Determination of Drift Velocity

The effective velocity of the drift electrons for the given running period was obtained by plotting (Figure 5.2) a range of possible drift velocities $vs$ the average $\chi ^2$ of the fitted tracks for each of these drift velocities. The best value of the drift velocity that corresponds to the $\chi ^2$ minima was selected as the effective drift velocity. A quadratic polynomial fit in Figure 5.2 yielded a value of $dv_{{\rm min} \chi^2}$ = $-$ B/2A = 49.925 $\mu$m/ns.

Figure 5.2: The average $\chi ^2$ of the fitted tracks vs drift velocity for the final running period. The best drift velocity is found to be 49.93 $\mu$m/ns which corresponds to the $\chi ^2$ minima.