DOCSLIB.ORG

Progress Towards a Measurement of the Electric Dipole Moment of the Electron Using Pbo∗

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Progress Towards a Measurement of the Electric Dipole Moment of the Electron Using Pbo∗ Abstract Progress Towards a Measurement of the Electric Dipole Moment of the Electron using PbO¤ Sarah Rachel Bickman 2007 We have proposed and begun implementing an experiment to look for an electric dipole 3 + moment (EDM) of the electron, de, using the metastable a(1) § state of the PbO molecule. A non-zero measurement of de within the next few orders of magnitude beyond the current limit ¡27 of jdej < 1:6£10 e-cm [1] would be clear evidence for physics beyond the standard model. We ¤ have designed and built a stable apparatus for the measurement of de using PbO in a heated vapor cell. Using this apparatus, the ­ doublet splitting in the a(1) J=1 state was measured to be 11.214(5) MHz. Without an applied electric ¯eld, the di®erence in g-factors between the ­ doublet states was found to be ±g=-31(9)£10¡4. Measurements of the Stark shift were found to be consistent with previous measurements [2]. The counting rate has been optimized and agrees with models. Three di®erent types of detectors with associated low-noise preampli¯ers were built and tested. To improve the sensitivity, an alternate detection scheme using reexcitation to the C0 state was explored and ultimately rejected in the form proposed here. In the ¯rst generation experiment, with the current fluorescence detection along the a(1)!X transition, the ¡25 p expected sensitivity to an electron EDM is ±de ¼10 e cm/ day. Two proposals for second generation experiments are considered. Progress Towards a Measurement of the Electric Dipole Moment of the Electron using PbO¤ A Dissertation Presented to the Faculty of the Graduate School of Yale University in Candidacy for the Degree of Doctor of Philosophy by Sarah Rachel Bickman Dissertation Director: David Paul DeMille December 2007 Copyright °c 2007 by Sarah Rachel Bickman All rights reserved. ii Acknowledgements This work never could have been accomplished without constant support, advice, and kindness from many people. Most important, I would like to thank my advisor, David DeMille, who has been the best advisor I could have imagined. Despite the decade that we have worked together, his exceptional patience, skillful teaching, and brilliant ideas continue to amaze me. Without his guidance I would have left physics countless times, and I am exceptionally grateful for his continual encouragement. Working with him has been a privilege. When it came time to form my thesis committee, it was obvious to me whom I wanted on it. I am grateful to these people not only for their time and advice on this committee, but also their time over the years. Steve Lamoreaux has helped us solve di±cult problems, even before he came to Yale. I have learned much in discussions with Daniel McKinsey about how to design an experiment and make a better measurement. Thomas Appelquist's excellent explanations has made him an invaluable resource. Bonnie Fleming has been a mentor and opened up new kinds of physics to me. I would also like to thank Larry Hunter who made some initial measurements on PbO, and since then has continued to provide advice on our more di±cult problems. In addition, I would like to thank him for his years of patience and skill in teaching me as an undergraduate. I have been fortunate to work with many talented, and supportive colleagues. I am grateful for our long friendships, and have learned much from all of them. David Kawall is the most persistent and careful person I have ever met. Paul Hamilton has consistently challenged me to think harder and work better. Yong Jiang can solve any computer or physics problem. This work never could have been accomplished without the help of many others: Frederik Bay, Valmiki Prasad, Yulia Gurevich, Amar Vutha, Richard Paolino, and Jordan Weil, and Hunter Smith. There are many others who contributed to this work. Vincent Bernardo and the entire Gibbs iii Machine Shop did much of the metal machining and advised on many of my designs. Sidney Cahn o®ered advice on electrical designs and many other issues. The entire DeMille group has cheerfully lifted shields