1. Latest Results on Hypernuclear Physics from the FINUDA Experiment Elena Botta INFN-Torino and Torino University 1

2. Overview DA  NE and FINUDA FINUDA Scientific Program Recent results Hypernuclear Spectroscopy MWD & NMWD 6  H observation 2

3. FINUDA: FIsica NUcleare a DA  NE DA  NE accelerator complex DA  NE Double Annular  -factory for Nice Experiments DA  NE Double Annular  -factory for Nice Experiments e- e+ KLOE FINUDA 32.5 m 23.3 m Energy (GeV)0.51 Luminosity (cm-2 s-1)10 32 Beam Hor. Dim. at IP (mm)2.11 Beam Vert. Dim. at IP (mm)0.021 R.M.S. Bunch length (mm)30 Crossing angle (mrad)25 Collision frequency (MHz)380.44 Bunches/ring120 Max number of particles/bunch9.0 10 10 Max total mean current (A)5.5 3

4. FINUDA: FIsica NUcleare a DA  NE The very first example of a (hyper)nuclear physics fixed-target experiment carried on at a collider ( DA  NE @ LNF) FINUDA 4 Optimized to produce hypernuclei A  Z in a completely new way

5. 5 data taking oct 2003 - jan 04 nov 2006 - jun 07 int. luminosity220 pb -1 960 pb -1 daily luminosity6 pb -1 10 pb -1 Total events (M)30200 Targets 6 Li (2), 7 Li (1), 12 C (3), 27 Al (1), 51 V (1) 6 Li (2), 7 Li (2), 9 Be (2), 13 C (1), D 2 O (1) Data takings Bari University & INFN Bari Brescia University & INFN Pavia Pavia University & INFN Pavia Torino University & INFN Torino Trieste University & INFN Trieste Torino Polytechnic & INFN Torino L.N.F. / INFN Frascati Seoul National University Teheran Shahid Beheshty University University of Victoria JINR Dubna Collaborating institutes FINUDA: the Collaboration Kyoto, KEK, RIKEN

6. The FINUDA detector Mechanical support (clepsydra) For: 2424 Straw Tubes (longitudinal + stereo) 16 Low-Mass Drift Chambers (LMDC) 18  -strip vertex detectors (ISIM/OSIM) Inner scintillator barrel – 12 slabs (TOFINO) 8 Targets Detector capabilities: Selective trigger based on fast scintilla- tion detectors (TOFINO, TOFONE) precise K - vertex identification (~ 1 mm 3 ) (ISIM P.ID.+ x,y,z resolution + K + tagging) p, K, p, d, … P.ID. (OSIM and LMDC dE/dx) High momentum resolution (6‰ FWHM for π- @270 MeV/c for spectroscopy) (1% FWHM for  - @270 MeV/c for decay study) (6% FWHM for π- @110 MeV/c for decay study) (2% FWHM for p @400 MeV/c for decay study) (tracker resolution + He bag + thin targets) Neutron detection TOF (TOFONE-TOFINO) Simultaneous study of formation and decay of strange hadronic systems by full event reconstruction Magnet end-cap Magnet yoke B = 1.0 T Super- conducting Coil e+e+ e-e- Apparatus designed for a typical collider experiment: Cylindrical geometry large solid angle (~ 2  sr) multi-tracks analysis 6 Outer scintillator barrel – 72 slabs (TOFONE)

7. 7 ( BR 49% - E kin ~ 16 MeV ) target region - 12 scintillators (TOFINO) - 8 silicon microstrips layer (ISIM) - 8 targets - 10 silicon microstrip layer (OSIM) some hundreds Φ/s The FINUDA interaction region

8. e + + e -   (1020)  K + + K - (127 MeV/c) K - stop + A Z  A  Z +  - A  Z  A (Z+1) +  - A  Z  A-2 (Z-1) + p + n A  Z  A-3 (Z-1) + p + n + n Hypernuclear Physics @FINUDA   MWD NMWD Spectroscopy - different targets in the same run ➥ high degree of flexibility - simultaneous tracking of μ + from the K + decay ➥ energy and rate calibration transparency ➥ “high” resolution spectroscopy - very thin targets (0.1 ÷ 0.3 g/cm 2 ) - coincidence measurement with large acceptance complete event ➥ decay mode study FINUDA key features 8 1N induced  p 2N induced  np

