Physics Commons^™

In-Beam Γ-Ray Spectroscopy Studies Of Medium-Spin States In The Odd-Odd Nucleus 186Re, David A. Matters, F. G. Kondev, N. Aoi, Y. Ayyad, A. P. Byrne, M. P. Carpenter, J. Carroll, C. J. Chiara, P. M. Davidson, G. D. Dracoulis, Y. D. Fang, C. R. Hoffmann, R. O. Hughes, E. Ideguchi, R. V. F. Janssens, S. Kanaya, B. P. Kay, T. Kibedi, G. J. Lane, T. Lauritsen, John W. Mcclory, P. Nieminen, S. Noji, A. Odahara, H. J. Ong, A. E. Stuchbery, D. T. Tran, H. Watanabe, A. N. Wilson, Y. Yamamoto, S. Zhu

Faculty Publications

Excited states in ¹⁸⁶Re with spins up to J=12ℏ were investigated in two separate experiments using 186W(d,2n) reactions at beam energies of 12.5 and 14.5 MeV. Two- and threefold γ-ray coincidence data were collected using the CAESAR and CAGRA spectrometers, respectively, each composed of Compton-suppressed high-purity germanium detectors. Analysis of the data revealed rotational bands built on several two-quasiparticle intrinsic states, including a long-lived K^π=(8⁺) isomer. Configuration assignments were supported by an analysis of in-band properties, such as |gK−gR| values. The excitation energies of the observed intrinsic states were compared with results from multi-quasiparticle blocking …

Measurement Of The Longitudinal Double-Spin Asymmetry For Neutral Pion Production In Polarized Proton Collisions At √S = 510 Gev, Taegyun Kim

Physics & Astronomy Honors Papers

Beyond the valence quarks' spin contribution to the total spin of a proton, gluon and sea quark contributions are becoming clear as well. For proton+proton collisions at a center of mass energy of 510 GeV , neutral pion production is dominated by gluon-gluon and gluon-quark scattering. An avenue to constrain the gluon polarization is the asymmetry, A_LL, in the production of neutral pions from collisions of longitudinally spin-polarized proton beams. Our experiment was performed with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), unique for its ability to collide spin-polarized proton beams. The Endcap Electromagnetic Calorimeter …

Lorentz-Symmetry Test At Planck-Scale Suppression With Nucleons In A Spin-Polarized 133 Cs Cold Atom Clock, H. Pihan-Le Bars, C. Guerlin, R.-D. Lasseri, J.-P. Ebran, Q. G. Bailey, S. Bize, E. Khan, P. Wolf

Publications

The authors introduce an improved model that links the frequency of the 133 Cs hyperfine Zeeman transitions.

Measurements Of Ep → E′Π+Π-P′ Cross Sections With Clas At 1.40 Gev < W < 2.0 Gev And 2.0 Gev² < Q² < 5.0 Gev², E.L. Isupov, V.D. Burkert, D.S. Carman, R. W. Gothe, R. Hicks, B. S. Ishkhanov, V. I. Mokeev, K. P. Adhikari, S. Adhikari, D. Adikaram, M. J. Amaryan, G. Charles, A. Klein, Y. Prok, B. Torayev

Physics Faculty Publications

This paper reports new exclusive cross sections for ep → e′π⁺π^-p′ using the CLAS detector at Jefferson Laboratory. These results are presented for the first time at photon virtualities 2.0GeV² 2 < 5.0GeV² in the center-of-mass energy range 1.4 GeV < W < 2.0 GeV, which covers a large part of the nucleon resonance region. Using a model developed for the phenomenological analysis of electroproduction data, we see strong indications that the relative contributions from the resonant cross sections at W < 1.74 GeV increase with Q². These data considerably extend the kinematic reach of previous measurements. Exclusive ep → e′π⁺π^-p′ cross section measurements are of particular importance for the extraction of resonance electrocouplings in the mass range above 1.6 GeV.

