Hi, Claus, I think there is a quite reasonable reason why we don't include Single Diffractive (SD) events in the inelastic cross-section. Our experimental definition of min-bias events(for all systems: pp, dA,AA) are Double Diffractive + Non-Diffractive (excluding SD), and our global detectors are designed to trigger them. We always require "Left" and "Right" for min-bias events. The experimental definition of min-bias triggers for many proton experiments is also usually associated to NSD events: ISR,UA5, E755, CDF... All other RHIC experiments are also mainly using NSD events for pp normalizations, not that this is the reason we use NSD for pp. Anyway, whatever we choose to do, it has to be clearly described in the paper. JH > -----Original Message----- > From: brahms-l-bounces@lists.bnl.gov > [mailto:brahms-l-bounces@lists.bnl.gov] On Behalf Of Claus O. > E. Jorgensen > Sent: Friday, February 13, 2004 5:37 AM > To: 'brahms-l' > Subject: RE: [Brahms-l] How to correct for missing NSD > fraction in pp: A proposal > > > > Hi JH, > > I (almost) agree - that would be the correct way to make this > correction. But why do you write NSD, shouldn't it simply be > all inelastic events? That's what goes into the nuclear > modification factor. For this analysis I don't see why we > need to care about NSD events at all. > > Ramiro, how do you make this correction? Do you scale the > spectrum by 0.85 or 0.72 or do you do something else? > > Cheers, > > Claus > > > > Hi, > > > > A trivial typo in my previous message. > > The correction factor should be A(pt)/B(pt) > > not B(pt)/A(pt). > > > > JH > > > > > -----Original Message----- > > > From: brahms-l-bounces@lists.bnl.gov > > > [mailto:brahms-l-bounces@lists.bnl.gov] On Behalf Of J.H. Lee > > > Sent: Thursday, February 12, 2004 10:38 AM > > > To: 'Claus O. E. Jorgensen'; 'Hironori Ito' > > > Cc: 'brahms-l' > > > Subject: [Brahms-l] How to correct for missing NSD > fraction in pp: A > > > proposal > > > > > > > > > > > > Hi, Claus and others, > > > > > > Here is what I think how we should correct for the > missing fraction > > > (~15%) of NSD events in pp. > > > > > > A: Calculate pt spectra from HIJING (NSD) without any trigger > > > conditions at given eta > > > B: Calculate pt spectra from HIJING (NSD) with the INEL trigger > > > condition at given eta > > > M: Measured pt spectra at given eta > > > R: Correction Factor: R(pt) = B(pt)/A(pt) > > > > > > Then, > > > C: Corrected spectra > > > C(pt) = R(pt)*M(pt) > > > > > > We cannot simply multiply 1/0.85 in the spectra, since > the bias is > > > nonuniformly distributed in all impact parameter AND in pt. If we > > > want to correct for the missing fraction in NSD in pp, I > think what > > > I described above is probably what we have to do. > > > > > > JH > > > > > > > -----Original Message----- > > > > From: brahms-l-bounces@lists.bnl.gov > > > > [mailto:brahms-l-bounces@lists.bnl.gov] On Behalf Of > Claus O. E. > > > > Jorgensen > > > > Sent: Wednesday, February 11, 2004 4:30 PM > > > > To: Hironori Ito > > > > Cc: brahms-l > > > > Subject: Re: [Brahms-l] INEL trigger efficiency in pp > > > > > > > > > > > > > > > > Thanks Hiro, > > > > > > > > It's still not completely clear to me what the correct > procedure > > > > for this efficiency correction is. > > > > > > > > We measure a number of tracks (Ntr) and a number of events > > > > (Nev) and divide those out to get the yield (Ntr/Nev). We know > > > > that we only pick up a fraction of the total cross > section (72%) > > > > so we can divide Nev by 0.72 to get the total number of > inelastic > > > > events, but what about the tracks in these (28%) > missing events? > > > > How do we evaluate the Ntr in the missed events. If we just > > > > calculate the yields by dividing Nev by the trigger efficiency > > > > (i.e. multiply the spectrum by > > > > 0.72) we somehow assume that the missing events don't have any > > > > tracks. Is that fair? > > > > > > > > I've tried to understand how STAR is doing it. It's not written > > > > explicitly, but this is how I interpret them: They > claim that they > > > > measure 85% of NSD events and gives an uncertainty of > 14% for the > > > > normalization to their NSD spectrum - I guess the > multiply their > > > > spectrum by 0.85 and the 14% is for the tracks in the missed > > > > events (it could in principle be zero or as abundant as in the > > > > measured events). They also claim that the NSD and total inel > > > > yields are almost identical (only a small difference at > low pt) - > > > > I'm