The Radioactive Ion Beams facility in Brazil
§  Introduction: RIB in the world
§  The RIBRAS (Radioactive Ion Beams in Brasil) system
§  Experiments with the single solenoid:
elastic scattering mesurements,α-particle production,total reaction cross
section
§  Experiments with the double solenoid system:
resonant scattering measurements
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Nuclides chart in 1965 and in 2011
protons
~1200 known
presently ~ 3500 and 283 stable
protons
neutrons
neutrons
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
§  Introduction
The Nuclides Chart in 1965 and in 2005
protons
~1200 known nuclides
neutrons
Presently more than 3000 known nuclei
and increasing ...
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
• 
Introduction:the ends of the nuclear landscape
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WeaklyBound-Mai/2015 Natal - Brasil
Halos and skins
Borromean nuclei (3-body systems)
New magic numbers and quenching of the shell
gaps.
Importance in astrophysics –
overcoming the A=5,8 gap
synthesis of elements heavier than Fe
New shapes and deformations – fundamental
symmetries
Superheavy elements
R. Lichtenthäler
the ends of the nuclear landscape: light exotic nuclei
17Ne
8
7
8B
6
1p-halo
5
4
3
2
1
2H
20Ne
22Ne
unstable neutron rich
19F
16O 17O 18O
18
20
14N
12C 13C
16
10B 11
B
7Be
6Li
9Be 10
7Li
3He 4
He
1H
unstable proton rich
10
9
2p-halo
proton number
• 
3H
8Li
Be
8He
4
10
9Li
12
proton halo
borromean
6He
11Li
2n-halo
WeaklyBound-Mai/2015 Natal - Brasil
24O
11Be
n
neutron number
stable
neutron halo
8
6
1 2
14
22
1n-halo
nuclei
B.E(MeV) (structure)
11Li (T =8.75ms)
0.300 (n+n+9Li)
1/2
6He (T =807ms)
0.973 (2n+alfa)
1/2
11Be (T =13.81s)
0.501 (n+10Be)
1/2
8B (T =770 ms)
0.137 (p+7Be)
1/2
R. Lichtenthäler
ρ
11Li
R
r
Radius of nucleus (fm)
For stable nuclei àR=r0*A1/3, r0~1.3 fm
but for halo nuclei: 11Li,6He, 11Be ...
R>r0*A1/3
Lithium isotopes
7Li
6Li
8Li
9Li
Number of neutrons
R > r0 A1/3
Tanihata - 1985
6He
3-body forces
11Li
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
•  Production of Radioactive Ion Beams(RIB)
In-flight
ISOL
•  Relatively easy to implement
•  Intense secondary beams
•  Not so good beam characteristics:
emitance and contaminations
WeaklyBound-Mai/2015 Natal - Brasil
•  More complex implementation
•  Requires a post accelerator
•  Good quality secondary beams
R. Lichtenthäler
RIB in the world
Dubna
Lanzhou
Present intensities ~ 105 to 107 pps
future: RIKEN (japão), FAIR (GSI), FRIB(EUA)‫‏‬, SPIRAL2 (França),
intensities will be of ~ 109 – 1012 pps !!
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R. Lichtenthäler
• The São Paulo Pelletron Accelerator
primary Li,Be,B,C,O,Si,Cl
I~500nAe-µAe
8 UD
WeaklyBound-Mai/2015 Natal - Brasil
2-5 MeV/A
R. Lichtenthäler
RIBRAS – since 2004
RIBRAS system
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
§  The RIBRAS system
scattering chamber
primary beam
mid scattering chamber
primary target
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R. Lichtenthäler
Superconducting solenoid
•  Magnet – NbTi
•  Field integral – 5 T.m.
•  Max. central field – 6.52 T
•  Max. current – 91.86 A
•  Inductance – 309 H
•  Stored Energy – 1.3 MJ
•  Lhe vessel 270 liters
•  Lhe boil-off rate 2.0 liters/day
•  LN2 Vessel 130 liters
•  LN2 – 15 liters/day
B
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R. Lichtenthäler
Selection by solenoids
v//
vt
B
!
! !
