Analysis of Time Resolution in HGCAL Testbeam

Using data from a 250 GeV electron run during the November 2016 HGCAL testbeam, the time resolution of the High Granularity hadronic endcap Calorimeter, HGCAL, was investigated, looking at the seven innermost Si cells, and using them as reference timers for each other. Cuts in the data was applied based on signal amplitude,$0.05 \hspace{1mm} V < A < 0.45 \hspace{1mm} V$, position of incoming beam particle,$0 \hspace{1mm} mm < TDCx < 22\hspace{1mm} mm$ and $-7\hspace{1mm} mm <TDCy < 11\hspace{1mm} mm$ and size of the time difference between two cells, $\vert t_1 - t_2 \vert < 200 \hspace{1mm} ps.$ Timewalk corrections, wrt in-cell amplitude, were applied to the cut data, with the Photek as reference.\\ Gaussian functions were fitted to the corrected $\Delta t$ distributions, and a time resolution of $15-50$ $ps$ was obtained, depending on which two cells were compared, and how the low-statistics cut were placed. We also confirmed a slight correlation between time resolution and distance between the two cells compared. \end{abstract}