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Optimizing Pinhole and Parallel Hole Collimation for Scintimammography with Compact Pixellated Detectors

Description: The relative advantages of pinhole and parallel hole collimators for scintimammography with compact, pixellated gamma detectors were investigated using analytic models of resolution and sensitivity. Collimator design was studied as follows. A desired object resolution was specified for a pixellated detector with a given crystal size and intrinsic spatial resolution and for a given object-to-collimator distance. Using analytic formulas, pinhole and parallel hole collimator parameters were calculated that satisfy this object resolution with optimal geometric sensitivity. Analyses were performed for 15 cm x 20 cm field of view detectors with crystal elements 1.0, 2.0 and 3.0 mm on a side and 140 keV incident photons. The sensitivity for a given object resolution was greater for pinhole collimation at smaller distances, as expected. The object distance at which the pinhole and parallel hole sensitivity curves cross each other is important. The crossover distances increased with larger crystal size for a constant object resolution and increased as the desired object resolution decreases for a constant crystal size. For example, for 4 mm object resolution these distances were 5.5 cm, 6.5 cm and 8 cm for the 1 mm, 2 mm and 3 mm crystal detectors, respectively. The results suggest a strategy of parallel hole collimation for whole breast imaging and pinhole collimation for imaging focal uptake. This could be accomplished with a dual detector system with a different collimator type on each head or a single head system equipped with two collimators and a rapid switching mechanism. Multipinhole collimators have the potential to increase sensitivity yet maintain high image resolution. An experimental SPECT phantom study with a four-pinhole collimator was acquired with a pixellated detector. The iterative maximum-likelihood expectation- maximization (MLEM) reconstruction of a hot sphere in a warm cylinder showed the potential of multipinhole collimation to improve sensitivity for tomographic pinhole ...
Date: November 1, 2002
Creator: Smith, Mark F.; Kieper, Douglas A.; Majewski, Stan; Weisenberger, Andrew G. & Welch, Benjamin
Partner: UNT Libraries Government Documents Department

Data for Elementary-Particle Physics

Description: These data are provided: Masses and .Mean Lives of Elementary Particles; Atomic and Nuclear Properties of Materials; Particle Scattering; Atomic and Nuclear Constants; Particle Decay and Reaction Dynamics; Tentative Data on Strongly lnteracting Particles and Resonances; and Clebsch-Gordan Coefficients and Spherical Harmonics.
Date: April 30, 1963
Creator: Rosenfeld, A. H. & Barkas, W. H.
Partner: UNT Libraries Government Documents Department

Final Report for "Infrared Fixed Points in Multiflavor Lattice Gauge Theory"

Description: The goal of the grant was to apply methods that we have developed with spin and pure gauge models to models with dynamical fermions which are considered as candidates for an alternative to the Higgs mechanism. The work on SU(3) with fundamental quarks and with sextet quarks is described.
Date: September 27, 2013
Creator: Meurice, Yannick & Sinclair, Donald K.
Partner: UNT Libraries Government Documents Department

Final Report for the University-Based Detector Research and Development for the International Linear Collider

Description: The U.S Linear Collider Detector R&D program, supported by the DOE and NSF umbrella grants to the University of Oregon, made significant advances on many critical aspects of the ILC detector program. Progress advanced on vertex detector sensor development, silicon and TPC tracking, calorimetry on candidate technologies, and muon detection, as well as on beamline measurements of luminosity, energy, and polarization.
Date: April 22, 2013
Creator: Brau, James E.
Partner: UNT Libraries Government Documents Department

Research in High Energy Physics

Description: This final report details the work done from January 2010 until April 2013 in the area of experimental and theoretical high energy particle physics and cosmology at the University of California, Davis.
Date: August 9, 2013
Creator: Conway, John S.
Partner: UNT Libraries Government Documents Department

Elementary Particle Physics at Baylor (Final Report)

