E421S Spectroscopy of n-rich nuclei around N=14,16 in deep

Probing the structure of neutron-rich O and
Ne isotopes using in-beam g spectroscopy with
deep-inelastic collision at LNL and Ganil
G. Benzoni
for the LNL-Ganil collaboration
Ne,F,O isotopes around N=14 and 16
Collaboration
Università degli Studi and INFN sezione di Milano
LNL, Laboratori Nazionali di Legnaro
Università and INFN sezione di Padova
Università di Camerino and INFN Perugia
INFN sezione di Genova
The Niewodniczanski Institute, Krakow
Institut de Physique Nucleaire, Orsay
IRES Strasbourg
GANIL, Caen
IPN, Lyon
Knowledge of the n drip line is
limited to the lightest nuclei,
up to O
• location of n drip line between F and O is not understood
 N=16 for O and N=22 for F
• role played by 1 and 2 p outside shell closure Z=8
• Nuclear structure of nuclei going towards the n drip line
Test of accurate shell model calculations in light nuclei
Example: A. Brown et al., http://www.nscl.msu.edu/~brown
Report of the E421S experiment (spokeperson F.Azaiez):
aim of the experiment
Mg
Na
Ne
24Ne
F
O
N
C
B
Be
Li
He
H
Deep Inelastic Collision reaction with light exotic beam
Population of exotic Ne-F-O isotopes
• cross section measurements
• g spectroscopy Ne-O-F
24Ne
@ 114 MeV + Pb or U target
Vamos+Exogam
Ibeam ~106
22Ne
@ 125 MeV +
208Pb
target
Prisma + Clara
LOI @LNL coming experiment
Report of the E421S experiment:
Experimental details
• reaction: 24Ne @ 7.923 MeV/A + 208Pb (10.9 mg/cm2)
24Ne5+ , I
.
5
beam ~ 1.5 10 pps
beam on target for 7 days
• setup: Vamos + EXOGAM
Vamos @ 45°
EXOGAM 11 detectors
(2 without Compton shield)
List of EXOGAM det. used
SO1 (ESS03FR)
SO2 (ESS05UK)
SO3 (ESS06UK)
SO4 (ESS07UK)
SO5 (ESS11UK)
SO7 (ESS12UK)
SO11 (ESS08UK)
ORTEC3 (ESS13UK)
ORTEC4 (ESS09UK)
ORTEC5 (ESS10UK)
ORTEC6 (ESS04FR)
Typical count rates:
• Ions: 30/min  Total Ion counts: 7*24*60*30 = 302400
 cross section determination is feasible
• Ion-gamma coincidence 70/h
Total Ion-gamma coinc. 7*24*70 = 11760
 only spectroscopy of inelastic ch.
• Beam stable
• Vamos very reliable
• Exogam stable
• Good local support
ID-plot
E (a.u.)
E
3 days of statistics (~ 1/2)
O
F
Report of the E421S experiment:
very preliminary spectra
Ne
Na
Working on mass separation
DE (a.u)
Ne (inelastic)
Conditions:
-Si-gamma coincidence
- Prompt gamma peaks
- calculated v/c
23F
~ 20 mb
(1p removal)
24Ne
~ 500 mb
Report of the E421S experiment:
future
26Ne
~ 80 mb
(2n pick up)
F
Ne
Calculations by
G.Pollarolo
Beam intensity required to study weaker channels
• to get to more exotic Ne isotopes  ~ 106
• to get to F  5.106
• to get to O  ~ 107
N.B: to have gamma info. Need to go to 108