Line-segment tracking aims to exploit the CMS outer tracker geometry to make an inherently parallelizable and acceleratable tracking algorithm.
CMS outer tracker geometry
The planned CMS tracker design contains double-layered silicon modules with a gap size of about 2mm (dubbed pT modules) in the outer tracker. This geometry can be used to reduce occupancy of hits by requiring coincidences of hits between two layers consistent with a minimum pT threshold.
ApproachHere we illustrate the segment linking algorithm in the outer tracker. The first graphic shows the creation of mini-doublets from detector hits and then segments from the mini-doublets. Segments are advantageous for a number of reasons including locality, sharing hits, and being inherently not dependent on the inner tracker layers. The right-hand figure then shows how track candidates are created from segments. (a non-exhaustive list of possible track candidates are shown).
ResultsGood (or poor) linking is then an indicator of a valid track candidate. Geometric variables distinguish good track candidates from unphysical ones. This approach is naturally parallelizable and vectorizable (quite different from a traditional Kalman-Filter approach). We are developing this algorithm with both CPU and GPU (CUDA) implementations.
- Avi Yagil
- Philip Chang
- Peter Wittich
- Peter Elmer
- Steve Lantz
- Michael (Tres) Reid
- Dan Riley
- Leonardo Giannini
- Slava Krutelyov
- Mario Masciovecchio
- Matevz Tadel
- Bei Wang
- Giuseppe Cerati
- Matti Kortelainen
- Allison Reinsvold Hall
- Brian Gravelle
- Boyana Norris
- 13 Apr 2022 - "Line Segment Linking project", Michael (Tres) Reid, IRIS-HEP Topical meeting
- 18 Oct 2021 - "Line segment tracking for Phase-II Tracking", Philip Chang, HLT Upgrade Workshop (CMS restricted)
- 7 Dec 2020 - "Segment Linking Development on GPUs", Michael (Tres) Reid, HLT developments with GPUs
- 3 Nov 2020 - "Line segment tracking for Phase-II Tracking", Philip Chang, HLT Upgrade Workshop (CMS restricted)
- 21 Sep 2020 - "Update on Segment Linking for HL-LHC", Philip Chang, Tracking POG meeting (CMS restricted)
- 23 Jun 2020 - "Update on Segment Linking for HL-LHC", Philip Chang, HLT Upgrade Workshop (CMS restricted)
- 20 Apr 2020 - "Parallelizable Track Pattern Recognition in High-Luminosity LHC", Philip Chang, Connecting The Dots 2020
- 3 Dec 2019 - "Segment linking for Phase-2 Tracking", Philip Chang, HLT Upgrade Meeting (CMS restricted)
- 2 Dec 2019 - "Segment linking for Phase-2 Tracking", Philip Chang, CMS Tracker Week - Tracking POG meeting (CMS restricted)
Several on IRIS-HEP and HL-LHC tracking
3 May 2022