Thanks Aki,
Here is how I did it:
Q**2 is in the range [0.08, 0.3} GeV**2
I used only 'basic' cuts (i.e. electron (+ Cherenkovs),
target (vertex) position (abs(zwl)<20.&&abs(zwr)<20.) and the
full range of energy Ee' = [0, 1]GeV. Though I used also
Ee' = [0.25, 1]GeV (this changes the behaviour at W > 1.3 GeV).
The asymmetries were calculated as follow (see Laurens van Buuren Thesis):
(there is no need to add sector index L,R)
A^{meas} = ((R+ - R-) / (R+ + R-)) * ((R+ + R-) / (R+ + R- - 4*Rbg))
where:
R+ = N++/Q++ + N--/Q--
R- = N+-/Q+- + N-+/Q-+
and for
Rbg (background) I used only the empty-target runs (almost all of them).
That again, the inclusive cross section is:
d^2Sigma/dOmega_e'dE_e' = Gamma{Sigma_T + epsilon * Sigma_L +
h*Pz[ cos(theta_star) * sqrt(1-epsilon^2) * Sigma_TT' +
sin(theta_star) * cos(phi_star) * sqrt(2epsilon*(1-epsilon)) *
Sigma_TL']}.
where:
Gamma = virtual photon flux factor
epsilon = virtual photon polarization
Sigma_T + epsilon * Sigma_L = Sigma_0
How did you get your asymmetries?!
We should get together and talk about it.
Have a nice weekend
-----------------------
Octavian F Filoti
Nuclear Physics Group
Univ. of New Hampshire
9 Library Way
Durham, NH 03824
phone: (603)862-1220
FAX: (603)862-2998
email: ofiloti@unh.edu
On Fri, 11 Mar 2005, Akihisa Shinozaki wrote:
> Hi Tavi,
>
> Please never mind my previous results. I found at least four mistakes in my
> code. Both data and simulations were not right results. I was basically
> collecting the "garbages" for the data. Also, the simulations did not took
> the pi+ channel into account by my mistakes. I am sorry if I made another
> confusions for you.
>
> So this is my another attempt for the p(e',e) results for you. This time only
> trigger 7 is considered. For e' selection, Cerenkov hits were required for
> the corresponding TOF counters.
>
> The file, asymmetryi.ps, shows the asymmetries from all the data obtained
> from last October to December (48 deg. only). The data are compared with my
> MAID and SL simulations. The simulated curves assume the dilution factor =
> 0.5 with no asymmetry offset. The data make good agreement with the
> simulations. It *seems* to me that your data do not quite match with mine in
> the left sector since your data do not go beyond the zero as much as my
> current result. I think we can discuss this later.
>
> peei_md.ps and peei_sl.ps show the data distributions of W, Q^2, Ee'(lab),
> and, Theta^e'(lab) . The blue (red) + points are the counting rate in events
> per Coulomb in the electron left (right) sector. The thiner lines are
> background (empty target spectrum). The thick curves are my MAID or SL
> simulations. The data spectra in peei_md.ps and peei_sl.ps are not the same
> because W<1.4 GeV is applied for MAID while the SL simulation requires W<1.3
> GeV. There is no radiative process considered and this should be one of the
> sources of the differences between the data and simulations. Since you are
> doing with GEANT, you could tell me more on the characteristics of my
> simulations.
>
> It is quite striking that the background rates are as high as the foreground,
> which is the main source of the error in the asymmetries. I am using the all
> empty target runs available but the statistics is still about one tenth of
> the foreground.
>
> I think that is all for now. Thank you!
> aki
>
>
>
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