Hitfinding in E895Mike Lisa
Outline
1D and 2D codes in broad strokes
Current status of codes
Operation of the 2D code
Running modes in 2D hitfinder
2D code- step 1: padwise correction
2D code- step 2: find clusters
2d code- step 3:Find peaks within each cluster
Note: can use a cut to see quickly if it is worthwhile to search for many peaks
We can cap number of peaks in a cluster by iterative threshold-raising.
2D code- step 4:initial guess at hit positions
2D code- Step 5: Fill hits table and save cluster structures for 2nd pass
Information for best possible fitting is built up.
The model of the data.
The model of the data
Crossing angles affect signal shape
2 passes allows fit of data with realistic model
Extracting final positions and dEby fitting to the model
Fitting the peaks - Initial guess
Fitting the peaks - Varying amplitudes
Fitting the peaks - varying position and amplitude (mode 6)
Width of 1-hit clusters indicates quality of model
Hit-by-hit comparison of widths of cluster patterns
Performance Measures ofhitfinder-tracker-dE/dx chain
Visual Performance Measures ofhitfinder-tracker-dE/dx chain
2 A×GeV data
4 A×GeV data
6 A×GeV data
8 A×GeV data
Summary of CPU times (hit+trk)
CPU of the second hitfitting pass
To do / to be understood
Email: lisa@mps.ohio-state.edu
Home Page: vdgus1.mps.ohio-state.edu/lisa.1/