### Session EK: Mini-Symposium on Probing Fundamental Symmetries with Nuclei, Neutrons, Muons, and Atoms III

Chair: Stuart Freedman, Lawrence Berkeley National Laboratory
Room: Queens 5

 Friday, October 16, 2009 9:00AM - 9:30AM EK.00001: Testing the CPT symmetry using slow antiprotons Invited Speaker: Ryugo Hayano In this antimatter'' overview talk, I will cover the following topics: (1) Why antimatter experiments are important? (2) CERN's antiproton decelerator (AD), and the goals of the major experiments in the AD hall. (3) Antiprotonic helium laser spectroscopy pursued by the ASACUSA collaboration. In a series of measurements, the antiproton- to-electron mass ratio was determined to the level of $2\times 10^{-9}$. In addition to being one of the most stringent CPT-symmetry tests, the antiprotonic-helium results now contribute to the CODATA recommended values of the fundamental physical constants. (4) Production and detection of antihydrogen by ATHENA, ATRAP and ALPHA collaborations. For example, in ATHENA (in 2002), some 100 antihydrogen atoms per second were produced by mixing $10^8$ positrons with $10^4$ antiprotons in a nested'' Penning trap. The next step is to confine them in a magnetic trap, but despite more then 5 years of hard work, antihydrogen trapping has not yet been successful. I will discuss why this is difficult, based on a recent re-analysis of the ATHENA data. (5) Production of ultra low energy antiprotons in ASACUSA, and future possibilities with the ELENA (extremely low energy antiproton ring). Friday, October 16, 2009 9:30AM - 9:45AM EK.00002: T-violation experiment using polarized 8Li at KEK-TRIAC and TRIUMF-ISAC Etsuko Seitaibashi If electrons emitted from polarized nuclei have non-zero transverse polarization, time reversal symmetry is broken. In order to search the electron transverse polarization, we have performed an experiment after developing an electron-transverse-polarimeter using a multi-wire-drift-chamber (MWDC). The electron transverse polarization can be determined by measuring Mott scattering angular distributions from a thin metal foil. A physics data taking run was performed in September 2008 at KEK-TRIAC. We have successfully reconstructed the Mott scattered electron tracks. From later year 2009, a new experiment is going to be performed at TRIUMF-ISAC. Since the beam intensity and polarization are a greatly increased, a significant improvement can be expected. In this presentation, the development status and the expected results of the TRIUMF experiment will be reported. Friday, October 16, 2009 9:45AM - 10:00AM EK.00003: New mechanism of phase enhancement in neutron interferometry and exotic'' interactions Vladimir Gudkov The possibility to search for anomalous gravitational'' interactions in neuron interferometric experiments has been recently considered for cold [1] and ultra cold [2] neutrons, where it was shown a very large contribution to the phase of neutron wave function from these anomalous interactions. To understand the origin of this phase enhancement, we consider one dimensional Schr\"{o}dinger equation which describes neutron propagation through materials. It is shown that in many cases this Schr\"{o}dinger equation can be transformed into Hill's equation, and/or, under some conditions, into Heun's and Mathieu's equations. The asymptotic solution of the considered equations shows that the contribution of weak exotic interactions to the phase of propagated neutrons is accumulated with a distance exponentially rather than linearly. This can lead to rather large enhancement factor for a contribution of these interactions into neutron phase. Using perturbation theory approach, one can see that this enhanced phase is also proportional to the value of neutron wavelength. This explains why one can see the phase enhancement only with very cold neutrons. \\[4pt] [1] G. L. Greene and V. Gudkov, Phys. Rev. C 75, 015501 (2007).\\[0pt] [2] V. Gudkov, H. M. Shimizu and G. L. Greene, NIM A (2009), in press. Friday, October 16, 2009 10:00AM - 10:15AM EK.00004: A study of liquid helium scintillation in the presence of an electric field for the nEDM experiment Takeyasu Ito , S. Clayton , J. Ramsey , M. Karcz , C.-Y. Liu , J. Long , H.