Near-Side Azimuthal And Pseudorapidity Correlations Using Neutral Strange Baryons And Mesons In D+Au, Cu+Cu, And Au+Au Collisions At √SNn = 200 Gev, B. Abelev, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, L. S. Barnby, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, M. Bombara, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, I. Bunzarov, J. Butterworth, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We present measurements of the near side of triggered di-hadron correlations using neutral strange baryons (Λ, Λ⁻) and mesons (K⁰_S) at intermediate transverse momentum (3 < p_T < 6 GeV/c) to look for possible flavor and baryon-meson dependence. This study is performed in d+Au, Cu+Cu, and Au+Au collisions at √^S_NN = 200 GeV measured by the STAR experiment at RHIC. The near-side di-hadron correlation contains two structures, a peak which is narrow in azimuth and pseudorapidity consistent with correlations from jet fragmentation, and a correlation in azimuth which is broad in pseudorapidity. The …

The Beam-Helicity Asymmetry For Two Pseudoscalar Mesons In Photoproduction And A Partial Wave Analysis For Excited Hyperons, Rafael A. Badui

FIU Electronic Theses and Dissertations

The first-time measurement of the angular dependence of the beam-helicity asymmetry for $\gamma p \rightarrow pK^{+}K^{-}$ is shown and compared to $\gamma p \rightarrow p\pi^{+}\pi^{-}$. The data obtained were from the CLAS g12 experiment at Jefferson Lab. The experiment utilized a beam of circularly polarized photons with energies between 1.1 and 5.4 GeV incident on an unpolarized liquid hydrogen target, which produced an unprecedented number of strange hadrons in photoproduction. The production mechanism for strange hadrons is not well understood. The beam-helicity asymmetry is a polarization observable that provides information on interfering production mechanisms in the reaction. It is shown …

Measurements Of Photon Beam Intensity At The High Intensity Gamma-Ray Source (Higs) Facility For Astrophysically Relevant Photodisintegration Reaction Cross Section, Evan G. Meekins

Senior Honors Projects, 2010-2019

How nuclear reactions in stars and stellar explosions such as supernovae have forged the elements out of hydrogen and helium leftover from the Big Bang is a longstanding, still timely research topic in nuclear astrophysics. Although there is a fairly complete understanding of the production of the chemical elements and their isotopes up to iron by nuclear fusion in stars, important details concerning the production of the elements from iron to uranium remain puzzling. Current knowledge is that the nucleosynthesis beyond iron proceeds mainly via neutron capture reactions and subsequent electron decays to stability. However, some 35 proton-rich stable isotopes, …

Hard Qcd Processes In The Nuclear Medium, Adam Freese

FIU Electronic Theses and Dissertations

The environment inside the atomic nucleus is one of the most fascinating arenas for the study of quantum chromodynamics (QCD). The strongly-interacting nature of the nuclear medium affects the nature of both QCD processes and the quark-gluon structure of hadrons, allowing several unique aspects of the strong nuclear force to be investigated in reactions involving nuclear targets. The research presented in this dissertation explores two aspects of nuclear QCD: firstly, the partonic structure of the nucleus itself; and secondly, the use of the nucleus as a micro-laboratory in which QCD processes can be studied.

The partonic structure of the nucleus …

On The Spin Evolution Of Isolated Pulsars, Oliver Quinn Hamil

Doctoral Dissertations

Neutron stars are the remnants of supernova explosions, and harbor the densest matter found in the universe. Because of their extreme physical characteristics, neutron stars make superb laboratories from which to study the nature of matter under conditions of extreme density that are not reproducible on Earth. The understanding of QCD matter is of fundamental importance to modern physics, and neutron stars provide a means of probing into the cold, dense region of the QCD phase diagram.

