Bulletin of the American Physical Society
2013 Fall Meeting of the APS Division of Nuclear Physics
Volume 58, Number 13
Wednesday–Saturday, October 23–26, 2013; Newport News, Virginia
Session KB: Electroweak Interactions I |
Hide Abstracts |
Chair: Alejandro Garcia, University of Washington Room: Pearl Ballroom I |
Friday, October 25, 2013 2:00PM - 2:12PM |
KB.00001: An update on the analysis of the Princeton $^{19}$Ne beta asymmetry measurement Dustin Combs, Frank Calaprice, Gordon Jones, Robert Pattie, Albert Young We report on the progress of a new analysis of the 1994 $^{19}$Ne beta asymmetry measurement conducted at Princeton University. In this experiment, a beam of $^{19}$Ne atoms were polarized with a Stern-Gerlach magnet and then entered a thin-walled mylar cell through a slit fabricated from a piece of micro channel plate. A pair of Si(Li) detectors at either end of the apparatus were aligned with the direction of spin polarization (one parallel and one anti-parallel to the spin of the $^{19}$Ne) and detected positrons from the decays. The difference in the rate in the two detectors was used to calculate the asymmetry. A new analysis procedure has been undertaken using the Monte Carlo package \textsc{Penelope} with the goal of determining the systematic uncertainty due to positrons scattering from the face of the detectors causing the incorrect reconstruction of the initial direction of the positron momentum. This was a leading cause of systematic uncertainty in the experiment in 1994. [Preview Abstract] |
Friday, October 25, 2013 2:12PM - 2:24PM |
KB.00002: Magneto-Optical trapping developments for the $^6$He $\beta$-$\overline{\nu}$ angular correlation experiment D.W. Zumwalt, A. Garcia, R. Hong, Y. Bagdasarova, D.W. Storm, H.E. Swanson, F. Wauters, A. Knecht, X. Flechard, E. Liennard, O. Naviliat-Cuncic, P. Mueller, W. Williams, T. O'Connor, K. Bailey In the search for beyond the Standard Model contributions of tensor currents in the weak interaction, our group is seeking to measure the $\beta$-$\overline{\nu}$ angular correlation in the decay of $^6$He (t$_{1/2}$ $\sim$ 807 ms). We will measure the time of flight of recoil daughter $^6$Li ions as they fall through an electric field to kinematically reconstruct the relative angle of the $\beta$ and $\overline{\nu}$. This requires precise knowledge of the initial position of the decay, which we achieve by confining the $^6$He atoms to a small region with a magneto-optical trap (MOT). To lower the detection of background decays from untrapped $^6$He atoms, we perform a MOT-to-MOT transfer within $\sim$15~ms using a pulsed push beam through a conductance-limiting aperture tube to provide differential pumping between two MOT chambers. Transfer efficiencies exceeding 60\% have been achieved. Recent results will be presented. [Preview Abstract] |
Friday, October 25, 2013 2:24PM - 2:36PM |
KB.00003: Detector calibrations and systematic uncertainties of the precision measurement of $\beta-\bar\nu_e$ angular correlation coefficient in $^6$He decay Ran Hong, Yelena Bagdasarova, Kevin Bailey, Xavier Fl\'echard, Alejandro Garcia, Andreas Knecht, Etienne Liennard, Peter Mueller, Oscar Naviliat-Cuncic, Thomas O'Connor, Derek Storm, Erik Swanson, Frederik Wauters, William Williams, David Zumwalt Precision measurement of the $\beta-\bar\nu_e$ angular correlation coefficient a can be used for searching for tensor-type weak currents. We constructed a system which detects $\beta$-particles and recoil ions from the $\beta$-decay of magneto-optical-trapped $^6$He atoms in coincidence. The time-of-flight of the $^{6}{\rm Li}$ ions guided by an electric field onto a Micro Channel Plate detector will be measured and the coefficient a can be extracted. Calibrations of the $\beta$ and recoil-ion detectors as well as estimations of systematic uncertainties via Monte Carlo simulations will be presented. [Preview Abstract] |
