1. First …. Hyper-meeting Who we are? (alphabetical order)
Michelangelo Agnello (Turin Politechnic, FP)
Ilaria Aimo (Turin Politechnic, PhD st.)
Elena Botta (Turin University, AP)
Stefania Bufalino (INFN-Torino/CERN Fellow)
Alessandro Feliciello (INFN-Torino)
Stefano Trogolo (Turin University, MTS)

2. FINUDA: FIsica NUcleare a DAFNE
What did we do before?
FINUDA: FIsica NUcleare a DAFNE
The very first example of a (hyper)nuclear physics fixed-target
experiment carried on at a collider LNF)
Optimized to produce hypernuclei ALZ in a completely new way
FINUDA

3. Hypernuclear Physics @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
- 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/cm2)
- coincidence measurement with large acceptance
complete event ➥ decay mode study

4. The FINUDA detector e+ e-
Detector capabilities:
Selective trigger based on fast scintilla-
tion detectors (TOFINO, TOFONE)
precise K- vertex identification (~ 1 mm3)
(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 MeV/c for spectroscopy)
(1% FWHM for MeV/c for decay study)
(6% FWHM for MeV/c for decay study)
(2% FWHM for MeV/c for decay study)
(tracker resolution + He bag + thin targets)
Neutron detection TOF (TOFONE-TOFINO)
Outer scintillator barrel – 72 slabs
(TOFONE) e+ e-
Super-
conducting
Coil
Mechanical support (clepsydra)
For:
2424 Straw Tubes (longitudinal + stereo)
16 Low-Mass Drift Chambers (LMDC)
18 m-strip vertex detectors (ISIM/OSIM)
Inner scintillator barrel – 12 slabs (TOFINO)
8 Targets
Simultaneous study of formation and decay of strange
hadronic systems by full event reconstruction
Apparatus designed for a typical collider experiment:
Cylindrical geometry
large solid angle (~ 2p sr)
multi-tracks analysis

5. And now … in ALICE
Analysis strategy for hypernuclei search-> to study the 3LH via its mesonic weak decay
3LH -> 3He + p-
Particle identification
Track selections
Topological cuts

6. Analysis Selections Track Selection • TPC refit;
•( (ITS refit … in the future ..)
• # TPC cluster >= 70
• Chi2/NDF < 4;
•|HeEta|<0.8;
•|PionEta|<0.8;
•|zPrimaryVertex|<10 cm;
PID with TPC information stored in the OADB
Helium tracks -2<=ns<=3;
Pions tracks |ns|<=2;
Topological cuts
He DAC from primary vertex > 0.02 cm;
Pion DCA from primary vertex > 0.4 cm;
DCA tracks < 0.7 cm;
• Cos(Pointing angle)>0.99

7. (3He+p-) Invariant mass spectrum
WORK IN (SLOW) PROGRESS!!!!

9. To do and to think about …
more systematics ….
background fitting/treatment
new PID not yet used …..
cut on regenerated 3He non applied …
vtx2 finding and fitting: V0 code copied in the task ….
better solution?
Asymmetry in nuclei/antinuclei production (only material regeneration?)
4LH?
Other “strange” nuclei?