DOCSLIB.ORG

Facilities and Methods Ultracold Neutrons—Physics and Production

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Facilities and Methods Ultracold Neutrons—Physics and Production facilities and methods Ultracold Neutrons—Physics and Production Introduction Free neutrons are the most funda- mental ones of the easily accessible, electrically neutral spin-1/2 systems. They take part in all the four known interactions: they strongly interact with nucleons and nuclear matter, they undergo weak β-decay, they have magnetic moments and gravitational mass. Although the neutron itself is a composite system, and thus, strictly speaking, not a fundamental particle, it is one of the finest probes for funda- mental physics. Neutrons can be and are used to study all interactions, to search for new interactions, to test fundamental quantum mechanics and symmetries of nature. Over the past five decades the field of slow neutron Figure 1. Dispersion relation of superfluid helium (c) and free neutron (a). precision physics developed and Neutrons with E » 1meV can excite a single phonon q » 0.7Å-1 with same energy could usually make major advance- and are thus down-scattered to the UCN energy range. The UCN production ments when new and more powerful rate (b) (circles) [16] shows the dominance of this single phonon process with neutron sources became available. respect to multiphonon processes. Very often experiments benefit from using slower neutrons and, thus, longer de Broglie wavelengths λ=2πh/(m · v), for example, thermal Besides numerous reviews, two new schemes for the production of neutrons at about 2,200 m/s average text books have been written on UCN UCN that have been studied in detail velocity have wavelengths of the typi- [2, 3]. For an update on the status of recently and are presently being real- cal atomic scale of about 1 Å. Fermi the field, readers are referred to two ized at various laboratories around the and Zinn [1] found that neutrons can recent workshops [4, 5]. In this article world. In particular, the UCN source be totally reflected from material we briefly review the peculiarities of project currently commissioning at surfaces under grazing angles of inci- ultracold neutrons, including their the Paul Scherrer Institut (PSI) in dence. To each material a critical generation and mentioning some of Villigen, Switzerland will allow for a (maximum) angle for total reflection their applications. next generation of more sensitive fun- of thermal neutrons exists that As several times already in the damental physics studies. becomes larger for smaller neutron past, we are today at a point at which velocities. Consequently, sufficiently fundamental physics applications slow neutrons will be reflected under require larger UCN intensities in Ultracold Neutrons all angles of incidence. These neu- order to further advance. Especially Ultracold neutrons are free trons are called “ultracold neutrons” the importance of the search for a (unbound) neutrons defined via their (UCN). Due to their specific proper- finite value of the electric dipole most important property: they can be ties (λ≥600 Å) they have opened a moment of the neutron pushes the stored! They have very low kinetic new door for the field of fundamental development of new and more power- energies below about 300 neV corre- physics. ful UCN sources. We describe the sponding to ~3.5 mK, hence their Vol. 20, No. 1, 2010, Nuclear Physics News 17 facilities and methods realistic storage containers (e.g., holes or slits) contribute considerably. UCN in Fundamental Physics The possibility to store UCN for relatively long observation times makes them unique and highly sensitive probes, testing our understanding of fundamental physics [2, 3, 6]. Most of these experiments today are statistically limited and further advancements strongly depend on new high-intensity sources for UCN. A key experiment is the search for a permanent electric dipole moment of the neutron (nEDM). A finite nEDM violates time-reversal invariance and, therefore, might help to understand the matter–antimatter asymmetry in our universe. It is tightly linked to some of the open problems in Figure 2. Experimentally determined temperature dependence of UCN modern physics, the so-called “strong production in deuterium [22]. The sharp increase with solidification is obvious. CP-problem” and the “SUSY CP- problem.” Its observation would be a clear indication for physics beyond the electro-weak Standard Model of name: ultracold. They can be confined In inhomogeneous magnetic particle physics [7–9]. Other impor- by the strong interaction (total reflec- fields, the kinetic energy change of tant studies with UCN include deter- tion at any angle of incidence from the neutrons can be expressed as mination of the neutron lifetime and Δ =± Δ| | surfaces of certain materials like Ni, Be, Ekin 60 · neV/T B , taking the decay parameters, strongly influenc- stainless steel), the magnetic moment positive sign if the spin component is ing