Quoting Michael Kohl <kohlm@mit.edu>:
> Eugene, Adrian:
> -keep MASCARAD off
> -compare pml,r-pwl,r with ELOSS=on to determine momentum loss for
> protons and electrons (only significant for protons).
I have to do this with ELOSS on AND off to determine momentum loss for
protons. which is already done.
> -correct measured data for momentum losses (relevant only for protons)
I sent out 4th degree polynomials of this momentum loss as a function of
p and theta a week ago. I am attaching a plot that shows the v16 (without
extended Bgrid - v17 plot will be available tomorrow) theta_e(theta_p) and
vice versa. I think we might be back to trusting theta based on these plots.
There are 8 of them, they are 2D with Profiles on top. The title of each is
given as:
T(e/p)_T(e/p)T(p/e)_vs_T(e/p)_(0/1)
which can be translated as:
theta_{e/p} - theta_{e/p}(theta_{p/e}) vs. theta_{e/p}
and the particle's sector (the first term) is 0=L, 1=R
>From the profiles it can be seen that the discrepancy is never more than
+0.2 degrees and it stays positive. Since theta_e(theta_p) and it's inverse
are always decreasing functions, any overestimation of theta_e/p will give
the positive discrepancy. This is great because it shows that with our errors
theta_e + dte - theta_e(theta_p+dtp) at its greatest possible propagated
error gives us dte ~ 0.14 degrees.
I have been plotting 2D Chi^2 distributions of Beam Energy as a function of
changes in p_e and theta_e or p_p and theta_p and I'm getting a valley that
shows great variation as a function of theta but minimal variation as a
function of p. This seems to be the case up to the point that I'm pushing
the BeamEnergy sigma(p) outside of a reasonable value.
> -determine residual dp's and dth's by imposing elastic kinematics.
I think: dp(theta_e,theta_p) and 0>dth>-0.15 degrees.
I still don't understand the shift in W from Mascarad, but I'll
try to look into it.
-eugene
> In case of electrons, this will "effectively" account for the shift
> (from rad+resol) and for the real "residual" kinematic correction in
> delta_p.
> -for all subsequent data analyses, use momentum loss correction +
> residual corrections from above to correct reconstructed data.
>
> Regards,
>
> Michael
>
>
> On Sat, 25 Mar 2006, Chi Zhang wrote:
>
> >
> > Hi Michael
> >
> > I can not agree with your reasoning.
> >
> > The reasoning is only valid if we generate the delta peak and the
> tail. The
> > MASCARAD channel in DGen only produces the tail. There is a channel
> that
> > mixes epel and MASCARAD but there is a problem of what fraction of
> events are
> > generated in either channel. I do not think we have resolved the
> problem of
> > how to make the admixture of pure elastic and radiate elastic yet.
> >
> > The bottom line is: without the resolutions, i.e. with the original
> pml/r
> > variables, there shall NOT have any shift. This is NOT the case if one
>
> > generates with MASCARAD channel alone in DGen. This will be the case
> if the
> > mixed channel of epel and mascarad is used but I do not know how to
> interpret
> > the results, both in terms of the cross section and asymmetries.
> >
> > we are comparing two cases:
> > no shift originally + resolution = shift (Bill T's case)
> > significant shift originally + resolution = more shift
> > I am not convinced that we did not put ourself in the second case.
> >
> > Since we are trying to derive the kinematic corrections, which
> themselves are
> > at the order of couple tens of MeV, a 10MeV shift in the ORIGINALLY
> TOSSED
> > events is significant.
> >
> > Chi
> >
> > On Thu, 23 Mar 2006, Michael Kohl wrote:
> >
> >> Chi,
> >>
> >> as long as the cutoff energy (10MeV) is much smaller than the
> resolution
> >> (30MeV) the resulting Mascarad-W is very well approximating the real
> one.
> >> Therefore, if we see a shift in the Mascarad centroid, that's
> expected!!
> >>
> >> Imagine the Blast resolution was 1 MeV, then one would have to choose
> a
> >> cutoff energy of significantly less than 1 MeV and hence the centroid
> would
> >> be shifted significantly less. This is exactly what we had discussed
>
> >> several times, remember BillT reporting at the January collaboration
>
> >> meeting:
> >> "The higher the resolution with which we looked at the scattered
> electron
> >> energy, the less of a shift we actually saw ... however the centroid
> does
> >> appear shifted because the radiation tail is convoluted with the
> resolution
> >> ... and the amount of shift is resolution-dependent"
> >>
> >>
> >>>> -What we really need is pml,r(before RAD+ELOSS) - pwl,r(after
> RAD+ELOSS)
> >>>
> >>> This is impossible. the best you can do is:
> >>> pwl,r(before RAD+ELOSS) - pwl,r(after RAD+ELOSS)
> >>> after binning and averaging pwl,r
> >>
> >> Can we use the "delta peak" for pml,r(before RAD+ELOSS)?
