Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session J07: Measurements of Antimatter and Searches for Dark MatterLive
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Chair: Derek Jackson Kimball, California State University - East Bay Room: E145-146 |
Wednesday, June 3, 2020 2:00PM - 2:12PM Live |
J07.00001: Analysis methods for detecting topological defect dark matter with GNOME Joseph Smiga, Hector Masia-Roig Certain dark matter candidates can form macroscopic topological defects (e.g., domain walls) and other structures (e.g., $Q$-balls) which could constitute a significant source of energy density for dark matter. These structures may form if dark matter consists of axions or axion-like particles (ALPs). In the case of ALPs, the field gradient can couple to fermionic spins, similar to a magnetic field. This coupling becomes significant when the ALP field undergoes a major change, e.g., across a domain wall. In order to observe these structures, the Global Network of Optical Magnetometers for Exotic physics searches (GNOME) project was established. GNOME consists of shielded magnetometers across the globe synchronized by GPS time. A set of analysis methods were developed to find statistically significant signals from structures crossing the network and to assess the sensit ivity of the network. [Preview Abstract] |
Wednesday, June 3, 2020 2:12PM - 2:24PM Live |
J07.00002: Progress Towards Directional Detection of Dark Matter in Diamond Mason Marshall, Raisa Trubko, Pauli Kehayias, Matthew Turner, Mark Ku, David Phillips, Alex Sushkov, Ronald Walsworth We are developing a method for directional direct detection of weakly interacting massive particle (WIMP) dark matter via induced nuclear recoil in diamond. A WIMP collision initiates a cascade of nuclear recoils, leaving a ~100nm track of crystal damage. The orientation of this asymmetric damage track allows us to determine the incoming particle’s direction, allowing discrimination between dark matter candidates and backgrounds such as solar neutrinos. Spectroscopy of quantum emitters such as nitrogen-vacancy (NV) centers can be used to localize and map these damage tracks. A diamond-based semiconductor detector incorporating NV centers would therefore allow directional WIMP detection at solid-state densities, enabling WIMP searches below the neutrino floor. Here, we present the proposed detection technique, as well as the development of micro- and nanoscale techniques for localization and mapping of damage tracks in a future detector. [Preview Abstract] |
Wednesday, June 3, 2020 2:24PM - 2:36PM Live |
J07.00003: Improved Axial Motion Detection for an Upgraded Electron and Positron Magnetic Moment Measurement Thomas Myers, Xing Fan, Sam Fayer, Benedict Sukra, Gerald Gabrielse The 0.28ppt measurement of the electron magnetic moment is the most precise test of the Standard Model [1], and it disagrees by 2.4$\sigma$ with the theoretical prediction [2][3]. A new apparatus is now being tested with twin goals of significantly improving this measurement, and measuring the positron magnetic moment at this improved precision, a direct test of CPT symmetry. Detecting the axial motion of one such lepton, a necessary step for this measurement, relies on a 200 MHz LC circuit to present a high impedance to the particle. Advances necessary to load positrons [4] created new challenges due to harmful interactions with this circuit, causing the impedance to degrade. A series of improvements were made, collectively restoring the impedance to a value sufficient for detecting single particles for the next measurement. [1] D. Hanneke, S. Fogwell, and G. Gabrielse, Phys. Rev. Lett. 100 120801 (2008). [2] R. H. Parker, C. Yu, W. Zhong, B. Estey, and H. Müller, Science 360 191 (2018). [3] T. Aoyama, T. Kinoshita, and M. Nio, Atoms, 7 28 (2019). [4] S. Fogwell Hoogerheide, J. C. Dorr, E. Novitski, and G. Gabrielse, Rev. Sci. Instrum. 86 053301 (2015). [Preview Abstract] |
Wednesday, June 3, 2020 2:36PM - 2:48PM Live |
J07.00004: Eliminating detector back action from electron/positron magnetic moment measurements Xing Fan, Sam Fayer, Thomas Myers, Benedict Sukra, Gerald Gabrielse Measurements of $g$-factor of an electron and a positron provide the most stringent test of the Standard Model. They are limited by detector back action that damps the single particle motion being detected. We present a quantum calculation that replaces the classical description used to date. We explore the reduced measurement linewidths and new measurement limits that become possible if the detection motion is decoupled from the particle during crucial parts of the measurements. [Preview Abstract] |
Wednesday, June 3, 2020 2:48PM - 3:00PM Live |
J07.00005: Mu-MASS: Towards the first CW spectroscopy of the 1S-2S transition in Muonium Zak Burkley, Ben Ohayon, Gianluca Janka, Carlos Vigo, Paolo Crivelli, Thomas Prokscha, Xiaojie Ni The Mu-MASS experiment aims for a 1000-fold improvement in the determination of the 1S-2S transition frequency in Muonium (M), the positive-muon/electron bound state. This substantial improvement beyond the current state-of-the-art is possible due to advances in accelerator and UV laser technology, as well as recent demonstrations in the extraction of cold M into vacuum. The results of Mu-MASS, which will take place at the Paul Scherrer Institute (PSI), will determine the muon mass to 1 ppb. In combination with the ongoing hyperfine splitting measurements at J-PARC, Mu-MASS will also determine the Rydberg constant at a few ppt independently of the proton radius. Such robust and reliable values of these constants can help shed light on interesting anomalies that have accumulated in the muon sector, such as the anomalous muon magnetic moment (g-2) and the muonic hydrogen Lamb shift measurement. This talk will review the status and plans for Mu-MASS, present our recent results at PSI of efficient production, tagging and detection of metastable Muonium in vacuum, and display the performance of the high power, CW 244 nm laser system for exciting the M 1S-2S transition which is currently being developed at the Institute of Particle Physics and Astrophysics at ETH Zurich. [Preview Abstract] |
