Difference between revisions of "Runs 4111(D2O)/4112(H2O)"

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If we consider the neutron time of flight uncertainty <math>U(t_n) = 7 ns</math> then the correlation plot changes to
 
If we consider the neutron time of flight uncertainty <math>U(t_n) = 7 ns</math> then the correlation plot changes to
  
[[File:tof_7ns_uncertty.png | 600 px]]
+
[[File:tof_7ns_uncertty.png | 400 px]]
 +
 
 +
If we consider the neutron time of flight uncertainty <math>U(t_n) = 1 ns</math> then the correlation plot changes to
 +
 
 +
[[File:tof_1ns_uncertty.png | 400 px]]

Revision as of 00:03, 11 September 2012

Subtraction of the stops for each detector in the case of D2O target. The length of the active area (scintillator) of the detector is 75.3 cm.

Run 4111 D2O deltaT.png

Subtraction of the stops for each detector in the case of H2O target:

Run 4111 H2O deltaT.png

Normalized superimposed timing spectra from D2O(black line)/H2O(red line) targets and bin-by-bin subtraction (green line) of D2O-H2O data:

Run 4111 subtr1.png

Run 4111 subtr2.png

Run 4111 subtr3.png

Run 4111 subtr4.png

Neutron energy distribution data analysis for run 4111:

File:D2O neutron spectra.pdf

Errors on the neutron energy for the case of Det M:

[math]E_n \pm U(E_n)=m_nc^2/2 \cdot 1/c^2 \cdot (l_n/t_n)^2 \cdot [1 \pm 2 \sqrt{U^2(l_n)/l^2_n + U^2(t_n)/t^2_n}][/math]

Where uncertainty in the neutron flight pass due to the finite width of the detector (14.8 cm) [math]U(l_n) = 14.8cm/2 \cdot cos(\theta)[/math] and uncertainty in zero time definition in neutron TOF spectrum [math]U(t_n)=10 ns[/math]

Correlation between the neutron energy and neutron energy uncertainty is plotted below:

Error plot detM.png

The above plot may look better if you plot [math]Energy[/math] -vs- ([math]Energy \pm Energy[/math]) 
As the energy increased the uncertainty increases to the point the the error bar is as big as the magnitude of the energy.

Simulation of the flight pass length uncertainty [math]U(l_n)[/math] for Det M(1,2):

Cylindrical target with dimensions of real target was used. It was filled with liquid D2. 1 MeV neutrons were generated inside the target unoformly and isotropically. The shortest distance from the target to the detector surface was 97.4 cm (corresponds to zero in the plot of the Delta_L)

The whole range fit:

Fit whole range.png

Central region fit:

Fit peak.png

As can be seen we have [math]U(l_n)[/math] of ~ 3.3 cm for the whole detector (no binning).

The correlation of neutron energy [math]E_n = m_nc^2/2 \cdot 1/c^2 \cdot (l_n/t_n)^2[/math] and uncertainty [math]U(E_n)= 2 \sqrt{(3.3cm)^2/l^2_n + (10ns)^2/t^2_n} \cdot 100\%[/math]

DetM neutron energy.png

If we consider the neutron time of flight uncertainty [math]U(t_n) = 7 ns[/math] then the correlation plot changes to

Tof 7ns uncertty.png

If we consider the neutron time of flight uncertainty [math]U(t_n) = 1 ns[/math] then the correlation plot changes to

Tof 1ns uncertty.png