Study of Hypernuclei with Heavy Ion Beams (HypHI) at GSI Shizu Minami　GSI, Germany on behalf of HypHI collaboration Introduction Phase 0 experiment R & D Detector system Trigger system Summary

Introduction Study of hypernuclei with Heavy Ion Beams Production of hypernuclei in flight Measurement of life time and decay property Magnetic moment Rare Isotope beam High probability to produce proton-rich or neutron-rich hypernuclei Heavy Ion collision Only way to produce hypernuclei with S < -2

Hypernuclei produced in beam fragment Hyperon(s) produced at participant region coalesce with a beam fragment Experimental study at Dubna with 3.7 A GeV 4He and 3.0 A GeV 6Li deduced production cross section of 4LH ~ 0.3mb, however small statistics. S. Avramenko, et, al, Nucl. Phys. A547 (1992) 95c The cross section obtained in the Dubna’s experiment was reproduced by the theoretical calculation based on the coalescence model. M. Wakai, H.Bando and M. Sano Phys. Rev. C38 (1988) 748, M. Sano and M. Wakai, Prog of Theor Phys. Suppl. 117 (1994) 99 L

Phase 0 experiment Purpose Observable To establish experimental method To investigate the mechanism of hypernuclear production at beam fragment region Observable Production cross sections and lifetimes of 3LH, 4LH and 5LHe. Polarization of 5LHe

Signal: 4H ->  Method 6Li beam with 2 A GeV in kinetic　 energy 　( Eth for　N+NL+K+N~1.6GeV) Measurement of decayed particles　from mesonic decay mode. 3LH  3He +p- 4LH  4He + p- 5LHe  4He + p + p- Reconstruction of secondary vertex ~20cm in average behind target Invariant mass Signal: 4H ->  BG: BG:

Signal: 4H ->  Experimental challenge Background p+ 3He/4He : request secondary vertex behind target L+ 3He/4He : reject events with 3He/4He at the detector just after target Trigger under high reaction rate He (Z=2 ) trigger Secondary vertex trigger Signal: 4H ->  BG: BG:

Detector system R&D Fast trigger <300nsec a (z=2) trigger Secondary Vertex trigger a (z=2) trigger p- trigger Fast trigger <300nsec Target: 12C with 8g/cm2 TR0: primary vertex, DE TR1,TR2 : decay vertex Dipole magnet : 0.7 T 1.4m depth TOF walls :Time of flight, DE, Position

Scintillating fibre detector DE at TR0 to reject background with a and L H7260 (32ch multi-anode PMT by HAMAMATSU) SCSF-78M -.83D. NON S-type by Kuraray Diameter is 0.83mm with 2 clads TR0 TR1 TR2 Test Exp. Sep. 2007 2 A GeV Ni beam scattered by C target

Invariant mass spectrum of 4LH with background Tools: Geant4, Ultra Relastivistic Quantum Molecular Dynamics calculations (UrQMD) Condition Production cross section of 4LH s is 0.1mb Branching ratio to p-+a is 0.5 Coalescence factor of 4LH production is 0.01 Nuclear reaction at target is 1 barn Expected Yields 2.6 x 103 / week 6Li beam with intensity of 107/sec. 12C target with 8g/cm2

Trigger R&D MC simulation for Trigger rate The beam intensity of 107/sec 40% of the beam expected to interact at the target. Full function of the trigger 0.017%, trigger rate is expected to be 0.8kHz. This value fulfils the requirement by the DAQ system which expected to accept up to 3kHz.

Logic module (VUPROM2) based on FPGA/DSP Fast trigger (<300ns) with No. of channels >1000ch Secondary vertex & time over threshold 192ch-TDC and Scaler for the scintillating fibre detector with 2.5 ns granularity Specifications VME 6U 256 LVDS I/O (VHDCI) FPGA Xilinx Virtex-4 (max. clk 450MHZ) TDC by VUPROM

He (z=2 ) trigger by time over threshold by TOF+ wall Plastic BC408: 2.5 x 4.5 x 100 cm3 , PMT Hamamatsu　H7415mod Amplitude of pulse height; proton:He:Li ~ 1 : 4 : 9 - 2 A GeV Ni beam scattered by C target @ Sep. 2007 Threshold ToT by VUPROM ~ He> 2.5ns 7ch DE DE by ADC ToT by VUPROM

Secondary Vertex Trigger Algorithms to realize by VUPROM2 Clustering of neighbouring channels up to size 8. Remove tracks from primary vertex Coincidence of TR1 and TR2 after rejection of primary vertex TR1 TR2 TR0 TR0 4LH p- 6Li a No. of cluster 3 4 4 After rejection Of primary vertex 0 1 1

Secondary vertex trigger study with Y-Layer of TR0, TR1, TR2 at Aug. 2008 6Li beam with 2 A GeV 8g/cm2 carbon target TR0 - 128ch ADC by CAEN TDC and SCALER by VUPROM2 TR1 and TR2 – 320ch Preliminary analysis shows reduction of trigger rate by Y-layer vertex trigger is 15 % ( 11 % by simulation) Further analysis is in progress Secondary vertex by offline analysis Algorithm of Secondary vertex trigger Hits after primary vertex rejection Hits after clustering Hits (raw)

Summary Phase 0 will be performed at next year, 2009 Phase 0 of HypHI to establish experimental technique for hypernuclear physics by heavy ion beams. Detector system have been designed with the help of Monte Carlo simulation.The yields of reconstructed hypernuclei are expected to be a few thousand / week. Trigger rate have been studied by MC simulations and obtained results fulfils the requirement by the DAQ system. R&D of detector system is in progress. Tests of detectors showed expected performance. Phase 0 will be performed at next year, 2009

Secondary Vertex resolution Momentum resolution s=0.27mm s=4.3mm p-: s=8.3MeV/c a: s=310 MeV/c