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Latest Results on Hypernuclear Physics from the FINUDA Experiment

This article provides an overview of the recent results obtained from the FINUDA experiment, including hypernuclear spectroscopy and weak decay studies. The FINUDA detector's capabilities and scientific program are discussed, along with key features and main topics of research.

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Latest Results on Hypernuclear Physics from the FINUDA Experiment

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  1. Latest Results on Hypernuclear Physicsfrom the FINUDA ExperimentElena BottaINFN-Torino and Torino University

  2. Overview • DAFNE and FINUDA • FINUDA Scientific Program • Recent results • Hypernuclear Spectroscopy • MWD & NMWD • 6LH observation

  3. FINUDA: FIsicaNUclearea DAFNE DAFNE DoubleAnnularF-factoryforNiceExperiments DAFNE accelerator complex KLOE 23.3 m 32.5 m e+ e- FINUDA

  4. FINUDA FINUDA: FIsicaNUcleare a DAFNE The very first exampleof a (hyper)nuclearphysicsfixed-target experimentcarried on at a collider (DAFNE@LNF) Optimizedto produce hypernucleiALZin a completelynew way

  5. Bari University & INFN Bari Brescia University & INFN Pavia Pavia University & INFN Pavia Torino Polytechnic & INFN Torino Torino University & INFN Torino Trieste University & INFN Trieste L.N.F. / INFN Frascati FINUDA: the Collaboration Collaborating institutes University of Victoria Seoul National University JINR Dubna • Kyoto, KEK, RIKEN Teheran ShahidBeheshty University Data takings

  6. Outer scintillator barrel – 72 slabs (TOFONE) Magnet yoke B = 1.0 T Magnet end-cap e+ • Mechanical support (clepsydra) • For: • 2424 Straw Tubes (longitudinal + stereo) • 16 Low-Mass Drift Chambers (LMDC) • 18 m-strip vertex detectors (ISIM/OSIM) • Inner scintillatorbarrel – 12 slabs (TOFINO) • 8 Targets Super- conducting Coil e- Simultaneousstudyofformationanddecayofstrange hadronicsystemsbyfull eventreconstruction The FINUDA detector • Detector capabilities: • Selective triggerbased on fast scintilla- • tion detectors (TOFINO, TOFONE) • precise K-vertexidentification (~ 1 mm3) • (ISIM P.ID.+ x,y,zresolution + K+tagging) • p, K, p, d, …P.ID.(OSIM and LMDC dE/dx) • High momentumresolution (6‰ FWHM for π- @270 MeV/c for spectroscopy) (1% FWHM for p- @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) • Apparatusdesignedfor a typicalcollider experiment: • Cylindricalgeometry • largesolid angle (~ 2psr) • multi-tracksanalysis

  7. The FINUDAinteractionregion target region - 12 scintillators (TOFINO) - 8 silicon microstrips layer (ISIM) - 8 targets - 10 silicon microstrip layer (OSIM) (BR 49% - Ekin ~ 16 MeV) some hundredsΦ/s

  8. - simultaneous tracking of μ+ from the K+ decay - different targets in the same run - very thin targets (0.1 ÷ 0.3 g/cm2) - coincidence measurement with large acceptance ➥ high degree of flexibility ➥ energy and rate calibration transparency ➥ “high” resolution spectroscopy complete event ➥ decay mode study HypernuclearPhysics@FINUDA e+ + e- f (1020)  K+ + K- (127 MeV/c) K-stop+ AZ  ALZ + p- ALZA(Z+1) + p- ALZA-2(Z-1) + p + n ALZA-3(Z-1) + p + n + n Spectroscopy Gp- MWD 1N induced Gp NMWD 2N induced Gnp FINUDA key features

  9. FINUDA ScientificProgram Main topics ( .. not complete!): Hypernuclear spectroscopy: PLB 622 (2005) 32: 12LC PLB 698 (2011) 219: 7LLi, 9LBe, 13LC, 16LO Weak Decay: NPA 804 (2008) 151: NMWD 5LHe, 7LLi, 12LC PLB 681 (2009) 139: MWD (5LHe,) 7LLi, 9LBe, 11LB, 15LN PLB 685 (2010) 247: NMWD & 2N 5LHe, 7LLi, 9LBe, 11LB, 12LC, 13LC, 15LN, 16LO PLB 701 (2011) 556: NMWD & 2N 5LHe, 7LLi, 9LBe, 11LB, 12LC, 13LC, 15LN, 16LO NPA, accepted for publication 2012: (n, n, p) events from 2N Rare Decays: NPA 835 (2010) 439; 4LHe, 5LHe 2-body decays Neutron-rich Hypernuclei: PLB 640 (2006) 145: upper limits 6LH, 7LH and 12LBe PRL 108 (2012) 042501: 6LH observation “By products”: - AKNC (PRL 94 (2005)212303, PLB 654 (2007) 80, PLB 669 (2008) 229) - (K0 K+) on 7Li at threshold (PLB 649 (2007) 25) - multinucleon K- absorption on 6Li,12C (NPA 775 (2006) 35) - A(K-stop, p+/-S-/+)A’ (PLB 704 (2011) 474)