Description: This report summarizes the activities of the Baylor University Experimental High Energy Physics (HEP) group on the Collider Detector at Fermilab (CDF) experiment from August 15, 2005 to May 31, 2012. Led by the Principal Investigator (Dr. Jay R. Dittmann), the Baylor HEP group has actively pursued a variety of cutting-edge measurements from proton-antiproton collisions at the energy frontier.
Date: August 25, 2012
Creator: Dittmann, J.R.
Partner: UNT Libraries Government Documents Department

Final report on SNAC 11

Description: This report details how the $5,000 DOE grant to support the workshop titled “Sterile Neutrinos at the Crossroads” (or SNAC11) was allocated and spent. The SNAC11 workshop covered three days during which there were 28 talks, multiple discussion sessions, a poster session with 9 posters delivered, and an impromptu public lecture on the OPERA superluminal neutrino result by the former project manager of OPERA (this was the first official OPERA talk on the subject in North America). The workshop scientific agenda can be viewed at http://www.cpe.vt.edu/snac/program.html. Emerging out of the workshop discussions, was the idea to write a comprehensive white paper describing the current state of the light sterile neutrino. This effort soon became an international collaboration. The final document, titled “Light Sterile Neutrinos: A White Paper” has nearly 200 authors, is 267 pages long, and cites 730 unique references. It has been posted the preprint archive as arXiv:1204.5379 [hep-ph]. Workshop local organizing committee co-chairs, Patrick Huber and Jonathan Link, are the white paper’s head editors. The white paper’s sections and section editors are as follows: 1. Theory and Motivation (Gabriela Barenboim, Valencia and Werner Rodejohann, MPI Heidelberg) 2. Astrophysical Evidence (Kev Abazajian, UC Irvine and Yvonne Wong, Aachen) 3. Evidence from Oscillation Experiments (Joachim Kopp, FNAL and Bill Louis, LANL) 4. Global Picture (Thierry Lasserre, CEA Saclay and Thomas Schwetz, MPI Heidelberg) 5. Requirements for Future Measurements (Bonnie Fleming, Yale and Joe Formaggio, MIT) 6. Appendix: Possible Future Experiments (Patrick Huber, Virginia Tech and Jon Link, Virginia Tech) In all 56 people participated in the workshop, of these 11 were young scientists. The workshop was covered in a feature article in Science (Science, 334, (2011), 304-306.). The DOE award was spent, as budgeted, as contractual services to VT CPE, which is the unit within the University which organizes conferences. ...
Date: June 26, 2013
Creator: Huber, Patrick
Partner: UNT Libraries Government Documents Department

High Energy Physics

Description: This grant covered an umbrella program of research in high-­‐energy particle physics at Southern Methodist University during the period 2004-­‐2013. The experimental program evolved during that time. At its early stages it included research on the CLEO experiment at CESR (Coan, Stroynowski, Ye), D0 experiment at Tevatron (Kehoe), preparation for the BTEV experiment at Fermilab (Coan) and construction and commissioning of the Liquid Argon Calorimeter for the ATLAS experiment at LHC (Stroynowski, Ye). In the last three years the program concentrated on the ATLAS experiment at LHC (Kehoe, Sekula, Stroynowski, Ye), D0 experiment at Tevatron (Kehoe) and NOvA experiment at Fermilab (Coan). Professor Sekula had a short-­‐term independent grant for which he is submitting a separate report. The theoretical physics program included work on non-­‐perturbative methods in the light cone representation (McCartor (deceased)), lattice calculations (Hornbostel), and determination of parton distribution functions (Olness). A summary of the accomplishments emphasizing results from the past three years is provided separately for each of the tasks.
Date: June 26, 2013
Creator: Strownowski, Ryszard
Partner: UNT Libraries Government Documents Department