Isolated pulsars are rotating neutron stars that emit beams of electromagnetic radiation into space which appear like lighthouses to observers on Earth. Observations …

Relativistic And Non-Relativistic Proton-Nucleus Scattering, Kinsey Ann Elisabeth Zarske-Williamson

Honors Theses

Calculations for proton-nucleus scattering often rely on transition amplitudes. We implement new transition amplitudes [7] with the relativistic equations. We can find the matrix elements of the operators between the usual Dirac spinor basis or the helicity spinor basis. The operators can also be written as a linear combination of non-relativistic spin operators. To transform from one basis to another, we need to find a transformation matrix. We must establish what one of the factors that appears in the transformed expression means in order to correctly complete our transformation matrix. Once this is resolved, our transformation matrix will be complete.

Design And Model Of The Frame For Hagrid (Hybrid Array Of Gamma Ray Detectors), Santiago Munoz

Masters Theses

Transfer reactions in inverse kinematics have provided critical information in the study of exotic nuclei. However, transfer reactions with charged particles suffer from poor resolution. The measurement of gamma-rays offers several advantages: they provide not only good resolution in measurements but also other information about the nuclei like lifetimes of unstable states. The combination of these two methods would be the ideal situation to gather information about nuclear structure.

HAGRiD, which stands for The Hybrid Array of Gamma Ray Detectors, is a LaBr3(Ce) [lanthanum bromide crystal with a cerium activator] scintillation array to measure gamma rays from transfer reactions and …

Structure And Decay Correlations Of Two-Neutron Systems Beyond The Dripline, Z. Kohley, T. Baumann, D. Bazin, G. Christian, P. A. De Young, J. E. Finck, R. A. Haring-Kaye, J. Hinnefeld, N. Frank, E. Lunderberg, B. Luther, S. Mosby, W. A. Peters, J. K. Smith, J. Snyder, Sharon L. Stephenson, M. J. Strongman, A. Spyrou, M. Thoennessen, A. Volya

Physics and Astronomy Faculty Publications

The two-neutron unbound systems of 16Be, 13Li, 10He, and 26O have been measured using the Modular Neutron Array (MoNA) and 4 Tm Sweeper magnet setup. The correlations of the 3-body decay for the 16Be and 13Li were extracted and demonstrated a strong correlated enhancement between the two neutrons. The measurement of the 10He ground state resonance from a 14Be(−2p2n) reaction provided insight into previous predictions that wavefunction of the entrance channel, projectile, can influence the observed decay energy spectrum for the unbound system. Lastly, the decay-in-target (DiT) technique was utilized to extract the lifetime of the 26O ground state. The …

Re-Analysis Of The World Data On The Emc Effect And Extrapolation To Nuclear Matter, Stacy E. Karthas

Honors Theses and Capstones

The EMC effect has been investigated by physicists over the past 30 years since it was discovered at CERN. This effect shows that the internal nucleon structure varies when in the nuclear medium. Data from SLAC E139 and JLab E03 103 were studied with the Coulomb correction and directly compared. The Coulomb distortion had a greater impact on the JLab data due to slightly lower energies and different kinematics. The EMC ratio was found to have a dependence on a kinematic variable, which was removed when Coulomb corrections were applied. The methodology was developed to apply Coulomb corrections, which had …

Timewalk Correction Analysis With Fadcs, Saptaparnee Chaudhuri

Theses and Dissertations

The upgraded CLAS12 (12 GeV) detector is built around a six-coil toroidal magnet that divides the active detection area into six azimuthal sectors. The Forward Time-of-Flight system (FTOF) is a major component of the CLAS 12 detector. It is used to measure the time-of-flight of the charged particles emerging from the interaction of the probing particle and the target. In each of the six sectors of the CLAS12, the FTOF system is comprised of three arrays of counters referred to as panel-1a, panel-1b, panel-2b. Panel-1b arrays consists of 62 counters each. This research focuses on the "timewalk corrections" analysis of …

First Observation Of 15be, J. Snyder, T. Baumann, G. Christian, R. A. Haring-Kaye, P. A. Deyoung, Z. Kohley, B. Luther, M. Mosby, S. Mosby, A. Simon, J. K. Smith, A. Spyrou, Sharon L. Stephenson, M. Thoennessen

Physics and Astronomy Faculty Publications

The neutron-unbound nucleus 15Be was observed for the first time. It was populated using neutron transfer from a deuterated polyethylene target with a 59 MeV/u 14Be beam. Neutrons were measured in coincidence with outgoing 14Be particles and the reconstructed decay energy spectrum exhibits a resonance at 1.8(1) MeV. This corresponds to 15Be being unbound by 0.45 MeV more then 16Be thus significantly hindering the sequential two-neutron decay of 16Be to 14Be through this state.

