Bulletin of the American Physical Society
78th Annual Meeting of the Southeastern Section of the APS
Volume 56, Number 9
Wednesday–Saturday, October 19–22, 2011; Roanoke, Virginia
Session BC: Nuclear Physics I |
Hide Abstracts |
Chair: Mark Pitt, Virginia Polytechnic Institute and State University Room: Crystal Ballroom C |
Thursday, October 20, 2011 8:30AM - 8:42AM |
BC.00001: A Study of the Ionization of Deuterium Gas by Pyroelectric Crystals Bryce Taylor, Stephen Shafroth, Werner Tornow Pyroelectric crystals produce a stream of electrons or positive ions when heated or cooled in a near-vacuum environment. We studied the behavior of these crystals in deuterium gas. We look at what portion of the positive ion beam consists of $D_2^+ $ and what portion is $D^+.$ Since $D_2^+ $ contains only half the energy of $D^+$ per deuterium atom after traversing a given potential difference, it has a notably lower cross-section for fusing than $D^+$ does, which lowers neutron yield. Looking at the equivalent dissociation question for $H_2 $ gas, we find that $<$0.1{\%} is ionized as $H^+$ based on magnetic deflection of the ions. Analogous results are assumed for $D_2$. Furthermore, we present a new phenomenon in which groups of positive ions arrive at the detector at the same time similar to multiple peaks present in electron spectra reported by Brownridge and Shafroth.\footnote{J. D. Brownridge, S. M. Shafroth, D. Trott, B. Stoner, and W. Hooke, Appl. Phys. Lett. \textbf{78}, 1158 (2001)} We provide a new theory on the workings of pyroelectric crystals based on the expulsion of gas trapped inside the crystal to explain these findings and other results. Funding provided by grant DOE DE-FG52-09NA29465. [Preview Abstract] |
Thursday, October 20, 2011 8:42AM - 8:54AM |
BC.00002: ABSTRACT WITHDRAWN |
Thursday, October 20, 2011 8:54AM - 9:06AM |
BC.00003: $N \rightarrow \Delta$ Asymmetry at Low $Q^2$ John Leacock The Qweak collaboration at Jefferson Lab is determining the weak charge of the proton. This is done by measuring the parity-violating asymmetry of polarized electrons scattered elastically from the proton at a low $Q^2$ of 0.026 $(GeV/c)^2$. The measured asymmetry is partially diluted by polarized electrons inelastically scattered off the proton. Some Qweak experiment running time was used to measure the asymmetry in the inelastic region, which is dominated by the $N \rightarrow \Delta$ transition. In addition to constraining backgrounds for Qweak the $N \rightarrow \Delta$ asymmetry measurement is sensitive to a weakly constrained and theoretically uncertain low energy constant $d_{\Delta}$. The term involving $d_{\Delta}$ (the ``Siegert'' term) is non-vanishing in the limit $Q^2 \rightarrow 0$, thus it can dominate the asymmetry at low $Q^2$. This hadronic electroweak radiative correction is driven by the same matrix element responsible for the large SU(3) breaking effects observed in hyperon decays. An update on the analysis will be presented. [Preview Abstract] |
Thursday, October 20, 2011 9:06AM - 9:18AM |
BC.00004: Inclusive DIS: Target Normal Single-Spin Asymmetry Tim Holmstrom An experiment (E07--013) to measure the target normal single spin asymmetry $A^n_N$ in inclusive deep-inelastic $n^{\uparrow}(e,e')$ reaction with a vertically polarized $^3$He target has completed data collection during Jefferson Lab's Hall A neutron transversity experiment (E06--010). The expected accuracy of this measurement is $\delta A^n_N = 3 \times 10^{-3}$. There are no previous measurements of this asymmetry on the neutron. The target normal spin asymmetry in DIS probes helicity--flip amplitudes at the quark level that are related to effects beyond the leading-twist picture of DIS. In view of the predicted rapid variation of the asymmetry between $10^{-2}$ (exclusive) and $10^{-4}$ (DIS-inclusive), a non-zero measurement would be sensitive to the transition from hadronic to partonic degrees of freedom. The status and perspectives of the data analysis will be discussed. [Preview Abstract] |
Thursday, October 20, 2011 9:18AM - 9:30AM |
BC.00005: Helicity-Correlated Systematics in the Q$_{weak}$ Experiment Joshua Hoskins The Q$_{weak}$ experiment at Jefferson Laboratory will provide a 4\% measurement of the proton's weak charge Q$_{w}^{p}$, using parity-violating electron scattering from Hydrogen at low momentum transfer. The experiment will measure a tiny parity-violating asymmetry $\sim$256 parts per billion, which means control and precise measurement of systematic errors is a must. While great care is being taken to suppress or eliminate helicity-correlated changes in electron beam properties at the source, broken symmetries in the experimental apparatus can produce false asymmetries in the detected signal. For Q$_{weak}$ we measure the detector sensitivities $\partial$A/$\partial$x$_{i}$ (i = 1..5) for first order offline correction of beam-related false asymmetries, using both regression against natural beam motion and a driven modulation system. I will discuss the methodology and status of the helicity-correlated detector sensitivities and how they relate to a precision measurement Q$_{weak}$. [Preview Abstract] |
