ITAMP WORKSHOP

Cold Antimatter

April 11-13, 2002

Organizers: Piotr Froelich and Gerald Gabrielse

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Abstracts	Schedule
Participants	Map

Online Presentations

Bollinger	Bowden	Cavagnero	Cohen
Dubin	Esry	Froelich	Gabrielse
Hayano	Kuzmin	Ordonez	Robicheaux
Rolston	Squires	Storry	Tan
Voronin	Walz	Yamazaki	Zygelman

Participants

Dr. John J.Bollinger NIST, MS 847.10, 325 Broadway, Boulder, CO 80305-3328 John.bollinger@boulder.nist.gov Mr. Nathaniel S. Bowden Physics Department, Harvard University, Cambridge, MA 02138 bowden@physics.harvard.edu Prof. Michael Cavagnero University of Kentucky, Dept. of Physics and Astronomy, 177 Chemistry-Physics Building Lexington, KY 40506-0055 mike@pa.uky.edu Dr. James S. Cohen Los Alamos National Laboratory T-4, MS-B212 Los Alamos, NM 87544 Cohen@lanl.gov Prof. Alex Dalgarno ITAMP, 60 Garden Street, MS 14, Cambridge, MA 02138 adalgarno@cfa.harvard.edu Prof. Daniel H.E. Dubin Dept of Physics , University of California, San Diego, 9500 Gilman Drive La Jolla CA 92093-0319 dhdubin@ucsd.edu Prof. Brett Esry Department of Physics, Kansas State University Manhattan, Kansas 66506 esry@phys.ksu.edu Prof. Piotr Froelich Department of Quantum Chemistry, Uppsala University, Box 518, 751 20 Uppsala, Sweden piotr@kvac.uu.se Prof. Gerald Gabrielse Department of Physics, Harvard University, Cambridge, MA 02138 gabrielse@physics.harvard.edu Prof. Sheldon L Glashow CAS Physics Department, Boston University, 590 Commonwealth Ave Boston, MA 02215-2521 slg@bu.edu Prof. Ryugo S. Hayano 7-3-1 Hongo, , Bunkyo-ku, Tokyo 113-0033, Japan hayano@phys.s.u-tokyo.ac.jp Mr. Stanislav G. Kuzmin University of California, San Diego, Physics Department, 0350, 9500 Gilman Drive La Jolla, CA 92093-0350 Skuzmin@physics.ucsd.edu Prof. Carlos A. Ordonez Department of Physics, University of North Texas, P.O. Box 311427 Denton, TX 76203-1427 cao@unt.edu Prof. Francis Robicheaux Physics Department, 206 Allison Laboratory, Auburn University, AL 36849-5311 francisr@physics.auburn.edu Dr. Steven Rolston NIST, 100 Bureau Drive, Gaithersburg, MD 20899-8424 Steven.rolston@nist.gov Dr. Hossein Sadeghpour ITAMP, 60 Garden Street, MS 14, Cambridge, MA 02138 hsadeghpour@cfa.harvard.edu Prof. Isao Shimamura RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan shimamur@rarfaxp.riken.go.jp Mr. Todd Squires Harvard University, Physics Department, Cambridge, MA 02138 squires@physics.harvard.edu Dr. Cody Storry Harvard University Physics Department, Jefferson 260 Cambridge, MA 02138 cody@hussle.harvard.edu Dr. Joseph N. Tan Harvard University, Department of Physics, 17 Oxford Street, Cambridge, MA 02138 joseph.n.tan@cern.ch jtan@hussle.harvard.edu Dr. Alexei Voronin P.N. Lebedev Physical Institute, Leninsky prosp. 53, , 117924 Moscow Russia avoronin@aha.ru Dr. Jochen Walz Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany jcw@mpq.mpg.de Prof. Yasunori Yamazaki Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Sakitama, Japan yasunori@phys.c.u-tokyo.ac.jp Prof. Bernard Zygelman Department of Physics, University of Nevada, Las Vegas, Las Vegas, Nevada 89154-4002 bernard@physics.unlv.edu

