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Elastic Neural NetElastic Neural Netfor standalone RICH ring findingfor standalone RICH ring finding
Sergey Sergey Gorbunov Gorbunov Ivan Ivan KiselKisel
DESY, Zeuthen KIPDESY, Zeuthen KIP, , UniUni-Heidelberg-Heidelberg KIPKIP
ACAT 2005, DESY, ZeuthenMay 22-27, 2005
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ACAT05 DESY, ZeuthenACAT05 DESY, Zeuthen S. Gorbunov, I. KiselS. Gorbunov, I. Kisel 22
EN EN –– Traveling Salesman Problem Traveling Salesman Problem
Discrete ENDiscrete EN
(*) Pentium IV/2.4 GHz(*) Pentium IV/2.4 GHz Nature, 326 (1987) 689
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ACAT05 DESY, ZeuthenACAT05 DESY, Zeuthen S. Gorbunov, I. KiselS. Gorbunov, I. Kisel 33
EN EN –– Ring Search : Idea Ring Search : Idea
CHEP’01, Beijing (2001) 162
Features:• External forces - minimizing
distances• Internal forces - constraint
on Fourier coefficients
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EN EN –– Ring Search : Implementation Ring Search : Implementation
Scheme:• Loop over hits• Finding a ring in a local area around the hit• Sorting of the found rings
Details:• No internal forces - fixed ring shape (circle)• External forces - minimize distances• Discrete ring evolution - direct finding of the
minimum in 2-3 iterations• Time ~ total number of hits
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RICH Detector in the CBM Experiment at GSIRICH Detector in the CBM Experiment at GSI
beam
2 m
mirror
R = 450 cm
gaseous radiator
40%He + 60%CH4N2
3.3
m
4.7
m
1 central Au+Au collision, 25 AGeV (UrQMD)
38 rings/event
33 electrons
5 pions
12.6 e from primary vertex
5 p from primary vertex
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EN EN –– Performance Performance
All set: N hits ≥ 5Ref set: N hits ≥ 15Extra set: 5 ≤ N hits < 15Reconstructed: ≥ 70% hits from the same MCClone: MC reconstructed few timesGhost: < 70% hits from the same MC
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ConclusionConclusion
• Efficient Efficient ring finder based on the elastic net• StandaloneStandalone – no track guidance necessary• SimpleSimple – suitable for hardware implementation• FastFast – can be used for triggering