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
4
Rare Decays of  He
Conclusions and prospects
DAFNE04 Frascati, June 8 2004
De Mori Francesca ,Turin University and INFN
Non Mesonic Weak Decays
In nuclear medium :
NNN
NNnNN (15%)
Dominant in medium-heavy hypernuclei(A12)
Unique opportunity to study the four-baryons weak interaction
DAFNE04 Frascati, June 8 2004
De Mori Francesca ,Turin University and INFN
2 6Li
1
OSIM
7Li
TOF
3 12C
Target
1 27Al
ISIM
1 51V
Beam pipe
5 cm
FINUDA allows in primis the measurement of emitted
nucleon spectra from :
27
7
51
12




C
DAFNE04 Frascati, June 8 2004
Al
V
Li
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
K

stop
 Z Z 
A
A

DAFNE04 Frascati, June 8 2004

  p(  N )  p  n(  N )
De Mori Francesca ,Turin University and INFN
12C
target
-1.8<B<11.MeV
7Li
target
-3.3<B<5.6 MeV
27Al
target
51V
target
-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 4He
exploiting 6Li target
Li is unstable
6

Some three-four body decay channels
K   6Li  5He  N  
K   6Li  4H  p  N  
K   6Li  4He  n  N  
Possible 2-body decays of
4 He with charged particles

DAFNE04 Frascati, June 8 2004
He  d  d
He  p  3H
4

4

Pd~570 MeV/c
Pt~510 MeV/c
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
dE/dx(OSIM)
PID (dE/dx in vertex silicon detectors)
DAFNE04 Frascati, June 8 2004
Momentum(MeV/c)
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
4
He
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
m
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
never observed before
4 He

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
KEK-PS
E307
O.Hashimoto et al. Phys.Rev.Lett.88:042503,2002
DAFNE04 Frascati, June 8 2004
De Mori Francesca ,Turin University and INFN