Schedule

Thursday, April 11, 2002

Friday, April 12, 2002

Saturday, April 13, 2002

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Thursday, April 11, 2002 (All sessions in Pratt Conference Room)  8:30 a.m. Coffee  8:45 a.m. Kate Kirby: Introduction  9:00 - 9:40 a.m. Gerald Gabrielse: Overview Talk -- Cold antihydrogen: are we there?  Session I: Accumulation of Cold Positrons and Antiprotons Chair: G. Gabrielse  9:45 - 10:15 a.m. Nathan Bowden -- Positron Accumulatin via the Ionization of Rydberg positronium 10:20 - 10:35 a.m.  Coffee 10:35 - 11:05 a.m. John Bollinger -- Sympathetically laser-cooled and compressed positron plasmas 11:10 - 11:40 a.m. Yasunori Yamazaki -- Production of ultraslow antiproton beam and its application to atomic collisions 11:45 - 2:00 p.m. Lunch Session II: Trapping Cold Antihydrogen Ingredients; Cold Plasmas   Chair: P. Froelich  2:00 - 2:30 p.m. Todd Squires -- Stability of a charged particle in a combined Penning-Ioffe Trap  2:35 - 3:05 p.m. Carlos Ordenez -- Plasma confinement in nested Penning traps for antihydrogen production and trapping  3:10 - 3:40 p.m. Dan Dubin -- Magnetic traps that can simultaneously confine neutral atoms and a nonneutral plasma in thermal equilibrium  3:45 - 4:15 p.m. Refreshments  4:15 - 4:45 p.m. Steve Rolston -- Cold neutral plasmas and Rydberg atom formation  4:50 - 5:20 p.m. Stanislav Kuzmin -- Numerical simulation of ultracold plasmas 5:30 p.m.  Reception in Perkin Lobby    Home  Back to Workshops  Top  Friday, April 12, 2002 (All sessions in Phillips Auditorium)  8:45 - 9:15 a.m.  Sheldon Glashow -- Antimatter in astrophysics Session III: Formation of Cold Antihydrogen   Chair: H. Sadeghpour  9:20 - 9:50 a.m. Joseph Tan -- Experiments looking for field-assisted recombination of antihydrogen  9:55 - 10:25 a.m. Francis Robicheaux -- Motion of highly excited atoms in strong magnetic fields 10:30 - 10:45 a.m.  Coffee 10:45 - 11:15 a.m. Jochen Walz -- Using lasers to produce and cool antihydrogen 11:20 - 11:50 a.m. Michael Cavagnero -- The few-body physics of antihydrogen formation 11:55 - 12:20 p.m. Cody Storry -- Two-stage Rydberg charge exchange: progress toward antihydrogen production  12:30 - 2:00 p.m.  Lunch Session IV: Collisions and Chemistry Involving Antihydrogen   Chair: A. Dalgarno  2:00 - 2:30 p.m. Bernard Zygelman -- Kinetics of antiproton-positron recombination in a cold plasma  2:35 - 3:05 p.m. Piotr Froelich -- Atom-antiatom interactions  3:10 - 3:40 p.m. A. Yu. Voronin -- Hydrogen-antihydrogen interaction at subkelvin temperatures  3:45 - 4:15 p.m. Refreshments  4:00 - 4:30 p.m. Isao Shimamura -- Laser-assisted collisional antihydrogen formation  Home  Back to Workshops  Top     Saturday, April 13, 2002 (All sessions in Phillips Auditorium)  Session V: Collisions and Spectroscopy with Antiprotons   Chair:  B. Zygelman  9:00 - 9:30 a.m. Jim Cohen -- Quasiclassical description of physics with antiprotons  9:35 - 10:05 a.m. Brett Esry -- Protonium formation in cold $\bar{p}$+H collisions 10:10 - 10:40 a.m. Ryugo Hayano -- High precision laser/microwave spectroscopy of antiprotonic helium atoms 11:30 a.m. Adjourn

