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18,935 Matching Results
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Top physics: measurement of the tt-bar production cross section in pp-bar collisions at s**(1/2) = 1.96 tev using dilepton event
We report a measurement of the t{bar t} production cross section using dilepton events with jets and missing transverse energy in p{bar p} collisions at a center-of-mass energy of 1.96 TeV. Using a 197 {+-} 12 pb{sup -1} data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the standard model and find good agreement. The combined result of the two techniques yields a t{bar t} production cross section of 7.0{sub -2.1}{sup +2.4}(stat){sub -1.1}{sup _1.6}(syst) {+-} 0.4(lum) pb.
Date:
October 14, 2004
Creator:
Acosta, D.
Object Type:
Report
System:
The UNT Digital Library
Top physics: search for anomalous kinematics in t anti-t dilepton events at cdf ii
We report on a search for anomalous kinematics of t{bar t} dilepton events in p{bar p} collisions at {radical}s = 1.96 TeV using 193 pb{sup -1} of data collected with the CDF II detector. We developed a new a priori technique designed to isolate the subset in a data sample revealing the largest deviation from standard model (SM) expectations and to quantify the significance of this departure. In the four-variable space considered, no particular subset shows a significant discrepancy and we find that the probability of obtaining a data sample less consistent with the SM than what is observed is 1.0-4.5%.
Date:
December 14, 2004
Creator:
Acosta, D.
Object Type:
Report
System:
The UNT Digital Library
Measurement of the cross section for prompt diphoton production in p anti-p collisions at s**(1/2) = 1.96-TeV
None
Date:
December 1, 2004
Creator:
Acosta, D.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M. G.; Ambrose, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the J/psi meson and b-hadron production cross sections in p anti-p collisions at s(NN)**(1/2) = 1960-GeV
We present a new measurement of the inclusive and differential production cross sections of J/{psi} mesons and b-hadrons in proton-antiproton collisions at {radical}s = 1960 GeV. The data correspond to an integrated luminosity of 39.7 pb{sup -1} collected by the CDF Run II detector. We find the integrated cross section for inclusive J/{psi} production for all transverse momenta from 0 to 20 GeV/c in the rapidity range |y| < 0.6 to be 4.08 {+-} 0.02(stat){sub -0.33}{sup +0.36}(syst) {mu}b. We separate the fraction of J/{psi} events from the decay of the long-lived b-hadrons using the lifetime distribution in all events with p{sub T} (J/{psi}) > 1.25 GeV/c. We find the total cross section for b-hadrons, including both hadrons and anti-hadrons, decaying to J/{psi} with transverse momenta greater than 1.25 GeV/c in the rapidity range |y(J/{psi})| < 0.6, is 0.330 {+-} 0.005(stat){sub -0.033}{sup +0.036}(syst) {mu}b. Using a Monte Carlo simulation of the decay kinematics of b-hadrons to all final states containing a J/{psi}, we extract the first measurement of the total single b-hadron cross section down to zero transverse momentum at {radical}s = 1960 GeV. We find the total single b-hadron cross section integrated over all transverse momenta for b-hadrons in the …
Date:
December 1, 2004
Creator:
Acosta, D.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M. G.; Ambrose, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for anomalous kinematics in t anti-t dilepton events at CDF II
None
Date:
December 1, 2004
Creator:
Acosta, D.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M. G.; Ambrose, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of charged particle multiplicities in gluon and quark jets in proton anti-proton collisions at s**(1/2) = 1.8-TeV
The authors report the first model independent measurement of charged particle multiplicities in quark and gluon jets, N{sub q} and N{sub g}, produced at the Tevatron in p{bar p} collisions with center-of-mass energy 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies 41 and 53 GeV by counting charged particle tracks in cones with opening angle of {theta}{sub c} = 0.28, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness Q = E{sub jet}{theta}{sub c} varies in the range from 12 GeV to 25 GeV. At Q = 19 GeV, the ratio of multiplicities r = N{sub g}/N{sub q} is found to be 1.64 {+-} 0.17, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with re-summed perturbative QCD calculations.