9. FINUDA Scientific Program Main topics (.. not complete!): Hypernuclear spectroscopy: PLB 622 (2005) 32: 12  C PLB 698 (2011) 219: 7  Li, 9  Be, 13  C, 16  O Weak Decay: NPA 804 (2008) 151: NMWD 5  He, 7  Li, 12  C PLB 681 (2009) 139: MWD ( 5  He,) 7  Li, 9  Be, 11  B, 15  N PLB 685 (2010) 247: NMWD & 2N 5  He, 7  Li, 9  Be, 11  B, 12  C, 13  C, 15  N, 16  O PLB 701 (2011) 556: NMWD & 2N 5  He, 7  Li, 9  Be, 11  B, 12  C, 13  C, 15  N, 16  O NPA, accepted for publication 2012: (n, n, p) events from 2N Rare Decays: NPA 835 (2010) 439; 4  He, 5  He 2-body decays Neutron-rich Hypernuclei: PLB 640 (2006) 145: upper limits 6  H, 7  H and 12  Be PRL 108 (2012) 042501: 6  H observation “By products”: - AKNC (PRL 94 (2005)212303, PLB 654 (2007) 80, PLB 669 (2008) 229) - (K 0 K + ) on 7 Li at threshold (PLB 649 (2007) 25) - multinucleon K- absorption on 6 Li, 12 C (NPA 775 (2006) 35) - A(K - stop,  +/-  -/+ )A’ (PLB 704 (2011) 474) 9

10. Hypernuclear Spectroscopy: p-shell absolute energy scale known at the level of 0.3 MeV (we know from the K +  – self calibrated apparatus) momentum resolution: 0.5-0.9% FWHM M. Juric et al., NPB 52 (1973), 1 H. Tamura et al. NPA 754 (2005) 58c O. Hashimoto, H. Tamura PPNP 57 (2006) 564 (E336 data) Formation probability it is connected to the number of events in the peaks, calculated taking into account acceptances and efficiencies (K +  – rate calibrated apparatus) First world measurement of formation probability M.Agnello et al., PLB 698 (2011) 219 10 B   = M( A Z) + M(  ) - M hyp

11. M. Juric et al., NPB 52 (1973), 1 H. Tamura et al. NPA 754 (2005) 58c M. Juric et al., NPB 52 (1973), 1 CERN O. Hashimoto, H. Tamura PPNP 57 (2006) 564 (E336 data) E930(‘01) Collaboration 0.37 ± 0.04 ± 0.05 M.Agnello et al., PLB 698 (2011) 219 O. Hashimoto, H. Tamura PPNP 57 (2006) 564 (E336 data) BNL 11 16  O 15  N

12. Constraints on the threshold K- nuclear potential from FINUDA A Z(K - stop,  - ) A  Z spectra M.Agnello et al., PLB 698 (2011) 219 A.Cieply et al., PLB 698 (2011) 226 the comparison with the FINUDA data slightly favors a deep K- nuclear potential 12 partial formation rates /(structure fractions)  1s L formation rates

13. Hypernuclear weak decay studies: p-shell Coincidence measurement p -- charged Non-Mesonic channel K - stop + A Z  A  Z +  - A  Z  A-2 (Z-1) + p + n NMWD 170-600 MeV/c charged Mesonic channel K - stop + A Z  A  Z +  - A  Z  A (Z+1) +  - S-EX 260-280 MeV/c MWD 80-110 MeV/c 13

14. MWD & NMWD in FINUDA: strategy 12  C 11  B kinetic energy (MeV) Inclusive production  - spectra K - np background corrected 11  B decay  - and p spectra (  qf decay)/K - np background subtracted & acceptance corrected p 11  B MWD NMWD -- p 12  C magnetic analysis !! 14

15. present data T. Motoba PTPS 117 (1994) 477 previous data A.Gal NPA 828 (2009) 72 A Mesonic decay ratio:   - /     - /   =  tot /    BR  strong nuclear structure effects  distortion, MWD enhancement proved ! Extensive calculations: Motoba et al., Progr. Theor. Phys. Suppl. 117 (1994) 477 Gal Nucl. Phys. A 828 (2009) 72. 7 Be: 3/2 - gs & 1/2 - (429keV) 3-body decays J  assignment: 7 Λ Li ( 1/2+), 9 Λ Be (1/2 + ), 11 Λ B ( 5/2 + ), 15 Λ N (3/2 + ) first determination M.Agnello PLB 681 (2009) 139 A.Gal NPA 828 (2009) 72 MWD indirect spectroscopic tool ! 15

