Fluid Interfaces

Over the past decade there has been a natural drive to extend the investigation of dynamic surfaces in fluid environments to higher resolution characterization tools. Various aspects of solution crystal growth have been directly visualized for the first time. These include island nucleation and growth using transmission electron microscopy and scanning tunneling microscopy; elemental step motion using scanning probe microscopy; and the time evolution of interfacial atomic structure using various diffraction techniques. In this lecture we will discuss the use of one such in situ method, scanning probe microscopy, as a means of measuring surface dynamics during crystal growth and dissolution. We will cover both practical aspects of imaging such as environmental control, fluid flow, and electrochemical manipulation, as well as the types of physical measurements that can be made. Measurements such as step motion, critical lengths, nucleation density, and step fluctuations, will be put in context of the information they provide about mechanistic processes at surfaces using examples from metal and mineral crystal growth.
Date: April 16, 2007
Creator: Orme, C. A. & Giocondi, J. L.
Object Type: Book
System: The UNT Digital Library
Initial State Radiation Studies at BaBar (open access)

Initial State Radiation Studies at BaBar

We present results from BABAR on events containing a hard radiated photon from the e{sup +}e{sup -} initial state and several exclusive final states. For the {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} final state the cross section is measured for center-of-mass energies from 0.6 to 4.5 GeV. Resonant structures are studied and confirmed to be dominated by the a{sub 1}(1260){pi}, with a contribution from f{sub 2}(1270){rho}(770). Similar studies are shown for {pi}{sup +}{pi}{sup -}K{sup +}K{sup -} and K{sup +}K{sup -}K{sup +}K{sup -} from their respective thresholds up to 4.5 GeV. From the {pi}{sup +}{pi}{sup -}{pi}{sup 0} final state the products of the branching fractions of the {omega} and {phi} mesons have been obtained and the cross section is measured from 1.05 to 3.00 GeV. In addition the J/{psi} branching fractions to all four final states have been measured.
Date: April 16, 2007
Creator: Petzold, A.
Object Type: Article
System: The UNT Digital Library
Making Amines Strong Bases: Thermodynamic Stabilization ofProtonated Guests in a Highly-Charged Supramolecular Host (open access)

Making Amines Strong Bases: Thermodynamic Stabilization ofProtonated Guests in a Highly-Charged Supramolecular Host

A highly-charged, cavity-containing supramolecular assembly formed by metal-ligand interactions acts as a host to dramatically shift the effective basicity of encapsulated protonated amine guests. The scope of encapsulated protonated amine and phosphine guests shows size selectivity consistent with a constrained binding environment. Protonation of the encapsulated guests is confirmed by {sup 31}P NMR studies, mass spectrometry studies, and the pH dependence of guest encapsulation. Rates of guest self-exchange were measured using the Selective Inversion Recovery method and were found to correlate with the size rather than the basicity of the guests. The activation parameters for guest self-exchange are consistent with the established mechanism for guest exchange. The binding constants of the protonated amines are then used to calculate the effective basicity of the encapsulated amines. Depending on the nature of the guest, shifts in the effective basicities of the encapsulated amines of up to 4.5 pK{sub a} units are observed, signifying a substantial stabilization of the protonated form of the guest molecule and effectively making phosphines and amines strong bases.
Date: April 16, 2007
Creator: Pluth, Michael D.; Bergman, Robert G. & Raymond, Kenneth N.
Object Type: Article
System: The UNT Digital Library
2\beta + \gamma from B^0 to D^\mp K^0 \pi^\pm Decays at BaBar: aSimulation Study (open access)

2\beta + \gamma from B^0 to D^\mp K^0 \pi^\pm Decays at BaBar: aSimulation Study

The authors present the results of a simulation study to perform the extraction of 2{beta} + {gamma} from B{sup 0} {yields} D{sup {-+}}K{sup 0}{pi}{sup {+-}} decays through a time-dependent Dalitz analysis of BaBar data.
Date: April 16, 2007
Creator: Polci, Francesco; Schune, Marie-Helene; Stocchi, Achille & /Orsay, LAL
Object Type: Article
System: The UNT Digital Library
Transverse Coherence Properties of the LCLS X-Ray Beam (open access)

Transverse Coherence Properties of the LCLS X-Ray Beam

Self-amplifying spontaneous radiation free-electron lasers, such as the LCLS or the European X-FEL, rely on the incoherent, spontaneous radiation as the seed for the amplifying process. Though this method overcomes the need for an external seed source one drawback is the incoherence of the effective seed signal. The FEL process allows for a natural growth of the coherence because the radiation phase information is spread out within the bunch due to slippage and diffraction of the radiation field. However, at short wavelengths this spreading is not sufficient to achieve complete coherence. In this presentation we report on the results of numerical simulations of the LCLS X-ray FEL. From the obtained radiation field distribution the coherence properties are extracted to help to characterize the FEL as a light source.
Date: April 16, 2007
Creator: Reiche, S.
Object Type: Article
System: The UNT Digital Library
Picosecond Soft-X-ray studies of Dense Plasma Regimes Progress Report (April 1, 2006 - March 31, 2007) (open access)

Picosecond Soft-X-ray studies of Dense Plasma Regimes Progress Report (April 1, 2006 - March 31, 2007)

Dense plasma diagnostics, soft x-ray laser interferometry, converging plasmas.
Date: April 16, 2007
Creator: Rocca, Jorge; Marconi, Mario; Shlyaptsev, Vyacheslav; Dunn, James; Moon, Stephen & Nilsen, Joseph
Object Type: Text
System: The UNT Digital Library