Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session ED: Mini-Symposium on Fundamental Symmetries (Proton/Neutron EDM and T-violation) |
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Chair: Koichiro Asahi, Tokyo Institute of Technology Room: Kohala 4 |
Thursday, October 9, 2014 7:00PM - 7:15PM |
ED.00001: The Storage Ring Proton EDM Experiment Yannis Semertzidis The storage ring pEDM experiment utilizes an all-electric storage ring to store $\sim 10^{11}$ longitudinally polarized protons simultaneously in clock-wise and counter-clock-wise directions for $10^{3}$ seconds. The radial E-field acts on the proton EDM for the duration of the storage time to precess its spin in the vertical plane. The ring lattice is optimized to reduce intra-beam scattering, increase the statistical sensitivity and reduce the systematic errors of the method. The main systematic error is a net radial B-field integrated around the ring causing an EDM-like vertical spin precession. The counter-rotating beams sense this integrated field and are vertically shifted by an amount, which depends on the strength of the vertical focusing in the ring, thus creating a radial B-field. Modulating the vertical focusing at 10kHz makes possible the detection of this radial B-field by a SQUID-magnetometer (SQUID-based BPM). For a total number of n SQUID-based BPMs distributed around the ring the effectiveness of the method is limited to the $N=n$/2 harmonic of the background radial B-field due to the Nyquist sampling theorem limit. This limitation establishes the requirement to reduce the maximum radial B-field to 0.1-1nT everywhere around the ring by layers of mu-metal and aluminum vacuum tube. The metho's sensitivity is $10^{-29}e \cdot \mbox{cm}$, more than three orders of magnitude better than the present neutron EDM experimental limit, making it sensitive to SUSY-like new physics mass scale up to 300 TeV. [Preview Abstract] |
Thursday, October 9, 2014 7:15PM - 7:30PM |
ED.00002: Fringe E-Fields of Flat and Cylindrical Deflectors in Electrostatic Charged Particle Storage Rings Eric Metodiev, Kevin Huang, Yannis Semertzidis, William Morse Analytic expressions for the potentials and fields of flat and cylindrical plates, including the fringe fields, are given. The analysis below extends and simplifies the current expression for the fields of flat plates and develops expressions for the fringe fields of cylindrical plates in terms of polar coordinates. The development of a FORTRAN program to output the field strength at a given location within the Proton Electric Dipole Moment (Proton EDM) ring is then described. Fourth-order Runge-Kutta integration is used to investigate the effect of fringe fields on particle and spin dynamics with precision tracking in the proposed Proton EDM experiment. [Preview Abstract] |
Thursday, October 9, 2014 7:30PM - 7:45PM |
ED.00003: Feasibility of maintaining in-plane polarization for a storage ring EDM search Edward Stephenson A search for an electric dipole moment (EDM) on charged particles using a storage ring requires beam polarization lifetimes approaching 1000 s for in-plane polarization. A feasibility study using beam bunching and sextupole field adjustment is underway with a 0.97-GeV/c vector-polarized deuteron beam at COSY. The polarimeter consists of a thick carbon target positioned at the edge of the beam and the EDDA scintillation detectors. The DAQ system assigns a clock time to each polarimeter event. Once calibrated against the RF-cavity, the clock time is used to select events associated with a maximal sideways polarization (precessing at 120 kHz). With this tool, the in-plane polarization magnitude is tracked versus time. Electron cooling reduces the depolarization from finite emittance and second-order momentum spread acting through synchrotron oscillations. Further lifetime improvement to the level of hundreds of seconds is achieved by adjusting sextupole fields located in the COSY ring arcs at places of large transverse beta functions and dispersion. The dependence of the reciprocal of the lifetime on sextupole field strength is nearly linear, permitting an easy location of the best field values. These typically occur near loci of zero chromaticity. [Preview Abstract] |
Thursday, October 9, 2014 7:45PM - 8:00PM |
ED.00004: Proposal of GEM-based position sensitive detector for the proton EDM measurement Seongtae Park, Yannis Semertzidis, Selcuk Haciomeroglu Since the first invention in 1997, Gas Electron Multiplier (GEM) detectors have been extensively studied for the use as calorimeters or position sensitive detectors in variety of fields. Its robustness against severe radiation environment and fast response time make it one of the best candidates for high rate measurement. Here we propose the GEM detectors as polarimeter detector for proton EDM (pEDM) measurement. In pEDM experiment, about 10$^{11}$ protons will be stored in the storage ring and 1{\%} of the particles will be scattered into detectors. The stored protons are slowly extracted in 1000 s. Based on this design we can estimate the detector rate has to be about \textgreater MHz. Since GEM is a gas detector with special geometric shape, it's time response is very fast ($\sim$ ns of rising time) and meets the requirement of the pEDM measurement. For the pEDM polarimeter, precise position sensing of the scattered protons is critical. The GEM detector can provide high flexibility in design and construction not only in detector's shape, but also in size and shape of the anode pads which collect signals which are directly connected to the spatial resolution of the detector. In this paper, we report the study results of the possibility of using GEM detectors for the pEDM measurement [Preview Abstract] |