-O. Meyer , G. Reddy The nEDM experiment, currently being developed to be constructed at the Fundamental Neutron Physics Beamline at Oak Ridge National Laboratory, will search for the neutron electric dipole moment (EDM) with a sensitivity roughly two orders of magnitude better than the current limit. In neutron EDM searches, the signature of an EDM appears as a shift in the neutron spin precession frequency upon an application of an electric field for neutrons precessing in a weak magnetic field. In the nEDM experiment, the neutron precession will be measured with respect to that of polarized $^{3}$He atoms, which will occupy the same volume as the neutrons and act as a co-magnetometer. Liquid helium (LHe) scintillation from the spin dependent $^{3}$He(n,p)t reaction will be used to determine the n-$^{3}$He precession frequency difference. The existing data on LHe scintillation in an electric field do not cover the expected electric field and operating temperature of the nEDM experiment. We measured the LHe scintillation yield dependence on the electric field strength up to $\sim$45 kV/cm in the temperature range of 0.2-1.1K at the saturated vapor pressure. In this talk, the results of the measurements will be presented, along with their implication for the nEDM experiment. Friday, October 16, 2009 10:15AM - 10:30AM EK.00005: Polarized $^{3}$He in the Neutron Electric Dipole Moment Experiment Jacob Yoder In the neutron electric dipole moment (nEDM) experiment to be performed using the Fundamental Neutron Physics Beamline at the Spallation Neutron Source, ultra-cold neutrons (UCN) are produced by interaction with superfluid $^{4}$He. The precession frequency of polarized UCN in the presence of a strong electric field is measured using a spin-dependent capture reaction on polarized $^{3}$He; the protons and tritons produced in the reaction are detected via the scintillation light they produce in the superfluid $^{4}$He. In this talk, the production of polarized $^{3}$He, its introduction into the superfluid $^{4}$He, its relaxation in interactions with the materials of the experiment, its transport to the measurement cells and eventual removal from the system will be discussed. Friday, October 16, 2009 10:30AM - 10:45AM EK.00006: Measurement of Systematic Error Effects for a Sensitive Storage Ring EDM Polarimeter Astrid Imig , Edward Stephenson The Storage Ring EDM Collaboration was using the Cooler Synchrotron (COSY) and the EDDA detector at the Forschungszentrum J\"{u}lich to explore systematic errors in very sensitive storage-ring polarization measurements. Polarized deuterons of 235 MeV were used. The analyzer target was a block of 17 mm thick carbon placed close to the beam so that white noise applied to upstream electrostatic plates increases the vertical phase space of the beam, allowing deuterons to strike the front face of the block. For a detector acceptance that covers laboratory angles larger than 9 $^{\circ}$, the efficiency for particles to scatter into the polarimeter detectors was about 0.1{\%} (all directions) and the vector analyzing power was about 0.2. Measurements were made of the sensitivity of the polarization measurement to beam position and angle. Both vector and tensor asymmetries were measured using beams with both vector and tensor polarization. Effects were seen that depend upon both the beam geometry and the data rate in the detectors. Friday, October 16, 2009 10:45AM - 11:00AM EK.00007: Modeling Systematic Error Effects for a Sensitive Storage Ring EDM Polarimeter Edward Stephenson , Astrid Imig The Storage Ring EDM Collaboration has obtained a set of measurements detailing the sensitivity of a storage ring polarimeter for deuterons to small geometrical and rate changes. Various schemes, such as the calculation of the cross ratio [1], can cancel effects due to detector acceptance differences and luminosity differences for states of opposite polarization. Such schemes fail at second-order in the errors, becoming sensitive to geometrical changes, polarization magnitude differences between opposite polarization states, and changes to the detector response with changing data rates. An expansion of the polarimeter response in a Taylor series based on small errors about the polarimeter operating point can parametrize such effects, primarily in terms of the logarithmic derivatives of the cross section and analyzing power. A comparison will be made to measurements obtained with the EDDA detector at COSY-J\"{u}lich. \\[4pt] [1] G.G. Ohlsen and P.W. Keaton, Jr., NIM \textbf{109}, 41 (1973). Friday, October 16, 2009 11:00AM - 11:15AM EK.00008: Development of Rb atomic magnetometer for EDM experiment with $^{129}$Xe spin maser Akihiro Yoshimi , Koichiro Asahi , Takeshi Inoue , Makoto Tsuchiya , Makoto Uchida , Takeshi Furukawa We have been investigating the frequency stability of the low-frequency nuclear spin maser with $^{129}$Xe aiming at EDM (permanent Electric Dipole Moment) experiment. One of the main sources for this frequency instability comes