F = qV ⊗ B
Bρ =
6He
7Li
y(m)
v
collimators
solenoid
2mE
q
Z(m)
lollipop
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
§  The RIBRAS system
First solenoid
angular acceptance
2 deg<Δθ <6 deg
ΔΩ=30 msr
Bρ =
mv
2mE
=
q
q
primary beam
1- primary target
2- collimator
3- Faraday cup
4- solenoid
WeaklyBound-Mai/2015 Natal - Brasil
5- lollipop
6-collimator
7- scattering chamber,secondary target
and detectors
R. Lichtenthäler
§  The RIBRAS system
The production target and Faraday cup
pA
I
N
T
E
G
R
A
T
O
Berillium foil 12
µm
R
PRIMARY BEAM
1 inch
25 mm
FARADAY CUP
PRIMARY TARGET
2.5 cm
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
§  The RIBRAS system
Secondary Beam
Production reaction
6He
9Be(7Li,6He)
8Li
9Be(7Li,8Li)
7Be
3He(6Li,7Be)
7Be
3He(7Li,7Be)
8B
3He(6Li,8B)
10Be
9Be(11B,10Be)
7Be
7Li(6Li,7Be)
Intensity (pps)
Iprimary ~ 300 nAe
Neutron halo
Borromean
proton halo
10+5
10+5
10+5
10+5
10+4
10+4
105
Energy of the secondary beams 10-30 MeV
depending on the beam.
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
§  The RIBRAS system
Scattering chamber and detection
system – silicon telescopes
250 mm
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
§  The RIBRAS system
Detection system with 1 solenoid
PPAC
X-Y
primary
20 µm
y
primary
z
silicon telescopes
Secondary
target
lollipop
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
E-E
Secondary beam profile:
reaction 9Be(7Li,8Li)
Parallel Plate Avalanche Counter (PPAC)
X-Y position sensitive gas detector
C. Mazur Saclay
Y
2 cm
4-5 mm
3-4mm Primary beam spot
+
magnifying factor 1.5
of the 1st solenoid
X
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Direct secondary beam at zero degrees
9Be(7Li,8Li)8Be
cocktail beam
ΔE
particle
150 mm²
ΔE
E
20µm
1000 µm
Detector at zero deg.
no secondary target
7Li
8Li
(0.98;1+) 8Li gs
lollipop
8Li
gs
ΔE-E telescope
7Li2+
8Li*
FWHM=470 keV
8Li3+
6He2+
p,d,t
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4He2+
alphas
R. Lichtenthäler
7Be+9Be
Identification spectra ΔE-E
6He+120Sn
6He+9Be
7Be
7Li
6Li
α
p
dt
t
6He+197Au
6He+58Ni
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
First solenoid tuned to
let the 7Li of primary
beam to come out. ..
8Li*(0.98MeV;1+)
8Li
ΔE
7Li 8Li*
8Li
gs
gs
7Li
lollipop
detector
E
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Secondary beam characteristics:
-energy resolution (depend on the beam)~0.5-1.0 MeV
- kinematics of the production reaction
-energy straggling in the primary target
beam
Energy
(MeV)
Kinematic
spread (MeV)
Energy
resolution
Purity
(1 solenoid)
FWHM
(MeV)
-maximum angular divergence < 1.3-4.5 deg
collimators and Faraday cup
-intensities – from 104 to 106 pps/Ae
production cross section, primary target thickness, primary
beam intensity
8Li
28.
0.250
0.500
40-80 %
6He
14.4
0.200
0.800
16 %
7Be
26.
0.700
>1MeV
2%
9Be(7Li,6He)10B
6He
7Li
target
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
above the Coulomb barrier: diffractive pattern
Fraunhofer diffraction
near-far interference
nuclear rainbow
Far side
Near side
12C+16O
Δθ=π/lg ; lg=kR
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Elastic scattering measurements
Calculations
•  Optical Model
•  CDCC 3 and 4 body
6He+51V
4He+51V
6He+9Be
6He+27Al
6He+120Sn
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Angular Distributions
6He+120Sn
4-body CDCC- M. Rodríguez-Gallardo
coupling to the breakup channel
elastic scattering P. Faria et al PRC81,044605(2010)
n
Τ
R
x
n
y
6He
α
U6He-Τ = <φ6He|Uα-9Be+Un-9Be+Un-9Be|φ6He>
modified 3-body CDCC – A.M Moro
Eb(2n-α)=1.6 MeV
Τ
2n
R
y
α
j=7
j=6
j=5
j=4
j=3
contínuum
j=2
i=1
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
gs
6He
Elastic angular distributions with 6He and 11Be projectiles: damping of the Fresnel diffaction peak!
4 body CDCC calculations
9,10,11Be+64Zn
diPietro et al.
6He+120Sn
predictions!
Y.Y. Yang et al.
