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I'll try my best to join today, at 15:00.<br>
<br>
Narbe<br>
<br>
<br>
On 05/01/2013 09:18 AM, Karl Slifer wrote:<br>
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<div>Hi all,</div>
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<div>The methodology is the central question and I think we have
to resolve any lingering doubts today. I highly encourage
that everyone really read Oscar's note (Eq 19 and 20) and his
last email before we discuss today. </div>
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</div>
<div>I would really not like to delay till tomorrow if possible
since time is so tight. I hope we can get a majority to
participate at 3pm. Please let me know if you can't.</div>
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<br>
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<div>-Karl</div>
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<div>---<br>
<div>Karl J. Slifer
<div>Assistant Professor</div>
<div>University of New Hampshire<br>
<div>Telephone : <a moz-do-not-send="true">603-722-0695</a></div>
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<br>
<div class="gmail_quote">On Tue, Apr 30, 2013 at 5:59 PM, O. A.
Rondon <<a moz-do-not-send="true"
href="mailto:or@virginia.edu">or@virginia.edu</a>> wrote:<br>
<blockquote class="gmail_quote">
Hi Dustin,<br>
<div class="im"><br>
Dustin Keller wrote:<br>
> You can only benefit from the systematic reduction if
you us Azz as<br>
> discussed yesterday. But at this point I am not
partial.<br>
><br>
> dustin<br>
><br>
<br>
</div>
In the experiment, we only have counts. What we need to show
to the PAC<br>
is how we go from the counts Npol and Nu, to Azz or b1. A
measured<br>
quantity needs to be on one side and physics on the other.
Lets say we<br>
start with your ratio Npol/Nu - 1 = Pzz*Azz, which only
requires Pzz >0.<br>
<br>
We need to prove that the lhs reproduces the rhs. We have,
in general,<br>
N = Q*e*A*l*sigma. But since N are counts from everything in
the target,<br>
it is not a simple matter of canceling quantities that stay
the same<br>
when the polarization changes:<br>
<br>
Npol = Qpol*epol*Apol*lpol*sigma_pol<br>
= Qpol*epol*Apol*lpol*[(sigma_N+3*sigma_Dpol)*pf +
sigma_He*(1-pf)]<br>
<br>
Nu = Qu*eu*Au*lu*[(sigma_N+3*sigma_D)*pf +
sigma_He*(1-pf)]<br>
<br>
sigma_N and sigma_He are the same, always unpol. And<br>
sigma_Dpol = sigma_D(1+Pzz*Azz).<br>
<br>
Then, since Apol = Au = A, and lpol = lu = l,<br>
<br>
Npol/Nu =<br>
(Qpol/Qu)*(epol/eu)*[(sigma_N+3sigma_D(1+
Azz*Pzz))*pf+..)]/[(sigma_N+..<br>
<br>
where I just put ..., because I don't see how it can be
simplified to<br>
just leave Azz*Pzz + 1, to equal the rhs.<br>
<br>
On the other hand, if instead of taking the ratio Npol/Nu
first, we take<br>
the difference first, it's indeed possible to isolate the
required<br>
Pzz*b1 on on side, like I do in my draft, eq. (19) or (20).
And in<br>
fact, we don't even need to bother with Azz, because we get
b1 without<br>
having to multiply Azz by F1, introducing one more
systematic error.<br>
<br>
So, in summary, once one substitutes all the ingredients for
your sigmas<br>
we get, or ought to get, eq.(19) or (20) back.<br>
<br>
In both of those equations, the systematics for Pzz, A, and
l(pf) are<br>
normalization factors, just like we want them to be, for
control of<br>
systematics, but the charge and the detector efficiency are
not common<br>
factors, they depend on the period when the data are taken,
either pol.<br>
or unpol.<br>
<br>
My point is that for the proposal, we must spell this all
out, to give<br>
explicit sources of errors, and to calculate times or
statistical errors<br>
correctly. For example, the statistical error must be
sqrt(Npol + N_U) ~<br>
sqrt(2N), because it is just the error of a difference, etc.<br>
<br>
We need to have a consensus on how the method is going to be
described<br>
in the proposal, which needs to be done in the most precise
way to avoid<br>
any confusion due to ambiguities.<br>
<br>
Cheers,<br>
<br>
Oscar<br>
<div class="HOEnZb">
<div class="h5"><br>
<br>
> On Tue, 30 Apr 2013, O. A. Rondon wrote:<br>
><br>
>> Hi,<br>
>><br>
>> Since I couldn't stay until the end of the
meeting, and I don't think<br>
>> there will be minutes of it, I would like to
share some ideas for the<br>
>> proposal draft.<br>
>><br>
>> Basically, what we need is an equation with the
measured quantity on one<br>
>> side and b1 or Azz on the other. Based on what
I think the consensus<br>
>> was, to measure polarized minus unpolarized
counts on a single cup with<br>
>> the target field aligned along the beam, I've
updated the draft of my<br>
>> method, see subsection 0.2, which discusses
this. Eq. (19) or eq. (20)<br>
>> meet the conditions stated above. This is the
approach I would subscribe<br>
>> to, unless there is another version that is
shown to also represent the<br>
>> procedure, which should be circulated as soon
as possible. The draft<br>
>> is here<br>
>> <a moz-do-not-send="true"
href="http://twist.phys.virginia.edu/%7Eor/b1/b1_method-v2.pdf">http://twist.phys.virginia.edu/~or/b1/b1_method-v2.pdf</a><br>
>><br>
>> Cheers,<br>
>><br>
>> Oscar<br>
>><br>
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