de mori francesca,turin university and infn dafne04 frascati, june 8 2004 very preliminary results...
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DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Very preliminary results of Non Mesonic Weak Decays in
FINUDA
De Mori Francesca for the FINUDA Collaboration
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Outlook:
NMWD in hypernuclei NMWD in FINUDA Proton single nucleon spectra of various
targets Rare Decays of Conclusions and prospects
4He
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Non Mesonic Weak Decays
In nuclear medium :NNN
NNnNN (15%)
Dominant in medium-heavy hypernuclei(A12)
Unique opportunity to study the four-baryons weak interaction
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
2 6Li
1 7Li
3 12C
1 27Al
1 51V
5 cm
OSIM
ISIM
TOF
Target
Beam pipe
FINUDA allows in primis the measurement of emitted nucleon spectra from :
27Al12C
51V7Li
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Event selection of NMWD protons
Selected positive tracks from K- vertex with specific energy loss in the band of proton
Presence of pion track from K- vertex required with pion momentum corresponding to the production of the hypernucleus in the bound region
)()( NnpNp
ZZK AAstop
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
12C target 7Li target
51V target 27Al target
Preliminary not acceptance-corrected
-1.8<B<11.MeV -3.3<B<5.6
MeV
-1.2<B<16.8 MeV
-0.2<B<20.2 MeV
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Rare Decays of 4He
6 4K Li He n N
4He d d 4 3He p H
6Li is unstable
6 5K Li He N
6 4K Li H p N
Pd~570 MeV/c
Pt~510 MeV/c
exploiting 6Li target
Some three-four body decay channels
Possible 2-body decays of 4He with charged
particles
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Deuteron pair of rare decays selection (4
He d+d):
Looking for positive tracks from K- vertex
Looking for dE/dx over the proton band
Looking for a pair of tracks of this kind back to back with momentum greater than 400 MeV/c
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
PID (dE/dx in vertex silicon detectors)
Momentum(MeV/c)
dE/d
x(O
SIM
)
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Angle between pairs of tracks
P>400MeV/c
sel.deuterons
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
First observation of 4He d-d rare decayFirst observation of 4He d-d rare decay
ten deuteron pairs observed
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Evento fujoka 2
d
d
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
d
d
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
d
d
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Conclusions & prospects First very preliminary results of NMWD in FINUDA:
single proton spectra from all 5 different targets Clear evidence of rare non mesonic decay of 4
He never observed before
needed neutron identification: we are working on it needed improved backtracking: we are working on it needed better mass identification for back-tracking for
deuteron momenta better reconstruction:we are working on it
we are on the way to increase the number of good events
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
Contribute to the proton spectrum of the background reaction:
K (np) p
n
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
DAFNE04 Frascati, June 8 2004 De Mori Francesca ,Turin University and INFN
O.Hashimoto et al. Phys.Rev.Lett.88:042503,2002
KEK-PS E307