our understanding of weak inter- interaction (repulsion of one spin com- antiparallel to the field B. actions and big bang nucleosynthesis ponent from field gradients due to the Also the gravitational interaction [6]. UCN are also being used to study neutron magnetic moment) and due to is on the same scale for UCN, fundamental quantum mechanics, search Δ =Δ Δ gravitation (limited vertical reach). Ekin h · 103 neV/m, where h is for exotic interactions, test baryon num- UCN reflection on walls via the the height difference. ber conservation, and measure proper- strong interaction can be well described The effects of all three interactions ties of the neutron itself, such as the by a potential step model solving the can be combined and used for UCN search for a tiny but finite charge of Schrödinger equation with a step traps. The energy spectrum of stored the neutron. height equal to the so-called Fermi UCN depends on peculiarities of the = π 2 (optical) potential: VF (2 h / m)·Na; trap and is a function of height with a where N is the number density in the material or magnetic field dependent The Production of UCN material assumed to be homogeneous, cut-off, typically below about Δh=3m. The typical kinetic energy of UCN a is the coherent scattering length, and m The storage time of UCN is fun- (~100 neV) is orders of magnitude is the mass of the neutron. For exam- damentally limited by the time con- below the typical neutron energy in a = β ple VF(Ni) 252 neV, VF (diamond) stant of neutron -decay of almost thermal moderator (~25 meV) of a = 304 neV. For kinetic energies below 15 minutes. Practically, also loss factors neutron source, such as a nuclear this threshold energy total reflection like nuclear absorption, inelastic reactor. The energy distribution of the occurs at any angle. up-scattering and imperfections of thermalized neutron gas is often 18 Nuclear Physics News, Vol. 20, No. 1, 2010 facilities and methods slowed down when climbing the grav- itational potential. Various developments have allowed one to increase the intensity of UCN considerably over the years. Clearly, the extracted intensity is proportional to the initial one, thus high initial neu- tron flux helps and could be increased by more than 4 orders of magnitude as compared to the first experiments. Also, the intensity in the tail of the Maxwell- Boltzmann distribution increases sig- nificantly when the temperature of the neutron gas is lowered, thus extract- ing UCN from a cold moderator of Figure 3. UCN production as function of incoming neutron energy [20]. The liquid hydrogen or deuterium gained dashed, colored curves display individual cold neutron energy distributions almost another 2 orders of magnitude. (intensity: vertical right scale) prepared from the “white” cold neutron beam Improvements were made on UCN using a neutron velocity selector and measured by time-of-flight. The measured guide quality by developing high UCN production cross-section (left vertical scale) for the individual energies is Fermi potential, very low roughness displayed as open circles. The red squares are the cross-sections calculated for surfaces, allowing a low-loss trans- the energy distributions, the solid black line is calculated as continuous port of UCN over many meters. function of energy. The cut-off at around 9 meV comes from cut-off of the Today’s highest UCN intensity is phonon density of states in the simple Debye model at the Debye temperature. obtained at the instrument PF2, which Above this energy, multiple phonon excitations still permit UCN production. has been in operation for more than 20 years at the high flux reactor of the Institute Laue-Langevin (ILL) in approximated by a Maxwell-Boltzmann control the background count rate of Grenoble. Vertical extraction over distribution and the amount of neutrons UCN detectors on a level of a few 17 m height through a curved replica in the very low energy tail is therefore counts per 1000 s allowed at that time guide system is used for initial deceler- rather small. Lower energy neutrons to detect similar UCN rates. Curved ation and background suppression. Then become further suppressed because of neutron guides were used to filter out a mechanical decelerator, the “neutron longer travel times in the moderator faster neutrons that could not fulfill turbine,” transforms very cold neutrons medium before extraction and the the necessary conditions for total of approximately 40 m/s into the UCN temperature of the extracted neutron reflection. Shapiro’s group in Dubna energy range. The neutron turbine gas is accordingly shifted to higher succeeded in detecting UCN this way (developed by A. Steyerl since 1975) values. Historically it was therefore in 1968 [10]. Steyerl (Munich) in consists of a set of curved blades mov- not even clear that a sizeable amount of 1969 [11] reported, independently, ing with a peripheral velocity 20 m/s ultracold neutrons could be extracted measured neutron cross-sections for in the same direction as the neutrons.