16. -- Spectrum of negative pions for events in which a proton is detected in coincidence with a  - Asking for the proton coincidence a clear peak emerges at 272 MeV/c (ground state) Background: K - np   - p  -  n π - NMWD p NMWD: p spectra coincidence measurement: method Acceptance corrected M. Agnello et al., NPA 804 (2008), 151: 5  He, 7  Li and 12  C 12  C 16

17. Garbarino PRC 69 (2004),054603 FINUDA NPA 804 (2008),151 KEK E462/E508 PLB 597 (2004), 249 Comparisons with theory and KEK results 5  He KEK E462/E508 PLB 597 (2004), 249 FINUDA NPA 804 (2008),151 12  C Garbarino PRC 69 (2004),054603 FINUDA NPA 804 (2008),151 15 MeV threshold ! 17

18. A low A high  from fit 12  C NMWD:  2N from ( , p) events M.Agnello et al., PLB 685 (2010) 247 NMWD p gaussian fit free  A low : spectrum area below  1N + 2N + FSI A high : spectrum area above  1N + FSI 2N(>70 MeV) ~ 5% 2N tot G.Garbarino, A.Parreno and A.Ramos, Phys.Rev.Lett. 91 (2003) 112501. Phys.Rev. C 69 (2004) 054603. assumption W.Alberico and G.Garbarino, Phys. Rev. 369 (2002) 1. assumption  2N /  NMWD &  n /  p independent on A 18

19. FSI &  NN contribution evaluation: systematics NMWD:  2N 19

20. systematics: all p-shell  NM 22 =  n /  p + 1 +  2 /  p 2/p2/p = 0.24 ± 0.10 Bhang et al., EPJ A33 (2007) 259. a + b A = R(A) = 0.5 +  2 /  p 1 +  2 /  p + b A FSI linear on A up to A=16 Assumption:  2 /  1 and  n /  p indipendent from A  supported by exp and theory Bauer et al., NPA 828 (2009) 29 Bhang et al., EPJ A33 (2007) 259: ~ 0.4 12  C M. Kim et al., PRL 103 (2009) 182502: 0.29 ± 0.13 12  C J.D.Parker et al., PRC 76 (2007), 035501: ≤ 0.24 (95% CL) 4  He N(  p  np) + A low + A high A low = 0.5 N(  p  np) + N(  np  nnp) + N p FSI-low N(  np  nnp) + N p FSI-low + N p FSI-high R = pp 22 = 1 – [R(A) – bA] [R(A) – bA] - 0.5 = 0.43 ± 0.25 20

21. NMWD:  2N from ( , p, n) events a + b A = R(A) = 22 0.5  p + b A  2 /  p not dependent on A N p ( E p >  p single spectra fit) N n (cos  ≥- 0.8, E p <  -20 MeV) = N(  np  nnp) + N FSI 0.5 N(  p  np) + N FSI R(A) =  2 /  p 0.39±0.16 stat +0.04 sys -0.03 sys  2 /  NM 0.21±0.07 stat +0.03 sys -0.02 sys low statistics direct measurement reduced error M. Kim et al., PRL 103 (2009) 182502: 0.29 ± 0.13 12  C FINUDA Coll. et al., PLB 685 (2010) 247: 0.24± 0.10 M. Kim et al., PRL 103 (2009) 182502: 0.29 ± 0.13 12  C FINUDA Coll. et al., PLB 685 (2010) 247: 0.24± 0.10 systematics: all p-shell M.Agnello et al., PLB 701 (2011) 556 21

22. 3 fourfold coincidence (  -,n,n,p) events: 1 exclusive 9  Be  6 Li+p+n+n event 2 exclusive  np  nnp 7  Li  4 He+p+n+n decay events First direct experimental evidence of 2N-induced NMWD !! M.Agnello et al., NPA in press doi: 10.1016/j.nuclphysa.2012.01.024 NMWD : evidence for ( , p, n, n) events p  = 276.93 MeV/c E tot = 178.3 MeV Q-value = 167 MeV p miss = 216.6 MeV/c E(n1) = 110.2 MeV E(n2) = 16.9 MeV E(p) = 51.0 MeV  (n1 n2) = 95°  (n1 p) = 102°  (n2 p) = 154° no n-n or p/n scattering 22