Friday, October 25, 2013 2:36PM - 2:48PM |
KB.00004: Status update on $\beta$-$\nu$ correlation measurement in $\beta$-decay of $^{8}$B Adrian Perez Galvan Precise measurements of the $\beta$-$\nu$ angular correlation coefficient ($a_{\beta \nu}$) in $\beta$-decay provide information on the presence of possible exotic couplings in the weak interaction. The $^{8}$Li-$^{8}$B radioactive mirror nuclei represent a particularly attractive system for these studies due to their small masses, large $Q$-value, and a triple-correlation between the charged lepton and the two $\alpha$-particles coming from the decay of the daughter $^{8}$Be that allows the extraction of $a_{\beta \nu}$ with higher sensitivity. Furthermore, it is possible to perform tests of the existence of second-class-currents in the Standard Model and the conserved-vector-current hypothesis by comparing correlation measurements in $^{8}$Li and $^{8}$B. Our collaboration has already performed detailed studies of the angular correlation with a trapped sample of cold $^{8}$Li ions in the Beta-Decay Paul trap (BPT) at Argonne National Laboratory with an uncertainty below 1\%. In this talk we present performance tests of our experimental setup with observed decays of $^{8}$B at the BPT as well as the current status on the effort to achieve a measurement with comparable sensitivity. [Preview Abstract] |
Friday, October 25, 2013 2:48PM - 3:00PM |
KB.00005: Report on the Measurement of the Beta Asymmetry Parameter, $A_{\beta}$, of $^{37}$K Spencer Behling, M. Anholm, D. Ashery, J.A. Behr, I. Cohen, I. Craiciu, B. Fenker, A. Gorelov, G. Gwinner, L. Kurchaninov, K. Olchanski, M. Mehlman, D. Melconian, P.D. Shidling, S. Smale The standard model of particle physics (SM) makes a prediction for the observed angular asymmetry of the emitted $\beta$ particles coming from the $\beta$-decay of a spin polarized nucleus. The TRINAT collaboration based at TRIUMF has a well established program of measuring SM observables in the $\beta$-decay of alkali atoms confined in a magneto optical trap (MOT). Recently an experiment was performed to measure $A_{\beta}$ of $^{37}$K that had been trapped in a MOT and spin polarized via optical pumping. In preparation for this experiment the entire experimental apparatus, the nuclear detectors, the trapping and optical pumping schemes, and the data acquisition systems were upgraded. Details of the upgrades made to the experimental setup and preliminary results from the analysis of the $^{37}$K beta asymmetry data will be presented. [Preview Abstract] |
Friday, October 25, 2013 3:00PM - 3:12PM |
KB.00006: Beta-Neutrino Correlation Measurements in $^{37}$K Melissa Anholm, D. Ashery, I. Craiciu, S. Behling, B. Fenker, A. Gorelov, G. Gwinner, L. Kurchaninov, M. Mehlman, D. Melconian, K. Olchankski, P.D. Shidling, S. Smale, J.A. Behr The TRIUMF Neutral Atom Trap utilizes a unique set of techniques to obtain samples of cold, polarized atoms. We have been particularly interested in trapping $^{37}$K atoms, which decay by $\beta^{+}$ emission in a mixed Fermi/Gamow-Teller transition to their isobaric analog, $^{37}$Ar. Because the higher-order standard model corrections to this decay process are well understood, it is ideal for for improving constraints on interactions beyond the standard model. By observing the daughter particles, we are sensitive to possible scalar, tensor, and right-handed vector currents in a process that is known to be predominantly a left-handed form of the weak interaction. Observations of overdetermined kinematics in the ion and $\beta$ time-of-flight spectra allow us to reconstruct the neutrino flight paths, thereby providing an effective strategy for measuring the $\beta$-asymmetry parameter, the recoil asymmetry, the $\beta$-neutrino correlation, and the tensor alignment parameter. Here I focus primarily on the latter two. [Preview Abstract] |
Friday, October 25, 2013 3:12PM - 3:24PM |
