Study of Hypernuclei with Heavy Ion (HypHI collaboration)

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1 Study of Hypernuclei with Heavy Ion (HypHI collaboration) Tomokazu Fukuda Osaka Electro-Communication Univ. Take R. Saito, S. Minami, S. Ajimura, Y. Mizoi, A. Sakaguchi et al. GSI, Mainz, Osaka EC, Osaka,...

2 Hypernuclei

3 Ordinary reactions ; (π+,k+),(k-,π-) : n --> Λ ¾ Cover limited region ¾ Hyperfragments ==> Heavy Ion Rections

4 Heavy-ion induced hypernuclear production at Dubna in He beam at 3.7 GeV/u on a polyethylene target 6 Li beam at 3.0 GeV/u on a polyethylene target Streamer chamber (tracking photographed) Only 22 events in total

5 Heavy-ion induced hypernuclear production σ~ 0.1μb

6 theoretical model (Wakai, Bando, Sano) Spectator -projectile fragment Λ participant coalescence of hyperons to projectile fragnent Spectator -target fragment

7 prediction of the cross section (Wakai, Bando, Sano) coalescence of hyperons meson induced reactions proj. fragment central Single Λ Hypernuclei μb ~ 1 mb Double Λ Hypernuclei pb 1-10 μb

8 huge combinatorial background due to uncorrelated (π -, 3 He) pairs central collision with open geometry spectrometer BNL- E A GeV/c Au + Pt 3 Λ H --> π He;

9 Hypernuclear = proj. fragment Heavy ion induced reaction at relativistic energies Heavy ion beams with E > 1.6 GeV/u needed Stable beam from the GSI s current accelerator SIS (< 2 A GeV) Stable beam at the GSI s future facility FAIR (< 20 A GeV) RI-beam from GSI s FRS (now, < 1.9 A GeV) and super-frs (future, < 3.5 A GeV)) Exotic hypernuclei Large Lorentz factor γ (>3) Effective lifetime : Longer by the Lorentz factor 200 ps -> 600 ps with γ =3 200 ps -> 4 ns with γ =20 Magnetic Moment of Hypernuclei

10 Accelerator facility at GSI Production of RI beams

11 Phase 0 The goal of the Phase 0 experiments To confirm hypernuclear production and To obtain reliable cross section data at 2 A GeV with 6 Li primary beams : 3 Λ H -> π He 4 Λ H -> π He 5 Λ He -> π He + p ( π - -mesonic decay mode) Lifetime polarization

12 TOF+ wall ALADIN magnet TOF start ALADIN TOFwall target scintillating fiber detectors(tr0,tr1,tr2)

13 ex. 4 Λ H -> π- + 4 He scintillating fiber detectors (TR0,TR1,TR2) TOF+ wall (ΔX ~ 1.5 cm) 4 He target TOF start (diamond detector) ALADIN magnet (0.7T) π - ALADIN TOFwall (ΔX ~ 2 cm)

14 Requirement for trigger Target TR0 target ex. 4 Λ H -> π- + 4 He 4 Λ H TR1 TR1 Beam intensity 10 7 Hz TR2 TR2 π- 4 He π k+ N Proton Signature of hypernuclear decay vertex is far from the target ---> trigger VME Logic module with FPGA

15 scintillating fiber detectors 0.83 mm φ TR0; x 5cm, y 5cm 32 ch PMT Tested with 2 A GeV 12 C beam ; time resolution ~ 230 ps, spatial resolution ~ 0.27 mm, ΔE/E ~ 15-20% (all in FWHM)

16 Monte Carlo : GEANT4 + UrQMD (Rapidity distribution at 2 A GeV) 6 Li on 12 C 12 C on 12 C n Λ K + π +

17 Missing mass spectrum (preliminary) 4 Λ H (ΔE ~ 3.2 MeV in σ) simulation Combinatorial B.G. without Kaon Identification

18 Rate (expected) Beam: 6 Li at 2A GeV, 10 7 /s Target: 12 C, 8g/cm 2 Expected cross sction (μb) Reconstructed events/week 3 Λ H x Λ H x Λ He x 10 4 ( trigger rate ~ 0.3 k Hz)

19 Next step --> RI Beams: E > 1.7 A GeV I > 10 5 /s FRS Super-FRS

20 Hypernuclear magnetic moments Hypernuclei toward the nucleon drip-lines Hypernuclear production at 20 A GeV at the FAIR facility Hypernuclear separator; a superconducting magnet (4m 5T) scintillator barrel sweeping magnet superconducting magnet detector for x,y,δe TR2 TR1 ALADIN Sci2 target 1m to beam dump TP-MUSIC collimator Sci1 Precession of the spin distribution of hypernuclei. Precession angle : 225 degrees with free-λ magnetic moment

