Hello All,

I am wondering if anyone is familiar with a reconstruction error that I am running into. When attempting to run reconstruction with the HPS2014OfflineTruthRecon.lcsim steering file, the process quits with an error caused by finding a negative value of the variable "t". Upon further investigation, it seems that a negative "t" will cause an imaginary path length of the track, calculated in WTrack.java. The physics behind calculating t is beyond me, involving combinations of a momentum vector, a magnetic field unit vector, and a unit vector of a plane. I am able to step through 590 events before this error occurs, so it seems to be something with this individual event that is stopping reconstruction from continuing.

The file being run through reconstruction is created from running an event file in SLIC with the HPS-Proposal2014-v5-6pt6 detector, and then passing this file through readout simulation with the HPS2014ReadoutNoPileup.lcsim. The output error is listed below.

As a test on the steering file and drivers, I ran a smaller input file through the same reconstruction without an error. However, out of 165 triggered events, I am only seeing 14 tracks. Is there a reason that so few tracks would be found? Thank you for the help.

University of New Hampshire

>> Event 585
>> Event 586
>> Event 587
>> Event 588
>> Event 589
>> Event 590
 getPathLengthToPlaneApprox ERROR t is negative (-0.09475479432494227)!
 p 0.30696444517303073 rho -0.0014649536585467351 a -4.4968868700000003E-4 A -3.2568853514089034E-4 B 0.8943517247214046 C -686.7142264081292
 track params: 0.2785713187164182, -0.12804764158077803, -0.01513249730159967, 0.30696444517303073, 16.49545255281126, 35.88633038244529, 0.656055763097405,
 xp [      702.45,      71.390,     -27.331]
 eta [     0.99953,    0.030515,      0.0000]
 h [      0.0000,      0.0000,     -1.0000]