g.raciti –dip. fisica& astronomia –univ. catania & infn – otranto 2005 fasci...
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G.Raciti –Dip. Fisica& Astronomia –Univ. Catania & INFN – Otranto 2005
FASCI RADIOATTIVI (Esotici)
Particelle o ioni instabili prodotti Particelle o ioni instabili prodotti artificialmente( ovvero non esistenti in artificialmente( ovvero non esistenti in natura) con caratteristiche energetiche natura) con caratteristiche energetiche e spaziali tali da poter essere e spaziali tali da poter essere riutilizzati come un “normale” fascio riutilizzati come un “normale” fascio ottenuto da un acceleratore.ottenuto da un acceleratore.
• (10(10-10-10sec)sec)• 1010-10-10sec)sec)• LiLi11 11 (neutron rich) (neutron rich) • SnSn107 107 (proton-rich) (proton-rich)
Normal Nucleus:
6 neutrons
6 protons (carbon)12C
Stable, found in nature
Exotic Nucleus:
16 neutrons
6 protons (carbon)22C
Radioactive, at the limit of nuclear binding
Characteristics of exotic nuclei:
Excess of neutrons or protons, short half-life, neutron or proton dominated surface, low binding
What is an exotic nucleus?
284 isotopes with T1/2 > 109 yearOur beams till 1989 !
Un po’ di Storia…
<1940495
Un po’ di Storia…
<1940 1940 495 822
Reactors: n on U
Un po’ di Storia…
<1940 1940 1950 495 822 1244
First Isotope Separator experimentNiels Bohr Institute 1951fast n on U: Kr and Rb isotopes
Un po’ di Storia…
<1940 1940 1950 1960495 822 1244 1515
Selective detection method: decay
Un po’ di Storia…
<1940 1940 1950 1960 1970
495 822 1244 1515 2010
Light-ion induced spallationHeavy-ion induced fusion
Un po’ di Storia…
<1940 1940 1950 1960 1970 1980495 822 1244 1515 2010 2270
Projectile and target fragmentation
Un po’ di Storia…
Stable
+ decay- decay
decay
p decay
spontaneous fission
Around 3000 of the expected 6000 nuclei Around 3000 of the expected 6000 nuclei have been observedhave been observed
Oggi
Produzione
NNprod prod = N= N inc inc N N targ targ
[ions/sec] [ions/sec] [nucl/cm[ions/sec] [ions/sec] [nucl/cm2 2 ] [cm] [cm22 ] ]
I(eA) NI(eA) NAA [gr/cm[gr/cm2 2 ] ] [cm [cm22 ] ]
ZZproj proj e [coul] A e [coul] Atarg targ [gr][gr]NNprod prod ==
I(enA) 10I(enA) 10-9 -9 10101919 6.02 10 6.02 102323 [[gr/cmgr/cm2 2 ] 10] 10-6 -6 [mbarn ] 10 [mbarn ] 10 -27-27
ZZproj proj 1.602 A 1.602 Atargtarg
NNprod prod ==
3.76 I(enA) 3.76 I(enA) [[gr/cmgr/cm2 2 ]] [mbarn ] [mbarn ]
ZZproj proj AAtargtarg
NNprod prod ==
[[gr/cmgr/cm2 2 ] = ] = [gr/ cm[gr/ cm3 3 ] ] tt[[m] 10m] 1022
Qualche calcolo…..