Load more

Recommended publications
  • NEUTRON ELECTRIC-DIPOLE MOMENT, ULTRACOLD NEUTRONS and POLARIZED 3He
    NEUTRON ELECTRIC-DIPOLE MOMENT, ULTRACOLD NEUTRONS AND POLARIZED 3He R. GOLUB~and Steve K. LAMOREAUXb aHahfl_Mejtfler Institut, Postfach 390128, Glienicker Strasse 100, 14109 Berlin, Germany b University of Washington, Department of Physics FM-15, Seattle, WA 98195, USA NORTH-HOLLAND PHYSICS REPORTS (Review Section of Physics Letters) 237, No. 1(1994)1—62. PHYSICS REPORTS North-Holland Neutron electric-dipole moment, ultracold neutrons and polarized 3He R. Goluba and Steve K. Lamoreauxb aHahnMeitner Institut, Postfach 390128, Glienicker Strasse 100, 14109 Berlin, Germany buniversily of Washington, Department of Physics FM-15, Seattle, WA 98195, USA Received May 1993; editor: J. Eichler Contents: 1. Introduction 4 5.3. Solution by use of the secular approximation 38 1.1. Historical background 4 5.4. Elimination of the pseudomagnetic field 2. Current experimental technique 8 suppression by feedback to w~ 39 2.1. Ultracold neutrons (UCN) 8 5.5. Effects of the z component of the pseudomagnetic 2.2. Neutron EDM measurements with stored UCN 10 field 42 2.3. Recent EDM experiments using UCN 13 5,6. Effects of offsets in the first-harmonic signal 44 3. Superfluid He neutron EDM with 3He 6. Noise analysis 45 comagnetometer 19 6.1. Model of the system for noise analysis 45 3.1. Introduction 19 6.2. Initial polarization and UCN density 45 3.2. Production of UCN in superfluid 4He 20 6.3. Analysis of harmonically modulated dressing 46 3.3. Polarization of UCN 21 6.4. Evolution of the UCN polarization and density 3.4. Polarization of 3He 22 under modulated dressing 46 3.5.
    [Show full text]
  • Neutron Scattering Facilities in Europe Present Status and Future Perspectives
    2 ESFRI Physical Sciences and Engineering Strategy Working Group Neutron Landscape Group Neutron scattering facilities in Europe Present status and future perspectives ESFRI scrIPTa Vol. 1 ESFRI Scripta Volume I Neutron scattering facilities in Europe Present status and future perspectives ESFRI Physical Sciences and Engineering Strategy Working Group Neutron Landscape Group i ESFRI Scripta Volume I Neutron scattering facilities in Europe - Present status and future perspectives Author: ESFRI Physical Sciences and Engineering Strategy Working Group - Neutron Landscape Group Scientific editors: Colin Carlile and Caterina Petrillo Foreword Technical editors: Marina Carpineti and Maddalena Donzelli ESFRI Scripta series will publish documents born out of special studies Cover image: Diffraction pattern from the sugar-binding protein Gal3c with mandated by ESFRI to high level expert groups, when of general interest. lactose bound collected using LADI-III at ILL. Picture credits should be given This first volume reproduces the concluding report of an ad-hoc group to D. Logan (Lund University) and M. Blakeley (ILL) mandated in 2014 by the Physical Science and Engineering Strategy Design: Promoscience srl Work Group (PSE SWG) of ESFRI, to develop a thorough analysis of the European Landscape of Research Infrastructures devoted to Neutron Developed on behalf of the ESFRI - Physical Sciences and Engineering Strategy Scattering, and its evolution in the next decades. ESFRI felt the urgency Working Group by the StR-ESFRI project and with the support of the ESFRI of such analysis, since many reactor-based neutron sources will be closed Secretariat down in the next years due to national decisions, while the European The StR-ESFRI project has received funding from the European Union’s Spallation Source (ESS) in Lund will be fully operative only in the mid Horizon 2020 research and innovation programme under grant agreement or late 2020s.