Experimental High Energy Physics Brandeis University Final Report

Description: During the past three years, the Brandeis experimental particle physics group was comprised of four faculty (Bensinger, Blocker, Sciolla, and Wellenstein), one research scientist, one post doc, and ten graduate students. The group focused on the ATLAS experiment at LHC. In 2011, the LHC delivered 5/fb of pp colliding beam data at a center-of-mass energy of 7 TeV. In 2012, the center-of-mass energy was increased to 8 TeV, and 20/fb were delivered. The Brandeis group focused on two aspects of the ATLAS experiment -- the muon detection system and physics analysis. Since data taking began at the LHC in 2009, our group actively worked on ATLAS physics analysis, with an emphasis on exploiting the new energy regime of the LHC to search for indications of physics beyond the Standard Model. The topics investigated were Z' -> ll, Higgs -> ZZ* -. 4l, lepton flavor violation, muon compositeness, left-right symmetric theories, and a search for Higgs -> ee. The Brandeis group has for many years been a leader in the endcap muon system, making important contributions to every aspect of its design and production. During the past three years, the group continued to work on commissioning the muon detector and alignment system, development of alignment software, and installation of remaining chambers.
Date: July 26, 2013
Creator: Blocker, Craig A.; Bensinger, James; Sciolla, Gabriella & Wellenstein, Hermann
Partner: UNT Libraries Government Documents Department

The Parity Non-Conserving Electron-Nucleon Interaction

Description: We present general ideas concerning the neutral weak eq interaction. Then we describe the salient features of the Weinberg-Salam model, discuss in detail the principles and methods of the SLAC polarized electron scattering experiment and atomic physics experiments, and summarize neutral weak interaction results and their implications.
Date: January 1, 1980
Creator: Commins, E. D. & Bucksbaum, P. H.
Partner: UNT Libraries Government Documents Department

Scaling, Multiplicity and Temperature of e{sup +}e{sup -} {yields} Hadrons

Description: Properties of meson production by e{sup +}e{sup -} annihilations for E{sub c.m.} = 3,0 to 31.2 GeV have been analyzed using the Bose-Einstein distribution modified for the Feynman-Yang scaling, Validity tests have been made with the P{sub T} and P{sub L} distributions measured with respect to the jet axis, The average charged multiplicity is found to follow an empirical power law E{sub c.m.}{sup 1/2}. The temperatures deduced from < P{sub T} > increase slowly with E{sub c,m,} . The scaling behavior is investigated in terms of the parameter {lambda} = 2<P{sub T}>/{pi}<P{sub L}> used to modify the Bose-Einstein distribution. An anomaly resembling a phase transition of the specific heat of the hadronic matter is found at a temperature near 127 MeV corresponding to the threshold for {Upsilon}(9.5) production.
Date: November 1, 1980
Creator: Hoang, T. F. & Cork, Bruce
Partner: UNT Libraries Government Documents Department

Final Report on DOE Grant DE-SC0001075 titled "Supersymmetry and Unification of Fundamental Interactions - SUSY2009

Description: SUSY2009 brought together researchers from a very broad area of fundamental physics including elementary particle theory, astrophysics and cosmology and string theory with a focus on supersymmetry. Thus the topic covered at the SUSY2009 conference included the following: Search for the Higgs boson, search for supersymmetry, supersymmetry phenomenology, theories of dark matter and direct and indirect detection, neutrino physics, accelerator experiments, electroweak physics, supersymmetry phenomenology, string theory, string phenomenology, extra Dimensions as well as other recent theoretical and experimental developments. The conference was successful in fostering interdisciplinary interactions between theorists and experimentalists.
Date: September 12, 2012
Creator: Nath, Pran
Partner: UNT Libraries Government Documents Department

Measurement of Single Spin Asymmetries in Semi-Inclusive Deep Inelastic Scattering Reaction n↑ ( e,e' pi{sup +}) X at Jefferson Lab