on countless occasions and provided advice. I am very lucky to have found a loving husband who is my equal in all respects, and who treats me as one. Daniel Farkas has become so much a part of my life that I cannot imagine being without him. I am looking forward to sharing our next adventure. It is an understatement to say that I am grateful to my parents. They have been my biggest source of encouragement and support and have shared every triumph and failure with me. They spent many years teaching me that \Education is not ¯lling a bucket, but lighting a ¯re"{William Butler Yeats. I never could have dreamed of being here today without them. My brother, Jed, has made me laugh when all else has failed, and has been one of the most enthusiastic members of my fan club. My friends Benjamin Turek, Alexandra Gueydan, Stephen Maxwell, Iva Maxwell, and Dale Li have added much needed humor and have provided wise advice. iv Contents Acknowledgements iii 1 Introduction 1 1.1 Introduction . 1 1.2 EDMs Violate Parity and Time Reversal Symmetries . 2 1.3 Direction of de ..................................... 3 1.4 Overview of Relevant Particle Theory . 4 1.5 General Method to Measure de ............................ 6 1.6 Enhancement Factors . 8 1.7 Enhancement Factor of PbO . 10 1.8 Relating a Measurement of the EDM of PbO to the EDM of Fundamental Particles 11 1.9 Other Current Experimental Approaches . 12 1.9.1 Atoms . 12 1.9.2 Molecules . 14 1.9.3 Solid State Materials . 17 1.10 Prospects for PbO as a System for Measuring de .................. 18 2 Experimental Methods 19 2.1 Level structure of PbO . 20 2.2 Excitation Sequence . 23 2.2.1 Horizontally Polarized Light, and No Electric Field . 23 2.2.2 Horizontally Polarized Light, With an Applied Electric Field . 25 2.2.3 Vertically Polarized Light and Microwave Excitation . 26 2.3 Quantum Beat Spectroscopy . 30 v 2.3.1 Contrast of Quantum Beats in Molecules . 34 2.4 Lifetime of the a(1) State and Density of Available Molecules . 38 2.5 Noise Sources . 40 2.5.1 Stray Magnetic Fields . 40 2.5.2 Magnetic Johnson Noise . 41 2.5.3 Ferromagnetic Materials . 42 2.6 Common Systematic E®ects . 43 2.6.1 Leakage Currents . 43 2.6.2 v £ E E®ects . 44 2.6.3 Berry's phases . 46 3 Apparatus 48 3.1 Vapor Cell . 49 3.1.1 Material Selection . 52 3.1.2 Gold Bonding Technique . 53 3.1.3 Birefringence of Sapphire Windows . 54 3.1.4 Stem . 55 3.1.5 Plunger . 55 3.1.6 Electric Field Homogeneity . 56 3.1.7 Leakage Currents . 57 3.1.8 Monitoring of Leakage Currents . 57 3.1.9 Material Selection . 57 3.2 Oven . 62 3.2.1 Eddy Current Suppression . 68 3.3 Vacuum System . 71 3.4 Magnetic Shielding . 75 3.5 Laser Excitation . 78 3.6 Microwave State Population . 80 3.7 Detection . 81 3.7.1 Filters . 83 3.7.2 Absorbing Filters . 88 vi 3.7.3 Winston Cones . 90 3.7.4 Monte Carlo Model of Detection . 93 3.7.5 Detectors . 101 3.7.6 PMTs . 102 3.7.7 Transimpedance Ampli¯ers . 106 3.7.8 Noise in Transimpedance Ampli¯ers . 107 3.7.9 PIN Photodiode . 116 3.7.10 APDs . 118 3.7.11 Recovery Time . 120 3.7.12 Final Choice of Detectors . 127 3.8 Data Acquisition and Analysis . 129 3.9 Data Acquisition Hardware . 129 3.10 Measurement Sequence . 130 3.11 Data Analysis . 130 3.11.1 Fitting Function . 130 3.11.2 Optimization of Computation . 133 4 Measurements of PbO Structure 134 4.1 Measurement of g-factor Di®erence and the ­-doublet Splitting . 135 4.2 g-factors with Applied Electric Fields . 141 4.3 DC Stark Shifts . 146 4.4 Summary of Measurements of a(1) State . 149 5 Measurements of Signal Magnitudes 150 5.1 Calculated Signal Sizes . 150 5.2 Attempted Improvements to SNR . 156 5.3 Optimal Conditions . 163 5.4 Conclusions on Signal Sizes . 164 6 Development Towards Future Generations 166 6.1 Laser Reexcitation to the C0 state . 166 6.1.1 Introduction . 166 vii 6.1.2 Determination of C0 Energy Level Structure . 168 6.1.3 Franck-Condon Factors . 174 6.1.4 ­-Doublet Splitting in the C0 state . 176 6.1.5 a(1)! C0 Excitation Cross Sections . 178 6.1.6 Determination of Expected Contrast With No Electric Field . 180 6.1.7 Determination of Expected Contrast With an Applied Electric Field . 182 6.1.8 Reexcitation Measurement Scheme . 186 6.1.9 a(1)! C Excitation Cross Sections . 193 6.2 Summary of C' Measurements . 194 6.3 Microwave Detection . ..