    [Show full text]
  • Signa Ture Redacted' Signature Redacted
    Ultracold Neutron Storage Simulation Using the MASSACUTS ILNSTITUTE Kassiopeia Software Package OF TECHNOLOGY by JUL 2 4 2019 Zachary Bogorad LIBRARIES Submitted to the Department of Physics ARCHIVES in partial fulfillment of the requirements for the degree of Bachelor of Science in Physics at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY June 2019 Massachusetts Institute of Technology 2019. All rights reserved. Signa ture redacted' A uthor ............................ D 4 tment of Physics May 10, 2019 Signature redacted_ C ertified by ....................... ose . Formaggio rofessor of Physics Thesis Supervisor Signature redacted Accepted by ................ Nergis Mavalvala Associate Department Head, Department of Physics 2 Ultracold Neutron Storage Simulation Using the Kassiopeia Software Package by Zachary Bogorad Submitted to the Department of Physics on May 10, 2019, in partial fulfillment of the requirements for the degree of Bachelor of Science in Physics Abstract The Kassiopeia software package was originally developed to simulate electromagnetic fields and charged particle trajectories for neutrino mass measurement experiments. Recent additions to Kassiopeia also allow it to simulate neutral particle trajectories in magnetic fields based on their magnetic moments. Two different methods were implemented: an exact method that can work for arbitrary fields and an adiabatic method that is limited to slowly-varying fields but is much faster for large precession frequencies. Additional interactions to simulate reflection of ultracold neutrons from material walls and to allow spin-flip pulses were also added. These tools were used to simulate neutron precession in the Paul Scherrer Institute's neutron electric dipole moment experiment and predict the values of the longitudinal and transverse relax- ation times as well as the trapping lifetime.
    [Show full text]
  • TRIUMF Ultracold Neutron Source
    TRIUMF Ultracold Neutron Source J.W. Martin (Spokesperson)1, L. Buchmann2, J.D. Bowman3, L. Clarke4, C. Davis2, B.W. Filippone5, M. Gericke6, R. Golub4, K. Hatanaka7, M. Hayden8, T.M. Ito9, S. Jeong10, I. Kato2, S. Komamiya11, E. Korobkina4, E. Korkmaz12, L. Lee6, Y. Masuda9, K. Matsuta13, A. Micherdzinska1, W.D. Ramsay6, S.A. Page6, B. Plaster14, I. Tanihata7, W.T.H. van Oers6, Y. Watanabe10, S. Yamashita11, and T. Yoshioka11 1University of Winnipeg, Winnipeg, MB 2TRIUMF, Vancouver, BC 3Oak Ridge National Laboratory, Oak Ridge, TN, USA 4North Carolina State University, Raleigh, NC, USA 5California Institute of Technology, Pasadena, CA, USA 6University of Manitoba, Winnipeg, MB 7Research Center for Nuclear Physics, Osaka University, Osaka, Japan 8Simon Fraser University, Burnaby, BC 9Los Alamos National Laboratory, Los Alamos, NM, USA 10KEK, 1-1 Oho, Tsukuba, Ibaraki, Japan 11The University of Tokyo, Tokyo, Japan 12University of Northern British Columbia, Prince George, BC 13Osaka University, Toyonaka, Osaka, Japan 14University of Kentucky, Lexington, KY, USA March 17, 2008 1 Executive Summary We propose the construction of the world’s highest density source of ultracold neutrons (UCN) at TRIUMF. The truly high density that could be obtained at TRIUMF would allow a class of precision measurements to be conducted with significantly improved statistical and systematic uncertainties, and thus more significant results. This source would therefore make a major impact on studies of fundamental physics with UCN that would complement and enhance the ISAC program. A window of opportunity exists to capitalize on the successes of Y. Masuda’s group at KEK and at RCNP, thereby allowing the TRIUMF project to surpass other proposed sources elsewhere.
    [Show full text]
  • Neutron Phase Spin Echo
    PHYSICAL REVIEW C 93, 045501 (2016) Neutron phase spin echo Florian M. Piegsa,1,* Patrick Hautle,2 and Christian Schanzer3 1ETH Zurich,¨ Institute for Particle Physics, CH-8093 Zurich,¨ Switzerland 2Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland 3SwissNeutronics AG, CH-5313 Klingnau, Switzerland (Received 25 January 2016; revised manuscript received 11 February 2016; published 8 April 2016) A novel neutron spin resonance technique is presented based on the well-known neutron spin echo method. In a first proof-of-principle measurement using a monochromatic neutron beam, it is demonstrated that relative velocity changes of down to a precision of 4 × 10−7 can be resolved, corresponding to an energy resolution of better than 3 neV. Currently, the sensitivity is only limited by counting statistics and not by systematic effects. An improvement by another two orders of magnitude can be achieved with a dedicated setup, allowing energy resolutions in the 10 peV regime. The new technique is ideally suited for investigations in the field of precision fundamental neutron physics, but will also be beneficial in scattering applications. DOI: 10.1103/PhysRevC.93.045501 I. INTRODUCTION the neutron spins in and out of their plane of precession.1 Here, γ =−2π × 29.165 MHz/T is the gyromagnetic ratio of the The neutron spin echo (NSE) technique was first proposed n neutron [27]. Detailed theoretical descriptions of the spin flip by Mezei in 1972 [1]. It describes a very sensitive method process, NSE, and NRSE can be found in Refs. [28–30]. to determine small changes in the neutron velocity caused by inelastic scattering in a sample [2].
