First observation of the heavy hyper-hydrogen isotope 6  H XIV International Conference on Hadron Spectroscopy Elena Botta INFN – Sezione di Torino & Universita’ di Torino for the FINUDA Collaboration

Talk outline n-rich hypernuclei DA  NE LNF-INFN n-rich hypernuclei search with FINUDA Previous results (partial statistics) Present results (global statistics): preliminary production rate and binding energy determination (preliminary) XIV International Conference on Hadron Spectroscopy

n-rich hypernuclei: physics motivations  -hypernuclei: –nuclear core compression ( 7  Li vs 6 Li: H.Tamura et al., Phys.Rev.Lett. 84 (2000) 5963 –  extra binding energy good candidates to show n excess and n halo tool to obtain infos on b-b interaction in low-density nuclear matter  NN force rôle (increasing with N/Z) connections with nuclear astrophysics extension of the Strange Nuclei chart S. Ajimura et al. Proposal for P10 – J-PARC directly produced hyperfragments SCXDC X XIV International Conference on Hadron Spectroscopy

(K - stop,  + ) K - + p   +  0  0 + p  n +  + (2-step) K - + p    +  +   + p  n +  (1-step) K.Kubota et al, NPA 602 (1996)  He ( 9 Be) U.L.= /K - stop ; 12  Be( 12 C) U.L.= /K - stop ; 16  C( 16 O) U.L.= /K - stop T.Y.Tretyakova et al., Nucl. Phys. A 691 (2001) 51c (  -, K + )  - + p   0 + n  0 + p   + K + (2-step)  - + p  K 0 +  K 0 + p  n + K + (2-step)  - + p  K + +  -  - + p  n +  (1-step) P.K.Saha et al., PRL 94 (2005) : 10  Li ( 10 B) d  /d  = 11.3±1.9 nb/sr T.Y.Tretyakova et al., Phys. At. Nucl. 66 (2003) 1651 n-rich hypernuclei (  np -2 states): production XIV International Conference on Hadron Spectroscopy

n-rich hypernuclei: 6  H L. Majling, NPA 585 (1995) 211c - binding energy - prod. rate ~ * hyp. prod. rate in (K - stop,  - ) Y. Akaishi et al., AIP Conf. Proc (2008) 277 K.S. Myint, et al., Few Body Sys. Suppl. 12 (2000) 383 Y. Akaishi et al., Frascati Phys. Series XVI (1999) 16 “coherent”  coupling in 0+ states   NN three body force 5.8 MeV XIV International Conference on Hadron Spectroscopy 4.2 MeV

DA  NE LNF-INFN Detector Detector capabilities: Selective trigger based on fast scintillation detectors (TOFINO, TOFONE) Clean K - vertex identification (ISIM P.ID.+ x,y,z resolution + K + tagging) , K, p, d, … P.I.D. (OSIM&LMDs dE/dx, TOF) High momentum resolution (6‰ FWHM for  MeV/c for spectroscopy) 1% FWHM for  MeV/c 2 % FWHM for  MeV/c for MWD study ( tracker resolution + He bag + thin targets) Solid angle ~ 2  srad Detector Detector capabilities: Selective trigger based on fast scintillation detectors (TOFINO, TOFONE) Clean K - vertex identification (ISIM P.ID.+ x,y,z resolution + K + tagging) , K, p, d, … P.I.D. (OSIM&LMDs dE/dx, TOF) High momentum resolution (6‰ FWHM for  MeV/c for spectroscopy) 1% FWHM for  MeV/c 2 % FWHM for  MeV/c for MWD study ( tracker resolution + He bag + thin targets) Solid angle ~ 2  srad 2003 data taking: 190 pb -1 (2 x 6 Li, 7 Li, 3 x 12 C, 27 Al, 51 V) 2006 data taking: 966 pb -1 (2 x 6 Li, 2 x 7 Li, 2 x 9 Be, 13 C, D 2 O) e + + e -   (1020)  K + + K - (127 MeV/c) K - stop + A Z  A  Z +  - Solenoid: B=1T XIV International Conference on Hadron Spectroscopy

n-rich hypernuclei search with FINUDA: previous results XIV International Conference on Hadron Spectroscopy M.Agnello et al., PLB 640 (2006) data sample background: K - + p   + +  -  +  n  + (~ MeV/c) K - + pp   + + n  +  n  + (~ MeV/c) cut on K - /  + distance production rate/stopped K - : U.L. (90% CL) 6  H: (2.5 ± 0.4 stat sys )  H: (4.5 ± 0.9 stat sys ) K - stop + 6 Li  6  H +  + K - stop + 7 Li  7  H +  +

6  H search with FINUDA from: “Proposal for a new FINUDA data taking” FINUDA Collaboration February data sample: 5x statistics K - stop + 6 Li  6  H +  + ( MeV/c) INCLUSIVE MEASUREMENT K - stop + 6 Li  6  H +  + ( MeV/c) 6  H  6 He +  - ( MeV/c) COINCIDENCE MEASUREMENT XIV International Conference on Hadron Spectroscopy

6  H search with FINUDA K - stop + 6 Li  6  H +  + ( MeV/c) 6  H  6 He +  - ( MeV/c) no evident signal/structure low production rate  new strategy XIV International Conference on Hadron Spectroscopy