Load more

Recommended publications
  • First Science Results from the LUX Dark Matter Experiment
    First Science Results from the LUX Dark Matter Experiment Daniel McKinsey, LUX Co-Spokesperson, Yale University Richard Gaitskell, LUX Co-Spokesperson, Brown University on behalf of the LUX Collaboration http://luxdarkmatter.org Sanford Underground Research Facility OctoberS 30, 2013 LUX Dark Matter Experiment / Sanford Lab Rick Gaitskell (Brown) / Dan McKinsey (Yale) 1 Composition of the Universe The Higgs particle has been discovered, the last piece of the Standard Model. But as successful as it has been, the Standard Model describes only 5% of the universe. The remaining 95% is in the form of dark energy and dark matter, whose fundamental nature is almost completely unknown. Image: X-ray: NASA/CXC/CfA/M.Markevitch et al.; www.quantumdiaries.org Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al. LUX Dark Matter Experiment / Sanford Lab 2 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 2 Evidence for Dark Matter Galaxy rotation curves The cosmic microwave background www.quantumdiaries.org Image: ESA and the Planck collaboration Gravitational lensing • 27% of the energy composition of the universe • Properties: • Stable and electrically neutral • Non-baryonic • Non-relativistic • Estimated local density: 0.3±0.1GeV·cm-3 • Candidates: WIMPs, axions, dark photons,... Colley, Turner, Tyson, and NASA LUX Dark Matter Experiment / Sanford Lab 3 Rick Gaitskell (Brown) / Dan McKinsey (Yale) 3 Weakly Interacting Massive Particles (WIMPs) A new particle that only very weakly interacts with ordinary matter could form Cold Dark Matter - Formed in massive amounts in the Big Bang. - Non-relativistic freeze-out.
    [Show full text]
  • Arxiv:2102.11982V1 [Quant-Ph] 23 Feb 2021 Ural Linewidth to Enable the Initialization of Only One of and Parallel to Each Other Γ23 ≈ Γ22Γ33
    Observation of vacuum-induced collective quantum beats Hyok Sang Han,1 Ahreum Lee,1 Kanupriya Sinha,2, ∗ Fredrik K. Fatemi,3, 4 and S. L. Rolston1, 4, † 1Joint Quantum Institute, University of Maryland and the National Institute of Standards and Technology, College Park, Maryland 20742, USA 2Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA 3U.S. Army Research Laboratory, Adelphi, Maryland 20783, USA 4Quantum Technology Center, University of Maryland, College Park, MD 20742, USA We demonstrate collectively enhanced vacuum-induced quantum beat dynamics from a three-level V-type atomic system. Exciting a dilute atomic gas of magneto-optically trapped 85Rb atoms with a weak drive resonant on one of the transitions, we observe the forward-scattered field after a sudden shut-off of the laser. The subsequent radiative dynamics, measured for various optical depths of the atomic cloud, exhibits superradiant decay rates, as well as collectively enhanced quantum beats. Our work is also the first experimental illustration of quantum beats arising from atoms initially prepared in a single excited level as a result of the vacuum-induced coupling between excited levels. Introduction.—Quantum beats are a well-studied phe- by the constructive interference between the transition nomenon that describes the interference between spon- processes in different atoms. The collective amplification taneously emitted radiation from two or more excited of the forward-scattered beat signal allows us to observe levels, resulting in a periodic modulation of the radiated vacuum-induced quantum beats and serves as an experi- field intensity [1]. This has been a valuable spectroscopic mental proof of collective effects in quantum beats.
