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Title: Antihydrogen production and precision experiments

Abstract

The study of CPT invariance with the highest achievable precision in all particle sectors is of fundamental importance for physics. Equally important is the question of the gravitational acceleration of antimatter. In recent years, impressive progress has been achieved in capturing antiprotons in specially designed Penning traps, in cooling them to energies of a few milli-electron volts, and in storing them for hours in a small volume of space. Positrons have been accumulated in large numbers in similar traps, and low energy positron or positronium beams have been generated. Finally, steady progress has been made in trapping and cooling neutral atoms. Thus the ingredients to form antihydrogen at rest are at hand. Once antihydrogen atoms have been captured at low energy, spectroscopic methods can be applied to interrogate their atomic structure with extremely high precision and compare it to its normal matter counterpart, the hydrogen atom. Especially the 1S-2S transition, with a lifetime of the excited state of 122 msec and thereby a natural linewidth of 5 parts in 10{sup 16}, offers in principle the possibility to directly compare matter and antimatter properties at a level of 1 part in 10{sup 16}.

Authors:
; ;  [1]
  1. and others
Publication Date:
Research Org.:
Los Alamos National Lab., NM (United States)
Sponsoring Org.:
USDOE Assistant Secretary for Human Resources and Administration, Washington, DC (United States)
OSTI Identifier:
442156
Report Number(s):
LA-UR-96-4788; CONF-9605253-1
ON: DE97002374; TRN: 97:005073
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: 3. Biellian conference on low energy antiproton physics, Rome (Italy), 19-25 May 1996; Other Information: PBD: 1996
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; ANTIMATTER; GRAVITATION; ANTIPROTONS; PARTICLE PRODUCTION; CPT THEOREM; HYDROGEN; TRAPPING

Citation Formats

Nieto, M.M., Goldman, T., and Holzscheiter, M.H. Antihydrogen production and precision experiments. United States: N. p., 1996. Web.
Nieto, M.M., Goldman, T., & Holzscheiter, M.H. Antihydrogen production and precision experiments. United States.
Nieto, M.M., Goldman, T., and Holzscheiter, M.H. Tue . "Antihydrogen production and precision experiments". United States. doi:. https://www.osti.gov/servlets/purl/442156.
@article{osti_442156,
title = {Antihydrogen production and precision experiments},
author = {Nieto, M.M. and Goldman, T. and Holzscheiter, M.H.},
abstractNote = {The study of CPT invariance with the highest achievable precision in all particle sectors is of fundamental importance for physics. Equally important is the question of the gravitational acceleration of antimatter. In recent years, impressive progress has been achieved in capturing antiprotons in specially designed Penning traps, in cooling them to energies of a few milli-electron volts, and in storing them for hours in a small volume of space. Positrons have been accumulated in large numbers in similar traps, and low energy positron or positronium beams have been generated. Finally, steady progress has been made in trapping and cooling neutral atoms. Thus the ingredients to form antihydrogen at rest are at hand. Once antihydrogen atoms have been captured at low energy, spectroscopic methods can be applied to interrogate their atomic structure with extremely high precision and compare it to its normal matter counterpart, the hydrogen atom. Especially the 1S-2S transition, with a lifetime of the excited state of 122 msec and thereby a natural linewidth of 5 parts in 10{sup 16}, offers in principle the possibility to directly compare matter and antimatter properties at a level of 1 part in 10{sup 16}.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 31 00:00:00 EST 1996},
month = {Tue Dec 31 00:00:00 EST 1996}
}

Conference:
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  • CPT invariance is a fundamental property of quantum field theories in flat space-time. Principal consequences include the predictions that particles and their antiparticles have equal masses and lifetimes, and equal and opposite electric charges and magnetic moments. It also follows that the fine structure, hyperfine structure, and Lamb shifts of matter and antimatter bound systems should be identical. It is proposed to generate new stringent tests of CPT using precision spectroscopy on antihydrogen atoms. An experiment to produce antihydrogen at rest has been approved for running at the Antiproton Decelerator (AD) at CERN. We describe the fundamental features of thismore » experiment and the experimental approach to the first phase of the program, the formation and identification of low energy antihydrogen.« less
  • It is known that the generally accepted theories of gravity and quantum mechanics are fundamentally incompatible. Thus, when one tries to combine these theories, one must beware of physical pitfalls. Modern theories of quantum gravity are trying to overcome these problems. Any ideas must confront the present agreement with general relativity, but yet be free to wonder about not understood phenomena, such as the dark matter problem. This all has led some {open_quotes}intrepid{close_quotes} theorists to consider a new gravitational regime, that of antimatter. Even more {open_quotes}daring{close_quotes} experimentalists are attempting, or considering attempting, the measurement of the gravitational force on antimatter,more » including low-energy antiprotons and, perhaps most enticing, antihydrogen.« less
  • An experiment aimed at producing antihydrogen atoms by the reaction of cold antiprotons stored in a Penning trap with injected ground state positronium atoms is described. The apparatus developed in an attempt to observe the charge conjugate reaction using proton projectiles is discussed. Technically feasible upgrades to this apparatus are identified which may allow, in conjunction with the PS200 trap, antihydrogen production at LEAR.
  • A positron accumulator based on a modified Penning-Malmberg trap has been constructed and undergone preliminary testing prior to being shipped to CERN in Geneva where it will be a part of an experiment to synthesize low-energy antihydrogen. It utilizes nitrogen buffer gas to cool and trap a continuous beam of positrons emanating from a {sup 22}Na radioactive source. A solid neon moderator slows the positrons from the source down to epithermal energies of a few eV before being injected into the trap. It is estimated that around 10{sup 8} positrons can be trapped and cooled to ambient temperature within 5more » minutes in this scheme using a 10 mCi source.« less
  • The formation of neutral antihydrogen requires the blending of high energy physics technology and atomic physics principles. One approach to the problem is to employ laser stimulated radiative recombination of positrons and antiprotons to form H-bar atoms in excited states. This can be implemented using the merged beam approach which allows very low energy collisions to occcur between fast moving collidants. Methods have been devised for overcoming the problems associated with the survival of the H-bar atoms and these will be discussed. Plans for a simulation experiment employing normal matter analogs will be presented. (AIP)