from the field fluctuation of the applied static magnetic field in a relatively long time scale. The present stability 30 nG of the applied field $B_{0}=30\ {\rm mG}$ in a time scale of $10^{4}\ {\rm s}$ should be suppressed in order to perform EDM experiment. We have been preparing for introduction of magnetometer to stabilize the magnet current to produce the $B_{0}$ field. This magnetometer utilizes NMOE (Nonlinear Magneto Optical Effect) in Rb atom. The expected sensitivity of this type of magnetometer achieves the order of pG. We will report on systematic measurement of NMOE in Rb atom with different type of Rb cells using a tunable external-cavity diode laser, and on present status for the development of this type of magnetometer. Friday, October 16, 2009 11:15AM - 11:30AM EK.00009: A $^{129}$Xe active spin maser with digitalized feedback Takeshi Inoue , Akihiro Yoshimi , Makoto Uchida , Takeshi Furukawa , Naoto Hatakeyama , Masato Tsuchiya , Hironori Hayashi , Koichiro Asahi Observation of non-zero value for an electric dipole moment (EDM) will imply the $T$-violation and hence the \textit{CP}-violation. We plan to search an EDM in a $^{129}$Xe atom. Experimentally, the EDM is deduced from a measured shift in frequency of the spin precession which occurs upon the reversal of an electric field applied. The shift should be extremely small so that a high precision of frequency, and hence a long precession time, are essential for the EDM search. This is where our active spin maser comes in. An active spin maser we are developing is a scheme in which the spin precession is maintained by applying the feedback field externally generated according to an optically detected spin precession signal. By using this scheme, the frequency precision of 9.3 nHz has been obtained for a measurement time of 30,000 s duration. We report on recent construction of a renewed Maser setup which employs a computer-based digitalized feedback system. Friday, October 16, 2009 11:30AM - 11:45AM EK.00010: Search for Dark Matter Axion with Rydberg Atoms Kenichi Imai , T. Arai , A. Fukuda , H. Funahashi , S. Ikeda , Y. Kido , A. Matsubara , S. Matsuki , T. Mizusaki , R. Nakanishi , M. Saeed , A. Sawada , K. Yamamoto Axion is a strong candidate of the dark matter in the universe. From various astrophysical arguments, the mass of the dark matter axion is expected to be in the region from 5 micro-eV to 0.1meV. At Kyoto, a novel single microwave photon detector (CARRACK) had been developed for the search of the dark matter axion. The axion is converted to a microwave photon in the strong magnetic field (7T) by Primakoff process in a cavity which is cooled to 10mK to avoid black-body radiation. The photon is then detected by a Rydberg atom, which is excited by absorbing the photon and then selectively ionized. After the extensive pioneering studies of the CARRACK detector, it was recently moved to a new laboratory and New-CARRACK collaboration was formed. In the previous work by using Rb Rydberg atoms, a stray electric field of an order of mV/cm limited the overall sensitivity of the detector because of its large Stark effect. The New CARRACK utilizes Potassium as Rydberg atom which is estimated to be much less sensitive to a stray electric field. We describe the New CARRAC detector and its sensitivity for the dark matter axion based on our spectroscopic measurements of Potassium Rydberg atoms. Friday, October 16, 2009 11:45AM - 12:00PM EK.00011: Depleted Argon for Large Scale Dark Matter Detectors Jason Spaans , Dongming Mei , Yongchen Sun , Christina Keller Our project aims to provide argon depleted of $^{39}$Ar by utilizing established thermal diffusion methods for isotopic separation. The depleted argon can then be used as a target material for next generation large scale dark matter detectors. Thermal diffusion exploits an established temperature gradient to produce a concentration gradient along the length of a vertical column. In this concentration gradient, the heavier isotopes accumulate at the bottom end of the column and the lighter isotopes at the top. We have built a thermal diffusion system that consists of a copper column encasing a tungsten wire which is heated to 1200 K. The copper column is surrounded by a water bath which is maintained at a temperature of 300 K, thus establishing a temperature gradient between the copper column and the tungsten wire. We expect to deplete the $^{39}$Ar isotope by a factor of 10 with the current design, with the ultimate goal of a depletion factor of 100. The preliminary results of this effort will be reported utilizing the more abundant isotope $^{36}$Ar.