Thursday, October 9, 2014 8:00PM - 8:15PM |
ED.00005: SQUID-based beam position monitoring for proton EDM experiment Selcuk Haciomeroglu One of the major systematic errors in the proton EDM experiment is the radial B-field, since it couples the magnetic dipole moment and causes a vertical spin precession. For a proton with EDM at the level of 10$^{-29}$ e.cm, 0.22 pG of B-field and 10.5 MV/m of E-field cause same vertical spin precession. On the other hand, the radial B-field splits the counter-rotating beams depending on the vertical focusing strength in the ring The magnetic field due to this split modulated at a few kHz can be measured by a SQUID-magnetometer. This measurement requires the B-field to be kept less than 1nT everywhere around the ring using shields of mu-metal and aluminum layers. Then, the SQUID measurements involve noise from three sources: outside the shields, the shields themselves and the beam. We study these three sources of noise using an electric circuit (mimicking the beam) inside a magnetic shielding room which consists two-layers of mu-metal and an aluminum layer. [Preview Abstract] |
Thursday, October 9, 2014 8:15PM - 8:30PM |
ED.00006: Non-metallic cryogenic sealing and actuating devices for systematic studies apparatus at NC State for the neutron Electric Dipole Moment Collaboration Austin Reid, Karen Daniels, Paul Huffman, Ekaterina Korobkina, Kent Leung, Mithi A. de los Reyes, Camen Royse We are developing a small-scale apparatus at NC State's ultracold neutron source to measure several systematic effects for the neutron electric dipole moment (nEDM) experiment. The apparatus will utilize both polarized 3He and UCN in the same measurement volume and allow one to measure the correlation functions that predict the geometric phase effect, optimize the parameters for critical dressing, and investigate the pseudomagnetic field caused by UCN scattering from polarized 3He. NMR techniques will be used to control the polarization of 3He and UCN, limiting the use of conducting material in the experimental volume. Due to this constraint we have developed nonmetallic detachable seals and a nonmetallic bellows that are superfluid helium tight. Kapton is flexible below 2K and can be folded with an origami pattern into a flexible and robust bellows capable of hundreds of actuation cycles without failure. Details of the apparatus as well as the bellows will be presented. [Preview Abstract] |
Thursday, October 9, 2014 8:30PM - 8:45PM |
ED.00007: He3 Correleation Function Research for nEDM Experiment at ORNL SNS Robert Dipert, Robert Golub, Haiyan Gao, Austin Reid, Pinghan Chu Seeking an upper limit of the Neutron Electric Dipole Moment (nEDM) is a test of CP violation beyond the Standard Model. The present nEDM upper limit is 3x10$^{-26}$ e cm. An experiment to be performed at the Oak Ridge National Lab (ORNL) SNS facility seeks to reach the 10$^{-28}$ e cm limit. At ORNL, $^3$He will be used as a comagnetometer, and polarization analyzer and detector. The systematic effects can be explored by measuring the position-position correlation function of $^3$He. We have developed theoretical expressions for the correlation function which differ from previous theories in the ballistic region. We have already measured into this region with X$_3$[He3:He4] molar concentration ratio as low as 10$^{-6}$. Limitations were the result of noise in the signal from copper around the cell and insufficient cooling. The apparatus formerly used has been updated to enable the testing of this theory in the transition between the diffuse (X$_3$ $>$ 4x10$^{-5}$) and ballistic (X$_3$ $<$ 8x10$^{-7}$) regions by removing the mentioned copper, updating cell design and facilitating lower temperatures ($\approx$300mK). [Preview Abstract] |
Thursday, October 9, 2014 8:45PM - 9:00PM |
ED.00008: Upscattering Cross Sections for Ultra Cold Neutrons from Gases Susan J. Seestrom The scattering of ultracold neutrons (UCNs) to energies above the escape potential of a trap is called upscattering. Upscattering due to interaction with residual gases is a potential loss mechanism for UCNs stored in a trap that can impact the extracted neutron lifetime. We have developed a method for measuring the cross sections for UCN upscattering from gases stored in a small measurement cell. Upscattered neutrons are measured directly in a $^{3}$He ionization chamber and transmitted UCN strike a $^{10}$B-coated surface at the edges of the measurement cell. The transmitted UCNs are then counted with a HPGe gamma-ray detector that counts 478 keV $\gamma$-rays from the$^{10}$B$(n,\alpha \gamma)^{7}$Li reaction. The analysis was guided by Monte Carlo descriptions of the LANL UCN source output. We will present cross sections measured for various noble and polyatomic gases, compare these results to calculated cross sections based on models of gas scattering kernels, and use these to estimate the impact of gas upscattering on the measurement of the neutron lifetime. [Preview Abstract] |