21 Hypernuclear separator Separation by the 4m 5T magnet 6 Li + 12 C at 20 A GeV 6 Li, 4 ΛHe, 4 He 5 Λ He 4 Λ H 3 ΛH, 3 H 3 Λ He, 3 He [cm]

22 The HypHI collaboration Argonne National Laboratory, USA Giessen University, Germany GSI (DVEE, KP2, KP3), Germany JINR, Dubna, Russia Johannes Gutenberg University Mainz, Germany KEK, Japan LNF, Frascati, Italy Moscow State University, Russia Nara Women s University, Japan Niels Bohr Institute, Denmark Osaka Electro-Communication University, Japan Osaka University, Japan Peking University, China RIKEN, Japan Soltan Institute for Nuclear Studies, Poland Tokyo University, Japan Tokyo University of Science, Japan Tohoku University, Japan TRIUMF, Canada Still expanding Spokesperson : Take R. Saito, GSI We plan to start the experiment in the beginning of 2008.

24 Hypernuclear gamma rays ΛN Spin dependent int.

25 Nagara event -- the best event in emulsion Uniquely identified Double Hypernucleus Lampha Tripple magic nucleus Takahashi et al., PRL 87 (2001) Unambiguously determined ΔB ΛΛ =1.01± MeV ΛΛ : weakly attractive

26 Several phases of LOI40 Phase 0: prove the method Production and mesonic decay of 3 ΛH, 4 ΛH and 5 ΛHe At the GSI current facility, cave C Phase 1 and 2: proton rich hypernuclei At the current facility, cave C

27 scintillator barrel target sweeping magnet Several phases of ALADIN LOI40 Phase 0: prove the method superconducting magnet detector for x,y,δe TR2 TR1 Production and mesonic decay of 3 Λ H, 4 Λ H and 5 Λ He At the GSI current facility, cave C Phase 1 and 2: proton rich hypernuclei At the current facility, cave C 1m to beam dump Phase 3: neutron/proton collimator rich hypernuclei Sci1 At the R3B cave in NuSTAR/FAIR TP-MUSIC Sci2 Phase 4: hypernuclear magnetic moments and hypernuclear drip lines Closed geometry, Hypernuclear separator at 20 A GeV At FAIR

29 Tracking trigger Made with scinitillating fiber trackers Secondary vertex behind the target Hypernuclear/Λ decay 500 MHz PMT Discriminator card with GSI chip-3 LVDS VME Logic module with FPGA and DSP T to VME bus HAMAMATSU 32 pixels From Mainz/KaoS collaboration VME Logic module with FPGA and DSP New development at GSI VME Logic module with FPGA and DSP Tracking trigger

30 polarization Λ polarziation P T ~ 1GeV/c

31 UrQMD: rapidity of Λ and charged kaons 6 Li on 12 C 12 C on 12 C

32 UrQMD: lab-angle v.s. momenta 6 Li on 12 C 12 C on 12 C K + θ (lab) π + Momentum [GeV/c]

33 β UrQMD: lab-angle v.s. β 6 Li on 12 C 12 C on 12 C K + θ (lab) π +

34 UrQMD: multiplicity v.s. lab-angle 6 Li on 12 C 12 C on 12 C multiplicity θ (lab)

35 New VME logic module Will be developed by Jan Hoffmann Purely VME based 128 (96) inputs 32 (64) outputs LVDS Fast logic calculations with a large FPGA at 500 MHz Slow complicated calculations by DSP Data transfer to the VME bus Based on a prototype developped by Jan Hoffmann Several prototypes will be available for the HypHI collaboration from January 2006 Modules will also be used by the MAMI C KaoS experiments

36 peripheral central Single Λ Hypernuclei μb ~ 1 mb Double Λ Hypernuclei pb 1-10 μb BNL E886 ; strangelet D6 beam line 14.6A GeV/c Si + Pt, 10.8A GeV/c Au + Pt ; P.R. C54(1996)R15 BNL E864 ; 11.5A GeV/c Au + Pt 1) exotic search ; N.P. A661(1999)185c 2) hypernuclear production ( 3 ΛH) ; P.R. C70(2004) Open geometry spectrometer

Hypernuclear magnetic moments

Hypernuclear magnetic moments The HypHI HI project at GSI/FAIR Hypernuclear spectroscopy with heavy ion collisions ons Progress Report Take R. Saito for the HypHI collaboration Helmholtz-University Young Investigators Group VH-NG-239