I= 10enA -> 0.6 10I= 10enA -> 0.6 1011 11 protons/sec protons/sec
Potenza (W)= I V = I (Energy/Charge state)
Es: I=1mA E=50 A MeV di O16 completamente strippato (O8+) :P = 1 10-3 (50 16/8) 106 =100 kW
Cl40 production yield in Ar+Be@50 AMeV
1,E+00
1,E+01
1,E+02
1,E+03
1,E+04
1,E+05
1,E+06
1 10 100 1000 10000
Primary Beam Current (enA)
Yiel
d (Io
ns/s
ec)
Thickness=100
Thickness=200
Thickness=300
Thickness=400
Thickness=500
ProductionTarget
Un Esempio…...Produzione
ProductionTarget
Cl 40 Induced Reactions for Target Thickness=5 mgr/cm2
and =1 barn
0,01
0,1
1
10
100
1 10 100 1000 10000Primary Beam Current ( enA)
Reaction P
roducts
Rate
(e
vents
/sec.) Thickness
=100Thickness=200Thickness=300Thickness=400Thickness=500
ProductionTarget
Cl 41 (Target=5mg/cm2 , Production Target 500 m)
0,01
0,1
1
10
100
1000
10000
1 10 100 1000 10000Primary Beam Current(enA)
Tim
e (s
econ
ds)
1 hour
1 min
=1mbarn
=0.5 barn
=1barn
…..Reazione
Intensità Minime di RIBsMethod Part
/secPhysics
Detection andidentification
10 –5 Limits of nuclei, Existence
Stripping reactions 10 4 Nuclear properties beyond thedrip lines
Massmeasurements
10 –2 Masses, explosivenucleosynthesis
Interaction crosssection
10 –2 Radii, nuclear size
Knockout reactions 10 5 Halos, cluster models,spectroscopic factors
Heavy-ion collisions 10 5 Nuclear compressibility, EOS,supernovae
Giant dipoleresonance
10 6 Nuclear size and shape, r-process
Nuclear size andshape, r-process
10 7 Nuclear compressibility, EOS,neutron stars, supernovae
Coulomb excitation(2+)
1 Evolution of shell structure, r-process
Elastic scattering 10 3 Radii, density distributionsInelastic scattering 10 3 Nuclear structure, rp-processNuclear structure,rp-process
10 4 Proton drip line, rp-process
Charge exchange 10 6 Gamow-Teller strength,supernova core evolution,
Lifetimes/-decaystudies
10 –3 Nuclear deformation, shellevolution, explosivenucleosynthesis, r-process,
NMR 10 Ground-state momentsMicro-secondisomers
10 –3 Shell structure, single particlestates
Reazioni di Produzione•Bassa EnergiaBassa Energia (Fusione, (Fusione, Fissione, Reazioni dirette , Fissione, Reazioni dirette , Deep Inelastic)Deep Inelastic)
•Alta EnergiaAlta Energia (Frammentazione Proiettile o (Frammentazione Proiettile o Targhetta, Spallation, Targhetta, Spallation, Fissione in volo)Fissione in volo)
- peripheral elastic and quasi-elastic ( QE ) collisions - semi-peripheral deep-inelastic collisions ( DIT ) collisions - incomplete ( ICF ) and complete ( CF ) fusion in central collisions - pre-equilibrium emision typically preceding ICF/CF and DIT
l )
l (angular momentum
Reazioni di Produzione Transfer Reactions
In generale:In generale:•Piccate ad angoli in avantiPiccate ad angoli in avanti• 1010-1 -1 – 10 mbarn– 10 mbarn
292 MeV 54Fe + 92Mo 146Er(p4n)141Ho
402 MeV 78Kr + 58Ni 136Gd(p4n)131Eu
A.A. Sonzogni et al., Phys. Rev. Lett. 83 1116 (1999)
D. Seweryniak et al., Phys. Rev. Lett. 86 1458 (2001)
Reazioni di Produzione Fusione
Reazioni di Produzione Frammentazione del
Proiettile
Participant-spectator reactions Participant-spectator reactions at relativistic energies ( above 100 AMeV )at relativistic energies ( above 100 AMeV )
Reazioni di Produzione (Frammentazione)
0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0N (A-Z)
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
Z
r-processpath
rp-processpath
RI yield in ions/s
>1012
1010
108
102
1.0110-4
10-6
106
104
R e g io n o fK n o w n N u c le i
Reazioni di Produzione Frammentazione della
Targhetta
Random removal of protons and neutrons from heavy target nuclei by energetic light projectiles (pre-equilibrium and equilibrium emissions).