Thursday, October 9, 2014 9:00PM - 9:15PM |
ED.00009: Angular Distribution of Prompt Gamma-rays for the Study of the Breaking of Discrete Symmetries in Compound Neutron Resonance Katsuya Hirota, Hideo Harada, Takashi Ino, Atsushi Kimura, Masaaki Kitaguchi, Kenji Sakai, Hirohiko Shimizu The weak interaction contained in the nuclear interaction can be observed as the P-violating asymmetry of the neutron capture cross section. The discovery of large enhancement of the P-violating asymmetry in p-wave compound resonances led to a systematic survey in 1990's. The largest enhancement is almost 10$^{\mathrm{6}}$ compared with the nucleon-nucleon P-violating effect and the enhancement is explained as the interference between incident s- and p-wave amplitude. The mechanism of the P-violation has been proposed theoretically to be applicable to enhance the experimental sensitivity to breaking of the symmetry under the time-reversal operation. The enhancement of T-violation is given as $\Delta \sigma_{\mathrm{cp}}=\kappa $(j) ($\omega $/$\upsilon )$ $\Delta \sigma_{\mathrm{p}}$ where $\Delta \sigma_{\mathrm{cp}}$ and $\Delta \sigma _{\mathrm{p}}$ are the CP- and P-violation cross section, $\upsilon $ and $\omega $ are the weak and CP-violating interaction matrix elements between compound resonances with opposite parities, and $\kappa $(j) is the ratio of the spin dependent factor of CP- and P-violation. The determination of $\kappa $(j) is necessary to estimate the experimental sensitivity to T-violation. Therefore we measured the gamma ray angular distribution of radiative decay from compound resonances and evaluated the $\kappa $(j). [Preview Abstract] |
Thursday, October 9, 2014 9:15PM - 9:30PM |
ED.00010: Time-Reversal Invariance Violation in Neutron Scattering at Spallation Neutron Sources Vladimir Gudkov The Time Reversal Invariant Violating (TRIV) effects in neutron transmission through a nuclei target are discussed. We explore the possibility to search TRIV at new high flux Spallation Neutron Sources using two important advantages of neutron nuclei interactions: the possibility of an enhancement of T-violating observables by many orders of magnitude, and the relatively large number of the nuclear targets, which provides the assurance of avoiding possible ``accidental'' cancelations of TRI-violating effects due to unknown structural factors related to the strong interactions. This include the absence of final state interactions for a set of specific observables, the possibility to avoid of false asymmetries arising from combinations of time-reversal-invariant interactions and asymmetries in real experiment, and the comparison of expected results with existing limits on neutron, nuclear and atomic electric dipole moments (EDMs). It is shown that TRIV observables are complementary to the EDM experiments and have potential for essential improving of the current limits on the TRIV interactions. [Preview Abstract] |
Thursday, October 9, 2014 9:30PM - 9:45PM |
ED.00011: T-Violation experiment using polarized Li-8 at TRIUMF Jiro Murata The MTV experiment searching T-Violating electron transverse polarization in polarized nuclear beta decay at TRIUMF is running. The main electron tracking detector as a Mott polarimeter was upgraded from a planer drift chamber to a cylindrical drift chamber (CDC), which has been commissioned and tested. In this talk, preparation status of the next physics production using the CDC will be presented. [Preview Abstract] |
Thursday, October 9, 2014 9:45PM - 10:00PM |
ED.00012: Development of a new scintillation-trigger detector for the MTV experiment using aluminum-metallized film tape Yuko Sakamoto, Sachi Ozaki, Saki Tanaka, Ryosuke Tanuma, Tatsuru Yoshida, Jiro Murata A new type of trigger-scintillation counter array designed for the MTV experiment at TRIUMF-ISAC has been developed, using aluminum-metallized film tape for wrapping. The MTV experiment aims to perform the finest precision test of time reversal symmetry in nuclear beta decay. In that purpose, we search non-zero T-Violating transverse polarization of electrons emitted from polarized Li-8 nuclei. It uses a cylindrical drift chamber (CDC) as the main electron-tracking detector. The trigger-scintillation counter consists of 12-segmented 1mm thick 300mm long thin plastic scintillation counters. This counter is placed inside the CDC to generate a trigger signal. The required assembling precision of $+$-0.5mm was a tricky point when we tried to use conventional total reflection mode. Indeed, produce an air-layer surrounding the scintillating bar to keep good light transmission was the main issue. For this reason, we tried to use a new wrapping material made of metallized-aluminum tape, which has a good mirror-like reflecting surface on both sides of the tape. Through this report, we will compare detection efficiency and light attenuation between conventional and new wrapping materials. [Preview Abstract] |
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