Re: First Draft of a ratios paper for 100+100

From: Claus O. E. Jorgensen (ekman@nbi.dk)
Date: Mon Apr 22 2002 - 15:47:33 EDT

  • Next message: Ramiro Debbe: "Re: First Draft of a ratios paper for 100+100"

    Hi all,
    
    Thanks to Michael, Radek and Steve for the comments. I've made some of
    the minor corrections you suggest, and updated to version 1.09.
    It can be found here:
    
    http://www.nbi.dk/~ekman/RatioDraft1.09.ps.gz   (or)
    http://www.nbi.dk/~ekman/RatioDraft1.09.pdf.gz
    
    Enjoy!
    
    Do we want to keep this discussion on the brahms-l list? If not, where
    should we keep it then?
    
    
    
    Michael, I haven't done anything about you comments to: 
    
    - how the papers underplay of the importance of the rapidity dependence.
    - weak decay corrections
    - what we can learn from the failure of HIJING and the success of AMPT?
    - description of model [3]
    - the thermal model
    - p+p and y=2 data in figure 4
    - the abstract
    - PACS
    
    
    Here's a few comments on what I have changed:
    
    - the title:
    
    > We show ratios of antihadrons/hadrons so the title is slightly
    > incorrect. Only the first word should be capitalised. For Sqrt(S_{nn})
    > I beleive the convention is to use nn rather than NN.
    
    You're right about the order of "hadrons" and "antihadrons" - it's
    fixed now. Personally I would prefer "Ratios of Charged
    Antiparticles-to-Particles...". One might think that the
    "antihadron-to-hadron ratios" are without identification of particles.
    
    
    - figure 1
    
    > For Figure 1 panels (c) and (d) why not put the symbols pi, k and p at
    > the appropriate mass**2.  For panel (c) the proton peak seems to be in
    > the right place but the pion peak seems to be at negative
    > mass**2. This implies some problem with either the momentum, time or
    > length scales used to derive mass**2. 
    
    I think it is too much with the pi, k and p symbols on the mass2
    plots. You're right about the negative pi mass2, I just need to redo
    the plots (and maybe the calibration). It'll be fixed. 
    
    > When we use C1 to veto pions is
    > there a significant inefficency for the kaons and protons? (This is
    > the infamous Cerenkov veto effect from NA44) From panel (c) this looks
    > about 5% for the protons. Since there are usaully more e- than e+
    > around it may not be the same for antiprotons. 
    
    Yes, there is a C1 misidentification factor for kaons and
    protons. This will change the pi-/pi+ ratio, but with very few percent
    (because of the small K/pi ratio). Misidentification of pions (pions
    above threshold that does not give a signal) is very close to zero, so
    the effect on the measured ratios is very small.
    
    I don't think the ratio of e-/e+ hitting C1 changes the
    misidentification from polA to polB runs. It's only the particles that
    make it through the magnetic field that can change the noise level in
    C1 from one polarity to the other. The numbers of e- and e+ can change
    slightly (but not as much as in fixed target experiments where you
    have a lot of delta-electrons), and I guess that most of these (e- and
    e+) will make nice tracks in the spectrometer and will therefore not
    lead to misidentification but inefficiency in C1. I should of course
    check this.  Maybe we should put in a sentence about this, but I don't
    think we should go into too much detail.
    
    
    - figure 2
    
    > For Figure 2 I would arrange the panels as in Fig 1, ie 2 rows and 2
    > columns. For y=2 the pbar/p ratio must have a very bad Chi**2/NDF, I'd
    > guess about 6, when fit to a constant.  This makes me suspect that the
    > errors are underestimated.  The panels should be labeled (a), (b), (c)
    > and (d).
    
    I've tried that the 2-rows-2-columns arrangement, but I don't like it
    - the range of the x axis in plot (a) and (c) is not the same, and it
    gets a bit confusing (PRL accepts figures that span both columns). The
    data points will soon be updated and we'll hopefully get smaller error
    bars, so don't worry about the Chi**2 and missing data in plot (d) - it'll
    be fixed. I've made a few changes in the figure.
    
    - figure 3 
    
    Scales, legends and symbols are now updated. I removed the HIJING
    prediction, and will add AMPT soon. You're right about the
    N(x-)/N(x+) notation - I've now written x-/x+ throughout the paper (and
    the first time a ratio is quoted specified that we are talking about
    "...the ratio between the number of negative and positive pions,
    pi-/pi+"). Is that clear enough? Do you really want to keep the 130
    GeV data in the plot?
    
    - figure 4
    
    > For Figure 4 why not add the 40 and 20GeV results from NA49. Also I
    > would put the labels AGS, SPS and RHIC on the top line of the box
    > around the graph. "SPS" should be properly centered. As noted above I
    > would add plots for the pp data and the ratios at y=2 or so.
    
    The numbers in figure 4 should really be checked. We should find the
    right references and add all the points we can find (any volunteers).
    
    Adding points for y=2 and for p+p would require more panels I think. 
    If someone has the time to dig the numbers out of the litterature I'll 
    be happy to make the plots (also as function of y/ybeam). What about
    chemical potential as function of sqrt(s_nn) at y=0 ?
    
    
    - references 
    
    Are updated. I don't know how to use BIBTEX - we can change that
    later.
    
    
    - language
    
    > Paragraph 4 say "with 2sigma of the expected velocity for a given
    > moment and particle type."  Put a period after "vertex distributions"
    > and start a new sentance with "Then the particle ..."
    
    The cut is not made only from 1/beta. It also takes the momentum
    resolution into account. Can we explain it more clear?
    
    
    ...Claus
    
    
    +-------------------------------------------------------------+
    | Claus Jørgensen                                             |
    | Cand. Scient.                  Phone  : (+45) 33 32 49 49   |
    |                                Cell   : (+45) 27 28 49 49   |
    | Niels Bohr Institute, Ta-2,    Office : (+45) 35 32 53 07   |
    | Blegdamsvej 17, DK-2100,       E-mail : ekman@nbi.dk        |
    | University of Copenhagen       Home   : www.nbi.dk/~ekman/  |
    +-------------------------------------------------------------+
    



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