SpallationSpallation
Reazioni di Produzione
Reazioni di Produzione (Frammentazione
Fissione)
Reazioni di Produzione (Frammentazione
Fissione)
Reazioni di Produzione Fissione
K.H. Schmidt et al., Model predictions of the fission-product yields for 238U (2001)
Optimum delle Reazioni di Produzione
Metodi di Produzione
•In-Flight (Fascio prodotto In-Flight (Fascio prodotto direttamente nella reazione)direttamente nella reazione)
Reazioni su targhette “spesse”Reazioni su targhette “spesse”
•ISOL (Prodotti di reazione ISOL (Prodotti di reazione accelerati in un secondo accelerati in un secondo acceleratore)acceleratore)
•DegradersDegraders•TaggingTagging
In F
light
Acceleratore Primario (Driver)Acceleratore Primario (Driver)
Target di ProduzioneTarget di Produzione
Selezionatore e.m.Selezionatore e.m.
UtenteUtente
ISO
L
Acceleratore Primario (Driver)Acceleratore Primario (Driver)
Target di ProduzioneTarget di Produzione
Selezionatore e.m.Selezionatore e.m.
UtenteUtente
AcceleratoreAcceleratore
RIBs Facilities nel mondo
RIBs Facilities in Europa
CRC, Louvain-la-Neuve, Belgiumdelivering ISOL beams since 1989
SPIRAL, Caen, Francedelivering IF beams since 1984delivering ISOL beams since 2001
REX-ISOLDE, Geneva, Switzerlanddelivering ISOL beams since 2001
GSI, Darmstadt, Germanydelivering IF beams since 1990
MAFF, Munich, Germanyunder construction
SPES, Legnaro, Italyproject
LNS-Catania-ItalyLNS-Catania-ItalyEXCYT: ISOL EXCYT: ISOL Under commissioningUnder commissioningFRIBS: IF since 2001FRIBS: IF since 2001
Production Yield
I = N12345
cross-section, : primary-beam intensity,N: target thickness,1: product release and transfer efficiency,
2: ion-source efficiency,
3: efficiency due to radioactive decay losses,
4: efficiency of the spectrometer,
5: post-accelerator efficiency.
N = Luminosity
I = Intensità particelle prodotteI = Intensità particelle prodotte
driver acceleratoror
reactor
thin target high-temperature thick target
fragment separator
experiment• detectors•spectrometers• ...
ion source
mass separator
storage ring
In Flight (IF) Isotope Separator On Line (ISOL)
heavy ions-fusion-fragmentation
light and heavy ions, n, e-spallation-fission-fusion-fragmentation
post accelerator
30 A MeV-GeV eventually slowed down
s
meV to 100 MeV/u
ms to several s
good beam quality
gas cell
~ ms
Confronto fra i due Metodi
Metodo ISOL
Isotopes Isotopes SeparationSeparationOnOnLineLine
•Driver ad alta intensità (Dissipazione Calore)•Targhette di produzione (Raffreddamento e Radioattività)•Efficienza Selezione(20%) •Efficienza di estrazione (30%)•Efficienza di Trasmissione alla Sorgente(30%)Potenza (W)= I V = I (Energy/Charge state)
Es: I=1mA E=50 A MeV di O16 completamente strippato (O8+) :P = 1 10-3 (50 16/8) 106 =100 kW
Beam
Metodo ISOL
Ottima qualità dei Fasci
secondary = productionNtarget beam x release – transport
x ionization
x transport - storage - post-acceleration
Isecondary/Itotal
Intensity
Purity
Event rate
Icounts(reaction) = Isecondary branching reaction
x Nsecondary target
x spectrometer
x detector
Icounts(decay) = Isecondary branchingx detector
Peak to backgroundRresolving power
(suppression of background, identification of events)
Figure di Merito
ISOL Running Facilities
Location Year Driver Post Accelerator
CRC, Louvain-la-Neuve, Belgium
1989 Cyclotron p, 30 MeV,
200A
cyclotronsK = 44 and
110
SPIRAL, GANIL, Caen, France
2001 2 cyclotronsheavy ions up to 95 MeV/u
6 kW
cyclotronK = 265
2 - 25 MeV/u
REX-ISOLDE, CERN, Geneva, Switzerland
2001 PS boosterp, 1.4 GeV, 2
A
linac0.8 - 2.2 MeV/u
HRIBF, Oak Ridge, USA
1998 cyclotronp, d, , 50 -100
MeV10 - 20 A
25 MV tandem
ISAC, TRIUMF, Vancouver, Canada
2000 synchrotronp, 500 MeV,
100 A
linac1.5 MeV/u
GANIL
GANIL-SPIRAL(ISOL)GANIL-SPIRAL(ISOL)
SPIRAL II
Louvain la Neuve (Belgio)
Louvain la Neuve
ISOLDE -CERN
Metodo In-Flight•Separazione ElettroMagnetica (Coktail di RIBS)•Uso di “Degrader”•Accettanza in angolo solido del FRS•RIBs non “monoenergetici”•Energia Energia incidente NON REGOLABILE
•Rese di Produzione più alte•Intensità di corrente 103 piu’ basse•Relativi problemi di radioattività •RIBs con vite medie piccole (<sec)
Overview of the Fragment Separation
Technique
DegraderQ1 Q2 Q3
Q4 Q5 Q6 Q7 Q8 Q9
Dipole 1
Dipole 2
Production Target
Final Focus
Intermediate Focus
RIBs IF-Running Facilities
In Flight
GANILNSCL-MSUGSIRIKENDUBNALANZHOULNS
C Cycl.C Cycl.sSISCycl.C Cycl.sCycl.Cycl.
