Proton Driver Meeting

26 - April - 2001
FNAL Black Hole

Presentations:-

• Weiren Chou: Announcements
• Fritz Dejhong: LSND Scenario and the Proton Driver
• Tom Dombek: Neutron Source

• Linac: This is strongly supported by S Holmes. He points out that it could help start a group at Fermilab for expert superconducting RF. So we are looking carefully into the superconducting option, while using the existing gallery.
• A SC Linac won't quite reach 600 MeV.
• Shaevits expects a report in time for the June HEPAP meeting.
• At SNOWMASS, there will be several joint meetings between accelerator and experimental working groups during the first week, and possibly more during the second week.
• The cost and technology are yet to be determined. It does not necessarily need to be superconducting.
• Key: be ready for Run II.

Question: Is slip stacking feasible for NUMI? Are we maxing out on the Main Injector? Ans: Probably yes.

Comment: Some HEPAP members, such as Janet Conrad, are very much in favor of a proton driver upgrade. They urge that the presentation be very high quality. Don't assume that all members already understand and appreciate the goals of the high energy community.

May 21-22: McGinnis talks about Run IIB. (slip-stacking, pbar source)

Write-ups

Motivation:
Assume that MiniBoone sees a signal. The next question is: Is there a new source of CP Violation (such as oscillations to a sterile nu)? If LSND is true, then it is natural to have three sterile neutrinos (assuming that the solar neutrino deficit is cause by neutrino oscillations). Useful references: Dick, Freund, Lindner, Ramanivo; Barger, Geer, Raja, Wishnat.

CPV arises from the interference between oscillations. Analyze nu_mu -> nu_e *and* nu_mu -> nu_tau, in order to reveal CPV parameters. If LSND is true, then these flavor oscillations could have nearly maximal CPV. Aside: a nuFactory would add sensitivity to three generations, by allowing observation of nu_e --> nu_tau.

Feasibility:
nu_mu -> nu_tau is doable with a new beamline like the NUMI high energy beamline, and an advanced detector like ICANOE (5 tonnes). A new tunnel would probably be needed. One would use 15--20GeV nu_mu and nu_mu_bar, for CPV studies.

nu_mu --> nu_e is very hard. The event rate is low, even for a huge detector. Might be best to wait for a neutrino factory.

Discussion: Be careful not to claim too much about nu_mu --> nu_e. The proton driver is the first stage of a nu Factory.

Physics Strategy:
Be prepared for a positive MiniBoone signal, with an aggressive program to go after this physics with the proton driver.

What exists elsewhere? SNS (National Spallation Neutron Source) is a $1.3B project. There are O(1000) users, mainly people from materials science. E = 0.02 eV. We do not want to compete with this!

Motivation for Fermilab: neutron dipole moment. FNAL advantages: peak intensities go as IE**0.8. ToF would be possible, with background greatly reduced by the low duty cycle.

Other topics: T-symmetry violation, baryon-number conservation, parity-violation in the strong interactions, RH weak currents, quantum mechanics on a macroscopic scale (Sam Werner).

Fermilab should aim for particle physics topics, and stay away from the things that are done at NIST. Tailor the target for each experiment, do not construct a general facility. Note the experiments can be placed relatively close the source.

Competition:

• 3 GeV Linac an LAMPF
• new sources at the AGS (note: BNL and LANL have established neutron physics groups. Fermilab has only one person : T.B.)

Tom showed a table showing existing and proposed sources. On the basis of this comparison, a proton driver upgrade (stage 1, stage 2) definitely is interesting.

Example experiment (W.M.Snow, NIM A440 (2000) 729-735): polarized neutron + proton --> deuteron + photon. Another example: Nature, vol 403, 6Jan2000.

Using Bragg scattering with silicon crystals, it may be possible to attain (mu/e about 10**-28). Recall there is a lower limit of 10**-28 of CPV has anything to do with the baryon asymmetry. This is a hot topic!!!

Conclusions: This would be a unique facility for fundamental particle physics experiments, and thus is close to the Fermilab `mission.' It would be on the scale of MiniBoone.

Snowmass: discuss in detail about a few experiments, and get local theorists involved. A writeup is available on the web.