Difference between revisions of "JB Absolute theta"

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[[Production Analysis|go_back]]
 
[[Production Analysis|go_back]]
  
== Beam ==
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[[JB Absolute theta(oldmethod)]]
  
I performed an MCNP simulation of a D2O target subject to an 10.5 MeV end-point bremsstrahlung beam.  A mock-up of our entire neutron detector array is included in the simulation. Detector physics is modeled by applying a detection threshold in terms of light output (MeVee), which is equal to the typical MeVee produced by 0.5 MeV neutrons within the scintillator.
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=Analysis=
  
A Cf252 source was also simulated, allowing me to apply the exact same analysis technique to simulation and experimental data .
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After my first attempt at reconstructing  the theta_abs distribution gave mediocre results, I decided to try again, but this time without integrating over experimental observables throught analysis, except for at the final step. To illustrate what I mean, see the histogram below:
  
[[File:2NCorrD2OExpvsMCNP.png|600px]]
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[[File:D2O3DHistogram.png|700px|thumb|center|alt=Large | Every singles event lies in a three dimensional space consisting of a PMT top and bottom time, and a specific detector. These observables can be recast as energy, vertical z position, and detector angle (54,78,102, ect). ]]
  
== MCNP-POLIMI ==
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The benefit of conducting the analysis in this 3D space, is that the neutrons correlated with the beam can be normalized to uncorrelated Cf252 neutrons detected in the same detector with similar positions and energies.
 
 
Below is an MCNP-POLIMI simulation of a cylindrical D20 target (axis length = 2"; dia. = 0.75") subject to a bremsstrahlung photon beam with an end point of 10.5MeV.  The plot below shows the relative distribution of neutron direction cosines w.r.t. the incident photon beam. All neutrons are from the photodisintegration of D20 and the direction cosine is taken as neutrons exit the target geometry.
 
 
 
[[File:MCNPSimD20Theta abs.png|650px]]
 

Latest revision as of 21:28, 22 November 2017

go_back

JB Absolute theta(oldmethod)

Analysis

After my first attempt at reconstructing the theta_abs distribution gave mediocre results, I decided to try again, but this time without integrating over experimental observables throught analysis, except for at the final step. To illustrate what I mean, see the histogram below:

Large
Every singles event lies in a three dimensional space consisting of a PMT top and bottom time, and a specific detector. These observables can be recast as energy, vertical z position, and detector angle (54,78,102, ect).

The benefit of conducting the analysis in this 3D space, is that the neutrons correlated with the beam can be normalized to uncorrelated Cf252 neutrons detected in the same detector with similar positions and energies.