Adam Blake, June 9 th 2008

Results Quick Review Look at Some Data In Depth Look at One Anomalous Event Conclusion

Stage in ProcessTotal Remaining Events All abnormal shower_speed events57 Obviously bad removed*12 Speed Difference † 11 Most Interesting4 *By obviously bad, one of the following is true: The plane did not fit right The event is just noise The event is on May 19 th, 2004 † Will explain seperately

HR1 RpHR2 Rp Opening Angle HR1 Track Length (rads) HR2 Track Length(rads) Shower Time HR1 Speed HR1 good tubes HR2 Speed HR2 good tubes

Up to this point

Correcting Time and Finding Distance Along Shower Axis Basic Problem: Find the closest point of approach for two lines in 3D space. Shower Axis UvUv RpRp MvMv TvTv b a

Correcting Time and Finding Distance Along Shower Axis Shower Axis UvUv RpRp MvMv TvTv b a From this calculation, b is now the slant depth (or distance along shower axis measured from R p. The time is calculated from the following formula: Because this formula relies on the tube time given in data, the reconstruction cannot use timing information to improve plane fits or to find the shower axis.

HiRes Reconstruction Correct tube times based on stereo planes Iterative Line fit to filter bad tubes Bootstrap error estimation for Cut Cuts Statistics

Data Processing CutsMy Cuts Both detectors must pass plane fits Minimum PE per tube: 1.0 Minimum Tubes per event: 6 Minimum Average PE per tube per event: 15.0 Maximum Track Length: Hr1 – 36.0°, Hr2 – 57.0° Minimum Track Length: Hr1 – 3°, Hr2 – 6° Cut if event crossing planes or tube binning 10° > Opening Angle 170° < Opening Angle Bootstrap σ >.0012 m/ns Hr1 adjusted tubes < 3 Hr2 adjusted tubes < 6 Track Length < 8 degrees Tubes in 1 mirror > 170 Ψ > 120 Plog < 2.0 Rp < 4km from either site Speed difference to Error difference ratio*

Compare standard deviation calculated in standard way to percentage of data cut. Look for obvious breaks in the data. At these points, calculate width and full width at half max of fits to binned data and look for appropriate statistical relations. Comparison of percentage data cut and drop in standard deviation for Bootstrap estimated error of HiRes 2.

This is the ratio of the difference in speeds to the combined error in the speeds calculated using the bootstrap method. The errors are correlated, so the covariant part of the correlation must be accounted for.

Resulting histograms for HiRes 1 and HiRes 2

Developed from set of Iron MC events thrown at the speed of light with energy 10E19, ~4500 of which made it through pass 4 and ~1800 made it through my cuts.

Developed from set of Iron MC events thrown at the speed of light with energy 10E19, ~4500 of which made it through pass 4 and ~1800 made it through my cuts

* Cuts are being reevaluated. This graph is done using current cuts but may change slightly. Proposed new cuts would increase apertures shown. Currently awaiting processing for other apertures.

Just a brief mention of what has been done with previous sets of “abnormal” events

Starting with first processed data runs in January, a good deal of effort has been put into looking at individual events to see why they have abnormal speeds. Overall, the number of events that were not “well understood” has changed from several hundred to the 11 mentioned earlier. Next slides: An example of what has been done.

Mono Plane FitsStereo Plane Fits

When I try to fit this, I get a vertical plane for HiRes 2 This type of event is reason for current Rp cut. The shower goes right over the top of the detector so planes do not fit well. This throws speed off.

This event is the event I have spent the most time on to this point. Other possible candidates will receive similar treatment.

The decision to focus on this event first resulted from: Good track in both mirrors Both Hr1 and Hr2 speeds match very closely Reconstructed Energy was available for this event from HiRes 2 Mono Speed is > 7 sigma from speed of light Other events will receive similar treatment to this event. This event has no HiRes 1 mono. It only has 6 good HiRes 1 tubes. That is enough to pass my cuts and stereo cuts but not mono. The various models used to try and explain this event have resulted in explanations for almost every other abnormal event – however they have not resulted in an explanation for this event.

Shower_speed is speed fit by my program sab_plane_fit is speed fit after refitting the plane using a plane fitter I wrote Shower_speed/Origin is speed fit by Origin based on points from shower_speed Hires_Soft/Mathematica is the HiRes plane fit used with Mathematica to correct tube times then fit in Origin Hires_Soft/Mathematica no weight is the HiRes plane fit used with mathematica to correct tube times then fit in Mathematica with no additional weighting No Correction, No weight is a fit performed straight on HiRes raw data with no corrections.

Comparison for plane vectors done by various fitting Rutgers and HiRes planes use relative timing to aide in plane fitting.

Comparison for various parameters. Mine refers to parameters calculated using my planes and Mathematica Reconstruction are values pulled from reconstruction.

The Reconstructed plane fits do not match the pre- reconstruction plane fits.

HiRes 1 planesHiRes 2 planes

Actual PlanesReconstructed Planes

 Theta consists of a rotation about the z axis.  Psi is a rotation about the axis perpendicular to both shower normal and shower core.  This is a non-weighted fit to HiRes 2 points

Still have a finite number of events that reconstruct with unusual speeds. Currently looking at rotating planes to see what would need to be done for planes to fit Also currently in the process of reevaluating cuts based on some slight changes to procedure Calculating Apertures with new cuts