1. General Issues for a Multi-MW driver
Get the right number of particles to the pion target at the right energy and rep rate.
Low energy linac – ion source ~50mA, beam chopping (ISIS/CERN FETS)
Acceleration, beam halo control
Beam accumulation – H stripping, injection, control
Bunch compression to 1ns for NF

2. Different Approaches
Full energy linac, accumulator and compressor rings (R. Garoby)
~200 MeV linac, RCS for accumulation, acceleration and compression (volunteer?)
FFAG acceleration (A. Ruggiero)

3. Comment
Target is arguably the most difficult part of the NF facility (c.f. SNS/ESS experience)
Proton driver must take account of target limitations (shock, heating) in its choice of energy and the length and structure of the bunch train.
Driver energy and target geometry determine pion/muon distribution and affect design of capture channel.
There is a need to maximise the number of muons entering the accelerating system.
Particularly close collaboration is therefore needed between driver, target and muon front-end groups to produce optimum operable system overall.
Inevitably means compromises between all regions of study.

4. Questions Is 4 MW still the required beam power?
Given a clean sheet, what is the optimum driver energy and “optimum” in terms of what?
What does the target want in terms of proton pulses (number of bunches, spacing, frequency)?
Which driver type (linac/RCS/FFAG) best meets these requirements?
Whose proton driver comes nearest? Where should future studies be directed?
Anything else?