23. Search for light n-rich hypernuclei Hypernuclei with a large neutron excess (Dalitz et al., N. Cim. 30 (1963) 489, L. Majling, NPA 585 (1995) 211c, Y. Akaishi et al., Frascati Physics Series XVI (1999) 59.) n-rich hypernuclei: production (K - stop,  + ) K - + p   +  0  0 + p  n +  + (2-step) S-EX + C-EX K - + p    +  +   + p  n +  (1-step) S-EX K.Kubota et al, NPA 602 (1996) 327. 9  He ( 9 Be) U.L.=2.3 10 -4 /K - stop ; 12  Be( 12 C) U.L.=6.1 10 -5 /K - stop ; 16  C( 16 O) U.L.=6.2 10 -5 /K - stop T.Y.Tretyakova et al., Nucl. Phys. A 691 (2001) 51c (10 -6 -10 -7 /K - stop ) M. Agnello et al. Phys. Lett. B 640 (2006) 145 6  H ( 6 Li) U.L.= (2.5 ± 1.4) 10 -5 /K - stop ; 7  H( 7 Li) U.L. = (4.5± 1.4) 10 -5 /K - s ; 12  Be( 12 C) U.L.= (2.0 ± 0.4) 10 -5 /K - stop ; (  -, K + )  - + p   0 + n  0 + p   + K + (2-step) AP + C-EX  - + p  K 0 +  K 0 + p  n + K + (2-step)  - + p  K + +  -  - + p  n +  (1-step) AP P.K.Saha et al., PRL 94 (2005) 052502: 10  Li ( 10 B) d  /d  = 11.3±1.9 nb/sr T.Y.Tretyakova et al., Phys. At. Nucl. 66 (2003) 1651 23

24. n-rich hypernuclei: 6  H L. Majling, NPA 585 (1995) 211c - binding energy - prod. rate ~ 10 -2 * hyp. prod. rate in (K - stop,  - ) Y. Akaishi et al., AIP Conf. Proc. 1011 (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 4.2 MeV 24 Dalitz et al., N. Cim. 30 (1963) 489 (binding energy 4.2 MeV)

25. 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(  - ) = 203.0 ± 1.3 MeV (203.5÷203.2 MeV with B  = 0÷6 MeV) cut on T(  + ) + T(  - ): 202÷204 MeV 6  H search with FINUDA 25 independent reactions: decay at rest

26. absolute energy scale:  +(235 MeV/c) from K  2  p < 0.12 MeV/c 26 249÷255 MeV/c (  p = 1.1 MeV/c) 130÷138 MeV/c (  p = 1.2 MeV/c) selection: T(  + )+T(  - ) = 202÷204 MeV 3 candidate events 2.7 10 7 K - stop events

27. Background sources: fake coincidences:  +(249÷255 MeV/c) &  - (130÷138 MeV/c) 0.27±0.27 ev. K - stop + 6 Li   + +  - + 4 He + n (end point ~190 MeV/c) n +  + (end point ~282 MeV/c) 0.16±0.07 ev. K - stop + 6 Li  4  H + n + n +  + (end point ~252MeV/c) 4 He +  - (p(  - ) = 133 MeV/c) negligible 6  H/K - stop production rate Total background: BGD1 + BGD2 = 0.43 ± 0.28 events on 6 Li Poisson statistics: 3 events DO NOT belong to pure background: C.L.= 99% R * BR(  -) = (3 – BGD1 – BGD2) (  (  -)) -1 (  (  +)) -1 / (n. K - stop on 6 Li) R * BR(  -) = (2.9 ± 2.0) 10 -6 /K - stop R = (5.9 ± 4.0) 10 -6 /K - stop (2.5 ± 0.4 +0.4 -0.1 ) 10 -5 /K - stop Agnello et al., PLB 64(2006) 145 6  H/K - stop production rate 27 M. Agnello et al., PRL 108 (2012) 042501

28. kinematics T tot (MeV) p(  + ) (MeV/c) p(  - ) (MeV/c) M( 6  H) formation (MeV/c 2 ) M( 6  H) decay (MeV/c 2 ) 202.5±1.3251.3±1.1135.1±1.25802.33±0.965801.41±0.84 202.7±1.3250.0±1.1136.9±1.25803.45±0.965802.73±0.84 202.1±1.3253.8±1.1131.2±1.25799.97±0.965798.66±0.84 mean value = 5801.4±1.1 B  = 4.0±1.1 MeV ( 5 He +  ) B  = 5.8 MeV ( 5 He +  )  NN force: 1.4 MeV formation – decay = 0.98±0.74 MeV  excitation spectrum of 6  H 28 M. Agnello et al., PRL 108 (2012) 042501 Akaishi Dalitz, Majling

29. … to combine and expand research activities in strangeness nuclear physics in the world 29