[ Identification | Description | Input parameters | Links ]

The Test_Incoherent_MS Instrument

Identification

• Site: Tests_samples
• Author: Daniel Lomholt Christensen and Peter Willendrup
• Origin: NBI
• Date: 20250603

Description

Test instrument for validation of magnitude of multiple scattering in Incoherent.comp.
The instrument considers "thin" and "thick" sample conditions.


For the thin sample conditions, the following analytical calulations find the
Neutron intensity at the detector to be 27.12:

$$
\frac{dN_{\rm real}}{dt}= \Psi A \rho_{\rm c}\sigma_{\rm inc}
\frac{\Delta \Omega}{4 \pi} a_{\rm lin} l_{unscattered}.
$$
Where $\Psi=1e7$, $A=1$, $\rho=0.0723$, $\sigma_{\rm inc}=\sigma_{\rm abs} = 5.08$, $\frac{\Delta \Omega}{4 \pi} = 10/99.95^2$
and $a_{\rm lin}= \exp(-(\sigma_{\rm inc} + \sigma_{\rm abs}\lambda/1.7982)\rho l_{avg})$.
$l_{unscattered}=0.1cm$ and is the path through the sample eg. unscattered path length.



For the thick sample condition, the general formula is the same,
But the attenuation is calculated using the effective length, instead of the actual
length:

\begin{equation} \label{eq:inc_layer_l}
l_{\rm app} = \int _{0}^{l_{\rm max}} a_{\rm lin}(z) dz
=  \int _{0}^{l_{\rm max}} e^{-2\mu z}dz
=  \frac{1-e^{-2\mu l_{\rm max}}}{2\mu },
\end{equation}


By scanning across thickness values, one then finds a curve, that should fit the
analytical calculations.

Input parameters

Links

• Source code for Test_Incoherent_MS.instr.
• A reference/HTML link for more information

[ Identification | Description | Input parameters | Links ]