    [Show full text]
  • Conditional Control of Quantum Beats in a Cavity QED System
    Conditional control of quantum beats in a cavity QED system D G Norris, A D Cimmarusti and L A Orozco Joint Quantum Institute, Department of Physics, University of Maryland and National Institute of Standards and Technology, College Park, MD 20742-4111, U.S.A. E-mail: [email protected] Abstract. We probe a ground-state superposition that produces a quantum beat in the intensity correlation of a two-mode cavity QED system. We mix drive with scattered light from an atomic beam traversing the cavity, and effectively measure the interference between the drive and the light from the atom. When a photon escapes the cavity, and upon detection, it triggers our feedback which modulates the drive at the same beat frequency but opposite phase for a given time window. This results in a partial interruption of the beat oscillation in the correlation function, that then returns to oscillate. 1. Introduction Quantum feedback [1] and quantum control [2] are important disciplines with relationships to quantum information science. The question of how to control a quantum system without disturbing it remains open in general [3], but the search for efficient protocols continues and the experimental realization is now using weak quantum measurements. (See for example the recent paper by Gillett et al. [4]). The detection of a photon escaping a quantum system at a random time heralds the preparation of a conditional quantum state. Manipulation of these states is essential in the field of quantum feedback. The preferential probe of this conditional measurement in quantum optics is the intensity correlation function which has been used since the pioneer work of Kimble et al.
    [Show full text]
  • Probing an Excited-State Atomic Transition Using Hyperfine Quantum
    Probing an Excited-State Atomic Transition Using Hyperfine Quantum Beat Spectroscopy C. G. Wade,∗ N. Sibali´c,J.ˇ Keaveney, C. S. Adams, and K. J. Weatherill Joint Quantum Centre (JQC) Durham-Newcastle, Department of Physics, Durham University, South Road, Durham, DH1 3LE, United Kingdom (Dated: October 10, 2018) We describe a method to observe the dynamics of an excited-state transition in a room temperature atomic vapor using hyperfine quantum beats. Our experiment using cesium atoms consists of a pulsed excitation of the D2 transition, and continuous-wave driving of an excited-state transition from the 6P3=2 state to the 7S1=2 state. We observe quantum beats in the fluorescence from the 6P3=2 state which are modified by the driving of the excited-state transition. The Fourier spectrum of the beat signal yields evidence of Autler-Townes splitting of the 6P3=2, F = 5 hyperfine level and Rabi oscillations on the excited-state transition. A detailed model provides qualitative agreement with the data, giving insight to the physical processes involved. u I. INTRODUCTION | i e+ Excited-state transitions in atomic systems are finding an e | i ¯hΩ increasing range of applications including quantum infor- | i ¯hωb e− e0 |e0 i mation [1], optical filters [2], electric field sensing [3{5] | i | i and quantum optics [6, 7]. They are also used for state lifetime measurements [8], frequency up-conversion [9], g g the search for new stable frequency references [10, 11] and | i | i multi-photon laser cooling [12]. However excited-state | transitions are inherently more difficult to probe than | ) ) ω ω ground-state transitions, especially if the lower state is ( ( short-lived.
    [Show full text]
  • Broader Impacts of XENON Research
    XENON: A Liquid Xe Dark Matter Search Experiment at LNGS Columbia University: Elena Aprile, Karl-Ludwig Giboni, Pawel Majewski, Kaixuan Ni, Bhartendu Singh, Masaki Yamashita Brown University: Richard Gaitskell, Peter Sorensen, Luiz DeViveiros University of Florida: Laura Baudis, David Day Lawrence Livermore National Laboratory: William Craig, Adam Bernstein, Chris Hagmann Princeton University: Tom Shutt, John Kwong, Kirk McDonald Rice University: Uwe Oberlack, Omar Vargas Yale University: Daniel McKinsey, Richard Hasty, Hugh Lippincott Contact person Elena Aprile ([email protected]) Letter of Intent 1 1. The physics case The goal of the XENON experimental program is direct detection of dark matter in the form of weakly interacting massive particles (WIMPs) with an array of ten identical liquid Xe detector modules each with a 100 kg fiducial mass (XENON100).Current theoretical models indicate that WIMP interaction rates probably lie between the current sensitivity of existing experiments which is equivalent to ~0.25 evts/kg/day and ~2 evts/100 kg/yr normalized for a Xe target. The best prospects for the unambiguous identification of a WIMP nuclear recoil signal lie in detectors that have negligible radioactive background competing with the dark matter signal. This can be achieved principally by using nuclear recoil discrimination in order to veto competing electron recoil events (associated with gamma and beta backgrounds), effective neutron shielding, and through the operation of a large homogeneous detector volume with 3-D position resolution. The latter information can be used to select single hit events characteristic of a WIMP interaction while rejecting multiple hit events associated with backgrounds that propagate from the edge of the detector into the fiducial volume.
