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Stefano Piano, FINUDA Collaboration – da ne 2004 - Frascati, 7 th – 11 th June 2004 Examining bounds states with FINUDA FINUDA COLLABORATION Stefano Piano.

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Presentation on theme: "Stefano Piano, FINUDA Collaboration – da ne 2004 - Frascati, 7 th – 11 th June 2004 Examining bounds states with FINUDA FINUDA COLLABORATION Stefano Piano."— Presentation transcript:

1 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 Examining bounds states with FINUDA FINUDA COLLABORATION Stefano Piano

2 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June Hypernuclei Present knowledge: Only one -hyp. bound state found: 4 He ( ) Pratically no data in heavier systems Possible explanations : a) [ A] B: previous expt.s were unable to detect B b) N N previous expt.s were unable to discriminate S/N c) no B bound system nothing to be seen ! FINUDA can detect the formation and decay of -hypernuclei in the (K - stop, ) reaction due to its tracking capabilities A -hyp. forms when a substitutes a N into a nucleus (S=-1) R.S. Hayano et al., Phys. Lett. B 231 (1989) 355 T. Nagae et al., Phys. Rev. Lett. 80 (1998) He

3 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 How to dig-out -hypernuclei with FINUDA K - stop + A B + prompt + N + N -hyp simulated event Reaction steps

4 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004

5 Silicon Vertex Detector PID Inner microstrip layer Outer microstrip layer

6 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June prompt x - + prompt x p + prompt x - x p + prompt in coincidence with daughter particles + + prompt + prompt x - p K - stopped + 12 C 12 -Be + + prompt + p + n p + -

7 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 K - stopped + 12 C 12 -Be + + prompt + p + n p + - … due to 12 -Be ??? due to proton contamination predicted ~ 4-7 MeV (*) (*) E.Oset et al, Phys. Rep. 188(1990)79

8 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 M [ p -] = 1114 MeV/c 2 Topology of a -hyp event for 12 C - + prompt p K - vertex: MeV/c p 500 MeV/c MeV/c K C 12 - Be + + prompt 12 - Be 12 Be + + n - + p

9 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June prompt p Topology of a -hyp event for 12 C - + prompt p vertex 12 - Be vertex Front view Side view Central region

10 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 K - stopped + 12 C 12 -Be + + prompt + p + n p + - [ - p] invariant mass distribution; ( +, -, p) coincidence Invariant mass, MeV/c 2 Entries / 4 MeV/c 2 needs to be improved !!!

11 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June prompt p + Topology of a -hyp event for 6 Li + + prompt - p vertex Central region front view

12 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June p Topology of a -hyp event for 51 V - + prompt p vertex 49 - Sc vertex Central region side view

13 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 Summary FINUDA/DA NE a unique facility for -hyp studies Initial analysis yields positive expectations for bound B beyond A=4 Improve data analysis: –Better pattern recognition increases a statistics: x3 –Better definition of improves (conversion reaction) invariant mass –Further improve to p PID Strategy for future analysis: –tune-up analysis for the reference nucleus 12 C –go for 6,7 Li, 27 Al and 51 V –have a glance at 0/+ -hyps –get theorists involved

14 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 A first glance at 6 Li

15 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June p + K - vertex: MeV/c p 271 MeV/c MeV/c K + vertex: MeV/c (p + - ) Inv. Mass = 1116 MeV/c 2 K Li ( 5 He+ - ) + + ( 5 He+ - ) 3 H + + n +n Topology of a -hyp event for 6 Li

16 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June p + K-K- K+K p Topology of a -hyp event for 6 Li

17 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June p + K-K- K+K p Topology of a -hyp event for 6 Li

18 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June Al target: typical event - + p K - vertex: MeV/c p 156 MeV/c MeV/c (p + - ) Inv. Mass = 1117 MeV/c 2 K Al ( 26 Mg+ - ) + + ( 26 Mg+ - ) 25 Na + + n

19 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June Al target: typical event - + p K+K+ K-K- - p +

20 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June V target: typical event - + p K - vertex: MeV/c p 248 MeV/c MeV/c (p + - ) Inv. Mass = 1110 MeV/c 2 K V ( 50 Ti+ - ) + + ( 50 Ti+ - ) 49 Sc + + n

21 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June V target: typical event - + p K+K+ K-K- - p +

22 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 Sigma Hypernuclei in FINUDA K stopped + A B + prompt + N + N

23 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 Monte Carlo simulations of S -hypernuclei binding energies and width are taken from: E.Oset et al., Phys. Rept. 188 (1990) 79 bound nucleons have Fermi mom. S mom. distr. prob. dens. funct. final state particles tested for Pauli kinematics of f.s.p. feeds GEANT3 (geom., en. loss, trajectories) E.Oset, A.Ramos, I.Vidana, private communication 2p 1s tot

24 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 K stop + 12 C 2p 1s tot 2p 1s tot 2p 1s tot

25 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 Monte Carlo simulations of background reactions: p - -spectra K - n - p - K - p + - K - p n - K - (NN) - N - n - K - n 0 - TOT

26 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 Monte Carlo simulations of background reactions: p - -spectra +,0 -hyp region

27 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June 2004 Monte Carlo simulations of background reactions: p + -spectra - -hyp region K - p - + K - p n + K - (NN) + N + n + TOT

28 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June Hypernuclei at 1.1 T trigger: + 17% of K + K - tagging with: – + prompt, -, p – two vertices – : invariant mass Starting-line

29 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June Hypernuclei at 0.6 T trigger: + prompt Þ 56% of 12 - Be improved tagging better track and vertex fitting Finishing-line

30 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June Hypernuclei in FINUDA at 0.6 T vertex region

31 Stefano Piano, FINUDA Collaboration – da ne Frascati, 7 th – 11 th June /o Hypernuclei in FINUDA trigger: - prompt tagging with: – - prompt, -, p – two vertices – : invariant mass background: o & quasi-free reactions


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