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 CD: Mini-Symposium on Fundamental Symmetries (Atomic EDM) |
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Chair: Harvey Gould, Lawrence Berkeley National Laboratory Room: Kohala 4 |
Wednesday, October 8, 2014 7:00PM - 7:30PM |
CD.00001: TBD Invited Speaker: Vincenzo Cirigliano |
Wednesday, October 8, 2014 7:30PM - 7:45PM |
CD.00002: Prospects for electric-dipole-moment measurements in radon Timothy Chupp A permanent electric dipole moment (EDM) of a particle or system would arise due to breaking of time-reversal, or equivalently CP symmetry. Experiments to date on the neutron, atoms and molecules have only set upper limits on EDMs. New techniques and systems in which the effects of CP violation would be greatly enhanced are driving the field forward. Systems that may be favorable for significant advances include $^{221,223}$Rn, where the combination of octupole collectivity and relatively closely spaced opposite parity levels would increase the nuclear Schiff moment by one or more orders of magnitude compared to other diamagnetic atoms, i.e. $^{199}$Hg. We have developed and tested at TRIUMF-ISAC an on-line EDM experiment that will collect and make measurements on the short-lived species ($T_{1/2}\approx$ 25 m) featuring high-efficiency collection and spin-exchange polarization of noble-gas isotopes. Nuclear-structure issues include determining the octupole collectivity as well as the spacing of opposite parity levels. Experiments are underway at ISOLDE, NSCL and ISAC to study the nuclear structure of isotopes in this mass region. I will report on progress and comment on how we learn about the basic physical parameters of CP violation from EDM measurements. [Preview Abstract] |
Wednesday, October 8, 2014 7:45PM - 8:00PM |
CD.00003: A New Search for the Atomic EDM of $^{129}$Xe at FRM-II (Munich Research Reactor) Jaideep Singh, Peter Fierlinger, Eva Kraegeloh, Florian Kuchler, Tobias Lins, Mike Marino, Jonas Meinel, Benjamin Neissen, Stefan Stuiber, Martin Burghoff, Isaac Fan, Wolfgang Kilian, Silvia Knappe-Grueneberg, Allard Schnabel, Frank Seifert, Lutz Trahms, Jens Voigt, Tim Chupp, Skyler Degenkolb, Fei Gong, Natasha Sachdeva, Earl Babcock Electric dipole moments (EDMs) arise due to the breaking of time-reversal or, equivalently, $CP$-symmetry. Although all searches have so far only set upper limits on EDMs, the motivation for more sensitive searches is stronger than ever. The present limit of $6\times 10^{-27}$ $e*$cm (95\% CL) for the $^{129}$Xe EDM helps constrain $CP$-violating parameters within nuclei. A new effort at FRM-II incorporating a $^3$He comagnetometer can potentially improve this limit by over three orders of magnitude. The noble gas mixture is polarized by spin-exchange optical pumping and then transferred into a high-performance magnetically shielded room. A SQUID magnetometer array measures the precession frequencies in the presence of applied electric- \& magnetic-fields. Recent test runs indicate that the experiment is capable of an EDM sensitivity of $10^{-28}$ $e*$cm in one day. [Preview Abstract] |
Wednesday, October 8, 2014 8:00PM - 8:15PM |
CD.00004: Experimental search for EDM in diamagnetic atom $^{129}$Xe using active nuclear spin maser Yuichi Ichikawa, Tomoya Sato, Yuichi Ohtomo, Yu Sakamoto, Shuichiro Kojima, Chikako Funayama, Chika Hirao, Takahiro Suzuki, Masatoshi Chikamori, Eri Hikota, Hirokazu Miyatake, Tsubasa Nanao, Kunifumi Suzuki, Masato Tsuchiya, Takeshi Inoue, Takeshi Furukawa, Akihiko Yoshimi, Christopher Bidinosti, Takashi Ino, Hideki Ueno, Yukari Matsuo, Takeshi Fukuyama, Koichiro Asahi A permanent electric dipole moment (EDM) which directly means $T$-violation attracts much attention, because an unknown \textit{CP}-violating phase which is necessary to understand the present matter-dominated Universe is expected to be probed by EDM. The present study aims at measuring the EDM