Dear Flemming and Jens Jorgen, I think we all agree that we want to get as much Au+Au as we can in order to finish our pt-y survey and to focus on selected topics like high-pt, clusters etc. Now to our second choice: The reference of all our observables is pp (or better nucleon-nucleon); and sooner or later we need a solid set of min. bias pp data covering all rapidities and high-pt. A minimum set of spectra are the rapidity distributions of p,K,pi. Unfortunately, I don't know how useful the data is we took during tha last run, both in terms of statistics and trigger. Before we have seen the pp results I cannot judge if we should take more pp data in RUN3 with the same trigger setup. What can we learn from dAu: One lesson we learned from NA49 is that one has to cover 4pi in order to understand pA and to e.g. select events where the projectile suffered many collisions. So, I don't know how well we can identify "grey protons" in our multiplicity arrays (our "grey neutrons" in the ZDC?). Even if we could, I doubt that we would learn much about soft physics (e.g. strangness production). But I think the dAu system is absoluteley necessary in order to falsify the high-pt hypotheses about suppression due to jet quenching and the vanishing of opposite side jets. Conclusion: BRAHMS needs both, a solid min. bias p+p data set as a general reference and dAu for high-pt physics. If I remember correctly, STAR and PHENIX have already taken a sufficient amount of pp data, so I guess they will go for dAu. A realistic (i.e. politically feasible) priority list could be: 1. as much Au+Au as possible 2. d+Au 3. p+p RUN4: One should keep in mind that we might have a (large) PHOS prototype available by then, so we should make sure that we get enough Au+Au running in order to measure high-pt at various rapidities. With best wishes, Dieter On Sat, 10 Aug 2002, Flemming Videbaek wrote: > Dear Jens Jorgen (and collaboration) > > I must admit that I do not think that pp should be the second priority. To me the choice was between dA and si-si since > afterall the HI program is where the focus of the Brahms baseline program is. > > - It has been well documented that at AGS, SPS one sees a smooth development from pp (or pBe) over pAu to heavy AA > and using pp as reference does not give so much information for the AA since does it address what the effect of 'cold' nuclear matter is on higher pt spectra. which the dA would do . You could even argue that 'low-multiplicity dA is equivalent > and could be measured, but clearly not very not as clean as pp. > > - I am concerned that we experimentally are NOT ready to do the pp measurements (and to lesser degree for dA) since the inel counters we used last January did in fact not work well- and we have yet to demonstrate in analysis that we can normalize the data properly. To really engage in this program another set of counters would have to be developed. > I do agree that we did not record enough pp data in Jan. and this should be redone, but the present state of analysis does > not tell us we are ready to do so. > > -In terms of the gluon saturation description > it is correct that the pp acts as a reference for dA (or better pA), so in sense to explore this one should > - To me the dA is probably not the best reference, while pA would be better, albeit not likely from the macjine point of view for several years. one example is the intrinsic non- description. > > It is also unfortunate that you have not brought your point up earlier since I did in fact circulate both at the collaboratrion meeting > as well as late June the intended species for the draft/proposal and had not envisioned a difference of opinion at this late stage. Never the less we should have a discussion on this and do welcome additional comments from others. > > We do agree on the priority one, and that 3 speciies is not realistic. > Politically the running of the AuAu is not a sure thing (star and phobos may very well /likely not want this!) > This is clearly the main agenda to push and having good arguments for and then possibly leave the other priorities > more open > > cheers > Flemming > > > ------------------------------------------------------ > Flemming Videbaek > Physics Department > Brookhaven National Laboratory > > tlf: 631-344-4106 > fax 631-344-1334 > e-mail: videbaek@bnl.gov > ----- Original Message ----- > From: Jens Jørgen Gaardhøje > To: brahms-l@bnl.gov > Cc: gardhoje@nbi.dk > Sent: Saturday, August 10, 2002 3:21 PM > Subject: Rhic Beam Use proposal DISCUSSIONl > > > Dear Flemming, > > It is unfortunate that the (very) provisional draft for the RBUP is transmitted during a weekend, normally not considered working hours, and with submission deadline on firstcoming monday. That does not leave much time for the collaborations comments or reflexion. > > I have however taken the time to peruse the forwarded draft. I will separately forward to you my more detailed comments on wording etc.,as time allows. > > Here, I wish, however, to raise the central issue of BRAHMS priorities for run 3. > > In my opinion the main priorities are: > > 1) as much Au+Au as we can get, for -supplementing missing settings for the hadronic survey > - focus on selected high statistics measurements ( high pt, HBT, coalescence, decays etc...) > 2) decent p+p data at forward angles as refenence for the Au+Au. > > In my mind, the d+Au, although 'a la mode' and favored by PHENIX and STAR is NOT our main 2nd priority. Of course we shall take data, if > that is the RHIC decision, but more useful for the ongoing physics is the 'elementary' reference spectra at all rapidities, notably the forward. > > I hold the opinion that a 3 beam species program is not avisable, as development overhead is prohibitive. > > I hope that the collaboration will have time and occasion to contribute to this discussion. > > 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. > ____________________________________________________________ > > > ----- Original Message ----- > From: Flemming Videbaek > To: brahms-l@bnl.gov > Sent: Friday, August 09, 2002 10:57 PM > Subject: Rhic Beam Use proposal > > > Dear Collaborator, > > As discussed at the collaboration meeting in May, and also in an e-mail a while before QM the Beam Use proposal for > run-3 (FY2003) has to be submitted by Monday afternoon at 4.30 pm Due to QM02 and my subsequent vacation the first draft has not been available before. I have had very little input from, the previous mailings that outlined the intended beam Use proposal, so the draft attached > to this e-mail should follows that outline. Some details i.e. required Luminosities still have to be worked out , and will be done so over the weekend. > > It is my intention to prepare a next draft by Sunday, but all comments received before Monday noon EDT will be duely considered. > I think the draft has about the right overall length; I will in particular be glad to receive suggested rewording of text, paragraphs, > input to the physics justifcations. The real battelewill be during the PAC meeting on August 26 since the requests > from the experiments are not very likely to overlap very well. > > We have in CDR as well as in previous RBUPs always mention the desire to measure clusters (d,t and heavier) but have never given > a real estimate for what is needed. I think if we are to keep this we should evaluate if this can be done within the ~7 weeks of Au-Au > running with at most 7*35 microb(-1) > > > best regards > Flemming > > > The document is attached as both a word doc as well as an pdf file. > > ------------------------------------------------------ > Flemming Videbaek > Physics Department > Brookhaven National Laboratory > > tlf: 631-344-4106 > fax 631-344-1334 > e-mail: videbaek@bnl.gov > -- ------------------------------------------------------------------- Dieter Roehrich | Fysisk institutt | Email: Dieter.Rohrich@fi.uib.no Universitetet i Bergen | Tel: +47-555-82722 Allegt. 55 | Fax: +47-555-89440 N-5007 Bergen, Norway | WWW: http://www.fi.uib.no/php/drhrich.html
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