    [Show full text]
  • Quantum Interference in the Field Ionization of Rydberg Atoms Rachel Feynman
    Bryn Mawr College Scholarship, Research, and Creative Work at Bryn Mawr College Physics Faculty Research and Scholarship Physics 2015 Quantum interference in the field ionization of Rydberg atoms Rachel Feynman Jacob Hollingsworth Michael Vennettilli Tamas Budner Ryan Zmiewski See next page for additional authors Let us know how access to this document benefits ouy . Follow this and additional works at: http://repository.brynmawr.edu/physics_pubs Part of the Physics Commons Custom Citation R. Feynman, J. Hollingsworth, M. Vennettilli, T. Budner, R. Zmiewski, D. P. Fahey, T. J. Carroll, M. W. Noel, "Quantum interference in the field ionization of Rydberg atoms," Physical Review A 92.4 (2015), 10.1103/PhysRevA.92.043412. This paper is posted at Scholarship, Research, and Creative Work at Bryn Mawr College. http://repository.brynmawr.edu/physics_pubs/88 For more information, please contact [email protected]. Authors Rachel Feynman, Jacob Hollingsworth, Michael Vennettilli, Tamas Budner, Ryan Zmiewski, Donald Fahey, Thomas J. Carroll, and Michael W. Noel This article is available at Scholarship, Research, and Creative Work at Bryn Mawr College: http://repository.brynmawr.edu/ physics_pubs/88 PHYSICAL REVIEW A 92,043412(2015) Quantum interference in the field ionization of Rydberg atoms Rachel Feynman,1 Jacob Hollingsworth,2 Michael Vennettilli,2 Tamas Budner,2 Ryan Zmiewski,2 Donald P. Fahey,1 Thomas J. Carroll,2 and Michael W. Noel1 1Department of Physics, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, USA 2Department of Physics and Astronomy, Ursinus College, Collegeville, Pennsylvania 19426, USA (Received 10 August 2015; published 13 October 2015) We excite ultracold rubidium atoms in a magneto-optical trap to a coherent superposition of the three m | j | sublevels of the 37d5/2 Rydberg state.
    [Show full text]
  • Quantum Beat Observations in Rubidium Vapor
    QUANTUM BEAT OBSERVATIONS IN RUBIDIUM VAPOR BY BRIAN JOSEPH RICCONI DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical and Computer Engineering in the Graduate College of the University of Illinois at Urbana-Champaign, 2012 Urbana, Illinois Doctoral Committee: Professor J. Gary Eden, Chair Professor Martin Gruebele Professor Gary R. Swenson Associate Professor P. Scott Carney Associate Professor Brian DeMarco Abstract Probing the interactions between a mode-locked laser pulse and saturated rubidium vapor with a pump–probe technique has resulted in observations of coherences within the atom that persist longer than 150 ps. Quantum beats due to the interference between the 7S and 5D5/2 energy states were observed by a four-wave mixing process. The difference frequency between the 5D–5P3/2 and the 5P3/2–5S transitions was also observed for interpulse delays up to 180 ps. The temporal evolution of the beat amplitude indicates the existence of a superfluorescent process and a scattering process detected simultaneously with the four-wave mixing process. A model was developed to explain the processes and was used to predict the range of pulse parameters for which the scattering process and four-wave mixing could be simultaneously detected. ii Acknowledgments It is a pleasure to thank those who have made this accomplishment possible. I owe my deepest gratitude to my adviser, J. Gary Eden, and to each of the members of my doctoral committee for their many constructive suggestions as I completed the research described here. I am also grateful for the assistance of and suggestions from all of the staff of the Laboratory for Optical Physics and Engineering.
