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Re: comment on simulation section
HI Elton,
I have made some corrections, comments below:
On Feb 7, 2008, at 11:58 AM, Elton Smith wrote:
> page 2, Figure 1 caption, first line, is this what you mean?
> 'related to the actual experiment' -> raw data and low-level
> calibrations
> that are bypassed in the MC event generator by directly producing
> hits in
> the detector.
These are part of the online data acquisition stream. It is mean to
visualize how our work and MC will dovetail into the framework once we
have a detector taking data.
> page 3, Section 2:
>
> The description of hit generation (top of page 3 for fcal and under
> 2.2
> for Bcal), at least I think that is what is described for what
> information
> is recorded is somewhat confusing. Assuming this is the generation of
> hits, I would state this explicitly: for the fcal each block (with
> energy
> above some threshold?) is recorded. I assume for the bcal, for each
> readout channel, one saves the summed energy, z-position, average
> time?
> The statement 'time of all energy deposits' is unclear unless one
> saves
> the energy of all particles in the shower?
>
> To clarify, I would simply point to the middle of the flow chart
> (page 2)
> and specify what information is stored for each hit during the
> simulation.
Have tried to clarify by highlighting regions of the Figure
> page 3, section 2.2 BCAL, second line
> 'active BCAL region' -> scintillating fibers
Not really -- there are no fibers (next sentence) in the main Geant
simulation.
> page 4, section 2.3, first line - not a sentence
> -> We believe the dominant contributions ..... However, there are
> additional...
I think this is OK -- While we believe ... , (comma) there
additional....
The first is just an introductory clause.
> page 5, Section 3 middle paragraph
> ...match THE generated photon momentum...
thanks
> page 5, 3.1 bottom line
> ...position ARE corrected FOR shower depth and non-linear effects.
done
> page 8, line before eq 9
> Do you mean 'position of the photon AT THE INNER SURFACE OF THE
> BCAL...'
>
> page 8, eq 9.
> I do not understand what the vectors are, and 'some parameter s' is
> too
> vague. This could be explained more clearly.
OK, I'll try to explain better. This is parametric eq. Any straight
path in 3D space is described by a vector that is the direction and a
point on the path. These c and a respectively.
> page 9, next to bottom line, question
> '...position resolution of a couple of millimeters...'
> Given a speed of 17 cm/ns, a sigma=100 ps corresponds to 1.7 cm, so I
> expect resolutions of a couple of centimeters. Since the text is
> consistent with figure 8, I am confused as to why the resolution is so
> good.
As noted in the second half of that sentence and listed explicitly in
Section 2.3 there is no time smearing for the BCAL implemented yet.
> page 11, bottom line, vertex errors
> Assuming the vertex position error is the 'size of the target
> (30cm)' for
> reconstruction seems to be very pessimistic. Does this uncertainty
> in the
> vertex position influence all the invariant mass plots? Should it be
> updated (even artificially) by assuming a charged particle z-position
> resolutions?
>
> page 12, last paragraph middle (figure 10)
> 'The plot on the right shows the efficiency in a window..." Do you
> mean
> the left plot?
Yes, thanks
> page 12, footnote, lacks final period.
>
> page 14, footnote, lacks final period.
they are there.
> page 15, figure 11, question
> Do we understand why the resolutions in the FCAL are much better
> than the
> resolutions in the BCAL? In the introduction Alex plots pi0 and eta
> widths
> and there seems to be little difference between FCAL and BCAL. What is
> different? If we know this we should add a note to the text. (Could
> it be
> the vertex resolution? see above).
>
>
> page 18, section 4.2.1 first paragraph last line
> two-photon decayS of the eta.
went with "two-photon decay mode of the eta" implying a singular decay
mode
> page 19, second paragraph, midle
> The expected hadronic background in this channel... (remove IS)
thanks
> page 21, figure caption / first paragraph
> It might be useful to specify how much running time 100,000 events
> corresponds to.
Good point -- added a sentence to the opening of this whole section:
To set the scale for the size for the statistical precision of the
data set, at peak \GX{} running one expects a physics channel with a
cross section of 1 $\mu$b to yield an event rate of approximately 125
Hz.
> page 23, figure 20 (right)
> It is hard to see the data symbols. If I read them correctly there
> seems
> to be substantial false P-wave found for masses around 0.9 GeV
> (about 20%)
> which seems to be quite large. Symbols in different colors would
> help see
> what is plotted, but there should be a comment on the amount of false
> resonant P-wave.
See previous comment on this one. We can remove if needed.
-Matt