Concepts, Problems, & Opportunities for use of Annihilation Energy:

An Annotated Briefing on Near-Term RDT&E to Assess Feasibility

RAND Note N-2302-AF/RC

B. W. Augenstein

ANTIPROTON () MANUFACTURING CONSIDERATIONS

lambda = (Number P-bar produced and collected)/(Number P in incident beam)

Linearized, factored lambda relation for discussion (more precise relations available, used for high lambda estimates)

Basic energy efficiency: Number P-bar produced per incident proton/Energy of incident proton

Relatively flat peak between 70 and 700 GeV P energy
Selection of P energy based on other design considerations

Conclusion on achievable l values
- l~10^-4: can do now
- l~10^-3: difficult near term goal
- l~10^-2: not impossible longer term goal

Given the basic antinucleon production, one can now estimate the fundamental parameter l, defined as the number of antiprotons producedand collected divided by the number of protons in the incident beam,employing a highly linearized formulation generally used in the highenergy physics labs. l accounts for collection as well as predictionconsiderations. Significant improvement in l can come from two basicsources--operating at appropriate proton energies, and being able tocollect over the broad exiting antinucleon momentum range along with anappropriately broad collector solid angle. Collector designs toaccomplish this are naturally complex and difficult to engineer, as wetry to collect more and more of the particles. l values in the 10^-3 to10^-2 range would likely require proton energies in excess of the largestcurrently being implemented (~ 120 GeV at Fermilab), while l ~ 10^-3

The basic energy inefficiencies in producing antiprotons fromprotons of energy E (in GeV) are now evident--the ratio of interest is:

stored energy in antimatter/energy to produce, collect antinucleons ~ 2*lambda/E

and of course the process of imparting an energy E to a proton is itselfnot 100% efficient. Despite this, use of antimatter evidently makessense in specific circumstances.

It should also be remembered that there is a very large absolutescale up issue at any value of l, if we are to produce operationallysignificant amounts of antimatter.

There are theoretical possibilities for collector designs which maybe promising and which differ from today's designs in significant ways.