Concepts, Problems, & Opportunities

Basic investigations
- Best estimates of production CS (; e⁺)
- Best estimates of spectrum
- General formulation of production + collection problem (nonlinearized form; utility of approximations)
- Collection yields vs. basic parameters (finite target; acceptance; matching conditions; etc.)
- Fraction of basic /P ratio achievable
Target designs
- Methods for alleviating high target heating, stresses (inc. bunching, debunching issues)
- Relative promise of pulsed vs. continuous operation; proton beam dither over target; target motion; etc
- Tolerable P beam intensities
- In-target focusing
Collection system design
- Solid angle
- Momentum bites
- Lens designs; depth of focus, target target absorption; etc.
- Absolute costs or relative costs vs. phase space volume
- Total beam transport system design
- Matching to storage rings/deceleration stages (cooling requirements)
- Unconventional collector possibilities
Intermediate stage considerations (i.e., between production and production of final product inserted into compact stage)
- Cooling stages needed
- Deceleration stages
- For antihydrogen production, optimizing conditions for , e⁺ recombination (process path)
- Energy balances, material balances
- Achievability of matching; self-consistency of total processes
- Power needs; optimization of energy efficiencies
Factory conceptual designs (factory = complete cycle, including P beam and going to product to be stored in compact storage)
- Overall system balances
- Process loss estimates
- Estimate of power needs
- Survey of powering options (cost, complexity, schedule issues)
Power production issues, if self-powered by electronuclear facilities (BNL design)
- Large target measurements in U assemblies
- P spectrum emerging from target
- Conceptual design for power production using emerging P
- Power cost best estimates
Total plant cost estimate
- Accelerator, production factory, electronuclear facilities, etc.
- Siting considerations
- Applicable cost element scaling laws
- Implications for product cost ($/mg)

The following two charts list some of the RDT&E study and experiment issues associated with production of antimatter and theassociated product cost. Many of these are already partially treated inthe appended references, but each item listed warrants much furtherconsideration.

For example, the CERN target has a nominal energy deposition limitof ~ 185-200 J/gm, at which point the temperature rise is greater than ~10³ C and shock waves begin to form which can fracture the target. This limit corresponds to a beam of ~ 2x10¹³ P/_mm²; still higher depositionswill cause target material depletion and reduction of antiprotonproduction. Even for a l = 10^-3 , a proton beam flux of - 2x10¹⁷ P/secis needed to achieve a production level of 10 milligrams of antimatterper year. Many solutions can be proposed (and some have beenconsidered) to heating, stress, etc. problems caused by such intensebeams. One possibility, for example, is to form a number of beamletsand at the same time move each beamlet relative to its associated targetat rates significantly greater than the target shock velocity of ~ 0.3mm/µsec. In turn, one option for this relative motion is to move thetarget against a fixed proton beam (to circumvent the problems of havingthe antiproton collection system track the motion of the proton beam inthe case where the target is fixed). The design challenge is then tomove targets at velocities of perhaps ~ 1.0 mm/µsec relative to thefixed beam, continuously. Conceptual schemes for this exist.

In a similar way, each item in the following two charts can beenlarged upon. The important point to emphasize, then, is that well-defined approaches can be formulated to resolve the uncertainties whichcurrently abound in the RDT&E issues posed by antimatter production andcollection.

For high energy physics, needs to reaccelerate accumulated antiprotonsto very great energies focuses attention on high quality beams. Maximizingantiproton production may modify or give different emphasis to processbounds.