Study of neutron-deficient nuclei below 100 Sn
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Transcript of Study of neutron-deficient nuclei below 100 Sn
Study of neutron-deficient nuclei below 100Sn
“Universa Universis Patavina Libertas”
1. Physical motivations
2. Experimental details
A. Gottardo, J.J. Valiente-Dobon,…
IntroductionIntroduction
The evolution of nuclear structure at the extremes of isospin is one of the major topics in modern nuclear
physics
The proton-rich nuclei close to the N = Z line below mass 100 are known to exhibit a variety of interesting phenomena: 1p and 2p radioctivity and higher-lying
spin-gap isomers
The proton-rich nuclei close to the N = Z line below mass 100 are known to exhibit a variety of interesting phenomena: 1p and 2p radioctivity and higher-lying
spin-gap isomers
Two-proton radioactivity in 94Ag
Spin-gap and seniority isomers Rp-process
94Ag (1)94Ag (1)
The 2p radioactivity strength suggest a very deformed
(3:1) 21+ isomer
The 2p radioactivity strength suggest a very deformed
(3:1) 21+ isomer
Nature, 439, 298 (2006)
This N = Z nucleus has two isomers (7+, 21+, t1/2 ~ 0.5 s), with the highest one decaying via one and two-proton
emission
This N = Z nucleus has two isomers (7+, 21+, t1/2 ~ 0.5 s), with the highest one decaying via one and two-proton
emission
The 21+ isomer also decays by two different 1p emission
PRL 95, 022501 (2005)
94Ag (2)94Ag (2)Mass measurements,
detailed γ spectroscopy of the daughter nucleus and following experiment did
not confirm the 2p emission… further studies
needed
Mass measurements, detailed γ spectroscopy of the daughter nucleus and following experiment did
not confirm the 2p emission… further studies
needed
The γ spectroscopy of 94 Ag will provide valuable information on nuclear structure in this N =Z nucleus, in particular
clarifying the structure above the proton-emitting isomer. T= 0 aligned pairing?
The γ spectroscopy of 94 Ag will provide valuable information on nuclear structure in this N =Z nucleus, in particular
clarifying the structure above the proton-emitting isomer. T= 0 aligned pairing?
PRC 77, 064304 (2008)
96Cd96CdThe 100Sn nucleus is a fundamental step in
uderstanding the nuclear force and the nuclear structure
The isotopes below 100Sn, with protons and neutrons filling the
g9/2 shell up to N,Z = 50, are crucial to infer the evolution of nuclear
structure towards the shell closure
A 16+ spin-gap isomer is predicted and decay spectroscopy has been
performed at GSI (FRS-Rising)
It is fundamental to also have prompt-spectroscopy data!
Acta Phys. Pol. B, 40, 611 (2009)
100In100In
In prompt spectroscopy we expect to see states from the πg9/2
-1-νd5/2 and πg9/2-1-νg7/2 multiplets, and perhaps
excitations of the 100Sn core for spins higher than 8+
100In is a 1p-hole – 1n-particle nucleus with respect to 100Sn: ideal case to study pn
interaction
Direct extraction of pn matrix elements Direct extraction of pn matrix elements
PRC 65, 021302(R) (2002))
101Sn101Sn
States from νd5/2 and νg7/2, νh11/2 are expected, together with the
excitation of the 100Sn core
101Sn is fundamental nucleus in shell model, being one neutron above 100Sn: ideal case to
study the double shell closure and the effect of tensor interaction
Ongoing discussion on the inversion of νd5/2 and
νg7/2, linked to tensor force
Ongoing discussion on the inversion of νd5/2 and
νg7/2, linked to tensor force
PRL 105, 162502 (2010))
How to study these nuclei?How to study these nuclei?
Gamma array: Agata, Galileo, Exogam2
Neutron array:
Neda
1. Channels with evaporation of 3 neutrons: 3n, 1p3n…
2. Channels with evaporation of 2 neutrons: 2n, 1p2n…
Fusion evaporation- reactions: proton-rich, high spin population
Fusion evaporation- reactions: proton-rich, high spin population
Charged particles:Diamant, Trace
Batch mode for exotic beamsBatch mode for exotic beamsPrimary proton
beam from cyclotron: 70MeV,
0.8 mA
The target then becomes the
source of the LNL TANDEM
Irradiation of a target to produce
56Ni
Irradiation of a target to produce
56Ni
Fusion-evaporation reaction with
NEDA – TRACE – AGATA/GALILEO
94Ag94Ag
Cross section ~ 50 μb
40Ca + 58Ni
p3n evaporation
40Ca + 56Ni
p1n evaporation
Cross section ~ 100 μb
Beam current > 10 pnA
Beam current ?
Beam to be produced in batch mode at LNL-SPES
Three – neutron detection efficiency ~ 0.1%
One – neutron detection efficiency ~ 25%
94-96Cd94-96Cd
Cross section ~ 100 μb - 6 μb
40Ca + 58Ni
2n-3n evaporation (95-
96Cd)
40Ca + 56Ni
1n?-2n evaporation (94-
95Cd)
Cross section ~ 150-9 μb
Beam current > 10 pnA
Beam current ?
Beam to be produced in batch mode at LNL-SPES
Three – neutron detection efficiency ~ 0.1%
Two – neutron detection efficiency ~ 5%
100In100In
Cross section ~ 4 μb
58Ni + 45Sc
3n evaporation
56Ni + 46Ti
pn evaporation
Cross section ~ 20 μb
Beam current > 10 pnA
Beam current ?
Beam to be produced in batch mode at LNL-SPES
Three – neutron detection efficiency ~ 0.1%
one – neutron detection efficiency ~ 25%
101-100Sn101-100Sn
Cross section ~ 4 μb
58Ni + 56Ti
3n evaporation:101Sn
56Ni + 56Ti
2n evaporation 100Sn
Cross section ~ 10 μb
Beam current > 10 pnA
Beam current ?
Beam to be produced in batch mode at LNL-SPES
Three – neutron detection efficiency ~ 0.1%
Two – neutron detection efficiency ~ 5%
ConclusionsConclusionsPhysics case to study many proton-rich nuclei below
A=100:
Attempts already done at Argonne with GS-FMA
The identification of evaporated neutrons and protons to select the reaction channel is a powerful tool to study exotic nuclei (better efficiency than FMA?)
The future avalability of 56Ni beam with the batch-mode technique will enable to study very exotic nuclei exploiting the capabilities of NEDA at full