Slides - Agenda

Reaction dynamics and nuclear structure of moderately
neutron-rich Ne isotopes by heavy ion reactions
Simone Bottoni
University of Milan & KU Leuven
INPC 2013 - Firenze
Outline
Outline
•Introduction to heavy ion reactions
•The PRISMA – CLARA experimental setup
•Reaction studies
•Nuclear structure studies
•Conclusions and perspectives
Simone Bottoni - University of Milan & KU Leuven
Introduction
Heavy ion reactions
Grazing impact parameter
b g = R1 + R2
Binary reactions
a +A
b+B
22Ne
Simone Bottoni - University of Milan & KU Leuven
+ 208Pb @ 128 MeV
Introduction
Theoretical models
Semi- classical model (GRAZING)
DWBA model (PTOLEMY)
•Inclusive calculations
•Calculations for specific excited states
•Elastic and transfer differential cross sections
•Elastic, inelastic and transfer differential cross sections
•Macroscopic factor for internal excitation
•Microscopic calculations
•Microscopic factor for transfer processes
•Deformation of excited states
Simone Bottoni - University of Milan & KU Leuven
The PRISMA – CLARA experimental setup @ LNL
ϑg = 70°
CLARA
PRISMA
Particle - γ coincidence measurements
Simone Bottoni - University of Milan & KU Leuven
The PRISMA – CLARA experimental setup @ LNL
PRISMA
CLARA
25 HpGe Clover
ε ~3 % @ Eγ= 1.3 MeV
2π
BGO
Composite Ge
50mm x 70mm
Optical elements:
•Magnetic quadrupole
•Magnetic dipole
Detectors
•Entrance detector (MCP)
•Focal plane detector (PPAC)
•Inonization chamber (IC)
Compton polarimeter
•ΔΩ ~ 80 msr
•ΔZ/Z ~ 1/60
•ΔA/A ~ 1/190
3 RINGS
θ ~ 100°-130°-150°
γ angular distributions
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Data analysis – Ions identification
Z selection
Charge states selection
(Z = 10)
22Ne
Mass spectra
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22Ne
Data analysis – Reaction studies
Elastic cross section
Inclusive cross sections
PRISMA
ELASTIC
CLARA
Normalization
GRAZING
DWBA fit
Optical parameters
Simone Bottoni - University of Milan & KU Leuven
Data analysis – γ spectroscopy
γ spectra
Doppler corrected event by event for v/c ≈ 10 %
Simone Bottoni - University of Milan & KU Leuven
Data analysis – Reaction studies
Inelastic cross sections
DWBA
DWBA
Peak integration
Q-value
22Ne
+ 208Pb @ 128 MeV
PRISMA+CLARA @ LNL
Simone Bottoni - University of Milan & KU Leuven
24Ne
+ 208Pb @ 182 MeV
VAMOS+EXOGAM @ GANIL
Data analysis – Nuclear structure studies
Deformation parameters
Very old measurement!
Closure of ν1d5/2 in 24Ne
Sensitivity to βC
Sensitivity to βN
Simone Bottoni - University of Milan & KU Leuven
24Ne
is a nucleus of key importance in the study of
shell evolution towards the “island of invertion”
Conclusions
Conclusions
•Importance of heavy ion reactions for nuclear reaction and nuclear structure studies
•Effectiveness of magnetic spectrometers and Ge detectors combination (PRISMA – CLARA)
•Study of the reactions 22Ne + 208Pb @ 128 MeV
•Experimental analysis of particle angular distributions
•Comparison with theoretical models (GRAZING & PTOLEMY)
•Study of nuclear structure – evidence of strong reduction of βC in 24Ne – additional investigations
•Perspectives: heavy ion reactions with exotic nuclei and a new generation of Ge detectors
array of high efficiency (e.g. AGATA)
Simone Bottoni - University of Milan & KU Leuven
List of collaborators
Collaboration
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Thank you for your attention
Simone Bottoni - University of Milan & KU Leuven
EXTRA SLIDES
Simone Bottoni - University of Milan & KU Leuven
The presorting of the data - PRISMA
MCP calibration
80x100 mm
The ions pass by a Carbon foil generating
secondary electrons which are accelerated
toward an anode by an electric field. The
anode is made of two orthogonal delay
lines, respectively on the horizontal and
vertical axis, which provide information on
the position of the ions by calculating
the difference in arrival time of the signals
at the two ends of each delay line.
MWPPAC calibration
Ionization Chamber
1000x130 mm
xres = 1 mm
tres = 0.1 ns
Filling gas: CF4
Simone Bottoni - University of Milan & KU Leuven
The presorting of the data - CLARA
BGO – antiCompton
Efficiency
Add-back requirement
Energy Resolution
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The GRAZING code
Semiclassical model GRAZING
The nucleus is described as an ensemble of
independent nucleons that can vibrate around
their spherical equilibrium shape.
MACROSCOPIC factor for surface excitation
whose form factor is proportional to the r-derivative
of the ion-ion potential and whose strength is given
by the experimental B(Eλ).
[First quadrupole and octupole vibrations.]
MICROSCOPIC factor for the exchange of nucleons
which takes into account the single particle properties
of the two colliding nuclei.
CLASSICAL orbits for relative motion
and system of coupled equations for time evolution
ION-ION POTENTIAL
TRANSFER
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The PTOLEMY code
DWBA model PTOLEMY
The Distorted Wave Born Approximation
PTOLEMY effective interaction for
inelastic cross section
OPTICAL potential
OPTICAL parameters
Simone Bottoni - University of Milan & KU Leuven
Deformation
@ 132MeV – Oak Ridge
20Ne+208Pb @ 131 MeV - Oak Ridge
CC analysis
22Ne+208Pb
22Ne+NatNi
– Isolde
Coul.Ex.
(t,p) @ 2.9 MeV – Palo Alto
DSAM
22Ne
28Ne+natPb
@ 1.3 GeV - Rikken
CC analysis
@ 1.2 GeV – MSU
CC analysis
18Ne+197Au
26Ne+natPb
@ 1.4 GeV - Rikken
CC analysis
Adopted values:
S. Raman, C.W. Nestor jr., P. Tikkanen, At. Data Nucl. Data Tables 78, 1 (2001).
Simone Bottoni - University of Milan & KU Leuven