10 - H1 - Desy

50 The H1 experiment at HERA
not be assigned to any physics class are classified as ’soft physics’ and strongly prescaled
(this effect is important for this analysis, for further details see section 4.3.3).
Events passing all the trigger levels are permanently written to tape in two different data
formats, Production Output Tapes (POTs) and Data Summary Tapes (DSTs). The POTs
contain the complete event data including raw and reconstructed information, while on
DSTs only a subset of predominantly reconstructed quantities is stored, which is sufficient
for most physics analyses. DSTs occupy roughly 10 kB per event of disk space, which is
an order of magnitude smaller than the data volume of the POTs. In the offline analysis
of the ep scattering data, calibration constants to the subdetector measurements, as well
as information on the detector alignment, are extracted. After the so-called reprocessing,
the corrected measurements are written to a further generation of DSTs. In this analysis
DST3 data reprocessing generation was used.