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Abstracts

Bollinger	Bowden	Cavagnero	Cohen
Dubin	Esry	Froelich	Gabrielse
Glashow	Hayano	Kuzmin	Ordonez
Robicheaux	Rolston	Shimamura	Squires
Storry	Tan	Voronin	Walz
Yamazaki	Zygelman

Sympathetically Laser-Cooled and Compressed Positron Plasmas B.M. Jelenkovic1, J.J. Bollinger1, A.B. Newbury2, T.B. Mitchell3, and W.M. Itano1 1NIST Boulder, CO 80305-3328   2Ball Aerospace, Boulder, Co 80301   3Dept. of Physics and Astronomy University of Delaware Newark, DE 19716 Abstract PDF

Positron Accumulation via the Ionization of Rydberg Positronium N.S. Bowden Department of Physics, Harvard University, Cambridge, MA 02138 We have demonstrated a simple and efficient positron accumulation mechanism based upon the ionization of Rydberg positronium. Rydberg positronium is formed near the surface of a tungsten moderator crystal within the cryogenic vacuum of an open cylinder Penning trap. Simply reversing the sign of trapping potentials leads to the accumulation of electrons at a rate identical to that of positrons, confirming the production and subsequent ionization of Rydberg positronium. The compatibility of this loading mechanism with the extremely good vacuum of a cryogenic Penning trap makes it ideally suited to experiments involving the interaction of positrons and antiprotons. Indeed, we have used this loading mechanism at the CERN Antiproton Decelerator facility to study positron cooling of antiprotons and in ongoing attempts to form antihydrogen. References: 1. J. Estrada et al., Phys. Rev. Lett. 84, 859 (2000). 2. G. Gabrielse et al., Phys. Lett. B 507, 1 (2001).

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Few-Body Processes in Antihydrogen Formation Michael Cavagnero University of Kentucky Department of Physics and Astronomy Lexington, KY 40506-0055 A two-stage charge exchange technique for the production of antihydrogen atoms is analyzed, with emphasis on requisite two-and three-body processes, including charge transfer and tunneling transfer. Cesium atoms prepared in Rydberg states undergo sequential rearrangement collisions that produce Rydberg positronium from positron-Cs collisions and Rydberg antihydrogen from positronium-antiproton collisions. Large cross sections for cold rearrangement collisions result in a high estimated rate for antihydrogen production.

Quasiclassical Description of Physics with Antiprotons James S. Cohen Theoretical Division Los Alamos National Laboratory Los Alamos, NM 87545 Talk PDF

Magnetic Traps That Can Simultaneously Confine Neutral Atoms and a Nonneutral Plasma in Thermal Equilibrium Daniel H. E. Dubin Department of Physics University of California, San Diego* 9500 Gilman Drive La Jolla CA 92093-0319 Several trap designs are proposed for the simultaneous confinement of neutral atoms and a non-neutral plasma in close proximity.[1] One design uses axially symmetric static magnetic fields with a magnetic minimum in a ring around the trap axis. Axial symmetry is required for confinement of the rotating non-neutral plasma, and the magnetic minimum traps the neutral atoms. Another design uses a rotating axially asymmetric magnetic field superimposed on a cusp field to create a time-averaged magnetic minimum (a "TOP" trap). The rotating asymmetry acts as a magnetic "rotating wall" to help confine the non-neutral plasma. In a third design, a cylindrically symmetric high-order multipole field traps the neutral atoms, which are made to rotate about the trap axis in order to avoid the magnetic null at the trap center. These designs may be useful for the production and confinement of cold antihydrogen. [1] D. H. E. Dubin, Phys. Plasmas 8, 4331 (2001) *Work supported by the NSF and the ONR.

