Dear Physics Study Group,

I thought I should send a note in response to some of the the comments that I have received.

The idea of the proton driver physics study was to collect the information about how a higher intensity booster could improve the physics program at the Lab. With this information, we can try to see how an improved booster would fit into future plans and provide a better program. Of course, timescales of when upgrades or new facilities can come online are important, but the first thing that is needed is the impact on the physics along with the realistic restrictions from the experiments and accelerator complex.

There has already been some spin-offs from the proton driver machine study, from ideas for improving the existing booster to a staged driver approach with an early ~1 GeV linac. Investigating incremental upgrades is being encouraged. It may be that this incremental approach could help the ongoing physics program while giving a path towards a future driver that would correct the current booster "bottleneck" and open up new physics opportunities such as a muon storage ring facility.

As part of the current study, I would hope that we find out how much higher luminosity the collider experiments can be provided and take, how much intensity the neutrino experiments can use, and how much better will the K experiments do with higher rate beams. With this information, we can then look to see how these improvements can be realized with upgrades and new facilities. For example, upgrades to the exsiting booster might translate into a 50% increase in Tevatron luminosity or neutrino beam intensity. A new linac might give a factor of two increase. It is important to understand the possibilities and limitations now since, I think, these options become less viable if delayed significantly.

Fermilab has a window over the next decade to make crucial major discoveries. Luminosity/intensity is going to be a critical issue in most of the program. We have found over the past year and a half that studies such as the Brighter Booster one are very important in guiding the future Lab program. The Brighter Booster study will be a source of information for shaping the future program and may hold the key to significant improvements.

Mike