  10. HypernuclearSpectroscopy: p-shell M.Agnello et al., PLB 698 (2011) 219 First world measurement of formation probability BL= M(AZ) + M(L) - Mhyp 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+mn – rate calibrated apparatus) absolute energy scale known at the level of 0.3 MeV (we know from the K+mn – self calibrated apparatus) momentum resolution: 0.5-0.9% FWHM

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

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

  13. p - Hypernuclear weak decay studies: p-shell Coincidence measurement chargedMesonicchannel chargedNon-Mesonicchannel K-stop + AZ  ALZ + p- ALZA(Z+1) +p- K-stop + AZ  ALZ+p- ALZA-2(Z-1) + p + n S-EX 260-280 MeV/c MWD 80-110 MeV/c NMWD 170-600 MeV/c

  14. MWD & NMWD in FINUDA: strategy Inclusive production p-spectra K-np background corrected 11LB 12LC 12LC p NMWD kinetic energy (MeV) NMWD MWD magneticanalysis !! 11LB 11LB decayp-and pspectra (Lqfdecay)/K-np background subtracted & acceptancecorrected p p-

  15. Mesonicdecayratio: Gp-/GL Jpassignment: 7ΛLi (1/2+),9ΛBe (1/2+), 11ΛB (5/2+),15ΛN(3/2+) first determination Gp- / GL = Gtot/ GLBRp- present data 7Be: 3/2-gs & 1/2- (429keV) T. Motoba PTPS 117 (1994) 477 M.Agnello PLB 681 (2009) 139 3-body decays previous data A.Gal NPA 828 (2009) 72 strong nuclear structure effects • Extensivecalculations: • Motobaet al., Progr. Theor. Phys. Suppl. 117 (1994) 477 • Gal Nucl. Phys. A 828 (2009) 72. A.Gal NPA 828 (2009) 72 A p distortion, MWD enhancement proved ! MWD indirect spectroscopic tool !

  16. NMWD:p spectra • coincidence measurement: method • Spectrum of negative pions for events in which a proton is detected in coincidence with aπ- • Asking for the proton coincidence a clear peak emerges at 272 MeV/c (ground state) • Background: K-npΣ-p • Σ-nπ- 12LC p- M. Agnello et al., NPA 804 (2008), 151: 5LHe, 7LLi and 12LC Acceptance corrected NMWD p

  17. Comparisons with theory and KEK results Garbarino PRC 69 (2004),054603 12LC 15 MeVthreshold ! FINUDA NPA 804 (2008),151 KEK E462/E508 PLB 597 (2004), 249 FINUDA NPA 804 (2008),151 5LHe FINUDA NPA 804 (2008),151 FINUDA NPA 804 (2008),151 KEK E462/E508 PLB 597 (2004), 249 Garbarino PRC 69 (2004),054603

  18. NMWD: G2N from(p-, p) events M.Agnello et al., PLB 685 (2010) 247 NMWD p gaussian fit free m 12LC mfrom fit Alow Ahigh W.Alberico and G.Garbarino, Phys. Rev. 369 (2002) 1. assumption Alow: spectrum area belowm 1N + 2N + FSI Ahigh: spectrum area abovem 1N + FSI 2N(>70 MeV) ~ 5% 2Ntot G.Garbarino, A.Parreno and A.Ramos, Phys.Rev.Lett. 91 (2003) 112501. Phys.Rev. C 69 (2004) 054603. assumption G2N/GNMWD & Gn/Gp independent on A

  19. NMWD: G2N FSI & LNN contribution evaluation: systematics

  20. Assumption: G2/G1andGn/Gpindipendent from A supported by exp and theory G2 [R(A) – bA] - 0.5 = 0.43 ± 0.25 = 1 – [R(A) – bA] Gp systematics: all p-shell Bauer et al., NPA 828 (2009) 29 Bhang et al., EPJ A33 (2007) 259: ~ 0.4 12LC M. Kim et al., PRL 103 (2009) 182502: 0.29 ± 0.13 12LC J.D.Parker et al., PRC 76 (2007), 035501: ≤ 0.24 (95% CL) 4LHe 0.5 +G2/Gp Bhang et al., EPJ A33 (2007) 259. Alow + b A 0.5 R(A) = a + b A = 1 +G2/Gp Alow + Ahigh G2 G2/Gp FSI linear on A up to A=16 = 0.24 ± 0.10 = GNM Gn/Gp+ 1 + G2/Gp N(Lnpnnp) + NpFSI-low N(Lpnp) + R = = N(Lnpnnp) + NpFSI-low + NpFSI-high N(Lpnp) +

  21. NMWD: G2N from(p-, p, n) events M.Agnello et al., PLB 701 (2011) 556 R(A) = G2/Gp 0.39±0.16stat +0.04sys-0.03sys G2 Nn(cos θ≥- 0.8, Ep<m-20 MeV) + b A G2/Gp not dependent on A systematics: all p-shell R(A) = a + b A = G2/GNM 0.21±0.07stat+0.03sys -0.02sys = 0.5 Gp Np(Ep>mp single spectra fit) M. Kim et al., PRL 103 (2009) 182502: 0.29 ± 0.13 12LC FINUDA Coll. et al., PLB 685 (2010) 247: 0.24± 0.10 N(Lnpnnp) + NFSI • low statistics • directmeasurement • reducederror 0.5 N(Lpnp) + NFSI

