Home » Hades » Pluto » [SOLVED] Beam Smear and Cross Sections
Re: Bear Smear and Cross Sections [message #13894 is a reply to message #13893] 
Tue, 28 August 2012 01:32 
Michael Kunkel
Messages: 53 Registered: June 2011

continuous participant 
From: *hr.hr.cox.net


I do understand that my thoughts are hard to convey, I appreciate the time you are taking with this. I wanted to clarify a typo in my previous message.
Instead of
Michael Kunkel wrote on Mon, 27 August 2012 21:07  Is _f the density function? If so, wouldn't using Input : _x s cos(theta), _y is differential cross section
Output : cross section suffice?

I wanted to say
Is _f the density function? If so, wouldn't using Input : _x s cos(theta), _y is differential cross section
Output : _f cross section suffice?
What I am finding hard to conceive here is how the distribution is generated.
Moreover, I want to clarify what I am trying to do, and hopefully I can understand my mistakes after this.
I have 64 models I will be using. I was assuming I could implement this as
model1>SetRange(1.77,1.8);
...
...
...
model64>SetRange(2.56,2.6);
model1>AddHistogram(example1,"value = Eval(_x); _f =_y * value");
makeDistributionManager()>Add(model1);
...
...
...
model64>AddHistogram(example64,"value = Eval(_x); _f =_y * value");
makeDistributionManager()>Add(model64);
In the above snipet I use 1 histogram for each model. Each histogram is derived from published data with
_x = Cos(theta)
_y = Differential Cross section
The histograms are extrapolated from TGraphs (see below);
c.m. 1.77 >1.8 GeV
c.m. 2.56 >2.6 GeV
As it can be seen from the plots above, the cross section depends on both the c.m. energy and Cos(theta);
I am trying to model this, however the example macro you provided states (lines 31 & 32):
//Input: _x is cos(theta), _y is the c.m. energy
//Output: _f: cross section
model>AddHistogram(distribution,"value = Eval(_x); _f = _y * value");
But cross section, from a physics stand point is proportional to Cos(theta) / s, where s is square of c.m. energy.
This is my a source of my confusion and also not understanding how to use what I already have, cos(theta) vs. diff XSection, is the other part of my confusion.
Thanks
[Updated on: Tue, 28 August 2012 01:34] Report message to a moderator



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