From: Jens Jørgen Gaardhøje (gardhoje@nbi.dk)
Date: Tue Aug 26 2003 - 16:04:33 EDT
Dear all We have continued the discussion here at NBI today on the priorities for runs IV and V. We still think that: 1) the main priority should be for a full long high luminosity Au+Au at top energy. 2) If - we are to have another run- we still prefer the lower energy, even though we have understood and noted Flemmings very reasonable concerns about luminosity and high pt particle production rate. If there is no 'second' run in RUN IV then the lower energy run should have precedence in RHIC RUN V over a different beam species. The reasons for 2) are the following: 1) Even though an FS high pt run may not be feasible, a y=0 or a y=1 run with the MRS would settle the issue of whether high pt suppression persist at lower energy. This is the main issue at RHIC. We see this 'energy density' argument as having more punch than the 'slab thickness' argument (to use MM's language). 2) If there are two runs in RUN IV, then we would not like to have RHIC start developping a new beam, eg. Si or Fe. This would probably require a significant 'development time'. By now we know what that means! 3) There are very interesting physics also in the 'soft' sector at lower energy, f.ex. the measurement of the stopping where we would cover a larger fraction of the possible rapidity interval and the determination of the (in)famous Kaon slopes between SPS and top RHIC energies. Opposed to this is the light ion program, which naturally also leads to a nice soft physics program along the lines of what we have published at 200GeV and better conditions for high pt running. I doubt, though, that the outcome would be very different from the peripheral collisions measured at the top energy in run IV, even if we could get a higher luminosity once the beam is developped (??). In any case the shaping up of the document can continue while we continue the discussion for another day or so. cheers JJ ____________________________________________________________ Jens Jørgen Gaardhøje, Assoc. Prof., Dr. Sc. Niels Bohr Institute, Blegdamsvej 17, 2100 Copenhagen, Denmark. Tlf: (+45) 35 32 53 09, secr. (+45) 35 32 52 09, Fax: (+45) 35 32 50 16. UNESCO Natl. Comm., secr. (+45) 33 92 52 16. Email: gardhoje@nbi.dk. ____________________________________________________________
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