    [Show full text]
  • Harvard University Department of Physics Newsletter
    Harvard University Department of Physics Newsletter FALL 2014 COVER STORY Probing the Universe’s Earliest Moments FOCUS Early History of the Physics Department FEATURED Quantum Optics Where Physics Meets Biology Condensed Matter Physics NEWS A Reunion Across Generations and Disciplines 42475.indd 1 10/30/14 9:19 AM Detecting this signal is one of the most important goals in cosmology today. A lot of work by a lot of people has led to this point. JOHN KOVAC, HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS LEADER OF THE BICEP2 COLLABORATION 42475.indd 2 10/24/14 12:38 PM CONTENTS ON THE COVER: Letter from the former Chair ........................................................................................................ 2 The BICEP2 telescope at Physics Department Highlights 4 twilight, which occurs only ........................................................................................................ twice a year at the South Pole. The MAPO observatory (home of the Keck Array COVER STORY telescope) and the South Pole Probing the Universe’s Earliest Moments ................................................................................. 8 station can be seen in the background. (Steffen Richter, Harvard University) FOCUS ACKNOWLEDGMENTS Early History of the Physics Department ................................................................................ 12 AND CREDITS: Newsletter Committee: FEATURED Professor Melissa Franklin Professor Gerald Holton Quantum Optics ..............................................................................................................................14
    [Show full text]
  • Experimental Triple-Slit Interference in a Strongly Driven V-Type Artificial Atom
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE RAPID COMMUNICATIONSprovided by Heriot Watt Pure PHYSICAL REVIEW B 96, 081404(R) (2017) Experimental triple-slit interference in a strongly driven V-type artificial atom Adetunmise C. Dada,1,* Ted S. Santana,1 Antonios Koutroumanis,1 Yong Ma,1,† Suk-In Park,2 Jindong Song,2 and Brian D. Gerardot1,‡ 1SUPA, Institute for Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom 2Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul 02792, Korea (Received 6 March 2017; revised manuscript received 31 July 2017; published 16 August 2017) Rabi oscillations of a two-level atom appear as a quantum interference effect between the amplitudes associated with atomic superpositions, in analogy with the classic double-slit experiment which manifests a sinusoidal interference pattern. By extension, through direct detection of time-resolved resonance fluorescence from a quantum-dot neutral exciton driven in the Rabi regime, we experimentally demonstrate triple-slit-type quantum interference via quantum erasure in a V-type three-level artificial atom. This result is of fundamental interest in the experimental studies of the properties of V-type three-level systems and may pave the way for further insight into their coherence properties as well as applications for quantum information schemes. It also suggests quantum dots as candidates for multipath-interference experiments for probing foundational concepts in quantum physics. DOI: 10.1103/PhysRevB.96.081404 Quantum interference effects [1,2] form the basis of many understood as a “quantum beat” between two dressed states photonic quantum information tasks, such as gate operations separated by the Rabi splitting (RS) energy in a driven for quantum computing [3–5], quantum state comparison two-level (artificial) atom [18].
    [Show full text]
  • Laser Cooling and Slowing of a Diatomic Molecule John F
    Abstract Laser cooling and slowing of a diatomic molecule John F. Barry 2013 Laser cooling and trapping are central to modern atomic physics. It has been roughly three decades since laser cooling techniques produced ultracold atoms, leading to rapid advances in a vast array of fields and a number of Nobel prizes. Prior to the work presented in this thesis, laser cooling had not yet been extended to molecules because of their complex internal structure. However, this complex- ity makes molecules potentially useful for a wide range of applications. The first direct laser cooling of a molecule and further results we present here provide a new route to ultracold temperatures for molecules. In particular, these methods bridge the gap between ultracold temperatures and the approximately 1 kelvin temperatures attainable with directly cooled molecules (e.g. with cryogenic buffer gas cooling or decelerated supersonic beams). Using the carefully chosen molecule strontium monofluoride (SrF), decays to unwanted vibrational states are suppressed. Driving a transition with rotational quantum number R=1 to an excited state with R0=0 eliminates decays to unwanted ro- tational states. The dark ground-state Zeeman sublevels present in this specific scheme are remixed via a static magnetic field. Using three lasers for this scheme, a given molecule should undergo an average of approximately 100; 000 photon absorption/emission cycles before being lost via un- wanted decays. This number of cycles should be sufficient to load a magneto-optical trap (MOT) of molecules. In this thesis, we demonstrate transverse cooling of an SrF beam, in both Doppler and a Sisyphus-type cooling regimes.