Protonium Formation in Cold $\bar{p}$+H Collisions Brett Esry Department of Physics Kansas State University Manhattan, Kansas 66506 I will present an adiabatic hyperspherical treatment of $\bar{p}$+H(1$s$), focusing on the production of bound $p\bar{p}$ pairs, protonium (Pn). While this system superficially resembles a molecule, the Born-Oppenheimer approximation is no longer valid. Making the solution more difficult, hundreds of Pn channels are open even for cold antiprotons, I will present the adiabatic hyperspherical potential curves as well as possible approaches to solving the dynamics on these curves.

Atom - Antiatom Interactions Piotr Froelich Department of Quantum Chemistry Uppsala University Box 518 751 20 Uppsala, Sweden   Talk PDF

Cold Antihydrogen: Are We There? Gerald Gabrielse* Professor of Physics Harvard Univeristy Cambridge, MA 02138 Many interesting measurements with cold antiprotons and positrons have been made recently. These will be introduced and summarized with the intent of identifying crucial problems yet to be solved, and places where our understanding must be improved. *Spokesperson for the ATRAP Collaboration

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High Precision Laser/Microwave Spectroscopy of Antiprotonic Helium Atoms Ryugo S. Hayano CERN Tokyo 113-0033, Japan Antiprotonic helium is a metastable (lifetime > 3 microseconds) 3-body system consisting of an antiproton, an electron and an alpha particle, which was serendipitously discovered by Tokyo group about 10 years ago. High-precision laser spectroscopy of antiprotonic helium-4 (as well as helium-3) is being done at CERN's new low-energy antiproton source, AD. The results are compared with the state-of-the-art 3-body QED calculations, from which we have deduced that the antiproton and proton charges and masses agree to within 60 ppb. Furthermore, we have recently succeeded to resolve the hyperfine structure of antiprotonic helium by means of a laser-microwave triple resonance method, which will enable us to deduce antiprotonic magnetic moment.

Numerical Simulation of Ultracold Plasmas S.G. Kuzmin and T.M. O'Neil Department of Physics University of California at San Diego, La Jolla, CA 92093 USA Abstract PDF One approach to the production of antihydrogen relies on three-body recombination in ultracold plasmas [1]. Such recombination has been studied in recent experiments where ultracold neutral plasmas were produced by abruptly photoionizing small clouds of laser-cooled atoms [2]. Indeed there has been speculation that the traditional theory of three-body recombination fails at the ultralow temperature of these plasmas. This talk will present the results of novel molecular dynamic simulations for the early time evolution ( ~350 plasma periods) of the plasmas. The simulations are challenging because it is necessary to follow three-body recombination into weakly bound (high n quasi-classical) Rydberg states, and the time scale for such states is short compared to that for the plasma dynamics. This kind of problem was faced earlier in computational astrophysics when studying binary star formation in globular clusters. The binary stars are the analogue of the high-n Rydberg atoms and the cluster of the plasma cloud. Thus, we adapted a code by Aarseth [3] that was developed originally for studies of binary star formation. In three-body recombination, the binding energy is carried off by a second electron and enters the plasma as heat. This heating raises theplasma temperature and dramatically reduces the predicted recombination rate. In the simulations, the observed rate is in reasonable agreement with theory [4], R = 3.9·10-9sec-1[n (cm-3)]2[Te(oK)]-9/2, but care must be taken to use the correct temporally evolving temperature, Te. This work is supported by NSF grant PHY-9876999. References [1] G. Gabrielse, et al., Phys. Lett. A 129, 38 (1988). [2] T.C. Killian, et al., Phys. Rev. Lett. 83, 4776 (1999); Kulin, et al., Phys. Rev. Lett. 85, 318 (2000); Killian, et al., Phys. Rev. Lett. 86, 3759 (2001). [3] S.J. Aarseth, in Multiple Time Scales, Ed. J.U. Brackbill and B.I. Cohen (New York: Academic), p. 377. [4] P. Mansback and J.C. Keck, Phys. Rev. 181, 275 (1969).