in the diamagnetic atom $^{129}$Xe to a size of 10$^{-28}$ $e$cm, stepping into a domain below the present upper limit by one order of magnitude. In the present experiment, we employ an active nuclear spin maser which has characteristics of the optical detection of the spin precession and the artificial production of the feedback field to sustain the spin precession over a long measurement duration. For the magnetometry in the measurement, a comagnetometer using $^{3}$He is incorporated to the spin maser system. In this presentation, the current status of our experiment will be given. [Preview Abstract] |
Wednesday, October 8, 2014 8:15PM - 8:30PM |
CD.00005: Progress of the $^{129}$Xe EDM search using active feedback nuclear spin maser Tomoya Sato, Yuichi Ichikawa, Yuichi Ohtomo, Yu Sakamoto, Shuichiro Kojima, Chikako Funayama, Takahiro Suzuki, Masatoshi Chikamori, Eri Hikota, Masato Tsuchiya, Takeshi Furukawa, Akihiro Yoshimi, Christopher Bidinosti, Takashi Ino, Hideki Ueno, Yukari Matsuo, Takeshi Fukuyama, Koichiro Asahi A permanent electric dipole moment (EDM) of a particle is an extremely sensitive probe for physics beyond the Standard Model. The objective of the present study is to search for the $^{129}$Xe EDM at a level of 10$^{-28}$ $e$cm, beyond the current upper limit. In this experiment, an active-feedback nuclear spin maser is employed to achieve a precision measurement. Systematic instability sets a limit on the precision in our study. Co-magnetometry using $^{3}$He spin maser was incorporated into the maser system to eliminate the frequency drift caused by magnetic field fluctuations. Moreover, a double-cell geometry with linearly polarized laser was introduced to reduce frequency drifts arising from contact interactions with polarized Rb atoms. Having integrated these improvements, the $^{3}$He/$^{129}$Xe dual spin maser was successfully operated. In the presentation, recent progress will be reported, including an analysis of spin maser frequencies, a study of electrode designs, and an estimation of possible systematic uncertainties. [Preview Abstract] |
Wednesday, October 8, 2014 8:30PM - 8:45PM |
CD.00006: Performance of an active nuclear spin maser with double-cell geometry Shuichiro Kojima, Tomoya Sato, Yuichi Ichikawa, Yuichi Ohtomo, Yu Sakamoto, Chikako Funayama, Takahiro Suzuki, Masatoshi Chikamori, Eri Hikota, Masato Tsuchiya, Takeshi Furukawa, Akihiro Yoshimi, Christopher Bidinosti, Takashi Ino, Hideki Ueno, Yukari Matsuo, Takeshi Fukuyama, Koichiro Asahi A permanent electric dipole moment (EDM) violates $T$-invariance and, through the \textit{CPT} theorem, its magnitude~sets limits on \textit{CP}-violation phases beyond the Standard Model. We aim to search for an EDM in $^{129}$Xe beyond the present upper limit at the level of 10$^{-28} e$cm. We use an active nuclear spin maser in order to achieve a precession frequency precision of 1 nHz in an applied electric field of 10 kV/cm. A co-magnetometer using $^{3}$He and a double-cell geometry have been incorporated into our setup in order to reduce systematic uncertainties. The Rb polarization causes shifts in the frequencies for $^{129}$Xe and $^{3}$He precession. The frequency shift for $^{129}$Xe cannot be canceled out by this type of co-magnetometer because the $^{129}$Xe-Rb coupling differs significantly from that of $^{3}$He-Rb one. We found that in the double-cell geometry, the dominant contribution to the frequency shift from the Rb polarization occurs in the pumping cell We attempt to clarify the mechanism and to reduce the frequency shift. [Preview Abstract] |
Wednesday, October 8, 2014 8:45PM - 9:00PM |