not sure I understand that, since I wouldn't expect > the single > > > > diffractive (SD) events to contribute with very many tracks > > > > (in their acceptance) but they are still events (and should > > > > go into Nev in the calculated yield). In other words I > > > > wouldn't expect the same yield in SD events as in NSD events. > > > > > > > > I'm a bit confused - who knows about these things and > what should > > > > the official BRAHMS procedure be? > > > > > > > > Cheers, > > > > > > > > Claus > > > > > > > > > > > > On Tue, 10 Feb 2004, Hironori Ito wrote: > > > > > > > > > Ok. JH pointed out to me that the option is IHPR2 not > > > > IHNT2. I run > > > > > hijing with non-single diffractive option. Now, it > > > > produces dn/deta > > > > > =2.5 at eta =0. This is right number. Using this > HIJING pp in > > > > > our BRAG (GEANT), INEL counter efficiency is now 85%. > So, as a > > > > summary, > > > > > this is my result. > > > > > > > > > > INEL efficency > > > > > 72% in total inelastic cross section > > > > > 85% in non-single diffractive cross section > > > > > > > > > > Hiro > > > > > > > > > > Hironori Ito wrote: > > > > > > > > > > > Hello. I guess I made a mistake in efficiency in > non-single > > > > > > diffractive events since 10% increase in dn/deta is not > > > > the same as > > > > > > 10% in cross section. As JH suggested, I tried to run > > > > Hijing with > > > > > > non-single diffractive option using IHNT2(13) =3 option. > > > > But, I did > > > > > > not see any change in dn/deta. Therefore, I am not quite > > > > sure how > > > > > > to run Hijing with this option. > > > > > > > > > > > > Hiro > > > > > > > > > > > > Hironori Ito wrote: > > > > > > > > > > > >> Hello. Since so many people asked about INEL efficency, > > > > I just dig > > > > > >> up my files. (I thought these things are checked by > > > someone who > > > > > >> are writing Ph.d thesis. :) ) Here is the conclusion I > > > > made. 1. > > > > > >> From the Hijing 1.383, our INEL counter is about 72% > > > > > >> efficient. (see > > > > > >> > > > > > http://www4.rcf.bnl.gov/~hito/run03/hijing_pp_inel_efficiency.gif > > > > ) > > > > > >> > > > > > >> 2. Now, looking into what HIJING 1.383 really is for > > > > pp. I looked > > > > > >> at dn/deta from raw hijing output. At, eta=0, it is > > > > 2.2 . From > > > > > >> UA5 ppbar results (see > > > > http://pdg.lbl.gov/2002/contents_plots.html > > > > > >> you can > > > > find a postscrip file there.), it shows 2.2 with the words > > > > > >> saying "The number per pseudorapidity interval is about > > > > 10% higher > > > > > >> if the rate is normalized excluding singly > diffractive events > > > > > >> rather than to the total inelastic rate." This tells me > > > > that Hijing pp produces the > > > > > >> total inelastic collisions. (This also means the > > > > following. Since > > > > > >> we don't trigger on single diffractive events, what we > > > > can measure > > > > > >> is 90% efficient at most. Our INEL is 72/90=80 % > efficient > > > > > >> for non-single diffractive events.) > > > > > >> > > > > > >> > > > > > >> If people need it, I can also dig my old files for dAu. > > > > > >> > > > > > >> > > > > > >> Hiro > > > > > >> > > > > > >> _______________________________________________ > > > > > >> Brahms-l mailing list > > > > > >> Brahms-l@lists.bnl.gov > > > > > >> http://lists.bnl.gov/mailman/listinfo/brahms-l > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > > Brahms-l mailing list > > > > > > Brahms-l@lists.bnl.gov > > > > > > http://lists.bnl.gov/mailman/listinfo/brahms-l > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > Brahms-l mailing list > > > > > Brahms-l@lists.bnl.gov > > > > http://lists.bnl.gov/mailman/listinfo/brahms-l > > > > > > > > > > > > > > > > > _______________________________________________ > > > > Brahms-l mailing list > > > > Brahms-l@lists.bnl.gov > > > http://lists.bnl.gov/mailman/listinfo/brahms-l > > > > > > > > > > > > > > > > _______________________________________________ > > > Brahms-l mailing list > > > Brahms-l@lists.bnl.gov > > > http://lists.bnl.gov/mailman/listinfo/brahms-l > > > > > > > > > _______________________________________________ > Brahms-l mailing list > Brahms-l@lists.bnl.gov http://lists.bnl.gov/mailman/listinfo/brahms-l > _______________________________________________ Brahms-l mailing list Brahms-l@lists.bnl.gov http://lists.bnl.gov/mailman/listinfo/brahms-lReceived on Fri Feb 13 11:17:24 2004
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