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Plasma Confinement in Nested Penning Traps for Antihydrogen Production and Trapping Carlos A. Ordonez Department of Physics University of North Texas Denton, Texas 76203-1427 Theory is reviewed that can be used to predict the behavior of an antihydrogen plasma confined in a nested Penning trap under conditions such that antihydrogen recombination and trapping are possible. A nested Penning trap produces a magnetic field, which provides plasma confinement perpendicular to the magnetic field, and an electric field associated with a nested-well potential profile. The nested-well potential profile provides simultaneous confinement for oppositely signed plasma species parallel to the magnetic field. If positrons and antiprotons are trapped in a nested Penning trap under conditions in which recombination occurs, trapping of a fraction of the antihydrogen atoms that are formed requires the magnetic field to produce a suitable magnetic well region. It is found that it is difficult to use existing theory to predict conditions that would be suitable for achieving antihydrogen recombination and trapping in a nested Penning trap, both because of the many competing factors that must be considered and because of the limited theoretical and experimental Penning trap research involving non-uniform magnetic fields and simultaneous confinement of oppositely signed plasma species. However, it may be possible to circumvent the problem associated with a limited knowledge base involving both non-uniform magnetic fields and simultaneous confinement of oppositely signed plasma species by considering a certain class of magnetic field configurations. A magnetic field configuration in the class would consist of regions of uniform magnetic field extending from opposite sides of a magnetic well region. Examples of such a configuration can include the Penning-Ioffe magnetic field configuration described in the preceding talk and a magnetic field configuration to be described by Dubin in the next talk that is formed by combining the field of a single current loop with a uniform field. For both the Penning-Ioffe and Dubin configurations, magnetic field lines near an axis extend from one end to the other and can be further extended to produce uniform magnetic field regions on both sides of the magnetic well region. For such a magnetic field configuration, the electric field used to provide axial plasma confinement can be applied in the regions of uniform magnetic field. Hence, the electric field would confine an antihydrogen plasma that threads the magnetic well region. If the antihydrogen plasma within the magnetic well region is neutral, then the plasma confinement properties associated with the non-uniform field region may approach that associated with confinement of a single charged particle, provided the effects of collisions between particles can be neglected. The effects of collisions on confinement can be neglected if, for example, the plasma recombines on a time scale short compared to times scales associated with collision-based transport processes. Two different methods are considered for obtaining a neutral antihydrogen plasma that threads the magnetic well region. For each method, a set of conditions is predicted for achieving antihydrogen recombination and trapping on a time scale short compared to times scales associated with collision-based transport processes. This material is based upon work supported by the National Science Foundation under Grant No. PHY-0099617.

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Motion of Highly Excited Atoms in Strong Magnetic Fields Francis Robicheaux Physics Department 206 Allison Laboratory Auburn University, AL 36849-5311 I will present the results of calculations of the dynamics of highly excited atoms in a strong magnetic field. I will show that weakly bound atoms live longer than expected from estimates of the vXB electric field. I will also show that the center of mass motion of the atom is strongly affected by the magnetic field.

Cold Neutral Plasmas and Rydberg Atom Formation Steven L. Rolston Atomic Physics Division National Institute of Standards and Technology Gaithersburg, MD 20899-8424 By photoionizing a laser-cooled gas of metastable xenon atoms, we create cold neutral plasmas with densities of 109 cm-3 and temperatures ranging from 1- 1000 K. Using plasma oscillations to determine the time dependent density, we find this unconfined system rapidly expands (10's of ms) due electron pressure. We have observed the formation of a significant number of Rydberg atoms during the expansion. The interpretation of this atom formation arising from three-body recombination, and the interplay with the plasma expansion dynamics will be discussed.