Date:
July 1, 2004
Creator:
Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the W boson polarization in top decay at CDF at s**(1/2) = 1.8-TeV
The polarization of the W boson in t {yields} Wb decay is unambiguously predicted by the Standard Model of electroweak interactions and is a powerful test of our understanding of the tbW vertex. We measure this polarization from the invariant mass of the b quark from t {yields} Wb and the lepton from W {yields} {ell}{nu} whose momenta measure the W decay angle and direction of motion, respectively. In this paper we present a measurement of the decay rate (f{sub V + A}) of the W produced from the decay of the top quark in the hypothesis of V + A structure of the tWb vertex. We find no evidence for the non-standard V + A vertex and set a limit on f{sub V + A} < 0.80 at 95% confidence level. By combining this result with a complementary observable in the same data, we assign a limit on f{sub V + A} < 0.61 at 95% CL. This corresponds to a constraint on the right-handed helicity component of the W polarization of f{sub +} < 0.18 at 95% CL. This limit is the first significant direct constraint on f{sub V + A} in top decay.
Date:
November 1, 2004
Creator:
Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurements of bottom anti-bottom azimuthal production correlations in proton - anti-proton collisions at s**(1/2) = 1.8-TeV
The authors have measured the azimuthal angular correlation of b{bar b} production, using 86.5 pb{sup -1} of data collected by Collider Detector at Fermilab (CDF) in p{bar p} collisions at {radical}s = 1.8 TeV during 1994-1995. In high-energy p{bar p} collisions, such as at the Tevatron, b{bar b} production can be schematically categorized into three mechanisms. The leading-order (LO) process is ''flavor creation'', where both b and {bar b} quarks substantially participate in the hard scattering and result in a distinct back-to-back signal in final state. The ''flavor excitation'' and the ''gluon splitting'' processes, which appear at next-leading-order (NLO), are known to make a comparable contribution to total b{bar b} cross section, while providing very different opening angle distributions from the LO process. An azimuthal opening angle between bottom and anti-bottom, {Delta}{phi}, has been used for the correlation measurement to probe the interaction creating b{bar b} pairs. The {Delta}{phi} distribution has been obtained from two different methods. one method measures the {Delta}{phi} between bottom hadrons using events with two reconstructed secondary vertex tags. The other method uses b{bar b} {yields} (J/{psi}X)({ell}X') events, where the charged lepton ({ell}) is an electron (e) or a muon ({mu}), to measure {Delta}{phi} between bottom …
Date:
December 1, 2004
Creator:
Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
Object Type:
Article
System:
The UNT Digital Library
The Rheology of Concentrated Suspensions
Research program on the rheological properties of flowing suspensions. The primary purpose of the research supported by this grant was to study the flow characteristics of concentrated suspensions of non-colloidal solid particles and thereby construct a comprehensive and robust theoretical framework for modeling such systems quantitatively. At first glance, this seemed like a modest goal, not difficult to achieve, given that such suspensions were viewed simply as Newtonian fluids with an effective viscosity equal to the product of the viscosity of the suspending fluid times a function of the particle volume fraction. But thanks to the research findings of the Principal Investigator and of his Associates, made possible by the steady and continuous support which the PI received from the DOE Office of Basic Energy Sciences, the subject is now seen to be more complicated and therefore much more interesting in that concentrated suspensions have been shown to exhibit fascinating and unique rheological properties of their own that have no counterpart in flowing Newtonian or even non-Newtonian (polymeric) fluids. In fact, it is generally acknowledged that, as the result of these investigations for which the PI received the 2001 National Medal of Science, our understanding of how suspensions behave under …
Date:
September 7, 2004
Creator:
Acrivos, Andreas
Object Type:
Report
System:
The UNT Digital Library
Solvation!
