[Frost] How do you find the dilution factor?

[Barry Ritchie]

Jo, just kibitzing here...

In doing your substraction, did you also try having the background be a
first order (i.e., linear) polynomial rather than a flat background,
again ignoring the 2pi stuff above the peak? There is clearly a slope to
the background below the peak, and it is likely that the real shape of
the background is more complicated, but, in the absence of detailed
knowledge of that shape, a linear function would be more reasonable.
Then the two results (flat and linear backgrounds) would help bracket
the uncertainties in the peak.

---BGR

Professor Barry G. Ritchie
Department of Physics
Arizona State University
Tempe, AZ  85287-1504
 
Telephone: (480) 965-4707
Fax: (480) 965-7954

-----Original Message-----
From: frost-bounces at jlab.org [mailto:frost-bounces at jlab.org] On Behalf
Of mcandrew at jlab.org
Sent: Friday, February 25, 2011 9:19 AM
To: Michael Dugger
Cc: frost at jlab.org
Subject: Re: [Frost] How do you find the dilution factor?

Sung,

I think I used dilution factor = (number of events in butanol - number
of
events in carbon)/number of events in butanol.

In order to obtain these values, I use the missing mass histogram from
butanol and the missing mass histogram from carbon scaled to butanol.

I explain it on this webpage:

http://www2.ph.ed.ac.uk/~s0783525/carbon_background.htm

The method still needs some improvement ie. taking into account energy
and
theta and is a first approximation.

Any further questions, let me know.

Have a good weekend,
Jo.

>
> Sung,
>
> My previous email was wrong. Your dilution factor equation makes sense
> with the use on the helicity web page. It took me a couple of minutes
to
> figure out how you put the dilution factor together.
>
> Sorry for the confusion.
>
> Take care,
> Michael
>
> On Fri, 25 Feb 2011, Michael Dugger wrote:
>
>>
>> Sung,
>>
>> I have been using the subtraction method, so there might be some
problem
>> with my understanding on how these dilution factors are put together
and
>> used.
>>
>> I could be wrong, but I think that your definition of the dilution
>> factor
>> might be inverted with respect to what I see on the helicity web
page:
>>
http://clasweb.jlab.org/rungroups/g9/wiki/index.php/Helicity_assignment_
for_g9a
>> Also there might be a sign problem.
>>
>> You might want to define how you are using the dilution factor. For
>> example:
>>
>> E = (1/(D*P))*[N_a - N_b]/[N_a + N_b],
>>
>> Or
>>
>> E = (D/P)*[N_a - N_b]/[N_a + N_b],
>>
>> where
>> D = dilution factor
>> P = beam*target polarizations
>> ...etc
>>
>> -Michael
>>
>> On Fri, 25 Feb 2011, Sungkyun Park wrote:
>>
>>> Hi Jo,
>>>
>>> In your update, I have a simple question.
>>> How do you find the Dilution Factor?
>>>
>>> I define the dilution factor as the ratio between the hydrogen and
the
>>> full butanol contribution to the cross section. I used the following
>>> equation:
>>>
>>> (Dilution factor) = 1 - N(carbon)/N(Butanol)*(Scaling Factor)
>>> where N(carbon) is the number of event in carbon and I count the
events
>>> in the missing mass plot of carbon. N(Butanol) is the number of
event
>>> in buutanol.
>>>
>>> Sung
>>> Florida State University
>>>
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