Wednesday, June 3, 2020 3:00PM - 3:12PM Live |
J07.00006: Demonstration of laser cooling of antihydrogen and its applications in precision antimatter experiments. Makoto Fujiwara, Takamasa Momose, Andrea Capra, Robert Collister, Timothy Friesen, David Gill, Adrew Evans, Michael Hayden, Alexander Khramov, Scott Menary, Mario Michan, Art Olin, Chkuman So, Robert Thompson Laser cooling is a technique which has revolutionized atom physics in the past 40 years, and is the basis of many of modern experiments in the field. However, until now, it has never been applied to an antimatter system. Here, we report the first demonstration of laser cooling of antihydrogen, the simplest form of atomic antimatter. By driving the 1S-2P transition in antihydrogen via pulsed Lyman-alpha radiation at 121 nm, we have performed Doppler cooling of magnetically trapped antihydrogen in the ALPHA experiment at CERN. In this talk, we will present preliminary results on our first laser cooling experiment. Furthermore, we will discuss far-reaching implications of the laser cooling technique in antimatter physics, and entirely new class of precision tools it will enable. These include anti-atomic fountains and anti-atom interferometers. [Preview Abstract] |
Wednesday, June 3, 2020 3:12PM - 3:24PM Live |
J07.00007: Dirac Equation as a Bridge to the Equivalence Principle for Antimatter Ulrich Jentschura The Dirac equation is interpreted as a bridge toward the description of the gravitational interaction of antimatter. It has long been known to atomic physicists that the Dirac equation allows for antiparticle solutions (of negative energy) which are described by the same equation that also has particle solutions (of positive energy). Hence, the Dirac equation, when properly coupled to a gravitational field, allows us to compare the quantum dynamics of a matter wave (of a quantum state describing matter) with that of an antimatter wave (of a quantum state describing antimatter). This comparison leads to an identification of the inertial mass of the particle solutions with the particle's gravitational mass, and, at the same time, to a relation of the inertial mass of the antiparticle solutions with the antiparticle's gravitational mass. A recent study published in [Int.J.Mod.Phys.A vol. 34, 1950180 (2019)] has revealed that the identification of the inertial and gravitational masses for antiparticles (antimatter) is just the same as for particles, and constitutes a straightforward and intrinsic prediction of the gravitationally coupled Dirac equation. This conclusion holds for arbitrary dynamic curved space-time backgrounds. [Preview Abstract] |
Wednesday, June 3, 2020 3:24PM - 3:36PM Live |
J07.00008: Searching for scalar dark matter with compact mechanical resonators Jack Manley, Dalziel Wilson, Russell Stump, Daniel Grin, Swati Singh Ultralight scalars are an interesting dark matter candidate which may produce a mechanical signal by modulating the Bohr radius. Recently it has been proposed to search for this signal using resonant-mass antennae. Here, we extend that approach to a new class of existing and near term compact (gram to kilogram mass) acoustic resonators composed of superfluid helium or single crystal materials, producing displacements that are accessible with opto- or electromechanical readout techniques. We find that a large unprobed parameter space can be accessed using ultra-high-Q, cryogenically-cooled, cm-scale mechanical resonators operating at 100 Hz to 100 MHz frequencies, corresponding to $10^{-12}-10^{-6}$ eV scalar mass range. [Preview Abstract] |
Wednesday, June 3, 2020 3:36PM - 3:48PM On Demand |
J07.00009: Detecting Dark Matter with Molecules Jesus Perez-Rios, Harikrishnan Ramani, Oren Slone, Rouven Essig The evidence for the existence of dark matter, which makes up about 85$\%$ of the matter density in the Universe, is overwhelming. Efforts to detect galactic dark matter particles in the laboratory are crucial for revealing the particle nature of dark matter. We propose a detection concept based on molecular excitations caused by the dark matter-nucleus scattering within the molecule. By mixing molecules of different isotopes, including those with an odd number of neutrons, we obtain sensitivity to both spin-independent interactions and spin-dependent interactions with the neutron. In addition, we explore various halides and hydrides molecules, which can provide sensitivity to spin-dependent interactions with the proton. [Preview Abstract] |
Wednesday, June 3, 2020 3:48PM - 4:00PM On Demand |
J07.00010: Electron-interacting dark matter: prospects for liquid xenon detectors and NaI detectors Benjamin Roberts, Victor Flambaum We investigate the possibility for the direct detection of low mass (\textasciitilde GeV) WIMP dark matter in scintillation experiments. Such WIMPs are typically too light to leave appreciable nuclear recoils, but may be detected via their scattering off atomic electrons. The DAMA Collaboration has recently presented strong evidence of an annual modulation in the scintillation rate observed at energies as low as 1 keV. Despite a strong enhancement in the calculated event rate at low energies, we find electron-interacting WIMPs cannot be consistent with existing constraints. Finally, we demonstrate that the potential scintillation event rate can be much larger than may otherwise be expected, meaning that competitive searches can be performed for GeV scale WIMPs using the conventional scintillation signals. This is important given the recent and upcoming very large liquid xenon detectors. Roberts and Flambaum, Phys. Rev. D 100, 063017 (2019); Roberts, Flambaum, and Gribakin, Phys. Rev. Lett. 116, 023201 (2016); Roberts, Dzuba, Flambaum, Pospelov, and Stadnik, Phys. Rev. D 93, 115037 (2016). \newline [Preview Abstract] |
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