Laser-Assisted Collisional Antihydrogen Formation Isao Shimamura RIKEN (Institute of Physical and Chemical Research) Wako Saitama 351-0198, Japan Talk PDF

Stability of a Charged Particle in a Combined Penning-Ioffe Trap Todd Squires Harvard University Physics Department Cambridge, MA 02138 The axial symmetry of a familiar Penning trap is broken by adding the radial magnetic field of an Ioffe trap. Despite the resulting loss of a confinement theorem, stable orbits related to adiabatic in-variants are identified, expressions are given for their frequencies, and resonances that must be avoided are characterized. It seems feasible to experimentally realize the new Penning-Ioffe trap to test these theoretical predictions. It also may be possible to simultaneously confine cold positrons and antiprotons in a Penning-Ioffe trap, along with any cold antihydrogen they may form.

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Two-Stage Rydberg Charge Exchange: Progress Toward Antihydrogen Production Cody Storry Harvard University Physics Department Jefferson 260 Cambridge, MA 02138 Two-stage Rydberg charge exchange in a cryogenic Penning trap has been proposed as an efficient method for cold antihydrogen production (1). In the first stage Rydberg cesium atoms traverse a cloud of cold positrons trapped in a cryogenic Penning trap(2). Charge exchange of the Rydberg electron from a cesium atom to a cold positron results in positronium in a state with similar binding energy to that of the incident excited cesium atom. The neutral positronium is not trapped in the fields of the Penning trap and exits the positron cloud in a random direction. Some positronium atoms then intersect a cloud of antiprotons previously trapped in an adjacent electrostatic well. A second charge exchange collision occurs when a positron from a positronium atom is captured by an antiproton resulting in the production of antihydrogen in a Rydberg state. In this talk I will discuss recent success in the first charge exchange collision between cesium atoms and cold positrons. In this process a small reservoir of cesium approximately three centimeters from the Penning trap axis is heated to about 60oC and provides a thermal beam of atoms. Laser excitation of the cesium beam in two steps results in excited atoms in the n=37 state. These atoms enter the Penning trap through a small hole in the electrode where cold positrons are trapped. A charge exchange collision results in positronium in Rydberg states with principal quantum number n~26. Positronium which travels along the trap axis is ionized in an electric field of ~100 V/cm. The resulting positrons are trapped and counted. Plans to improve this technique and create antihydrogen with two-stage Rydberg charge exchange at CERN will be discussed. (1) E.A.Hessels, D.M. Homan and M.J. Cavagnero, Phys. Rev. A. 57, 1668 (1998). (2) J. Estrada, T. Roach, J.N. Tan, P. Yesley, and G. Gabrielse, Phys. Rev. Lett. 84, 859 (2000).

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Experiments Looking for Field-Assisted Recombination of Antihydrogen Joseph N. Tan Department of Physics, Harvard University, Cambridge, MA 02138, U.S.A. Large numbers of positrons and antiprotons have been trapped and cooled to near 4K at CERN. 1 I will discuss our efforts in the ATRAP Collaboration2 to observe field-assisted recombination of antihydrogen. We have developed techniques to characterize and combine positron and antiproton clouds. Positron bunches (density ~ 107 /cm3) can be launched into a region containing ~ 5x104 antiprotons. To study field-assisted recombination, an electric field pulse is used to open the Coulomb interaction potential during the short interval when a positron bunch is superposed upon the confined antiprotons. The detection scheme uses nearby stripping/trapping wells to collect antiprotons from field-ionized atoms, which can be counted using annihilation detectors. 1G. Gabrielse, et al, ATRAP Collaboration, Physics Letters B507, 1-6 (2001). 2 Members of ATRAP are shown at http://hussle.harvard.edu/~atrap/ .