Top-Quark Production And Qcd, Nikolaos Kidonakis, Ben D. Pecjak

Faculty and Research Publications

We review theoretical calculations for top-quark production that include complete next-to-leading-order QCD corrections as well as higher-order soft-gluon corrections from threshold resummation. We discuss in detail the differences between various approaches that have appeared in the literature and review results for top-quark total cross sections and differential distributions at the Tevatron and the LHC.

The Role Of Llnl's Fast Calibration Facility In Diagnosing Nif Fusion Plasmas, Joshua G. Thompson, Carey Scott, Greg V. Brown

STAR Program Research Presentations

The Fusion and Astrophysics (FAST) Calibration and Diagnostic Facility uses the original Electron Beam Ion Trap (EBIT-I) to profile x-ray filters that are used in the Dante Soft X-Ray Diagnostic at the National Ignition Facility (NIF). FAST has an advantage over any other facility not only for its high accuracy, but also for its proximity to NIF in the Lawrence Livermore National Laboratory (LLNL). This makes for highly accurate and near-instantaneous filter calibration turnover.

EBIT-I was first constructed to create, trap, and observe static highly charged ions (HCIs) and conduct experimental astrophysics (creating an x-ray spectroscopy catalogue of ions). To …

Study Of Z Boson Production In Pbpb Collisions At √Snn = 2.76 Tev, S. A. Chatrchyan, V. Khachatryan, A. M. Sirunyan, Marc M. Baarmand, Marcus Hohlmann, H Kalakhety, Robert M. Ralich, Igor Vodopiyanov, B. Dorney, S. Guragain

Aerospace, Physics, and Space Science Faculty Publications

A search for Z bosons in the þ decay channel has been performed in PbPb collisions at √sNN = 2:76 TeV with the CMS detector at the LHC, in a 7:2 b 1 data sample. The number of opposite-sign muon pairs observed in the 60–120 GeV=c2 invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of ½33:8 5:5ðstatÞ 4:4ðsystÞ 10 8, in the jyj < 2:0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.

Double Ionization Of Helium By Ion Impact Analyzed Using Four-Body Dalitz Plots, M. F. Ciappina, Michael Schulz, T. Kirchner, Daniel Fischer, R. Moshammer, J. D. Ullrich

Physics Faculty Research & Creative Works

We have performed experimental and theoretical studies of double ionization of helium by 6 MeV proton impact using a recently developed tool, four-particle Dalitz plots [Schulz et al., J. Phys. B 22, 3091 (2007)] which enable the representation of multiple differential cross sections as a function of all four fragments in a single spectrum without loss of any part of the total cross section. As a result, the relative importance of the various interactions between the fragments can be studied in great detail. Comparisons of experimental data with theoretical first-order calculations and simulations for the higher-order (TS-2) process show that …

Fractal Dimensions In Perceptual Color Space: A Comparison Study Using Jackson Pollock’S Art, Jonas R. Mureika

Physics Faculty Works

The fractal dimensions of color-specific paint patterns in various Jackson Pollock paintings are calculated using a filtering process that models perceptual response to color differences (L*a*b* color space). The advantage of the L*a*b* space filtering method over traditional red-green-blue (RGB) spaces is that the former is a perceptually uniform (metric) space, leading to a more consistent definition of “perceptually different” colors. It is determined that the RGB filtering method underestimates the perceived fractal dimension of lighter-colored patterns but not of darker ones, if the same selection criteria is applied to each. Implications of the findings to Fechner’s “principle of …

