From: Jens Jørgen Gaardhøje (gardhoje@nbi.dk)
Date: Sun Mar 09 2003 - 08:54:23 EST
Friends As a general comment I think that we should investigate objectively the ability to study flow in Brahms. T his could be done rather easily, I think, through model simulations. The salient issue is the precision in determination of the angle of emission relative to the reaction plane, thus the difference between two angles that are only determined with finite precision due to the finite segmentation in azimuthal angle and to the inherent physics (fluctuations and broad distributions). We have looked at bit into this in preparing for ALICE. The sensitivity to v2, i.e. the value of the measured v2, depends on the phi segmentation. I'll try to look up some of the plots that were made. In any case a concrete study will answer the question of 'good' or 'bad'. 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: Ian Bearden To: brahms-l@bnl.gov Sent: Sunday, March 09, 2003 1:25 PM Subject: Re: Flow Measurements in BRAHMS (Re: BNL workshop 6-8 March) Hi JH, I know that our current configuration is not optimal, but that is not the same as it being impossible. What implication would a rearrangement of the Si have on our ability to measure centrality? I guess essentially zero since we still have the tiles and the ZDC...is this guess correct? I agree with you that we should really try to look at this, but it is not clear to me that we should wait until the next AuAu run (in 200N, where N is unknown, I guess) to try to do it. Cheers, Ian On fredag, mar 7, 2003, at 17:48 Europe/Copenhagen, J.H. Lee wrote: Hi, Ian, As we all know, our current configuration is not suitable for that. We only have 6 segmentations in phi, and they are not event fully covered. Only 2 rows of Tile, and no row in Si have 2pi coverage in phi. The 2 rows in Tile are sitting eta ~ 1.5-2, where v2 is significantly smaller that values at y=0. If we are not going to get more Au+Au data, we probably can try very hard to get some information out of what we had, but the resolution and systematic error are going to be pretty miserable. I still believe that the better way to measure it at BRAHMS is either reconfigure (rotate) silicon (high segmentation in eta -> high segmentation in phi) or make a new detector for the next Au+Au run. We are still the only experiment which can measure particle dependent flow in y=0 to 3. What we should do is measure reaction plane using silicon or/and new flow detector, and look at particle yields as a function of (rapidity, phi, centrality). I think a good candidate for a new/additional flow detector would be a reasonably well-segmented (>16 ) in phi pizza-shaped scintillators covering ~1-2 units of pseudo-rapidity around beam pipe. JH ----- Original Message ----- From: "Ian Bearden" <bearden@nbi.dk> To: <brahms-l@bnl.gov> Sent: Friday, March 07, 2003 4:45 AM Subject: Re: BNL workshop 6-8 March > And another thing.... > > Can we get the event plane from the Si+Tiles? That would be a good > thing, I think. Who is/has looked into this? > Cheers, > Ian > p.s. Bjxrn, the appropriate response to such theorists is to say that > you KNOW they can come up with a fully microscopic model of > relativistic heavy ion collisions, so could they just please go do it! > On torsdag, mar 6, 2003, at 17:31 Europe/Copenhagen, Bjorn H Samset > wrote: > > > > > On Wed, 5 Mar 2003, Flemming Videbaek wrote: > > > >> Dear Collegue > >> > >> Attache is the ref to the agena for the workshop the next comign days > >> at > >> BNL. Bjoern Samset is speaking for Brahms tomorrow morning at 9.20 > >> > >> See the web ref for the program in general > >> Flemming > >> > > > > Hello all. The presentation seemed to go well, and judging by the > > number > > of questions both during and after the talk people were paying good > > attention to what we showed. The main questions and comments were about > > our identified hadron spectra and the mt fit we use - some were > > sceptical > > about our ratios because they did not trust our spectra at the low and > > high ends of the fit range. Also, we got told by several theorists that > > they KNOW we can do elliptic flow with Si+Tiles, so would we please > > just > > go and to the analysis? ;-) > > > > The presentation can be found on the BRAHMS presentations page. > > > > Ping :-) > > > > -- > > Bjorn H. Samset Phone: 22856465/92051998 > > PhD student, heavy ion physics Adr: Schouterrassen 6 > > Inst. of Physics, University of Oslo 0573 Oslo > > \|/ > > ----------------------------> -*- <----------------------------- > > /|\ > > > > >
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