Description: What constitutes the spin of the nucleon? The answer to this question is still not completely understood. Although we know the longitudinal quark spin content very well, the data on the transverse quark spin content of the nucleon is still very sparse. Semi-inclusive Deep Inelastic Scattering (SIDIS) using transversely polarized targets provide crucial information on this aspect. The data that is currently available was taken with proton and deuteron targets. The E06-010 experiment was performed at Jefferson Lab in Hall-A to measure the single spin asymmetries in the SIDIS reaction n↑(e, e′π{sup ±}/K{sup ±})X using transversely polarized {sup 3}He target. The experiment used the continuous electron beam provided by the CEBAF accelerator with a beam energy of 5.9 GeV. Hadrons were detected in a high-resolution spectrometer in coincidence with the scattered electrons detected by the BigBite spectrometer. The kinematic coverage focuses on the valence quark region, x = 0.19 to 0.34, at Q{sup 2} = 1.77 to 2.73 (GeV/c){sup 2}. This is the first measurement on a neutron target. The data from this experiment, when combined with the world data on the proton and the deuteron, will provide constraints on the transversity and Sivers distribution functions on both the u and d-quarks in the valence region. In this work we report on the single spin asymmetries in the SIDIS n↑(e, e′π{sup +})X reaction.
Date: June 1, 2010
Creator: Allada, Kalyan
Partner: UNT Libraries Government Documents Department

Isospin Decomposition of the Photoproduced Sigma pi System Near the Lambda(1405)

Description: Recent experimental results for the reaction \gamma + p \to K^+ + \Sigma + \pi\ from CLAS at Jefferson Lab are discussed. It was found that the mass distributions or &quot;line shapes&quot; of the three charge combinations \Sigma^+ \pi^-, \Sigma^0 \pi^0 and \Sigma^- \pi^+ differ significantly. Our results show that the \Lambda(1405), as the I=0 constituent of the reaction, must be accompanied by an I &gt; 0 component. We discuss phenomenological fits to the data to test the possible forms and magnitudes of these amplitudes. A two-amplitude I=0 fit of Breit-Wigner form to the \Sigma^0\pi^0 channel alone works quite well. The addition of a single I=1 amplitude works fairly well to model all the line shapes simultaneously.
Date: September 1, 2013
Creator: U., Carnegie Mellon & U., Indiana
Partner: UNT Libraries Government Documents Department

A Measurement of the Weak Charge of the Proton through Parity Violating Electron Scattering using the Qweak Apparatus: A 21% Result

Description: After a decade of preparations, the Qweak experiment at Jefferson Lab is making the first direct measurement of the weak charge of the proton, Q^p_W. This quantity is suppressed in the Standard Model making a good candidate for search for new physics beyond the SM at the TeV scale. Operationally, we measure a small (about -0.200 ppm) parity-violating asymmetry in elastic electron-proton scattering in integrating mode while flipping the helicity of the electrons 1000 times per second. Commissioning took place Fall 2010, and we finished taking data in early summer 2012. This dissertation is based on the data taken on an initial two weeks period (Wien0). It will provide an overview of the Qweak apparatus, description of the data acquisition and analysis software systems, and final analysis and results from the Wien0 data set. The result is a 16% measurement of the parity violating electron-proton scattering asymmetry, A = -0.2788 +/- 0.0348 (stat.) +/- 0.0290 (syst.) ppm at Q^2 = 0.0250 +/- 0.0006 (GeV)^2. From this a 21% measurement of the weak charge of the proton, Q_w^p(msr)= +0.0952 +/- 0.0155 (stat.) +/- 0.0131 (syst.) +/- 0.0015 (theory) is extracted. From this a 2% measurement of the weak mixing angle, sin^2theta_W(msr)= +0.2328 +/- 0.0039 (stat.) +/- 0.0033 (syst.) +/- 0.0004 (theory) and improved constraints on isoscalar/isovector effective coupling constants of the weak neutral hadronic currents are extracted. These results deviate from the Standard Model by one standard deviation. The Wien0 results are a proof of principle of the Qweak data analysis and a highlight of the road ahead for obtaining full results.
Date: August 1, 2013
Creator: Beminiwattha, Rakitha
Partner: UNT Libraries Government Documents Department