Isomers And Seniority In The Trans-Pb Nuclei, J. J. Ressler, C. W. Beausang, R. F. Casten, N. V. Zamfir, H. Ai, H. Amro, M. Babilon, R. Cakirli, J. A. Caggiano, G. Gurdal, A. Heinz, R. O. Hughes, S. D. Langdown, E. A. Mccutchan, D. A. Meyer, C. Plettner, J. Qian, P. H. Regan, M.J. S. Sciacchitano, N. J. Thomas, E. Williams, A. Yamamoto

Physics Faculty Publications

Low-energy excited states of ²¹⁰Ra and ²⁰⁸Ra were investigated at the Wright Nuclear Structure Laboratory of Yale University. Fusion evaporation recoils were selected using the gas-filled spectrometer, SASSYER. Delayed γ -rays, following isomeric decays, were detected at the focal plane of SASSYER with a small array of HPGe detectors. Transitions following the proposed J ^π = 8⁺ isomers were observed, and the half-lives measured. The experiments are discussed and results compared to expectations from the seniority scheme.

Novel Neutron Detector For N-N Scattering Length Measurement, Eva Wilcox

Theses and Dissertations

The neutron-neutron (n-n) scattering length is a fundamental parameter in nuclear physics; however, measurements are plagued with large uncertainties caused by neutron detector cross talk. Many experimentalists also rely upon computer code to calibrate their neutron detectors. Experiments give one of two different numbers but there is still no adequate explanation for this discrepancy. We have developed a new neutron detector expressly for the purpose of improving the n-n scattering length measurement. It offers two important advantages: 1) minimal cross talk and 2) high counting efficiency. We calibrated the detector from 1 MeV to 6 MeV at 1 MeV increments. …

Theoretical Status Of The Top Quark Cross Section, Nikolaos Kidonakis, Ramona Vogt

Faculty and Research Publications

We discuss the most recent calculations of the top quark total cross section and transverse momentum distributions at the Tevatron and the LHC. These calculations include the soft-gluon corrections at next-to-next-to-leading order (NNLO). The soft NNLO corrections stabilize the scale dependence of the cross section.

Manifestation Of The Color Glass Condensate In Particle Production At Rhic, Kirill Tuchin

Kirill Tuchin

We discuss general properties of the Color Glass Condensate. We show that predictions for particle production in p(d)A and AA collisions derived from these properties are in agreement with data collected at RHIC.

Heavy Quark Production By A Quasi-Classical Color Field In Proton-Nucleus Collisions, Kirill Tuchin

Kirill Tuchin

We calculate the inclusive heavy quark production cross section for proton-nucleus collisions at high energies. We perform calculation in a quasi-classical approximation (McLerran-Venugopalan model) neglecting all low-x evolution effects. The derived expression for the differential cross section can be applied for studying the heavy quark production in the central rapidity region at RHIC.

Pion-Induced Transport Of Π Mesons In Nuclei, S. G. Mashnik, R. J. Peterson, A. J. Sierk, Michael R. Braunstein

All Faculty Scholarship for the College of the Sciences

A large body of data for pion-induced neutral pion continuum spectra spanning outgoing energies near 180 MeV shows no dip there that might be ascribed to internal strong absorption processes involving the formation of Δ’s. This is the same observation previously made for the charged pion continuum spectra. Calculations in an intranuclear cascade model or a cascade exciton model with free-space parameters predict such a dip for both neutral and charged pions. We explore several medium modifications to the interactions of pions with internal nucleons that are able to reproduce the data for nuclei from ⁷Li through Bi.

Limitation Of The Semirelativistic Approach In Sum Rules And Related Calculations In Atomic Physics, M. L. Rustgi, P.T. Leung, S. A. Long

Physics Faculty Publications and Presentations

It is shown that the semirelativistic approach, when applied consistently to atomic calculations involving the Thomas-Reiche-Kuhn sum rule or its applications, may lead to very inaccurate results.