8B+208Pb
6He+208Pb
@ 27 MeV
WeaklyBound-Mai/2015 Natal - Brasil
θ1/4
lg
R. Lichtenthäler
Four-body effects in 6He+58Ni,
V. Morcelle et al., PLB 732, 228 (2014)
4-body CDCC- M. Rodríguez-Gallardo
Τ
n
R
x
n
y
6He
α
No free parameters!
U6He-Τ = <φ6He|Uα-T+Un-T+Un-T|φ6He>
modified 3-body CDCC – A.M Moro
Eb(2n-α)=1.6 MeV
Τ
2n
R
y
α
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
6He
6He+27Al
elastic scattering, E. Benjamin et al, PLB647,30(2007)
Optical Model
Modified São Paulo potential
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
6He+9Be
angular distributions, K.C.C. Pires PRC83,064603(2011)
Δθ~30deg
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
6He+27Al E. Benjamin et al, PLB647,30(2007)
6He+27Al
espalhamento elástico, E. Benjamin et al,
PLB647,30(2007)
Modelo optico
Potencial de São Paulo modificado
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
6He+9Bi
elastic scattering – an optical model analysis
Τ
2n
R
y
6He
α
U6He-Τ = <φ6He|Uα-9Be+U2n-9Be|φ6He>
where Uα-9Be is known empirically and
U2n-9Be is adjusted to fit the data
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
6He+9Bi
elastic scattering – optical model
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
What we learn? Characteristics of the optical
potential
r
W
long range absorption
V
system
V(MeV)
rr(fm)
ar(fm)
W(MeV)
ri (fm)
ai(fm)
6He+9Be
47
1.2
0.8
3.3
2.41
0.86
6He+120Sn
216
0.9
0.9
12.4
1.4
0.75
σ reac =< χel | W | χel >
R=rr,i(Ap1/3+At1/3)
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
An alternative optical model analysis
W
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• 
• 
VF is a Folding potential, the parameters λ, ω,
are close do 1
Ws, ri, ai=0.7 are obtained from a systematics by
P. Mohr of the volume integrals JI for several systems
WV=0
ΔI=12.7 MeV
EI=1.171MeV for 120Sn
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
polarization potential
r
V
Results for the potentials 6He+120Sn
P. Mohr et al, PRC82,044606(2010)
dependence of the absorptive potential (surface) with energy
Energy
6He
4He
r
Reactions at the turning point
Peripheral reactions
6He
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
4He
S-matrices
6He
ΔL
4He
L0
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
What we learn from total reaction cross section?
§ 
reduced reaction cross
section
σ red =
§ 
Reduced reaction cross section X reduced energy
σ reac
exotic
( A p1 / 3 + At 1 / 3 ) 2
tightly bound
reduced energy
E red =
E cm
1/ 3
1/ 3
( A p + At )
Z p Zt
σ reac =< χel | W | χ el >
WeaklyBound-Mai/2015 Natal - Brasil
σhalo=σ6He+120Sn-σ4He+120Sn
~760 mb
~ 1/2 of the total reaction cross section
P.N. de Faria et al.
PRC81,044605(2010)
R. Lichtenthäler
•  Reduced total reaction cross section
Reaction cross-section obtained from
the elastic scattering (CDCC,OM,CC)
σ red =
E red
6He+120Sn
exotic
tightly bound
σ reac
( A p1 / 3 + At 1 / 3 ) 2
σhalo=σ6He+120Sn-σ4He+120Sn
Ecm
1/ 3
1/ 3
=
( A p + At )
Z p Zt
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Reduced total reaction cross section for medium-heavy masses
Wong formula
σ red =
2E
σ reac
!w
Wong formula
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Reduced cross-sections for intermediate mass systems A~60
exotic
6He+58Ni
6He+51V
6He+64Zn
weakly bound
tightly bound
8B+58Ni
6Li+51V
9Be+64Zn
6Li+58Ni
6Li+64Zn
7Be+58Ni
4He+58Ni
4He+51V
16O+64Zn
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Reduced cross section for light systems (9Be target).
enhancement
WeaklyBound-Mai/2015 Natal - Brasil
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Percent enhancement for several systems
[this work]
[this work]
[this work]
guideline
σ reac (exp) − σ psp ( 6 Li)
Δσ =
σ psp ( 6 Li)
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
•  other reaction channels: breakup or transfer?
elastic
6He
ΔE
breakup
6He+120Sn
7Li
target
4He
fusion
transfer
4He
6He
alphas
E (channels)
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
•  other reaction channels: breakup or transfer?
120Sn(6He,α)122Sn
Continuum’
Q-optimum considerations
EBf
EB=0.973 MeV
Qopt=0 for neutron transfer
2n-transfer
6He
But for breakup Q<0 !
