sPHENIX EMCal discussion

[EdwardOBrien <eobrien AT bnl.gov>]

    Hi Virginia,
     Thank you for your answers. I do suggest that you label the x-axis
     on both the linearity and resolution plots the same. I think
    that "Energy" is a more typical label for this quantity
    than "Input Energy". I would also use the same nomenclature for
    "measured energy" and <E>.  I would recommend using <E> for both
    y-axis labels and then in the caption add a remark that <E> is the
    measured energy so that it is clear for the reader.

    If the explanation of the difference in THP and UIUC tower performance
    at low energies is due to low statistics then perhaps the error bars that
    appear on the plots reflect the statistical uncertainty but not the
    errors associated with a poor fit. In other words, if a difference
    in the apparent performance is due to fluctuations due to poor
    statistics then then error bars of the THP and UIUC data points should
    overlap. If they don't then the error is underestimated or there is
    another component contributing to the different values.

    Ed
  

On 10/27/2016 10:23 AM, Bailey, Virginia Ruth wrote:

Hi Ed,

You are correct that the dp/p component is the beam momentum spread incorporated into the fits.  The x-axis for both linearity and resolution plots is the input energy (perhaps it would make more sense to label both the same thing).  You are also correct that the measured energy is the same as the <E>.

I believe you are referring to the plots on the right of slides 4 and 5 (the resolution plots) when comparing the THP and UIUC points.  These points depend both on the mean and spread of the energy distributions.  The 2 GeV point for THP is quite low due to low statistics for that run, causing the distribution to be narrow.  As you can see on the left, the measured mean energies are close for the THP and UIUC blocks so I would think the difference in the resolution points comes from the energy spread.

Best,

Virginia

---

From: EdwardOBrien [eobrien AT bnl.gov]
Sent: Wednesday, October 26, 2016 4:33 PM
To: Bailey, Virginia Ruth; sphenix-emcal-l AT lists.bnl.gov
Subject: Re: [Sphenix-emcal-l] EMCal Testbeam paper plots

    Hi Virginia,
     I have a couple of questions about the plots that I probably should know
    if I had attended all of the EMCal meetings.

    All plots show a fit result with a dp/p of 2% component. Is this just the
    momentum dispersion of the beam that has been incorporated into
    all fit results?

    For the plots on p. 3-9 the x axis of the plot on the left is labeled Input Energy
    and the x-axis on the plot on the right is labeled Energy. What is the difference
    between Input Energy and Energy?

     Is the Measured Energy in the y axis label on the left plots the same as the
    <E> in the formula on the y axis labels of the right plots?

    If I look at the plots on slides 4 and 5, I see that the UIUC 10deg and THP 10deg
    data points sit on top of each other everywhere except the 2, 3 and 4 GeV on
    the left plot. Is that because the width of the reconstructed energy distribution
    was different in the THP and UIUC modules for those beam energies? In some cases
    the THP points are above the UIUC points while in other cases they are below.
    Is there an explanation on how this could be? Thanks.

    Ed


     

On 10/25/2016 11:27 AM, Bailey, Virginia Ruth wrote:

Hello all,

Attached are the latest versions of the EMCal plots for the test beam paper.  I've also included the linearity and resolution plots for the UIUC and THP data separately, though I believe we've decided the combined plots are best for the paper.  Comments are appreciated.

Best,

Virginia

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