KB.00007: Development of an Electrostatic Ion Beam Trap for the Study of Beta Decay Correlations Yuan Mei, Brian Fujikawa Precision measurements of beta decay correlation parameters, to the level of 0.1\% or better, can be used to test the Standard Model and to search for possible evidence of new physics such as Supersymmetry. We are developing an Electrostatic Ion Beam Trap (EIBT) to measure the beta-neutrino correlation parameter of short lived radioactive isotopes produced by the 88-inch Cyclotron. The EIBT uses two opposing sets of electrodes to create a parallel pair of electrostatic mirrors to confine ions. Position sensitive beta telescopes and microchannel plates will be used to record the beta and recoil nucleus, thus allowing the reconstruction of the momentum vectors of both the beta and recoil nucleus on an event-by-event basis. I will describe the EIBT and provide an update of the status of this program. [Preview Abstract] |
Friday, October 25, 2013 3:24PM - 3:36PM |
KB.00008: Report on current status of TAMUTRAP facility P.D. Shidling, M. Mehlman, S. Behling, Y. Boran, B. Fenker, D. Melconian The Texas A{\&}M University Penning Trap (TAMUTRAP) facility is currently under construction and will take advantage of the radioactive ion beams to become available when the upgrade to the Cyclotron Institute, Texas A{\&}M University, TAMU Re-accelerated Exotics (T-REX) is completed The primary goal of the TAMU-TRAP facility is to test the Standard Model (SM) for a possible admixture of a scalar (S) or tensor (T) type of interaction in T $=$ 2 superallowed beta delayed proton emitters. This information will be inferred from the shape of the observed proton energy spectrum. Additional goals for this facility are mass measurements, lifetime measurements, and ft values. The two main components in the TAMUTRAP facility are a radio-frequency quadrupole (RFQ) for cooling and bunching the ions and Penning trap system with two cylindrical Penning traps. Offline tests of the RFQ coupled to the injection optics has recently started, with beam being successfully injected into and extracted from the RFQ. Further tests are being performed in order to determine absolute efficiency of the RFQ and injection optics. Several additional parts of the TAMUTRAP beam line have also been fabricated and are being tested. A brief overview of the TAMUTRAP facility and its current status will be presented. [Preview Abstract] |
Friday, October 25, 2013 3:36PM - 3:48PM |
KB.00009: Kinetic energy of shakeoff atomic electrons from $^{37}$K $\beta^+$ decay J.A. Behr, A. Gorelov, C. Farfan, S. Smale, K. Olchanski, L. Kurchananov, M. Anholm, R.S. Behling, B. Fenker, P.D. Shidling, M. Mehlman, D. Melconian, D. Ashery, G. Gwinner We have measured the kinetic energies from 0 to 30 eV of atomic shakeoff electrons from the $\beta^+$ decay of $^{37}$K. Despite much experimental and theoretical work on the distribution of final ion charge states, shakeoff electrons from $\beta^-$ decay have only been measured with energies above 150 eV [Mitrokhovich, Nucl. Phys. Atom. Energy, 11 125 (2010)]. We use our magneto-optical trap's time-varying magnetic quadrupole field combined with a uniform electric field as a spectrometer. Our result has more 15 eV electrons than a model using the sudden approximation and hydrogenic wavefunctions [Levinger Phys. Rev. 90 11 (1958)]. The total energy carried away by electrons is, as expected, a negligible correction to superallowed Ft values. Understanding the energy of these low-energy electrons is important for their use in precision $\beta$ decay to select events coming from trapped atoms and start time-of-flight for the recoil ions. Our results could provide a benchmark for shakeoff electron calculations used for biological radiation damage [Lee, Comp. Math. Meth in Medicine doi:10.1155/2012/651475]. [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