K - stop + 6 Li  6  H +  + 6  H  6 He +  - M(K - ) + 3 M(n) + 3M(p) – B( 6 Li) = M( 6  H) + T( 6  H) + M(  + ) + T(  + ) M( 6  H) = 4 M(n) + 2M(p) – B( 6 He) + T( 6 He) + M(  - ) + T(  - ) T(  + ) + T(  - ) = M(K - ) + M(p) – M(n) – B( 6 Li) + B( 6 He) –T( 6 He) – T( 6  H) – M(  + ) – M(  - ) = 203 ± 1.3 MeV (203.5÷203.2 MeV with B  = 0÷6 MeV) cut on T(  + ) + T(  - ): 202÷204 MeV independent reactions: decay at rest 6  H search with FINUDA XIV International Conference on Hadron Spectroscopy

selection: T(  + )+T(  - ) = 202÷204 MeV XIV International Conference on Hadron Spectroscopy Preliminary absolute energy scale:  +(235 MeV/c) from K  2  p = 0.2 MeV/c

 - momentum (MeV/c)  + momentum (MeV/c) 3 candidate events K - stop events 249÷255 MeV/c (  p =1.1 MeV/c) 130÷138 MeV/c (  p =1.2 MeV/c) XIV International Conference on Hadron Spectroscopy Preliminary

1 candidate event ++ -- XIV International Conference on Hadron Spectroscopy Preliminary (251.3±1.1 MeV/c) (135.1±1.2 MeV/c)

Background sources: fake coincidences:  +(249÷255 MeV/c) &  - (130÷138 MeV/c) K - stop + 6 Li   + +  He + n (end point ~190 MeV/c)  +  n +  + (end point ~282 MeV/c) K - stop + 6 Li  4  H + n + n +  + (end point ~252 MeV/c) 4 He +  - (p(  - ) = 133 MeV/c) K - stop + 6 Li    He different 6  He  6 Li +  - (p(  -) = MeV/c) 6 Li  Li  6  He +  + (end point 278 MeV/c) nuclei (  (  0 )) K - stop + 6 Li  3  H +  + + n + n + n (end point 242 MeV/c) 3  H  3 He +  - (p(  -) = 115 MeV/c) K - stop + 6 Li  3 He + n + n +  +  + (T tot < 182 MeV)   n  - K - stop + 6 Li  3 He +  + + n + n +  - (T tot < 180 MeV)  +  n +  + 6  H/K - stop production rate XIV International Conference on Hadron Spectroscopy

Preliminary Background evaluation: fake coincidences: T tot (202÷204 MeV) &  + (249÷255 MeV/c) &  - (130÷138 MeV/c) for targets other than 6 Li 1 event for all other targets  0.27±0.27 bgd events on 6 Li = BGD1 K - stop + 6 Li   + +  He + n (end point 190 MeV/c)  +  n +  + (end point 282 MeV/c) Monte Carlo simulation of the process (detector acceptance, trigger, PR, reconstruction, PId, selections ) 1 event for K - stop from MC * BR(K - stop p   +  - ) * [1 - (  + n  p)] * BR(  +  n  + ) * BR( 4 He + n)  0.48 ± 0.48 bgd events on 6 Li = BGD2 Vander Velde-Wilchet et al., Nucl.Phys. A241 (1975) C Katz et al., Phys. Rev. D 1 (1970) He H.Outa, Ph.D. thesis: 4 He BR( 4 He + n ) = 100% 6  H/K - stop production rate XIV International Conference on Hadron Spectroscopy

6  H/K - stop production rate Background evaluation: K - stop + 6 Li  4  H + n + n +  + (end point 252 MeV/c) 4  H  4 He +  - (p(  - ) = 133 MeV/c) Monte Carlo simulation of the process (detector acceptance, trigger, PR, reconstruction, Pid, selections ) 2 events for K - stop from MC * BR( 4  H hyperfr. production on 7 Li) * (P CEX (  N)) 2  bgd events on 6 Li = BGD3 H.Tamura et al., Phys. Rev. C 40 (1989) R479 P CEX (  N) =  totCEX  nucl N A /A x = 0.16  totCEX = 30 mbarn Jenefsky et al., Nucl. Phys. A 290 (1977) 407 x= R 0 A 1/3 = cm 6 Li radius XIV International Conference on Hadron Spectroscopy Preliminary

6  H/K - stop production rate XIV International Conference on Hadron Spectroscopy R = (events – BGD1 – BGD2 – BGD3) (  (  -)) -1 (  (  +)) -1 / (n. K - stop on 6 Li)  (  ) =  D  MC R = (1.2 ± 0.8) /K - stop BGD2: work in progress !! BGD3: work in progress … 6 Li target purity ~ 90%  R = (1.3 ± 0.9) /K - stop selection cut vs T res.  R = (2.3 ± 1.6) /K - stop (2.5 ± ) /K - stop Systematic error: work in progress Very preliminary !!

kinematics T tot (MeV) T(  + ) (MeV) T(  - ) (MeV) p(  + ) (MeV/c) p(  - ) (MeV/c) M( 6  H) formation (MeV/c 2 ) M( 6  H) decay (MeV/c 2 ) 202.5± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± MeV 5 H +  3 H + n + n +  4  H + n + n Majling Akaishi XIV International Conference on Hadron Spectroscopy mean value = ±0.74 Preliminary

…… thank you!