deletions | additions       diff --git a/subsection_Secondary_Electrons_Secondary_electrons__.tex b/subsection_Secondary_Electrons_Secondary_electrons__.tex  index ceab10f..7c282c7 100644  --- a/subsection_Secondary_Electrons_Secondary_electrons__.tex  +++ b/subsection_Secondary_Electrons_Secondary_electrons__.tex 
...
\begin{equation}  \epsilon \approx \frac{E_e}{\frac{3}{2}k_BT}  \end{equation}  The best detection ratio for SE can be obtained by changing the distance between the sample and an ESD, the detection area of an ESD and also by adjusting the best bias voltage $V$. The expression for detection ratio $R$ excludes the effects of cascade amplification from the gaseous molecules. The effective cascade gain $A$ of the gas can be expressed as the ratio of the current detected by ESD to the escaped SE current taking the detection ratio $R=1$.  \begin{equation}  A = \frac{I_{detected}}{I_0 \delta(\theta)} = exp\left( APd\space exp\left( -B\frac{Pd}{V} \right) \right)  \end{equation}  where the $P$ is the pressure in the sample chamber and $A$ and $B$ are the parameters for different gases which have to be determined experimentally. The product $Pd$ in the expression is the characteristic coefficient, $C = Pd$, dictating the gain. For either pressure or distance being large, the gain drops significantly since the electric field is not able to accelerate SE through a region with dense gases. Usually in ESEM, $P=20 \space Torr \approx 2670 Pa$ and $d \approx 1 \space mm$ so $C \approx 2.67 \space Pa\dot m$.  \subsection{Backscattered Electrons}  text here