14.983MeV
very weak
122Sn
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Alpha particles from the 6He+120Sn collision: two neutron (6He,4He) transfers?
energy distribution of alphas
angular distributions
total cross section
650 mb ~ σhalo
DWBA 2n-transfer to
continuum and bound
states (calculations by A. Moro)
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
•  The double solenoid system – since 2011
scattering chamber
mid scattering chamber
primary beam
primary target
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
•  The double solenoid system
Crossover mode
Solenoid 1
Solenoid 2
Primary
beam
lollipop
colimator
Faraday cup
lollipop
1 meter
Primary target
Secondary
target
parallel mode
Solenoid 1
Solenoid 2
Rad. shield
γ detector
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
6He
Beam purity
1 solenoid
6He
2 solenoids
6He
beam 16%
Solenoid 1
beam 92% purity
Solenoid 2
absorber
Primary beam
lollipop
Faraday cup
Primary target
WeaklyBound-Mai/2015 Natal - Brasil
Colimator
Beam
blocker
(lollipop)
R. Lichtenthäler
8Li
Beam purity
1 solenoid
double solenoid
Solenoid 1
Solenoid 2
absorber
Primary beam
lollipop
Faraday cup
Primary target
WeaklyBound-Mai/2015 Natal - Brasil
Colimator
Beam
blocker
(lollipop)
R. Lichtenthäler
Excitation function measurements. Experiments with the thick target method
-resonances in 6He+p=7Li and 8Li+p=9Be.
CH2 12 mg/cm2
protons
6He
E6He=12.2 MeV
E cm = E lab
Silicon telescope
ΔE E
spectrum of light particles
range
MT
1
= E lab
M p + MT 7
resonances in the CN
50µm
1000µm
11.7
11.2
Ecm+Q
7He
10.8
p+6He ; 9.975 MeV
7Li
WeaklyBound-Mai/2015 Natal - Brasil
GS ; 0 MeV ; 3/2-
R. Lichtenthäler
15 mg/cm2 pure carbon target
α
6He
no protons
t
d
α
p
WeaklyBound-Mai/2015 Natal - Brasil
d
t
R. Lichtenthäler
p(6He,p)6He
WeaklyBound-Mai/2015 Natal - Brasil
p(6He,p)6He excitation functions
R. Lichtenthäler
6He
on pure carbon target
alphas
tritium
no protons
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
p(6He,p)6He excitation function
p(6He,n)6Li excitation function by
Rogachev et al. PRL
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
The p(8Li,p)8Li scattering
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Evidence of a four-body state in 9Be
J=5/2J=5/2+
multi-channel R-matrix analysis
α
t
p n
Eexc=18.7 MeV
Eexc
9Be
GS
This resonance is observed only in the 8Li(p,d)7Li
reaction and not in the inverse reaction indicating that
the 7Li is excited.
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
•  The future
2004
2011
2015
γ
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
2015
gamma cave
neutron detector
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
RIBRAS collaboration:
Universidade de São Paulo, IFUSP
R. Lichtenthäler Fo, A. Lépine-Szily, V.Guimarães, M. A. Gonzalez Alvarez, K.C.C. Pires, R. Pampa Condori,
V.Scarduelli, L.Gasques, V. A. Zagatto, U.U. da Silva, E.Leistenschneider, N. Deshmukh, Y.Yang, S. Appannababu,
G. A. Scotton, J. Duarte
IEAv-USP
M. S. Hussein
Universidad de Sevilla, Espanha
M. Rodríguez-Gallardo, A.M. Moro
Université Libre de Bruxelles
P. Descouvemont
University of Edinburgh
A. Estrade
Laboratorio Tandar, Buenos Aires, Argentina
A. Arazi
CEADEN, Havana, Cuba
I.Padron, J. Arteche, R. Arteche
Instituto de Pesquisas Energeticas e Nucleares (IPEN)
J.M.B. Shorto
Universidade Federal Fluminense (UFF)
P.R.S. Gomes, J. Lubian, P. N. de Faria, D. R. Mendes, M.C. Morais
Universidade Federal de São Paulo (UNIFESP)
M. Assunção
Universidade Federal Rural do Rio de Janeiro (UFRRJ)
V. Morcelle
Universidade Federal da Bahia (UFBA)
A. Barioni
University of Notre Dame, EUA
J. Kolata
Faculty of Science, The M.S. University of Baroda, India
Surjit Mukherjee
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler
Thank you!
WeaklyBound-Mai/2015 Natal - Brasil
R. Lichtenthäler