This dissertation consists of two closely related parts: theory development and coding of correlation effects in a model potential for solvation, and study of solvent effects on chemical reactions and processes. The effective fragment potential (EFP) method has been re-parameterized, using density functional theory (DFT), more specifically, the B3LYP functional. The DFT based EFP method includes short-range correlation effects; hence it is a first step in incorporating the treatment of correlation in the EFP solvation model. In addition, the gradient of the charge penetration term in the EFP model was derived and coded. The new method has been implemented in the electronic structure code GAMESS and is in use. Formulas for the dynamic dipole polarizability, C{sub 6} dispersion coefficient and dispersion energy were derived and coded as a part of a treatment of the dispersion interactions in the general solvation model, EFP2. Preliminary results are in good agreement with experimental and other theoretical data. The DFT based EFP (EFP1/DFT) method was used in the study of microsolvation effects on the S{sub N}2 substitution reaction, between chloride and methyl bromide. Changes in the central barrier, for several lowest lying isomers of the systems with one, two, three and four waters, were …
Date:
December 19, 2004
Creator:
Adamovic, Ivana
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors
The underlying hypothesis of this project was that optimal alpha emitter-based radioimmunotherapy (RAIT) could be achieved by pairing the physical half-life of the radioisotope to the biological half-life of the targeting vehicle. The project had two specific aims. The first aim was to create and optimize the therapeutic efficacy of 211At-SAPS-C6.5 diabody conjugates. The second aim was to develop bispecific-targeting strategies that increase the specificity and efficacy of alpha-emitter-based RAIT. In the performance of the first aim, we created 211At-SAPS-C6.5 diabody conjugates that specifically targeted the HER2 tumor associated antigen. In evaluating these immunoconjugates we determined that they were capable of efficient tumor targeting and therapeutic efficacy of established human tumor xenografts growing in immunodeficient mice. We also determined that therapeutic doses were associated with late renal toxicity, likely due to the role of the kidneys in the systemic elimination o f these agents. We are currently performing more studies focused on better understanding the observed toxicity. In the second aim, we successfully generated bispecific single-chain Fv (bs-scFv) molecules that co-targeted HER2 and HER3 or HER2 and HER4. The in vitro kinetics and in vivo tumor-targeting properties of these molecules were evaluated. These studies revealed that the bs-scFv molecules selectively …
Date:
November 24, 2004
Creator:
Adams, Gregory P.
Object Type:
Report
System:
The UNT Digital Library
Pulse length dependence of laser conditioning and bulk damage in KD2PO4
An experimental technique has been developed to measure the damage density {rho}({phi}) variation with fluence from scatter maps of bulk damage sites in plates of KD{sub 2}PO{sub 4} (DKDP) crystals combined with calibrated images of the damaging beam's spatial profile. Unconditioned bulk damage in tripler-cut DKDP crystals has been studied using 351 nm (3 {omega}) light at pulse lengths of 0.055, 0.091, 0.30, 0.86, 2.6, and 10 ns. It is found that there is less scatter due to damage at fixed fluence for longer pulse lengths. The results also show that for all the pulse lengths the scatter due to damage is a strong function of the damaging fluence. It is determined that the pulse length scaling for bulk damage scatter in unconditioned DKDP material varies as {tau}{sup 0.24 {+-} 0.05} over two orders of magnitude of pulse lengths. The effectiveness of 3 {omega} laser conditioning at pulse lengths of 0.055, 0.096, 0.30, 0.86, 3.5, and 23 ns is analyzed in term of damage density {rho}({phi}) at 3 {omega}, 2.6 ns. The 860 ps conditioning to a peak irradiance of 7 GW/cm{sup 2} had the best performance under 3 {omega}, 2.6 ns testing. It is shown that the optimal conditioning …
Date:
November 10, 2004
Creator:
Adams, J. J.; Weiland, T. L.; Stanley, J. R.; Sell, W. D.; Luthi, R. L.; Vickers, J. L. et al.
