Implementation of PV-independent BGI lines
Summary
This MR expands on !1031 (merged), 'Preparation for beam gas imaging data collection'. It adds an additional filter that accepts events based on the extrapolation of VELO tracks into a specified cylindrical region about the beamline. It also adds new lines that use this filter. These new lines parallel the Hlt1BGIPVsCyl.* lines introduced in !1031 (merged).
Requirements
At this time, it is unclear how well the Allen PV reconstruction and the lines based thereupon will support a beam-gas-imaging (BGI) luminosity calibration. This MR implements an alternate strategy for selecting events that have a beam-gas interaction for analysis that is based on tracks extrapolated to their positions of closest approach (poca) to the beamline.
We define a volume of interest that is a cylinder coaxial with the \hat{z} axis and with boundary parameters z_{\min}, z_{\max}, and \rho_{\max}^2:
z_{\min} <= z < z_{\max}\rho^2 < \rho_{\max}^2
Rather than requiring a fully reconstructed PV in this region, we count the number of tracks whose extrapolated poca to the beamline lie within this volume of interest, N(poca\ in\ V) . If this count exceeds a threshold, the event passes the filter,
N(poca\ in\ V) >= n_{\min}
Implementation
Filter
The new filter defined in this MR uses the dev_velo_kalman_beamline_states_view as its primary input. These serve as the extrapolated poca for the VELO tracks.
The implementation structure is a copy-mode of the CheckPV filter. The kernel operates on a single state and increments a shared atomic accumulator if the state is within the volume of interest. threadIdx.x==0 initializes the accumulator and checks the final sum against the configured threshold.
Lines
The new lines parallel the BGI lines introduced in !1031 (merged) and have the same structure with instances of the new filter replacing the instances of CheckCylPV.
Meta
Related to #223