Below please find the messages and new figures which Ralph Dollan sent out on Dc. 20 and Dec. 21, 2007
as a web page, with links to the figures.
(The Mail server rejects messages which it finds too long (over 10000 characters, including attachments).)
Happy Holidays to all, and a happy, healthy and successful New Year 2008!
Message of Dec.20 :
attached are some remastered figures:
I changed fonts, scales etc. and increased the artificial offset of the 160A
electron and positron point.
pol2011 - polarization plot
pol2011b - the same without superscripts (as Peter proposed)
pol2011_dark, pol2011b_dark - the same as the figures above, but the errorbands
of the expected polarization are a bit darker for better visibility
asym2011, asym2011b - the pure asymmetries
asymmetries_140_2 - the single asymmetries of the 140A point
pol_and_asym2011 - the polarization plot combined with the asymmetry plot
In addition here are some comments to version 7.4.
- on P2,C1,L3: it says "... were separated in an analyzing magnet D2..."
D2 in Fig.1 is not the analyzer magnet but the spectrometer.
Since the analyzer magnet is a solenoid and the "separator" Dipoles, we
should not mix these.
It's also not consistent with the description in the caption of figure 1.
- P2,C2,L49: "...to measure the longitudinal polarization of the photons..."
The photons are circularly polarized.
- P3,C1,L2: do we want to mention the sixth spectrometer energy since we
don't show the results of the 150A point?
- P3,C1,L10: 150A -> 160A
- Table1: here the asymmetries are given in percent and the polarization
values and the analyzing power in absolute numbers, what brings the
asymmetries and the polarization to the same order of magnitude- is this
Do we want to state an error for the analyzing power?
If you need more/other changes in the figures or other input, please let me
Message of Dec.21 :
here are some polished figures:
PhotonNumberHelicity19b - the undulator spectrum relabeled
pol2122_dark - the polarization plot relabeled
central_csi_160 - the energy deposition in better quality(3 times with
different x axis title...)
asymmetries_140_2_b.eps - the single asymmetries relabeled
Concerning the analysis:
Eq. 24 describes the background subtraction in general, were n_s,b are
the number of undulator-on/off events or beam pulses or triggers. In a
"normal" cycle this number is after cuts etc. in the order of <1500.
Technically, the background subtraction and the normalization is done
(has to be done - we have to combine the correct signal-background pairs
from the CsI and the silicon counter) in one go according to eq. 31-33
in the Appendix A.5.
We found out, that it is equivalent
- to normalize to the photon flux and correct with the asymmetry
measured in P1
- or directly normalize to P1
The number of positrons does not enter here - we are using the
un-calibrated readings from the P1 counter for the normalization/correction.
I hope, this explanation helps.
Up to which detail do we want to describe the analysis, do we want to
come up with formulas...?
p.s. I wish everybody Merry Christmas and a happy new Year...!
(PDT or GMT-8h) by
Achim W. Weidemann.
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