CD.00007: Performance check of cell with newly designed electrode for $^{129}$Xe EDM measurement Yu Sakamoto, Christopher Bidinosti, Yuichi Ichikawa, Tomoya Sato, Yuichi Ohtomo, Shuichiro Kojima, Chikako Funayama, Takahiro Suzuki, Masato Tsuchiya, Takeshi Furukawa, Akihiro Yoshimi, Takashi Ino, Hideki Ueno, Yukari Matuo, Takeshi Fukuyama, Koichiro Asahi A permanent electric dipole moment (EDM) can be detected as a difference between the spin precession frequencies measured with an electric field applied parallel and antiparallel to a magnetic field. We aim to make a measurement of the $^{129}$Xe EDM at a level of d$\sim$10$^{-28}$ ecm by using a nuclear spin maser. The amplitude of the maser signal is proportional to the nuclear spin polarization. The polarization of $^{3}$He that acts as a co-magnetometer, is sensitive to the interactions with the electrodes used to generate the electric field. Previously, we used a transparent electrode made of ITO (Indium Tin Oxide) to allow transmission linearly polarized laser light into the cell. However, $^{3}$He polarization in a cell with such electrodes was measured to be $\sim$ 0.1{\%}, which is ten times smaller than no electrodes. In order to solve the problem, we adopted an electrode made from a mesh of Molybdenum. The geometry also reduces the contact area between $^{3}$He gas and the electrode. We measured $^{3}$He polarization at a cell with the mesh electrode by means of adiabatic fast passage NMR. [Preview Abstract] |
Wednesday, October 8, 2014 9:00PM - 9:15PM |
CD.00008: Development of a high intensity laser for efficient spin exchange optical pumping in a spin maser measurement of the $^{129}$Xe EDM Chikako Funayama, Takeshi Furukawa, Tomoya Sato, Yuichi Ichikawa, Yuichi Ohtomo, Yu Sakamoto, Shuichiro Kojima, Takahiro Suzuki, Masatoshi Chikamori, Eri Hikota, Masato Tsuchiya, Akihiro Yoshimi, Christopher Bidinosti, Takashi Ino, Hideki Ueno, Yukari Matsuo, Takeshi Fukuyama, Koichiro Asahi We aim to search for an atomic electric dipole moment (EDM) in $^{129}$Xe beyond the present upper limit at the level of 10$^{-28} \quad e$cm. The enhancement of the spin polarization through the efficient spin-exchange optical pumping process is important for stable maser operation. Previously, a distributed feedback (DFB) laser and a spatially separated tapered amplifier (TA) were used for the optical pumping. The characteristics of the TA-DFB laser, such as its narrow line width and high frequency stability, enable us to produce a large spin polarization. However, the power of the TA-DFB laser was not sufficient for stable operation of the $^{3}$He spin-maser comagnetometer. Recently, we have been preparing a new laser system containing an external cavity laser diode (ECLD) and a more intense TA for more efficient pumping. In the presentation, we discuss the Rb and noble gases polarizations achieved with our new ECLD compared to that with the DFB laser, and evaluate the advantages gained by employing the ECLD. [Preview Abstract] |
Wednesday, October 8, 2014 9:15PM - 9:30PM |
CD.00009: Estimation of Schiff moments using the nuclear shell model Eri Teruya, Naotaka Yoshinaga, Ryoichi Arai, Koji Higashiyama The existence of finite permanent electric dipole moment (EDM) of an elementary particle or an atom indicates violation of time-reversal symmetry. The time reversal invariance implies violation of charge and parity symmetry through the CPT theorem. The predicted fundamental particle's EDMs are too small to be observed in the Standard Model. However, some models beyond the Standard Model produce much larger EDMs which may be observed in future. Thus, if we observe finite EDMs, we can conclude that we need a new extended model for the Standard Model and the specific value of an EDM gives a constraint on constructing a new model. Experimental efforts searching for atomic EDMs are now in progress. The EDM of a neutral atom is mainly induced by the nuclear Schiff moment, since the electron EDM is very small and the nuclear EDM is shielded by outside electrons owing to the Schiff theorem. In this work we estimate the Schiff moments for the lowest 1/2$^{\mathrm{+}}$ states of Xe isotopes around the mass 130. The nuclear wave functions beyond mean-field theories are calculated in terms of the nuclear shell model. We discuss influences of core excitations and over shell excitations on the Schiff moments. [Preview Abstract] |