  22. NMWD: evidence for(p-, p, n, n) events 3 fourfold coincidence (p-,n,n,p) events: 1 exclusive 9LBe6Li+p+n+n event 2 exclusive Lnpnnp7LLi4He+p+n+n decay events pp- = 276.93 MeV/c Etot = 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 q (n1 n2) = 95° θ (n1 p) = 102° θ (n2 p) = 154° no n-n or p/nscattering M.Agnello et al., NPA in press doi: 10.1016/j.nuclphysa.2012.01.024 First direct experimental evidence of 2N-induced NMWD !!

  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. Akaishiet al., Frascati PhysicsSeries XVI (1999) 59.)n-rich hypernuclei: production (K-stop, p+) K- + p L+p0p0+ p n +p+ (2-step) S-EX + C-EX K- + pS-+p+ S- + pn +L (1-step) S-EX K.Kubotaet al, NPA 602 (1996) 327. 9LHe(9Be) U.L.=2.3 10-4/K-stop; 12LBe(12C) U.L.=6.1 10-5/K-stop; 16LC(16O) U.L.=6.2 10-5/K-stop T.Y.Tretyakovaet al., Nucl. Phys. A 691 (2001) 51c (10-6-10-7/K-stop) M. Agnello et al. Phys. Lett. B 640 (2006) 145 6LH(6Li) U.L.= (2.5 ± 1.4) 10-5/K-stop; 7LH(7Li) U.L.= (4.5± 1.4) 10-5/K-s; 12LBe(12C) U.L.= (2.0 ± 0.4) 10-5/K-stop; (p-, K+) p- + p p0+ np0+ p  L+ K+(2-step) AP + C-EX p- + p K0 +LK0 + p  n + K+(2-step) p- + p K+ + S-S- + pn +L (1-step) AP P.K.Sahaet al., PRL 94 (2005) 052502: 10LLi (10B) ds/dW = 11.3±1.9 nb/sr T.Y.Tretyakovaet al., Phys. At. Nucl. 66 (2003) 1651

  24. n-rich hypernuclei: 6LH Dalitz et al., N. Cim. 30 (1963) 489 (binding energy 4.2 MeV) • L. Majling, NPA 585 (1995) 211c • binding energy • prod. rate ~ 10-2 * hyp. prod. rate in (K-stop, p-) 4.2 MeV 5.8 MeV 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” L-S coupling in 0+ states  LNN three body force

  25. 6LHsearch with FINUDA K-stop + 6Li  6LH+p+ 6LH 6He + p- M(K-) + 3 M(n) + 3M(p) – B(6Li) = M(6LH) + T(6LH) + M(p+) + T(p+) M(6LH) = 4 M(n) + 2M(p) – B(6He) + T(6He) + M(p-) + T(p-) T(p+)+ T(p-) = M(K-) + M(p) – M(n) – B(6Li) + B(6He) –T(6He) – T(6LH) – M(p+)– M(p-) = 203.0± 1.3MeV (203.5÷203.2 MeV with BL= 0÷6 MeV) cut on T(p+) + T(p-): 202÷204 MeV independent reactions: decay at rest

  26. absolute energy scale: m+(235 MeV/c) from Km2 Dp< 0.12 MeV/c selection: T(p+)+T(p-) = 202÷204 MeV 249÷255 MeV/c(sp= 1.1 MeV/c) 130÷138 MeV/c (sp= 1.2 MeV/c) 3 candidate events 2.7 107 K-stop events

  27. 6LH/K-stop production rate • Background sources: • fake coincidences:p+(249÷255 MeV/c) &p-(130÷138 MeV/c) 0.27±0.27 ev. • K-stop + 6Li  S++p-+ 4He + n(end point ~190 MeV/c) • n +p+(end point ~282 MeV/c) 0.16±0.07 ev. • K-stop + 6Li 4LH +n + n + p+(end point ~252MeV/c) • 4He + p-(p(p-) = 133 MeV/c) negligible • 6LH/K-stop production rate • Total background: BGD1 + BGD2 = 0.43 ± 0.28 events on 6Li • Poissonstatistics: 3events DO NOT belongto pure background: C.L.= 99% • R * BR(p-) = (3– BGD1 – BGD2) (e(p-))-1 (e(p+)) -1 / (n. K-stopon 6Li) • R * BR(p-) = (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 M. Agnello et al., PRL 108 (2012) 042501

  28. kinematics mean value = 5801.4±1.1 BL= 4.0±1.1 MeV (5He + L) BL= 5.8 MeV (5He + L) LNN force: 1.4 MeV formation – decay = 0.98±0.74 MeV excitation spectrum of 6LH Dalitz, Majling Akaishi M. Agnello et al., PRL 108 (2012) 042501

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

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