Hydrogen -Antihydrogen Interaction at SubKelvin Temperatures A. Yu. Voronin1, J. Carbonell2 1 P.N. Lebedev Physical Institute, 53 Leninsky pr., 117924 Moscow, Russia 2 Institut des Sciences Nucleaires, 53 Av. Des Martyrs, F38026 Grenoble The main properties of the interaction of antihydrogen with atomic hydrogen under the conditions of ultra cold trap1 (T=10-3 K) are established in the framework of the coupled-channels model.2,3 They include the scattering length, elastic and inelastic cross sections and Protonium formation spectrum. The annihilation cross-section behavior differs from the predictions obtained within semiclassical models extrapolated to low energies.4-7 It is shown that observables behavior is determined by a family of nearthreshold metastable states.8 Strong isotope effect in low energy scattering of HHbar and HbarD is predicted.9 The enhancement of strong interaction effects as well as the possibility of fundamental symmetries check is discussed. The effects of collisional shift and broadening of 2S - 1S transition line are estimated. References: 1. G. Gabriels et al., Hyp.Int. 84, 371 (1994). 2. A.Yu. Voronin, J.Carbonell, Phys.Rev. A57, 4335 (1998) 3. A.Yu. Voronin, J.Carbonell, Few-Body Systems Suppl. 10, 207(1999) 4. E. Fermi, E.Teller, Phys. Rev. 72 399 (1947). 5. D.L. Morgan Jr.,V.W. Hughes, Phys.Rev. D2, 1389 (1970) 6. W.Kolos et al., Phys.Rev. A11, 1792 (1975) 7. D.L. Morgan Jr., Hyp. Int. 44, 399 (1988) 8. J.Carbonell et al. Few-Body Systems Suppl. 8, 428 (1995) 9. A.Yu. Voronin, J.Carbonell, Nucl. Phys. A689 (2001) 529c

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Using Lasers to Produce and Cool Antihydrogen J. Walz (*), P. Fendel, A. Pahl, H. Pittner, B. Schatz, and T.W. Haensch Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (*) CERN-Fellow, CERN, CH-1211 Geneve 23 Lasers can play an important role in antihydrogen production. Laser-stimulated recombination and recombination spectroscopy will be examined. Radiation at Lyman-alpha (121.6 nm) is essential in a later phase of antihydrogen experiments. The first source of continuous coherent radiation at Lyman-alpha will be reviewed. Laser cooling of antihydrogen in a magnetic trap and high-resolution laser spectroscopy will be discussed.

Production of Ultraslow Antiproton Beam and Its Application to Atomic Collisions Y. Yamazaki [1,2], N. Kuroda[1], K. Yoshiki Franzen[2], M. Hori[3], Z. Wang[1], S. Yoneda[1], H.A. Torii[1], B. Juhasz[4], D. Horvath[4], A. Mohri[2], and K. Komaki[1] [1] Institute of Physics, University of Tokyo, Komaba, Tokyo, 153-8902, Japan [2] Atomic Physics Laboratory, RIKEN, Hirosawa, Wako, Saitama, 351-0198, Japan [3] CERN, CH-1211 Geneva 23, Switzerland [4] KFKI Research Institute for Particle and Nuclear Physics, H-1525, Budapest, Hungary   Talk PDF

Kinetics of Antiproton-Positron Recombination in a Cold Plasma Bernard Zygelman Department of Physics University of Nevada, Las Vegas Las Vegas, Nevada 89154-4002 Because of predicted [1] favorable scaling laws, the three-body recombination of antiprotons and positrons in a low temperature plasma is a leading candidate for the mechanism in which antihydrogen atoms are produced in the laboratory. In this talk we will present an application of the collisional-radiative theory, introduced by Bates-Kingston-McWhirther (BKMc)[2], to the problem of the recombination of positrons with antiprotons in a cold plasma. We apply the theory to investigate the role of the various radiative and collisional processes in a recombining plasma. We explore the effects of external fields on the recombination rate. [1] G. Gabrielse, S. L. Rolston, L. Haarsma, and K. Wells, Phys. Lett. A 129, 38 (1988) [2] D. R. Bates, A. E. Kingston and R. W. P. McWhirther, Proc. R. Soc. A 267, 297 (1962)

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