    [Show full text]
  • New Search for Mirror Neutron Regeneration
    New Search for Mirror Neutron Regeneration L. J. Broussard1;∗, K. M. Bailey1, W. B. Bailey1, J. L. Barrow2, K. Berry1, A. Blose3, C. Crawford3, L. Debeer-Schmitt1, M. Frost1;2, A. Galindo-Uribarri1, F. X. Gallmeier1, C. E. Gilbert1;2, L. Heilbronn2, E. B. Iverson1, A. Johnston2, Y. Kamyshkov2, P. Lewiz2, I. Novikov4, S. I. Penttilä1, S. Vavra2, and A. R. Young5 1Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 2University of Tennessee, Knoxville, TN 37996 USA 3University of Kentucky, Lexington, KY 40506 USA 4Western Kentucky University, Bowling Green, KY 42101 USA 5North Carolina State University, Raleigh, NC 27695 USA Abstract. The possibility of relatively fast neutron oscillations into a mirror neutron state is not excluded experimentally when a mirror magnetic field is considered. Direct searches for the disappearance of neutrons into mirror neutrons in a controlled magnetic field have previously been performed using ultracold neutrons, with some anomalous results reported. We describe a technique using cold neutrons to perform a disappearance and regeneration search, which would allow us to unambiguously identify a possible oscillation signal. An experiment using the existing General Purpose-Small Angle Neutron Scattering instrument at the High Flux Isotope Reactor at Oak Ridge National Laboratory will have the sensitivity to fully explore the parameter space of prior ultracold neutron searches and confirm or refute previous claims of observation. This instrument can also conclusively test the validity of recently suggested oscillation-based explanations for the neutron lifetime anomaly. 1 Introduction that can resolve the ambiguity associated with the source of ultracold neutron losses [14, 15]. The astrophysical evidence for dark matter is strong.
    [Show full text]
  • The Physics of Ultracold Neutrons and Fierz Interference in Beta Decay
    The Physics of Ultracold Neutrons and Fierz Interference in Beta Decay Thesis by Kevin Peter Hickerson In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 2013 (Defended October 9, 2012) ii © 2013 Kevin Peter Hickerson All Rights Reserved iii Acknowledgements I am very indebted to my research adviser, Dr. Bradley Filippone, who kindly asked me to join his research group, led me toward a rewarding path into nuclear physics, and gave precious advice to work and experiment with ultracold neutrons. I am appreciative of my previous employer, Bill Gross, who enabled me to pursue my work outside of physics, ranging in far-reaching fields such as tablet computing, rapid pro- totyping, low-cost food production, and my personal favorite, solar energy. I wish to show much appreciation to Dr. Chris Morris, Dr. Mark Makela, Dr. Takeyasu Ito, John Ramsey, Walter Sondheim and Dr. Andy Saunders of Los Alamos National Lab- oratory, whose ingenuity and creativity and mentoring were invaluable for designing the many neutron experiments we performed at LANSCE. I am also grateful to all the graduate students and postdocs who have worked on the ultracold neutron projects with me. Their hard work and late hours make these experiments successful. Finally, I am very grateful to my family, my friends, my wife, Anna, and my children, Melanie, Brian, and Jack for tolerating my many long trips to Los Alamos to work on this research and supporting me during my years in graduate school. iv Abstract In the first component of this thesis, we investigate the physics of ultacold neutrons (UCN).
