1. 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

2. 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

3. 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

4. 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

5. 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:

6. 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:

7. 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

8. 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
TR TR1 TR2
Test Exp. Sep. 2007
2 A GeV Ni beam scattered by C target

9. 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

10. 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.

11. 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

12. 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 Sep. 2007
Threshold
ToT by VUPROM ~ He> 2.5ns 7ch DE
DE by ADC
ToT by VUPROM

13. 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
TR TR2
TR0
TR0
4LH p-
6Li a
No. of cluster
After rejection
Of primary vertex

14. Secondary vertex trigger study with
Y-Layer of TR0, TR1, TR2 at Aug. 2008
6Li beam with 2 A GeV
8g/cm2 carbon target
TR ch
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)

15. 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

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