> >> Is pml,r with MASCARAD just the tail, or is it an admixture of the
> "delta
> >> peak" and the Mascarad-tail?
> >>
> >>
> >> Regards,
> >>
> >> Michael
> >>
> >>
> >>
> >>
> >>
> >> On Thu, 23 Mar 2006, Chi Zhang wrote:
> >>
> >>>
> >>>
> >>>> -I'm still doubtful about the electron spectrum with and without
> >>>> Mascarad.
> >>>> In Adrian's plot "Wcorr.gif" from 2006/03/01 (see meeting minutes)
> the
> >>>> radiated elastic peak maximum differs from the unradiated one by
> ~10-15
> >>>> MeV. I don't see such a difference in your comparison of MASCARAD
> on/off.
> >>>> I have a suspicion why. MASCARAD is used in the generator. Is it
> >>>> perhaps that pml,r is the generated momentum *after* the event has
> been
> >>>> radiated? (Experts may want to comment!!) Then, of course, both
> pml,r
> >>>> and pwl,r are shifted by the same amount, and the differences
> pml,r-pwl,r
> >>>> must look the same for both MASCARAD on and off.
> >>>
> >>> This is the case. when comparing pml-pwl, there is no point to do
> >>> with/without MASCARAD. The non gaussian shape is a result of the
> "impact
> >>> angle" dependent resolution that is simulated in the blastmc. The
> >>> resolution is worse at very forward angle as you can see form the
> >>> tossed1.ps. The wiggling, if I remember correctly, is an artifact
> due to
> >>> the non-exact reversion of the cubic t2d/d2t relation used in
> >>> recon/blastmc. It is not present when one uses the linear t2d/d2t.
> but the
> >>> size of the wiggles is only 5 MeV anyway.
> >>>
> >>>> -What we really need is pml,r(before RAD+ELOSS) - pwl,r(after
> RAD+ELOSS)
> >>>
> >>> This is impossible. the best you can do is:
> >>> pwl,r(before RAD+ELOSS) - pwl,r(after RAD+ELOSS)
> >>> after binning and averaging pwl,r
> >>>
> >>> I would like to repeat a point I made before. I think we should be
> careful
> >>> reading into Adrian's W plot. The mascarad has a minimum photon
> energy of
> >>> 10MeV!!!!
> >>>
> >>> I repeat, minimum photon energy 10MeV!!!!
> >>>
> >>> This means every single event MASCARAD generates emits a photon with
>
> >>> energy
> >>>> =10MeV. so none of them belongs to the original delta peak. but we
> know
> >>>> the
> >>> delta peak persists and is only reduced by about 20%. i.e.
> significant
> >>> fraction of the events do not radiate. So all MASCARAD generates is
> some
> >>> kind of tail. Then ofcourse the peak is shifted by about 10MeV but
> this is
> >>> merely an artifact. if you do kinematic correction based on this
> artifact
> >>> ... ...
> >>>
> >>> On the other hand, it is not clear to me after a few attmept to
> understand
> >>> it, how to reproduce the delta part with MASCARAD. I think MASCARAD
>
> >>> experts should gather and give a better view of what is being
> generated
> >>> and what it means.
> >>>
> >>> Chi
> >>>
> >>
> >>
> >> +-------------------------------------+--------------------------+
> >> | Office: | Home: |
> >> |-------------------------------------|--------------------------|
> >> | Dr. Michael Kohl | Michael Kohl |
> >> | Laboratory for Nuclear Science | 5 Ibbetson Street |
> >> | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 |
> >> | Middleton, MA 01949 | U.S.A. |
> >> | U.S.A. | |
> >> | - - - - - - - - - - - - | - - - - - - - - -|
> >> | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de |
> >> | Work: +1-617-253-9207 | Home: +1-617-629-3147 |
> >> | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 |
> >> | http://blast.lns.mit.edu | |
> >> +-------------------------------------+--------------------------+
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
>
>
> +-------------------------------------+--------------------------+
> | Office: | Home: |
> |-------------------------------------|--------------------------|
> | Dr. Michael Kohl | Michael Kohl |
> | Laboratory for Nuclear Science | 5 Ibbetson Street |
> | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 |
> | Middleton, MA 01949 | U.S.A. |
> | U.S.A. | |
> | - - - - - - - - - - - - | - - - - - - - - -|
> | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de |
> | Work: +1-617-253-9207 | Home: +1-617-629-3147 |
> | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 |
> | http://blast.lns.mit.edu | |
> +-------------------------------------+--------------------------+
>
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--------------------------------------------------------------------------
Eugene Geis
PhD Student, Physics Department, ASU
Research Affiliate, MIT-Bates Laboratory of Nuclear Science
eugene.geis@asu.edu
--------------------------------------------------------------------------
http://quickreaction.blogspot.com
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