    [Show full text]
  • Ultracold Neutrons in Canada and Japan
    Ultracold Neutrons in Canada and Japan Jeff Martin The University of Winnipeg February 2009 research supported by Natural Sciences and Engineering Research Council Canada Canada Foundation for Innovation Manitoba Research & Innovation Fund Japan Society for the Promotion of Science International Spallation Ultracold Neutron Source Spokespeople: Y. Masuda (KEK), J.W. Martin (Winnipeg) Collaborators: J.D. Bowman, J. Birchall, L. Buchmann, L. Clarke, C. Davis, B.W. Filippone, M. Gericke, R. Golub, K. Hatanaka, M. Hayden, T.M. Ito, S. Jeong, I. Kato, S. Komamiya, E. Korobkina, E. Korkmaz, L. Lee, K. Matsuta, A. Micherdzinska, W.D. Ramsay, S.A. Page, B. Plaster, I. Tanihata, W.T.H. van Oers, Y. Watanabe, S. Yamashita, T. Yoshioka (KEK, Winnipeg, Manitoba, ORNL, TRIUMF, NCSU, Caltech, RCNP, SFU, LANL, Tokyo, UNBC, Osaka, Kentucky) We propose to construct the world©s highest density source of ultracold neutrons and use it to conduct fundamental and applied physics research using neutrons. Ultracold Neutrons (UCN) ● What are UCN? ● Interactions of UCN. ● How to make UCN. ● Plans for the International Spallation Ultracold Neutron Source (i-SUN). ● Experiments that we would do there. Ultracold Neutrons (UCN) ● UCN are neutrons that are moving so slowly that they are totally reflected from a variety of materials. ● So, they can be confined in material bottles for long periods of time. ● Typical parameters: – velocity < 8 m/s = 30 km/h – temperature < 4 mK – kinetic energy < 300 neV ● Interactions: – gravity: V=mgh – weak interaction (allows UCN to decay) – magnetic fields: V=-µ •B – strong interaction Gravity ● Question: If I threw something straight up at an initial speed of 30 km/h, how high would it go? ● Answer (from high-school physics): – about 3 meters (10 feet).
    [Show full text]
  • Ultracold Neutrons: Their Role in Studies of Condensed Matter
    Ultracold neutrons: Their role in studies of condensed matter R. Golub Hahn Meitner Institut, 14109 Berlin, Germany Ultracold neutrons, that is, neutrons whose energy is so low that they can be contained for long periods of time in material and magnetic bottles, provide the basis for the currently most sensitive experiments seeking to detect the neutron electric dipole moment and to measure the neutron lifetime. The goal of this article is to review the work that has been done to date in applying ultracold neutrons to the study of condensed matter and to discuss the future prospects for this type of research. [S0034-6861(96)00202-4] CONTENTS decay lifetime. Pendlebury (1993) gives a review of the current situation with detailed references. I. Introduction 329 In the present article we should like to address the A. Short history of ultracold neutron research 329 issue of the application of ultracold neutrons to studies B. Ultracold neutrons and condensed matter 331 of condensed matter. In comparison with the applica- II. Reflection and Tunneling from Surfaces and More tions mentioned above, the use of UCN scattering as a Complex Structures 331 tool to study condensed matter is still in its infancy. We A. UCN reflectometry 333 shall review what has already been done in this field and III. Elastic Scattering 334 give a few pointers to possible future developments. A. Scattering from homogeneous substances 334 In order to be totally reflected at all angles of inci- B. Scattering from static inhomogeneities 335 dence from an appropriate surface, and hence to have IV. Inelastic Scattering 336 the ability to be stored for long periods of time, neutrons V.
    [Show full text]
  • Gravitational and Centrifugal Quantum States of Matter (Neutrons) and Anti-Matter (Anti-Hydrogen Atoms)
    Gravitational and centrifugal quantum states of matter (neutrons) and anti-matter (anti-hydrogen atoms) INSTITUT MAX VON LAUE - PAUL LANGEVIN 24.01.13 V.V. Nesvizhevsky Gravitational and centrifugal quantum states of matter (neutrons) and anti-matter (anti-hydrogen atoms) The Uncertainty Principle: strictly speaking, you cannot say that you know the position (height) of a water droplet in the turning point and simultaneouly say that the vertical velocity in this point equals zero… INSTITUT MAX VON LAUE - PAUL LANGEVIN 24.01.13 V.V. Nesvizhevsky Gravitational and centrifugal quantum states of matter (neutrons) and anti-matter (anti-hydrogen atoms) as well as you cannot say that an apple is fixed at some height and simultaneously say that is not moving… INSTITUT MAX VON LAUE - PAUL LANGEVIN 24.01.13 V.V. Nesvizhevsky Gravitational and centrifugal quantum states of matter (neutrons) and anti-matter (anti-hydrogen atoms) and when it is moving, this is not a smooth classical motion Quantum bounces [P.W. Langhoff, Shroedinger particle in a gravitational well, Am. J. Phys. 39 (1971) 954; R.L. Gibbs, The quantum bouncer. Am. J. Phys. 43 (1975) 25; J. Gea-Banacloche, A quantum bouncing ball, Am. J. Phys. 67 (1999) 776] INSTITUT MAX VON LAUE - PAUL LANGEVIN 24.01.13 V.V. Nesvizhevsky Gravitational and centrifugal quantum states of matter (neutrons) and anti-matter (anti-hydrogen atoms) There are 4 known fundamental interactions: electromagnetic, stong, weak and gravitational Quantum states of a massive particle should exist independent of the fundamental nature of a bounding potential Preceeding experiment: observation of gravitational phase-shift [R.