    [Show full text]
  • Two-Phase Xenon Time Projection Chambers for WIMP Searches and Other Applications
    Two-Phase Xenon Time Projection Chambers for WIMP Searches and Other Applications Nicole A. Larsen Yale University Department of Physics Advisor: Daniel McKinsey Thesis Prospectus May 24, 2012 Abstract Astronomical evidence indicates that 23 % of the energy density in the universe is comprised of some form of non-standard, non-baryonic matter that has yet to be observed. One of the predominant theories is that dark matter consists of WIMPs (Weakly Interacting Massive Particles), so named be- cause they do not interact electromagnetically or through the strong nuclear force. In direct dark matter detection experiments the goal is to look for evidence of collisions between WIMPs and other particles such as heavy nuclei. Here, the challenge is to measure exceedingly rare interactions with very high precision. In recent years xenon has risen as a medium for particle detection, exhibiting a number of desirable qualities that make it well-suited for direct WIMP searches. The LUX (Large Underground Xenon) experiment is a 350-kg xenon-based direct dark matter detection experiment currently deployed at the Homestake Mine in Lead, South Dakota, consisting of a two-phase (liq- uid/gas) xenon time projection chamber with a 100-kg fiducial mass. Its projected sensitivity for 300 days of underground data acquisition is a cross-section of 7 × 10-46 cm2 for a WIMP mass of 100 GeV, representing an improvement of nearly an order of magnitude over previous WIMP-nucleon scattering cross-section limits. Furthermore, two-phase xenon-based technologies are useful in many other applications, in- cluding other fundamental physics searches, imaging of special nuclear materials, and medical imaging.
    [Show full text]
  • Radiative Lifetime and Landé-Factor Measurements of the Se I 4P35s
    Radiative lifetime and Landé-factor measurements 3 5 of the Se I 4p 5s S2 level using pulsed laser spectroscopy. Diploma paper by Raoul Zerne Contents Page ABSTRACT 1 1. INTRODUCTION 2 2. THEORY 5 2.1 Lifetime determinations 5 2.2 Quantum-beat through pulsed optical excitation 7 2.3 Optical double-resonance 9 3. EXPERIMENTS 13 3.1 The cell arrangement 13 3.2 Experiment setup 14 3.3 Lifetime measurements 16 3.4 Quantum-beat measurements 20 3.5 Cptical double-resonance measurements 22 4. CALIBRATION OF THE MAGNETIC FIELD 26 5. DISCUSSION 31 ACKNOWLEDGEMENTS 33 REFERENCES 34 Abstract This diploma project consists of spectroscopic examinations of atomic selenium. Natural selenium was thermally dissociated in a quartz resonance cell keeping the background pressure of selenium 3 5 molecules low by differential heating. The 4p 5s S2 level was excited by frequency-tripled pulsed dye-laser radiation at 207 nm. From time-resolved recordings of the fluorescence decay at 216 nm the natural radiative lifetime of the S level was determined to be 493(15) ns. Quantum-beat and optical double resonance measure- ments in an external magnetic field yielded g =2.0004(10) for the Lande factor. 1. INTRODUCTION Laser spectroscopy has revolutionized atomic and molecular spectroscopy. The use of tunable lasers have made completely new types of experiments possible, and investigations which were impossible with conventional light sources can now be performed. The great advantage of lasers is the very high intensities that can be obtained in a small frequency interval. The spatial properties of laser beams are also of great importance.
    [Show full text]