Object Type:
Article
System:
The UNT Digital Library
Production of e+e- Pairs Accompanied by Nuclear Dissociation in Ultra-peripheral Heavy Ion Collisions
We present the first data on e{sup +}e{sup -} pair production accompanied by nuclear breakup in ultra-peripheral gold-gold collisions at a center of mass energy of 200 GeV per nucleon pair. The nuclear breakup requirement selects events at small impact parameters, where higher-order corrections to the pair production cross section should be enhanced. We compare the pair kinematic distributions with two calculations: one based on the equivalent photon approximation, and the other using lowest-order quantum electrodynamics (QED); the latter includes the photon virtuality. The cross section, pair mass, rapidity and angular distributions are in good agreement with both calculations. The pair transverse momentum, p{sub T}, spectrum agrees with the QED calculation, but not with the equivalent photon approach. We set limits on higher-order contributions to the cross section. The e{sup +} and e{sup -} p{sub T} spectra are similar, with no evidence for interference effects due to higher-order diagrams.
Date:
April 7, 2004
Creator:
Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Allgower, C.; Amonett, J. et al.
Object Type:
Article
System:
The UNT Digital Library
{phi} meson production in Au + Au and p + p collisions at {radical}s{sub NN}=200 GeV
We report the STAR measurement of {psi} meson production in Au + Au and p + p collisions at {radical}s{sub NN} = 200 GeV. Using the event mixing technique, the {psi} spectra and yields are obtained at midrapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the {psi} transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential while the p+p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that {psi} production in central Au+Au collisions is suppressed relative to peripheral collisions when scaled by the number of binary collisions (<N{sub bin}>). The systematics of <p{sub T}> versus centrality and the constant {psi}/K{sup -} ratio versus beam species, centrality, and collision energy rule out kaon coalescence as the dominant mechanism for {psi} production.
Date:
June 1, 2004
Creator:
Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type:
Article
System:
The UNT Digital Library
Photon and neutral pion production in Au+Au collisions at {radical}s{sub NN} = 130 GeV
We report the first inclusive photon measurements about mid-rapidity (|y| < 0.5) from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV at RHIC. Photon pair conversions were reconstructed from electron and positron tracks measured with the Time Projection Chamber (TPC) of the STAR experiment. With this method, an energy resolution of {Delta}E/E {approx} 2% at 0.5 GeV has been achieved. Reconstructed photons have also been used to measure the transverse momentum (p{sub t}) spectra of {pi}{sup 0} mesons about mid-rapidity (|y| < 1) via the {pi}{sup 0} {yields} {gamma}{gamma} decay channel. The fractional contribution of the {pi}{sup 0} {yields} {gamma}{gamma} decay to the inclusive photon spectrum decreases by 20% {+-} 5% between p{sub t} = 1.65 GeV/c and p{sub t} = 2.4 GeV/c in the most central events, indicating that relative to {pi}{sup 0} {yields} {gamma}{gamma} decay the contribution of other photon sources is substantially increasing.
Date:
January 8, 2004
Creator:
Adams, J.; Adler, C.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type:
Article
System:
The UNT Digital Library
Azimuthal anisotropy in Au+Au collisions at {radical}s{sub NN} = 200 GeV
The results from the STAR Collaboration on directed flow (v{sub 1}), elliptic flow (v{sub 2}), and the fourth harmonic (v{sub 4}) in the anisotropic azimuthal distribution of particles from Au+Au collisions at {radical}s{sub NN} = 200 GeV are summarized and compared with results from other experiments and theoretical models. Results for identified particles are presented and fit with a Blast Wave model. For v{sub 2}, scaling with the number of constituent quarks and parton coalescence is discussed. For v{sub 4}, scaling with v{sub 22} and quark coalescence predictions for higher harmonic flow is discussed. The different anisotropic flow analysis methods are compared and nonflow effects are extracted from the data. For v{sub 2}, scaling with the number of constituent quarks and parton coalescence are discussed. For v{sub 2}{sup 2} and quark coalescence are discussed.
