Hi Aki and all...
I have attached my 'newest' MAID asymmetries, can you try to reproduce
them with your code?! I still suspect a bug which couldn't find it yet!
If you consider
N++ = N-- = N+- = N-+
for the empty runs, then we have the same asymmetries!
How can you get N++ (empty)?! There is no target spin state!
I looked at empty runs and I got indeed different numbers, for example:
===========================================================================
->runs: 8637-8638 8640-8642 9362-9364 9366-9368 9370-9370 9373-9380
9383-9384 9729-9733 9735-9739 9741-9745 9972-9978 9980-9986 9989-9993
10116-10118 10302-10307 10311-10315 10363-10369 10371-10375 11114
-11120 11530-11535 11537 11711 11718-11720 11730 11732-11734 11859
-11864 12015-12019 12021-12022 12230 12233 12320-12322 12455-12460
12463 12632-12633 12635-12637 12640 12978-12979 12980-12981 12983
-12986 13095-13096 13215-13220
(EMPTY runs)
___________________________________________________________________________
Charge in (beam-target) polarization states:
( h, P) charge
--------- -----------
( +1, +1) 7920.8193
( -1, +1) 7836.8804
( +1, -1) 8058.1035
( -1, -1) 7796.1763
Total Charge = 31611.9795
===========================================================================
You might be right here, we need to discuss 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,
>
> Your vertex cut which is now employed to mine as well seems quite reasonable.
> I have Q^2<0.4 GeV^2 cut as well because both models have this restrictions.
> I am currently trying to emply the timing cuts.
>
> As for the asymmetry computation, I think you need to subtract the background
> not only from the denominator but also the numerator as well. In other words,
> R_+ - R_-
> A_{meas.} = -------------------------,
> R_+ + R_- with,
> N_++ (hyd.) N_++ (empty) N_-- (hyd.) N_--
> (empty)
> R_+ = ------------------ - --------------------- + ---------------- -
> ------------------ ,
> Q_++(hyd.) Q_++(empty) Q_--(hyd.) Q_--(empty)
>
> R_- = ( your answer ).
>
> I think the left side is particularly vulunarable to the background, which
> caused the "shift" you have created. Please see eq. (5.9) in the Laurens van
> Buuren Thesis. Eq.(5.12) is only accutate if the background has no
> asymmetries. In the unpol. runs, the left side creates non zero asymmety! I
> do not know why!
>
> Thank you,
> aki
>
>
>
>
>
> Octavian F Filoti wrote:
>
>>
>> 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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