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

COMPARING ANTIMATTER, MATTER BEAM LETHALITY

Comparisons difficult to make commensurate

Simplified energy deposition phenomena

Beam	H Beam
Three primary deposition sources: Primary beam slowdown Deposits beam energy E in range Annihilation effects: Intranuclear absorption, deexcitation Deposits E_N in total range _N Exiting pions Deposits E_p in total range _p	One primary deposition source: Primary beams slowdown Deposits beam energy E_P in range _P For E = E_P, ~ _P

Resultant simplified 1-dimensional overlapping deposition representation
Pion, proton ranges in matter
- Annihilation at arbitrarily low E produces long range pions
- Protons require E_P ł several hundred MeV for _P ~ _p

Taking into account these intranuclear effects makes difficultcomparative estimates of normal matter and antimatter beam targeteffects. A very simplified one-dimensional estimate indicates that theregion where intranuclear effects are important includes, but issomewhat larger than, the region where annihilations occur (this latterregion being also the region where the primary beam is slowed down andbrought to rest). The reason for this is the smearing-out produced bythe deexcitation phenomenology.

To the best of our knowledge, no fully adequate treatment of thecombined phenomena involved in slowdown, intranuclear absorption,deexcitation exists; a really useful treatment would have to combineintranuclear absorption codes with transport codes, etc.

In the absence of such treatments, highly simplified estimates ofthe phenomenology are all that is available. The next chart shows someestimates of this sort.

Another aspect of annihilation phenomenology which differssignificantly from normal matter beam phenomenology is that the kineticenergy of the normal particle is all important in producing targeteffects, while for antimatter beams the annihilation energy generallydominates the target effects at accelerator potentials convenient towork with. One could in principle work at much lower acceleratorpotentials for antimatter beams, although technical difficulties of beamformation, control, and shaping arise.