Non-Prompt Tracks with the SiD Baseline Detector. ALCPG07 FNAL Oct 22 – 26 2007 Bruce Schumm Santa Cruz Institute for Particle Physics. Many have contributed…. SLAC: Tim Nelson. Kansas State: Dima Onoprienko, Eckard von Toerne.
Non-Prompt Tracks with the SiD Baseline Detector
Oct 22 – 26 2007
Santa Cruz Institute for Particle Physics
Many have contributed…
SLAC: Tim Nelson
Kansas State: Dima Onoprienko, Eckard von Toerne
Santa Cruz: Chris Betancourt, Chris Meyer, Tyler Rice, Lori Stevens, Bruce Schumm, Eric Wallace
In all its glory:
The SiD Tracker
“Inside-Out” Tracking requires 4 VXD layers
For e+e- qq, 5% of charged tracks originate outside of rorg = 2cm
“Cheat” these particles and their hits away (remove them from the banks). How well can we do on remaining “non-prompt” tracks?
Initial Tool: Axial Barrel Track Finder (ABTF)
Originally written by Tim Nelson to find tracks when VXD is tired or sick.
Finds tracks in 5-layer central tracker by extending three-hit seeds inward.
Optimized for non-prompt tracks (relax IP constraint, add a few tricks) by UCSC students.
UCSC students also added capability to use modular z information
Apply to qq events at Z Pole and at Ecm = 500 GeV (require at least 4 hits; all fakes are 4-hit)
Kansas State’s “Garfield” Algorithm
Extrapolates calorimeter “stubs” into tracker, attaching hits as appropriate
Adapted by UCSC students to run as third-pass tracker, after “cheating” and ABTF
Goal: improve efficiency and/or clean up 4-hit tracks and, if we can, reconstruct the 3-hit tracks.
Start with Z-Pole Events
ABTF 4-hit tracks already fairly pure; can Garfield help with leftovers?
Garfield gets a few more. But what about3-hit tracks?
Not so exciting.
Can we reliably reconstruct tracks that originate outside the second tracking layer?
Instead, UCSC students proposed matching precise three-hit tracker seeds to Garfield stubs
e.g.: Position-matching for isolated muons (mm)
Seed-to-Stubs Performance; Z qq
Next Steps: GSMB?
With Jonathan’s help, will generate meta-stable e+e- stau+ stau- with stau+ ++ gravitino
Signature will be stiff charged track with kink (1-prong tau) or star (3-prong tau) in midst of tracker
Challenge will be to reconstruct kink again SM background of e+e- +-
We’ve just started on this.
In the abstract, four-hit tracks (Rorg < 46 cm, compared to Rmax = 125 cm) seem possible with tracker + cal assist
Three-hit tracks (Rorg < 72 cm) very scenario-dependent, so trying to look at meaningful signature (GSMB)… what else?
Use these signatures to pin down value of z segmentation
What about detector concepts other than SiD?
Note: Much of this work done with junior and senior UG physics majors.