Probing the structure of neutron-rich N=12-16 F,O,Ne isotopes using deep-inelastic collisions

G. BenzoniG. Benzoni, A. Bracco, S. Leoni, N.Blasi, F. Camera, F. Crespi, B. Million, O. Wieland,

Università degli Studi and INFN sezione di MilanoG. De Angelis, A. Gadea-Raga, D. Napoli, A. Stefanini, L. Corradi, E. Fioretto, J.J. Valiente-Dobon, N. Marginean

LNL, Laboratori Nazionali di LegnaroS. Lunardi, S.M. Lenzi,D. Bazzacco, E. Farnea, G. Montagnoli, C. Ur, S.Beghini, F.Scarlassara,

Università and INFN sezione di PadovaM.Trotta,

INFN NapoliG. Lobianco, C. Petrache,

Università di Camerino and INFN PerugiaA.Zucchiatti, M.Castoldi,

INFN sezione di GenovaA. Maj, M. Kmiecik, K. Mazurek, J. Styczen, W. Meczynski, K. Zuber,

The Niewodniczanski Institute, KrakowF.Azaiez, F. Ibrahim, D. Verrey, M. Stanoiu, Ch. Bourgeois,

Institut de Physique Nucleaire, OrsayG. DuLove, D. Curien, Ch. Beck,

IRES StrasbourgH. Savajols, M. Rejmund, A. Navin, G. DeFrance,

GANIL, CaenN. Redon, M. Meryer, O. Stezowski

IPN, Lyon

HHe

LiBeBC

NO

FNe

NaMg

31F24O

H.Sakurai et al., Phys. Lett. 448B (1999) 180

M.Fauerbach et al., Phys.Rev.C53 (1996) 647

Search for the n-dripline…

• 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

Test of accurate shell model calculations in light nuclei

24O

23O

Population of n-rich Ne, F and O nuclei

CNO

FNe

NaMg

31F24O

Information on reaction

dynamics in light nuclei

Aim of the project:

Outline : current status of • O isotopes • F isotopes

• Ne isotopes

26Mg @ 130 MeV + 208Pb/U target

20OMSU exp

Oxygen isotopes

E. Tryggestad et al., Phys. Lett. B541, 52-58(2002).

Experimental info for N = 12 and 14

1710

4852

3199

3710

± 9

0

expSM M. Stanoiu et al., Phys. Rev. C69, 034312 (2004).

Need to firmly establish these transitions

GANIL exp

Oxygen isotopes

Experimental info for N = 15 and 16

Search for first excited state Recoil shadow technique with CLARA

No evidence for excited states…

M. Stanoiu et al., Phys. Rev. C69, 034312 (2004).

GANIL exp

A. Brown et al., http://www.nscl.msu.edu/~brown

400 = 8.8 ns ?

Sn = 2.7 MeVSn = 3.7(4) MeV

M.Belleguic et al. NPA682(2001)136c

F isotopes: N = 16

25F

26F

27FZ.Elekes et al. PLB599(2004)17

Need to firmly establish these transitions

GANIL expCourtesy of F.Azaiez

Ne isotopes : Isle of inversion and n gap evolution from N=20 to N=14 (16)

Proposed experiment @ Prisma + Clara

• 26Mg @ 130 MeV + 208Pb/U target• 18O @ 110 MeV + 208Pb target

Beam time request: 7 days of 26MgWith possibly 2 days of 18O

Future proposal: 22Ne @ 125 MeV + 208Pb target (LOI)

More details on the proposal

• grazing angle: 80° angle of Prisma• Prisma efficiency @ grazing angle: 3-5 %• 60-70% efficiency at focal plane cfr. 24Mg+24Mg experiment (F.Hass)

• 24 to 25 Clovers setup Clara• efficiency ~ 3 %• Peak/Total ~ 50%• Position = 104°– 156°• FWHM ~ 10 keV @ 1.3 MeV and v/c = 10%

30000 p- coincidences in weakest channels in 7 days( ~1000 p-coincidences

E*1

E*2

Measurement of the gamma decay from pygmy resonance using netron transfer reaction at 15 MeV/u(d,p) in inverse kinematics

For more neutron rich nuclei this yield is expected to be much larger

A. Voinov et al, PRC (2002)

Gamma-ray particle coincidence , difference techniqueobtain also the level density, important information for calculationsof reaction rates in the r-process

Before After

Courtesy of A.Gadea

Coaxial HPGe + BGO in add back

B.Million et al NIM A452(2000)422

Euroball Cluster in Add Back (no BGO)

HPGe for High Energy gamma rays

Complementary to in-beam spectroscopy with fragmentation reactions

• high lying states in Ne, F, and O isotopes• n-odd isotopes in particular…known less accurately• Information on reaction mechanism with light n-rich nuclei• complete distributions of production yields in order to study the N/Z equilibration process in deep inelastic reactions induced by neutron-rich beams

24Ne @ 114 MeV + Pb or U target

22Ne @ 125 MeV + 208Pb target

Vamos+Exogam

Proposed joint experiments:

Prisma + Clara

Stable and radioactive beams to study similar nuclei comparison of cross sections and reaction mechnisms

Ibeam ~106