Measurement of the Proton&#x27;s Weak Charge at the Qweak Experiment

Description: The Qweak experiment at Jefferson Laboratory measures the parity violating asymmetry of polarized electrons scattering from a proton target at very low momentum transfer. In the Standard Model, this asymmetry reveals the proton&#x27;s coupling to the neutral vector current, the weak charge. This value, measured directly for the first time, will provide a precision test of the Standard Model and will constrain the possibility of relevant physics beyond the Standard Model. The planned precision will probe certain classes of new physics at the ~2 TeV scale. In order to challenge the precise predictions, the asymmetry will be measured with a 2.5 percent accuracy. To achieve such a precision, great care has to be taken on many aspects of the experiment. The very low momentum transfer reduces the hadronic effects to the asymmetry and must be determined to half of a percent accuracy. Beam stability is controlled and monitored constantly and background events are carefully studied.
Date: October 1, 2011
Creator: Rajotte, Jean-Francois
Partner: UNT Libraries Government Documents Department

Determination of the Azimuthal Asymmetry of Deuteron Photodisintegration in the Energy Region E{sub {gamma}} = 1.1 - 2.3 GeV

Description: Deuteron photodisintegration is a benchmark process for the investigation of the role of quarks and gluons in nuclei. Existing theoretical models of this process describe the available cross sections with the same degree of success. Therefore, spin-dependent observables are crucial for a better understanding of the underlying dynamical mechanisms. However, data on the induced polarization (P{sub y}), along with the polarization transfers (C{sub x&#x27;} and C{sub z&#x27;} ), have been shown to be insensitive to differences between theoretical models. On the other hand, the beam-spin asymmetry {Sigma} is predicted to have a large sensitivity and is expected to help in identifying the energy at which the transition from the hadronic to the quark-gluon picture of the deuteron takes place. Here, the work done to determine the experimental values of the beam-spin asymmetry in deuteron photodisintegration for photon energies between 1.1 – 2.3 GeV is presented. The data were taken with the CLAS at the Thomas Jefferson National Accelerator Facility during the g13 experiment. Photons with linear polarization of ~80% were produced using the coherent bremsstrahlung facility in Hall B. The work done by the author to calibrate a specific detector system, select deuteron photodisintegration events, study the degree of photon polarization, and finally determine the azimuthal asymmetry and any systematic uncertainties associate with it, is comprehensively explained. This work shows that the collected data provide the kinematic coverage and statistics to test the available QCD-based models. The results of this study show that the available theoretical models in their current state do not adequately predict the azimuthal asymmetry in the energy region 1.1 – 2.3 GeV.
Date: May 20, 2012
Creator: Zachariou, Nicholas
Partner: UNT Libraries Government Documents Department

An Overview of Longitudinal Spin Structure Measurements from JLab

Description: Jefferson Lab is currently one of the facilities leading the investigation of the spin structure of the nucleon. Over the past 15 years, several high precision measurements have been completed, extending our knowledge of the polarized structure functions g{sub 1} and g{sub 2} down to Q{sup 2} = 0.02 GeV{sup 2}. In particular, the low-Q{sup 2} range ({&lt;=} 0.1 GeV{sup 2}) from these data allows us to make a benchmark-check of Chiral Perturbation theory ({chi}PT). Previous results for the moments of the spin structure functions in this region have shown mixed agreement. For {Gamma}{sub 1}, the first moment of g{sub 1}, we find good consistency between data and theory. However, we have seen a surprisingly large discrepancy with {chi}PT calculations for the {delta}{sub LT} spin polarizability on the neutron, which is significantly less sensitive to the {Delta}-resonance contribution. These proceedings will discuss the recent experimental effort at low Q{sup 2} from Jefferson Lab, including a discussion of preliminary results on the neutron. The new results on the neutron still show a sizeable discrepancy between data and theory. However, new calculations show improved agreement with data for some observables. In addition, new proton data for g{sub 2} is also expected to help resolve the disagreement for {delta}{sub LT}.
Date: August 1, 2013
Creator: Sulkosky, Vincent A.
Partner: UNT Libraries Government Documents Department