Date:
September 29, 2004
Creator:
Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Akhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Centrality and pseudorapidity dependence of charged hadron production at intermediate p{sub T} in Au+Au collisions at {radical}s{sub NN} = 130 GeV
We present STAR measurements of charged hadron production as a function of centrality in Au + Au collisions at {radical}s{sub NN} = 130 GeV. The measurements cover a phase space region of 0.2 < p{sub T} < 6.0 GeV/c in transverse momentum and -1 < {eta} < 1 in pseudorapidity. Inclusive transverse momentum distributions of charged hadrons in the pseudorapidity region 0.5 < |{eta}| < 1 are reported and compared to our previously published results for |{eta}| < 0.5. No significant difference is seen for inclusive p{sub T} distributions of charged hadrons in these two pseudorapidity bins. We measured dN/d{eta} distributions and truncated mean p{sub T} in a region of p{sub T} > p{sub T}{sup cut}, and studied the results in the framework of participant and binary scaling. No clear evidence is observed for participant scaling of charged hadron yield in the measured p{sub T} region. The relative importance of hard scattering process is investigated through binary scaling fraction of particle production.
Date:
April 15, 2004
Creator:
Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Hadronization geometry and charge-dependent two-particlecorrelation on momentum subspace (eta, phi) in Au-Au collisions atsqrt(sNN) = 130 GeV
We present the first measurements of charge-dependent two-particle correlations on momentum-space difference variables {eta}{sub 1}-{eta}{sub 2} (pseudorapidity) and {phi}{sub 1}-{phi}{sub 2} (azimuth) for primary charged hadrons with transverse momentum 0.15 {le} p{sub t} {le} 2 GeV/c and |{eta}| {le} 1.3 from Au-Au collisions at {radical}s{sub NN} = 130 GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings to higher-dimensional fragmentation of a hadron-opaque bulk medium.
Date:
September 23, 2004
Creator:
Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
K(892)* resonance production in Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV at RHIC
The short-lived K(892)* resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of K* in {radical}s{sub NN} = 200 GeV Au+Au and p+p collisions reconstructed via its hadronic decay channels K(892)*{sup 0} {yields} K{pi} and K(892)*{sup +-} {yields} K{sub S}{sup 0}{pi}{sup +-} using the STAR detector at RHIC. The K*{sup 0} mass has been studied as function of p{sub T} in minimum bias p + p and central Au+Au collisions. The K* p{sub T} spectra for minimum bias p + p interactions and for Au+Au collisions in different centralities are presented. The K*/K ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias p + p collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. The nuclear modification factor of K* at intermediate p{sub T} is similar to that of K{sub S}{sup 0}, but different from {Lambda}. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate p{sub T} (2 < p{sub T} {le} 4 GeV/c). A significant non-zero K*{sup 0} elliptic flow (v{sub 2}) is observed in Au+Au collisions …
Date:
December 9, 2004
Creator:
Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurements of Transverse Energy Distributions in Au+Au Collisions at {radical}s{sub NN} = 200 GeV
Transverse energy (E{sub T}) distributions have been measured for Au+Au collisions at {radical}s{sub NN} = 200 GeV by the STAR collaboration at RHIC. E{sub T} is constructed from its hadronic and electromagnetic components, which have been measured separately. E{sub T} production for the most central collisions is well described by several theoretical models whose common feature is large energy density achieved early in the fireball evolution. The magnitude and centrality dependence of E{sub T} per charged particle agrees well with measurements at lower collision energy, indicating that the growth in E{sub T} for larger collision energy results from the growth in particle production. The electromagnetic fraction of the total E{sub T} is consistent with a final state dominated by mesons and independent of centrality.
Date:
July 2, 2004
Creator:
Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Minijet Deformation and Charge-independent Two-particleCorrelations on Momentum Subspace (eta,phi) In Au-Au Collisions atsqrt(sNN) = 130 GeV
We present first measurements of charge-independent correlations on momentum-space difference variables {eta}{sub 1}-{eta}{sub 2} (pseudorapidity) and {phi}{sub 1}-{phi}{sub 2} (azimuth) for charged primary hadrons with transverse momentum within 0.15 {le} p{sub t} {le} 2 GeV/c and |{eta}| {le} 1.3 from Au-Au collisions at {radical}s{sub NN} = 130 GeV. We observe strong charge-independent correlations associated with minijets and elliptic flow. The width of the minijet peak on {eta}{sub 1}-{eta}{sub 2} increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of partons to a longitudinally-expanding colored medium. New methods of jet analysis introduced here reveal nonperturbative medium effects in heavy ion collisions.