    [Show full text]
  • Experiments with Ultracold Neutrons
    Experiments with ultracold neutrons - first 50 years. Yu.N. Pokotilovski1 Joint Institute for Nuclear Research 141980 Dubna, Moscow region, Russia Abstract This year is 50 anniversary of the first experimental observation of ultracold neutrons (UCN). I present my reminiscences of the first experiment in Dubna, first encounter with F.L. Shapiro – pioneer of the UCN investigations, and the early stage of the UCN experiments. Present status of investigations with UCN is shortly reviewed. PACS: 28.20.-v; 29.25.Dz; 14.20.Dh; 13.30.-a. Keywords: ultracold neutrons. 1 Prologue. My 1968 before UCN. 1968 was the last year of my postgraduate studentship in Moscow academic Institute. The topic of my work was the experimental study of interactions of high energy protons with big (quasi-infinite) uranium targets - so called electronuclear method of generation of neutrons and fuel isotopes. The experimental part was performed at the JINR synchrocyclotron and consisted in the measurement of production of neutrons and 239Pu in big uranium targets of different depletion and different central proton beam targets, bombarded by protons in the energy range 300-660 MeV. At that time this method was considered as a possible radical alternative to the arXiv:1805.05292v1 [physics.hist-ph] 14 May 2018 breeder-reactor-plus-fuel-reprocessing industry and as a way to solve the future world energy problem due to involvement of all uranium to energy production without en- richment process. Later, when it became clear that situation with mineral sources of energy is not as sad as was predicted, this theme was put aside.
    [Show full text]
  • Search for Low-Energy Upscattering of Ultracold Neutrons from a Beryllium Surface
    XJ9800298 COOBlUEHMfl OBbEflMHEHHOrO MHCTMTVTA flflEPHbIX MCCJlEflOBAHMM AyoHa E3-98-41 Al.Yu.Muzychka, Yu.N.Pokotilovskij P.Geltenbort* SEARCH FOR LOW-ENERGY UPSCATTERING OF ULTRACOLD NEUTRONS FROM A BERYLLIUM SURFACE ""Institute Laue-Langevin, Grenoble, France $ 2 9-40 1998 © 06beAHHeHHbiPi HHCTmyT AAepHbix ucc^eAOBanuPi. fly6Ha, 1998 1 Introduction There is the well-known and long-standing puzzle of ultracold neutron (UCN) storage times in closed volumes or, equivalently, of anomalous losses of UCN upon reflection from the inner surfaces of UCN traps. The most surprisingly large discrepancy in the experimental and pre­ dicted loss coefficients was observed for the most promising materials for high UCN storage times: cold beryllium [1, 2] and solid oxygen [3]. The anomaly consists in an almost temperature independent (in the temperature interval 10-300 K) wall loss coefficient (~ 3 ■ 10-5), corre­ sponding to the extrapolated inelastic thermal neutron cross section <r* ~ 0, 96. This experimental figure for Be is two orders of magnitude higher than the theoretical one, the latter being completely deter­ mined at low temperatures by the neutron capture in Be (0.0086). The experiment/theory ratio for a very cold oxygen surface achieves three orders of magnitude [3]. Approximate universality of the loss co­ efficient for beryllium and oxygen, and the independence of the Be fig­ ures from temperature, forces one to suspect a universal reason for this anomaly. A series of experiments to find the channel by which UCN leave the trap are described in [2]. None of the suspected reasons has been confirmed: surface contaminations by dangerous elements with large absorption cross-sections, penetration of UCN through possible micro-cracks in the surface layers of Be, the hypothetical process of milliheating of UCN due to collisions with a low frequency vibrating surface, the upscattering of UCN due to thermal vibrations of the wall nuclei.
    [Show full text]