PDF uncertainties at large x and gauge boson production

Description: I discuss how global QCD fits of parton distribution functions can make the somewhat separated fields of high-energy particle physics and lower energy hadronic and nuclear physics interact to the benefit of both. In particular, I will argue that large rapidity gauge boson production at the Tevatron and the LHC has the highest short-term potential to constrain the theoretical nuclear corrections to DIS data on deuteron targets necessary for up/down flavor separation. This in turn can considerably reduce the PDF uncertainty on cross section calculations of heavy mass particles such as W&#x27; and Z&#x27; bosons.
Date: October 1, 2012
Creator: Accardi, Alberto
Partner: UNT Libraries Government Documents Department

Photoproduction and Decay of Light Mesons in CLAS

Description: We present preliminary experimental results on photoproduction and decay of light mesons measured with CLAS setup at JLAB . This include Dalitz decay of pseudoscalar and vector mesons, radiative decay of pseudoscalar mesons as well hadronic decays of pseudoscalar and vector mesons. The collected high statistics in some of decay channels exceeds the world data by an order of magnitude and some other decay modes are observed for the first time. It is shown how the CLAS data will improve the world data on transition form factors of light mesons, Dalitz plot analyses, branching ratios of rare decay modes and other fundamental properties potentially accessible through the light meson decays.
Date: August 1, 2013
Creator: Amaryan, Moskov Jamalovich
Partner: UNT Libraries Government Documents Department

Quark Contributions to Nucleon Momentum and Spin from Domain Wall fermion calculations

Description: We report contributions to the nucleon spin and momentum from light quarks calculated using dynamical domain wall fermions with pion masses down to 300 MeV and fine lattice spacing a=0.084 fm. Albeit without disconnected diagrams, we observe that spin and orbital angular momenta of both u and d quarks are opposite, almost canceling in the case of the d quark, which agrees with previous calculations using a mixed quark action. We also present the full momentum dependence of n=2 generalized form factors showing little variation with the pion mass.
Date: December 1, 2011
Creator: S. N. Syritsyn, J. R. Green, J. W. Negele, A. V. Pochinsky, M. Engelhardt, Ph. Hagler, B. Musch, W. Schroers
Partner: UNT Libraries Government Documents Department

Constrained gamma-Z interference corrections to parity-violating electron scattering

Description: We present a comprehensive analysis of gamma-Z interference corrections to the weak charge of the proton measured in parity-violating electron scattering, including a survey of existing models and a critical analysis of their uncertainties. Constraints from parton distributions in the deep-inelastic region, together with new data on parity-violating electron scattering in the resonance region, result in significantly smaller uncertainties on the corrections compared to previous estimates. At the kinematics of the Qweak experiment, we determine the gamma-Z box correction to be Re\box_{gamma-Z}^V = (5.61 +- 0.36) x 10^{-3}. The new constraints also allow precise predictions to be made for parity-violating deep-inelastic asymmetries on the deuteron.
Date: July 1, 2013
Creator: Hall, Nathan Luke; Blunden, Peter Gwithian; Melnitchouk, Wally; Thomas, Anthony W. & Young, Ross D.
Partner: UNT Libraries Government Documents Department

Nucleon and Delta axial-vector couplings in 1/N{sub c}-Baryon Chiral Perturbation Theory

Description: In this contribution, baryon axial-vector couplings are studied in the framework of the combined 1/N{sub c} and chiral expansions. This framework is implemented on the basis of the emergent spin-flavor symmetry in baryons at large N{sub c} and HBChPT, and linking both expansions ({xi}-expansion), where 1/N{sub c} is taken to be a quantity order p. The study is carried out including one-loop contributions, which corresponds to order xi to the third for baryon masses and order {xi} square for the axial couplings.
Date: August 1, 2013
Creator: Goity, Jose Luis & Calle Cordon, Alvaro
Partner: UNT Libraries Government Documents Department