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A measurement of the gravitational acceleration of the antiproton

Description: A fundamental experiment in gravity proposed by us, is the measurement of the gravitational force on antimatter. This measurement would constitute the first direct test of the Weak Equivalence Principle (WEP) for antimatter. The availability of low-energy antiprotons at CERN has made such an experiment feasible, and a proposal to carry out such a measurement has been accepted by the CERN Program Committee. We plan to use a time-of-flight technique similar to that pioneered by Fairbank and Witteborn in their measurement of the gravitational force on an electron. Very slow particles are launched into a vertical drift tube and the time-of-flight spectrum of these particles is recorded. This spectrum will exhibit a cut-off point directly related to the gravitational acceleration of the particles. Obtaining very slow antiprotons involves several stages of deceleration. Antiprotons from LEAR will be initially decelerated from 2 MeV to tens of kilovolts by passing them through a thin foil. After capture and cooling in a series of ion traps, the antiprotons will be in a thermal distribution with a temperature of a few degrees Kelvin. These ultra-cold antiprotons will then be released a few at a time into the drift tube. A detector will measure the arrival time of the particles at the exit of the drift tube. H{sup {minus}}-ion, which have almost identical electromagnetic properties to the antiprotons, will be used for comparison and as a calibration standard. 7 refs., 1 fig.
Date: January 1, 1990
Creator: Holzscheiter, M.H.
Partner: UNT Libraries Government Documents Department

Falling antimatter: An experiment to measure the gravitational acceleration of the antiproton

Description: According to some theories of gravity, antimatter will fall faster than matter in the earth's gravitational field. An experiment to measure the gravitational force on the antiproton is under construction. Antiprotons of a few MeV from the LEAR facility of CERN will be slowed down and caught in a large Penning electromagnetic trap. They will then be cooled and transferred to Penning cooling and launching traps. The gravitational acceleration will be measured by the time-of-flight in a drift tube shielding stray electronic fields, and will be compared with that measured for H/sup /minus// ions. Progress on a number of fronts is described. 9 refs., 2 figs.
Date: January 1, 1988
Creator: Dyer, P.; Camp, J.; Holzscheiter, M.H. & Graessle, S.
Partner: UNT Libraries Government Documents Department

Formation of low-energy antihydrogen

Description: Antihydrogen atoms, produced near rest, trapped in a magnetic well, and cooled to the lowest possible temperature (kinetic energy) could provide an extremely powerful tool for the search of violations of CPT and Lorentz invariance. The author describes plans to trap antiprotons and positrons in a combined Penning trap and to form a significant number of cold antihydrogen atoms for comparative precision spectroscopy of hydrogen and antihydrogen.
Date: March 1, 1999
Creator: Holzscheiter, M.H. & Collaboration, ATHENA
Partner: UNT Libraries Government Documents Department

Tests of CPT, Lorentz invariance and the WEP with antihydrogen

Description: Antihydrogen atoms, produced near rest, trapped in a magnetic well, and cooled to the lowest possible temperature (kinetic energy) could provide an extremely powerful tool for the search of violations of CPT and Lorentz invariance. Equally well, such a system could be used for searches of violations of the Weak Equivalence Principle (WEP) at high precision. The author describes his plans to form a significant number of cold, trapped antihydrogen atoms for comparative precision spectroscopy of hydrogen and antihydrogen and comment on possible first experiments.
Date: March 1999
Creator: Holzscheiter, M. H.
Partner: UNT Libraries Government Documents Department

Antihydrogen production and precision experiments

Description: 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}.
Date: December 31, 1996
Creator: Nieto, M.M.; Goldman, T. & Holzscheiter, M.H.
Partner: UNT Libraries Government Documents Department

Physics with ultra-low energy antiprotons

Description: The experimental observation that all forms of matter experience the same gravitational acceleration is embodied in the weak equivalence principle of gravitational physics. However no experiment has tested this principle for particles of antimatter such as the antiproton or the antihydrogen atom. Clearly the question of whether antimatter is in compliance with weak equivalence is a fundamental experimental issue, which can best be addressed at an ultra-low energy antiproton facility. This paper addresses the issue. 20 refs.
Date: January 1, 1989
Creator: Holtkamp, D.B.; Holzscheiter, M.H. & Hughes, R.J. (Los Alamos National Lab., NM (USA))
Partner: UNT Libraries Government Documents Department

First beam at DARHT-II

Description: The second axis of the Dual Axis Radiographic Hydro-Test (DARHT) facility will provide up to four short (<100 ns) radiation pulses for flash radiography of high-explosive driven implosion experiments. To accomplish this the DARHT-I1 linear induction accelerator (LIA) will produce a 2-kA electron beam with 18-MeV kinetic energy, constant to within 2 0.5% for 2-ps. A fast kicker will cleave four short pulses out of the 2-ps flattop, with the bulk of the beam diverted into a dump. The short pulses will then be transported to the final-focus magnet, and focused onto a tantalum target for conversion to bremsstrahlung pulses for radiography. DARHT-II is a collaborative effort between Los Alamos, Livermore, and Berkeley National Laboratories. The first tests of the second axis accelerator, described herein, were performed to demonstrate the technology and to meet the performance requirements for closing out the DARHT-II construction project.
Date: January 1, 2003
Creator: Ekdahl, C. A. (Carl A.); Abeyta, E. O. (Epifanio Orlando); Caudill, L. D. (Larry D.); Dalmas, D. A. (Dale Allen); Eversole, S. A. (Steven A.); Harrison, J. F. (James F.) et al.
Partner: UNT Libraries Government Documents Department

Beyond metric gravity: Progress on PS-200

Description: The reconciliation of quantum mechanics and gravity on varying distance scales requires changes to General Relativity that may be testable implications. We briefly review the status of tests with matter of the inverse square law and the principle of equivalence, then report on progress on the drift-tube measurement section of PS- 200, the experiment to measure the gravitational acceleration of antiprotons.
Date: January 1, 1993
Creator: Goldman, T.; Brown, R.E.; Camp, J.B.; Darling, T.; Dyer, P.; Holzscheiter, M.H. et al.
Partner: UNT Libraries Government Documents Department