Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session C9: SPS and Undergraduate Research I |
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Sponsoring Units: SPS Chair: Gary White, Society of Physics Students/American Institute of Physics Room: Hyatt Regency Jacksonville Riverfront City Terrace 5 |
Saturday, April 14, 2007 1:30PM - 1:42PM |
C9.00001: Precision atomic mass measurement of Xe-136 in a Penning trap Elizabeth Wingfield, Matthew Redshaw, Joseph McDaniel, Edmund Myers A Penning trap is a device that traps charged particles using a uniform magnetic field and the electric field produced by several electrodes. An ion placed in a magnetic field revolves at the cyclotron frequency given by fc = (1/2$\pi$)(qB/m) where B is the magnetic field and q and m are the charge and mass of the ion, respectively. After allowing for the electric field one can measure the mass of an ion by comparing its cyclotron frequency to that of an ion of known mass [1]. In my talk I will describe a recent mass measurement of Xe-136. The mass of Xe-136 is important to experimentalists attempting to observe neutrinoless double-beta decay. A peak in the electron's total-energy spectrum corresponding to its Q-value identifies this decay. With the mass now known to 0.1 part-per-billion the limitation in the efficiency due to the uncertainty in the mass of Xe-136 is eliminated [2]. \newline \newline [1] W.Shi, M.Redshaw, and E.G. Myers, Phys. Rev. A \textbf{72}, 022510 (2005). \newline [2] M. Redshaw, E.Wingfield, J. McDaniel, E.G. Myers. Accepted to Phys Rev. Lett. [Preview Abstract] |
Saturday, April 14, 2007 1:42PM - 1:54PM |
C9.00002: Simulation of the Lineshape Response of a Large NaI Detector Daniel Mittelberger, Gerald Feldman A Monte Carlo simulation of a high-resolution large-volume NaI detector has been created using the GEANT4 toolkit. This simulation models the components of the detector (a cylindrical core, four annular quadrants, and Pb shielding) and outputs the energy deposited in each NaI component to a file for analysis using the ROOT analysis package. To more accurately characterize the detector's intrinsic response, the simulation output is smeared using a Gaussian function which is determined by fitting the simulation to experimental in-beam data. Using this response function, the simulation can then model the detector lineshape for the scattering geometry with a carbon or liquid deuterium target using a tagged photon beam of variable energy. The effects of detector acceptance, finite target volume, and photon absorption in the target material are all taken into account. The comparison of the simulation to both in-beam and scattering data will be presented. [Preview Abstract] |
Saturday, April 14, 2007 1:54PM - 2:06PM |
C9.00003: Using MCNP for Compton Scattering Calculations with BGO Scintillators Jeremy Board, Phillip Womble, Alexander Barzilov Compton scattering is the process wherein photons scatter on the electrons within a material. In a detector, some of these scattered photons leave the detector with only part of their full energy. This creates a continuum which changes the signal to noise ratio with a gamma ray spectrum. For high resolution detectors such as high purity Ge (HPGe) solid state gamma ray detectors, a secondary detector surrounds the HPGe. The purpose of the secondary detector (made of a high Z material) is to detect the scattered photons. When both detectors have coincident photon events, a special circuit stops the data acquisition from acquiring the signal from the HPGe. Our goal is to design the optimal Compton ``suppressor'' using bismuth germinate scintillators for gamma rays whose energies are much larger than 1 MeV. Currently such suppressors are designed for energies less than 2 MeV. We are using the Monte Carlo N-particle code to calculate the amount of photon scattering in the HPGe into geometry of BGO surrounding the HPGe crystal. We are estimating both photon and electron fluence through the volume of BGO. [Preview Abstract] |
Saturday, April 14, 2007 2:06PM - 2:18PM |
C9.00004: ABSTRACT HAS BEEN MOVED TO R14.00008 |
Saturday, April 14, 2007 2:18PM - 2:30PM |
C9.00005: Lifetime Measurements and Deformation in $^{79}$Sr Y.K. Ryu, R.A. Kaye, S.R. Arora, S.L. Tabor, T. Baldwin, D.B. Campbell, C. Chandler, M.W. Cooper, C.R. Hoffman, J. Pavan, M. Wiedeking, J. D\"oring, Y. Sun, S.M. Gerbick, O. Grubor-Urosevic, L.A. Riley High-spin states in $^{79}$Sr were produced following the $^{54}$Fe ($^{28}$Si, 2pn) fusion-evaporation reaction using a beam energy of 90 MeV at the FSU Tandem-Linac facility, and the resulting de-exciting $\gamma $ rays were detected with the FSU Ge array of 10 Compton-suppressed detectors. The $^{54}$Fe target was thick enough so that all of the synthesized nuclei could stop completely in the target, resulting in Doppler-shifted $\gamma $-ray line shapes that could be analyzed using the Doppler-shift attenuation method. In all, 23 lifetimes were measured in three separate band structures using this method, and then used to infer transition quadrupole moments and quadrupole deformations using the rotational model. The results show good qualitative agreement with the predictions of both cranked Woods-Saxon and projected shell model calculations. The band based on a d$_{5/2}$ single-particle orbit, verified in this study through $\gamma -\gamma $ coincidences, intensity measurements, and directional correlation of oriented nuclei ratios, was found to have the largest average deformation ($\beta _{2,ave}$ = 0.41) among the three bands, in agreement with the calculations. [Preview Abstract] |
Saturday, April 14, 2007 2:30PM - 2:42PM |
C9.00006: Radar Detection of Meteors and Cosmic Rays John Marino With a simple experimental ensemble of a dipole antenna, a receiver, and a sound card attached to a PC, we are able to observe meteors and nearby aircraft, as well as cosmic ray candidates. We report on the operating characteristics of this ensemble, its performance, and its possible use as a relatively inexpensive cosmic ray detection device. [Preview Abstract] |
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