Thursday, October 20, 2011 9:30AM - 9:42AM |
BC.00006: M{\o}ller Polarimetry for the Qweak Experiment Joshua Magee The Standard Model of particle physics has been extremely successful in describing particle interactions in a wide-ranging regime of energy scales. Low-energy, parity-violating experiments enable high-precision experimental tests of Standard Model predictions. Currently, Jefferson Lab is performing one such investigation to determine the weak charge of the proton, Qweak, to 4\% precision using ep scattering. By making a precise measurement of the weak charge, this experiment will provide tighter constraints on some classes of ``new physics'' at 2 TeV or higher. To calculate the parity-violating asymmetry and determine Qweak one needs precise knowledge of the incoming electron beam polarization. The Qweak experiment, which is underway in Jefferson Lab's Hall C, uses both M{\o}ller and Compton polarimetry to determine the 1 GeV beam polarization. The Hall C M{\o}ller polarimeter is particularly relevant as it uses a superconducting magnet to saturate thin, pure iron, foils out of plane. This provides precise measurements of beam polarization to within 1\% uncertainty. Since the addition of the Compton device the M\o ller polarimeter has undergone a re-commissioning phase, followed by myriad studies to reduce the systematic errors to the 0.57\% level required by Qweak. A brief overview of the Hall C M{\o}ller device, followed by preliminary results of these studies and of the Spring 2011 experiment run, will be provided. [Preview Abstract] |
Thursday, October 20, 2011 9:42AM - 9:54AM |
BC.00007: A Diamond Micro-strip Electron Detector for Compton Polarimetry Amrendra Narayan, Vladas Tvaskis, Dipangkar Dutta, Jeffery Martin The Qweak experiment in Hall C at Jefferson Lab aims to measure the weak charge of the proton with a precision of 4.1{\%} by measuring the parity violating asymmetry in polarized electron-proton elastic scattering. Beam polarimetry is the largest experimental contribution to the error budget. A new Compton polarimeter was installed for a non-invasive and continuous monitoring of the electron beam polarization with a goal of 1{\%} systematic and 1{\%} per hour statistical precision. The Compton-scattered electrons are detected in four planes of diamond micro-strip detectors. These detectors are read out using custom built electronic modules that include a pre-amplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use Field Programmable Gate Array based general purpose logic modules for event selection and histogramming. The polarimeter was commissioned during the first run period of the Qweak experiment. We will show the preliminary results from the electron detector obtained during the first run period of Qweak experiment. [Preview Abstract] |
Thursday, October 20, 2011 9:54AM - 10:06AM |
BC.00008: Sticky Dark Matter in the Effective Field Theory Approach Andriy Badin, Alexey Petrov There is experimental evidence that Dark Matter (DM) makes up about 25\% of the Universe's mass and is expected to be nonrelativistic in most models. We explore the possibility of the creation and existence of a bound state of Dark Matter and standard model (SM) particles. Such bound states can potentially be created and detected during direct DM search experiments (DAMA, CDMS, XENON etc.). We work in a model-independent approach to determine conditions under which such bound states can be created. Our results appear to be dependent upon the nuclei used in the DM direct detection experiments. In this scenario we determine the region of DM parameter space that provides a simultaneous fit to DAMA and CDMS data. [Preview Abstract] |
Thursday, October 20, 2011 10:06AM - 10:18AM |
BC.00009: Hadronic loop correction of charmonium decays Di-Lun Yang Recently, the effect of next leading order correction from intermediate hadronic loops to the charmonium decays has been widely studied. However, the coupling constants of the charmonium multiplets and heavy mesons cannot be directly measured from experiments. In this talk, we will present the investigation of hadronic loop correction to both hadronic decays and radiative decays of the lowest excited states of charmonia and try to extract the reasonable coupling constants. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700