Raymond A. Lewis

Are antiprotons forever

Abstract Up to more than one million antiprotons from a single LEAR spill have been captured in a large Penning trap. Surprisingly, when the antiprotons are cooled to energies significantly below 1 eV, the annihilation rate falls below the background. Thus, very long storage times for antiprotons have been demonstrated in the trap, even at the compromised vacuum conditions imposed by the experimental setup. The significance for future ultra-low-energy experiments is discussed.

ANTIPROTON-CATALYZED MICROFISSION/FUSION PROPULSION SYSTEMS FOR EXPLORATION OF THE OUTER SOLAR SYSTEM AND BEYOND

Production and trapping of small numbers of antiprotons for space applications are feasible, setting the stage for antiproton-catalyzed microfission/fusion (ACMF) reactions as a source of propulsive power. A spacecraft designed around an ACMF engine has been designed. Details, including Isp, thrust, structural features, power systems, radiation shields, ion drivers, payload and system masses, will be reviewed. Staging of the spacecraft in space, including requisite propulsion and trajectory parameters and scientific goals for aggressive (Isp=10,000 sec, thrust=150 kN, ΔV=100 km/sec) outer solar system and extraplanetary missions will be discussed.

An antiproton catalyst for inertial confinement fusion propulsion

This paper discusses the concept of an inertial confinement fusion propulsion system involving an antiproton catalyst (for antiproton-induced fission). It is argued that, when the two processes, fusion and antimatter annihilation, are combined into one system, a viable candidate propulsion system for planetary exploration emerges. It is shown that as much as 7.6 GW of power, well within the requrements for interplanetary travel, can be achieved using existing driver technologies and available quantities of antiprotons.

Antiproton portable traps and medical applications

Several medical applications utilizing antiprotons stored and transported in a portable Penning trap are considered. These include production of radioisotopes for PET, radiography and radiotherapy. Specifications of a portable antiproton trap suitable for this work are discussed, and progress on the development of such a trap is reported.

Antiproton-Boosted Microfission

The concept of microfission, whereby a small target of fissile material is burned under compression, was introduced nearly 20 years ago; the size of the target is limited by the magnitude of the compression and by the initial number of fissions that start the chain reaction. A burst of antiprotons at maximum compression can allow target size to be significantly reduced. Antiprotons were previously shown to be a strong source of neutrons and pions; under conditions of high density, they enable a significant reduction in burn time and, hence, target size. In this paper, possible applications are discussed, including space propulsion and intense neutron and X-ray sources.

Production and trapping of antimatter for space propulsion applications

Production and trapping of antiprotons for space propulsion applications are reviewed. Present and foreseeable production rates at Fermilab are discussed, and experiments on trapping, confinement and transport of large quantities of antiprotons, as well as synthesis of atomic antihydrogen, are outlined.

AIMStar: Antimatter initiated microfusion for pre-cursor interstellar missions

We address the challenge of delivering a scientific payload to 10,000 A.U. in 50 years. This mission may be viewed as a pre-cursor to later missions to Alpha Centauri and beyond. We consider a small, nuclear fusion engine sparked by clouds of antiprotons, and describe the principle and operation of the engine and mission parameters. An R&D program currently in progress is discussed.

Neutron yields for antiproton microfission experiments

Neutrons that are produced following antiproton annihilation on uranium nuclei are transported through compressed targets by the SCATTER Monte Carlo code in support of antiproton microfission experiments. The SCATTER code and necessary input data are described. Results show that the high-energy (>20 MeV) component of the source is responsible for the majority of the neutron yield. Results for a wide range of uniformly compressed targets are presented for moderation levels of hydrogen-to-uranium ratios of 0:1, 3:1, and 9:1 in [sup 235]U targets and [sup 238]U. Moderation is found to increase neutron yields at a given [rho]r. Uniformly compressed unmoderated [sup 238]U targets demonstrate 9 to 16% lower yields than [sup 235]U. Four targets under different, nonuniform compression conditions are considered. The average yield in these cases is [approximately]21.8[+-]0.2 neutrons per source antiproton, an increase of 34% over the 16.3 primary neutrons per antiproton. The average yield of the nonuniform compression cases agrees within error with uniformly compressed targets.

Containment and Neutron Production by Charged Pions in Antiproton Microfission Experiments

Containment and interaction of charged pions in a solid linear implosion system are simulated. Pions are generated from annihilation of antiprotons at the surface of a compressed target. A three-dimensional Monte Carlo code has been developed to simulate the interaction of charged pions with the system. Neutron yields are presented for several 27-g uranium targets compressed under different initial plasma conditions. Effects on neutron yields from the diffused magnetic field and density profiles at peak compression are discussed. Results show that the magnetic field at peak compression significantly increases overall neutron yields.

Trapping antimatter for space propulsion applications

Production and trapping of antiprotons for space propulsion applications are reviewed. Present and foreseeable production rates at Fermilab are discussed, and experiments on trapping, confinement and transport of large quantities of antiprotons are outlined.