Date:
November 4, 2004
Creator:
Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Centrality and pseudorapidity dependence of charged hadron production at intermediate p{sub t} in Au+Au collisions at {radical}s{sub NN} = 130 GeV
We present STAR measurements of charged hadron production as a function of centrality in Au + Au collisions at {radical}s{sub NN} = 130 GeV. The measurements cover a phase space region of 0.2 < p{sub T} < 6.0 GeV/c in transverse momentum and 11 < {eta} < 1 in pseudorapidity. Inclusive transverse momentum distributions of charged hadrons in the pseudorapidity region 0.5 < |{eta}| < 1 are reported and compared to our previously published results for |{eta}| < 0.5. No significant difference is seen for inclusive p{sub T} distributions of charged hadrons in these two pseudorapidity bins. We measured dN/d{eta} distributions and truncated mean p{sub T} in a region of p{sub T} > P{sub T}{sup cut}, and studied the results in the framework of participant and binary scaling. No clear evidence is observed for participant scaling of charged hadron yield in the measured pT region. The relative importance of hard scattering process is investigated through binary scaling fraction of particle production.
Date:
April 15, 2004
Creator:
Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
Object Type:
Article
System:
The UNT Digital Library
Computational Modeling of K-shell Argon Spectra from Z-pinch Dynamic Hohlraum Experiments
Z-pinch dynamic hohlraum experiments on the Z-Machine at Sandia National Laboratories measured K-shell argon spectra using a focusing spectrometer with spatial resolution. The spectra are modeled using Hullac atomic data input, Cretin nonlocal thermodynamic equilibrium (nlte) atomic kinetics and radiative transfer calculations, and Dakota optimization capabilities. Hullac provides atomic structure and cross section data for Ar XIX, Ar XXVIII (n=1 (illegible) 5), Ar XXVII (n=1 (illegible) 10), and Ar XXVI (n=1 (illegible) 5), where n is the principal quantum number. Cretin calculates the area-integrated spectral intensity escaping an argon doped Dcapsule as a function of electron density, electron temperature, and capsule radius. Dakota optimizes the plasma properties for the best to the measured spectrum by minimizing an objective function comprise of argon spectral line ratios and full-width at half-maximums (fwhms). We highlight the framework of this general spectroscopic capability and discuss the extension to magnetized plasmas using Totalb spectral line shapes.
Date:
October 27, 2004
Creator:
Adams, M L; Sinars, D B; Scott, H A; Brandon, S T; Chung, H K & Lee, R W
Object Type:
Article
System:
The UNT Digital Library
Tracing Geothermal Fluids
Geothermal water must be injected back into the reservoir after it has been used for power production. Injection is critical in maximizing the power production and lifetime of the reservoir. To use injectate effectively the direction and velocity of the injected water must be known or inferred. This information can be obtained by using chemical tracers to track the subsurface flow paths of the injected fluid. Tracers are chemical compounds that are added to the water as it is injected back into the reservoir. The hot production water is monitored for the presence of this tracer using the most sensitive analytic methods that are economically feasible. The amount and concentration pattern of the tracer revealed by this monitoring can be used to evaluate how effective the injection strategy is. However, the tracers must have properties that suite the environment that they will be used in. This requires careful consideration and testing of the tracer properties. In previous and parallel investigations we have developed tracers that are suitable from tracing liquid water. In this investigation, we developed tracers that can be used for steam and mixed water/steam environments. This work will improve the efficiency of injection management in geothermal fields, lowering …
Date:
March 1, 2004
Creator:
Adams, Michael C. & Nash, Greg
Object Type:
Report
System:
The UNT Digital Library