From pinkenburg@bnl.gov Sat Sep 8 07:54:56 2001 Date: Fri, 07 Sep 2001 14:10:01 -0400 From: Chris Pinkenburg Reply-To: e895-l@bnl.gov To: e895-l@bnl.gov Subject: Re: Longitudinal Flow draft Hi Jenn, sorry for putting in my comments so late, we used the last two weeks of (non-) performance of rhic to do daq development. Anyway, finally I got to get some coffee and sit down with your nice draft (and I haven't read Davids comments yet - so this is unbiased and probably sometimes duplicated). The data look really neat, and just for consistency, are the 4 pi proton yields you get by integrating over dN/dy reasonable (do we approximately conserve the total charge)? For fig 1, I might have misunderstood the caption but as far as I understand it midrapidity should be in the middle and forward scaled up by factors of 10, backward scaled down by factors of 10, while the figure just scales both of them down (which is fine by me). BTW, If you do a set dmod 1 in your draw kumac the lines will always stay full not go from full to dashed to dotted to dash dotted back to full. The reason the fits don't really follow the data at midrapidity is radial flow? Fig 3 doesn't present a linear dependance but a logarithmic one (it's linear due to the log scale for the beam energy). Now on to the text... Abstract is the same like fig 3 with the linear dependance. Maybe some rephrasing in terms of "overshoot of the cern data is gone" instead of line slope would be better. I am not sure what to make out of the first paragraph of the introduction. Where is the connection to longitudinal flow and how did NA49 got longitudinal flow out of a double hump structure? That sounds like the recipe you use to extract beta is not applicable for sps energies since it doesn't describe the data. The last sentence promises a substantially different result, but I couldn't find that discussion. As far as I understand our tracking, we don't take the momentum from the radius of the curvature but track the particle through the magnetic field figuring out the momentum somehow. (I think leaving out the radius, just saying we figure it from the curvature describes it). I don't see a place where you need the impact parameter in fm, why don't we just stick to 5% centrality? The analysis section refers to two manuscripts in preparation I haven't seen so far. But then it becomes pretty specific on what was done, so I don't know what these refs could add to that. Our GEANT version is 3.21 (at least it claims that when you start it up). Are there any errors assigned to the efficiency correction which propagate to the presented spectra? (and I would be careful with the "unusual" good forward/backward symmetry that doesn't go well with experiments with the usual lousy symmetry preservation). How different is the longitudinal flow when you treat forward/backward seperately? The line of argument in the result section would gain from some little reordering. E.g. The sentence the effect of the chemical potential... does not affect Eq.2, would fit better after you introduce eq.2. The fitted T(y) probably has an error associated with it, how does this affect the fit, plotting a band instead of a line would accomodate for that (same for the full blown longitudinal flow inclusion). To make the Schnedermann approach clearer (at least I got confused) leave out the plural in "For this second analysis...". I kind of mixed the multiple sources mentioned previously with dealing with multiple beam energies you probably talk about here. dN_th/dy is Eq. 2 (maybe is calculated/extracted) m is the mass of the emitted particle. That should go in the explanation of eq 2. Can you put the errors on beta in the table? In fig 3 there is an error bar. The conclusion and my own figuring basically says that the previous slope was based on using a FOPI value which was calculated using a different formalism. Chances are we get a FOPI referee so I would leave out this "may be a valid interpretation" - Willi Reisdorf may go ballistic here and - on a more serious note - a lot of effort went into that FOPI analysis and it is probably more sophisticated than the simple "more than one source" idea which is presented here. The plot you refer to shows that quite clearly (the original is from Stachel NPA 610, the other ones are just copies of this one). But certainly more points at more energies help make a convincing argument. But now what did we learn, why did we bother to look at longitudinal flow? Some concluding remarks should be included. The previous systematic was interpreted in terms of reduced stopping at sps energies. Can we say anything more about this with the new data (like no change in stopping) and how valid is the sps value in light of the double humps (you are member of NA49 not so)? One other general thing, which is more for Declan I suppose. I am confused about the different authos lists we seem to use. Can we agree to a current list of authors? On my qm contribution I asked spefically for everyone to check the author list (no response) but it certainly is different from yours. Again nice piece of work (and an impressive forward/backward symmetry of the data) Chris -- ************************************************************* Christopher H. Pinkenburg ; pinkenburg@bnl.gov Brookhaven National Laboratory ; phone: (631) 344-5692 Physics Department Bldg 510 C ; fax: (631) 344-3253 Upton, NY 11973-5000 ************************************************************* From pinkenburg@bnl.gov Sat Sep 8 07:55:01 2001 Date: Fri, 07 Sep 2001 14:21:42 -0400 From: Chris Pinkenburg Reply-To: e895-l@bnl.gov To: e895-l@bnl.gov Subject: Re: Longitudinal Flow draft Hi Jenn, oops forgot one thing... in the pid section you mention that beyond 8GeV/c p/d/t should disentangle again and blame it on statistical errors that we don't see that. From looking at our pid plots, I doubt that we can see the relativistic rise or would be able to disentangle anything there even if we had all the stats we want. On the other hand how many d/t are there anyway? Just taking the proton cut a'la Paul looks very exponential. I assume we would see a change in slope if the d/t would seperate again from the protons. Do you have the momentum resolution at these high momenta? Chris -- ************************************************************* Christopher H. Pinkenburg ; pinkenburg@bnl.gov Brookhaven National Laboratory ; phone: (631) 344-5692 Physics Department Bldg 510 C ; fax: (631) 344-3253 Upton, NY 11973-5000 *************************************************************