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

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

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

ACAT05 DESY, ZeuthenACAT05 DESY, Zeuthen S. Gorbunov, I. KiselS. Gorbunov, I. Kisel 44

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

ACAT05 DESY, ZeuthenACAT05 DESY, Zeuthen S. Gorbunov, I. KiselS. Gorbunov, I. Kisel 55

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

ACAT05 DESY, ZeuthenACAT05 DESY, Zeuthen S. Gorbunov, I. KiselS. Gorbunov, I. Kisel 66

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

ACAT05 DESY, ZeuthenACAT05 DESY, Zeuthen S. Gorbunov, I. KiselS. Gorbunov, I. Kisel 77

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