Wednesday, October 8, 2014 9:30PM - 9:45PM |
CD.00010: Studies of the $^{198}$Hg(d,d$^{\prime}$) and $^{198}$Hg(d,p) reactions A. Diaz Varela, P.E. Garrett, V. Bildstein, A.T. Laffoley, A.D. MacLean, E.T. Rand, C.E. Svensson, G.C. Ball, T. Faestermann, R. Hertenberger, H.-F. Wirth Limits on the electric dipole moment (EDM) continue to decrease for $^{199}$Hg, the most stringent upper limit for a nuclear EDM to date. The experimental limit on the observed atomic EDM for $^{199}$Hg is converted to limits on fundamental CP-odd interactions via a calculation of the nuclear Schiff moment, requiring knowledge of the nuclear structure of $^{199}$Hg. The $E3$ and $E1$ strength distributions to the ground state of $^{199}$Hg, and $E2$ transitions amongst excited states, would be ideal information to further constrain $^{199}$Hg Schiff moment theoretical models. The high level density of $^{199}$Hg makes those determinations challenging, however similar information can be obtained from exploring surrounding even-even Hg isotopes. As part of a campaign to study the Hg isotopes near $^{199}$Hg, two reactions, $^{198}$Hg(d,d$^{\prime})^{198}$Hg and $^{198}$Hg(d,p)$^{199}$Hg were studied using the Q3D spectrograph at the Maier-Leibnitz Laboratory (MLL) at Garching, Germany. A 22 MeV deuterium beam was used to impinge a $^{198}$Hg$^{32}$S target. The (d,d$^{\prime}$) reaction allows us to probe the desired $E2$ and $E3$ matrix elements, while the (d,p) reaction provides information on the neutron single-particle states of $^{199}$Hg. [Preview Abstract] |
Wednesday, October 8, 2014 9:45PM - 10:00PM |
CD.00011: Investigation of the E2 and E3 matrix elements in $^{200}$Hg using direct nuclear reactions Evan Rand, Vinzenz Bildstein, Alejandra Diaz Varela, Paul Garrett, Baharak Hadinia, Drew Jamieson, Badamsambuu Jigmeddorj, Alex Laffoley, Kyle Leach, Andrew MacLean, Carl Svensson, Gordon Ball, Thomas Faestermann, Ralf Hertenberger, Hans-Friedrich Wirth To date, $^{199}$Hg provides the most stringent limit on an atomic electric dipole moment (EDM). The existence of a permanent EDM would be a clear signal of CP violation from new physics beyond the Standard Model. Theoretical nuclear-structure calculations for $^{199}$Hg are challenging, and give varied predictions for the excited-state spectrum. Understanding the E2 and E3 strengths in $^{198,199,200}$Hg will make it possible to develop a nuclear structure model for the Schiff strength based on these matrix elements, and thereby constrain present models that predict the contribution of octupole collectivity to the Schiff moment of the nucleus. This work comprises two experiments using the Q3D magnetic spectrograph at the Maier-Leibnitz Laboratory. These experiments utilized a 22~MeV deuteron beam incident on a target of $^{200}$Hg$^{32}$S. The first experiment accesses the E2 and E3 matrix elements in $^{200}$Hg via inelastic deuteron scattering. The second experiment, $^{200}$Hg$(d,t)^{199}$Hg, yields important information on the single-particle nature of $^{199}$Hg. Preliminary results will be presented. [Preview Abstract] |
Wednesday, October 8, 2014 10:00PM - 10:15PM |
CD.00012: Nuclear electric dipole moment of 3-body systems in the Gaussian expansion method Nodoka Yamanaka, Emiko Hiyama The nuclear electric dipole moment is a very sensitive probe of CP violation beyond the standard model, and for light nuclei, it can be evaluated accurately using the few-body calculational methods.In this work, we evaluate the electric dipole moment of 3-body nuclear systems using the Gaussian expansion method with the Av8 nuclear force, and assuming the one-meson exchange model for the P, CP-odd nuclear force. [Preview Abstract] |
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