SISSI+LISEA1200FRS or ESRRIPSACCULINNA&COMBAS
RIBLLFRS-CT
<95 A MeV<200 A MeV<1.2 A GeV<150 A MeV<100 A MeV<80 A MeV<50 A MeV
Laboratory Accelerators RIB Separator RIB Energies
(msr) P/P (%) MaxB(Tm) Length (m)
FRIBs 4.0 +/- 1.1 4.0 23
Present 1.1 +/-0.65 2.7 23
GANIL-LISE 1.0 +/-2.5 3.2 18
GSI-FRS 0.7-2.5 +/-1 9-18 74
RIKEN 5.0 +/-3 5.76 21
NSCL-A1200 (A1900)
0.8- 8 +/-1.5 5.4 22
JINR 6.4 +/-1 4.5 14.5
Fragment Separators
Magnetic rigidity
The force qvB on a charged particle moving with velocity v in a dipole field of strength B is equal to it’s mass multiplied by it’s acceleration towards the centre of it’s circular path.
2
2
qc
Av
q
p
q
mvB
mvqvBF
Curvature
radius
which can be written as:
B is called magnetic rigidity
If we put in all the correct units we
get:
B = 33.356·p [KG·m] or:
B = 3.3356·p [T·m] (if p is in
[GeV/c])
Magnetic Dipole (I)
A dipole is the ion-optical equivalent of a
prismA dipole introduce dispersion, i.e. a relation between momentum and positionA/q selection with a certain acceptance in momentun width
00
0
p
p
p
pp
Reference momentu
m
Reference trajectory
DIPOLE SELECTION
Magnetic dipole (II)Here we consider two different types of dipoles, represented by two examples: ALADIN:: A Large Acceptance DIpole magNet dipole magnet of the FRS (Fragment Recoil Separator)
ALADIN: to evaluate the velocity of a fixed charged particle (momentum reconstraction): once B is know by the measurement of the trajectory of the ion, the evaluation of the velocity can be done if the A/Z of the charged particle is already known.
Large acceptance in angle and momentum
FRS dipole: Magnetic selection in mass, charge state and speed.
Limited acceptance in angle and momentum
Only particles with a limited range of bending radii, centered around 0, can pass. The binding radius 0 is defined by the geometry of the magnet.
Quadrupole (I)
Magnetic field
Hyperbolic contour
x · y = constant
A Quadrupole has 4 poles, 2 north and 2 southThey are symmetrically arranged around the
centre of the magnetThere is no magnetic field along the central axis
On the x-axis (horizontal) the field is vertical and given by: By x
On the y-axis (vertical) the field is horizontal and given by: Bx y
The field gradient, K is defined as:
)( 1Tmdx
Bd y
Quadrupole (II)
A pair of quadrupoles with a drift section in between is the ion-optical equivalent of a lens.
Force on particles
It focuses the beam horizontally and defocuses the beam vertically.
Rotating this magnet by 90º will give a vertical focusing and an horizontal defocusing
Located in an intermediate focal plane on the beam line
Better separation of isotopes with the same A/q ratio
Reduction of “contaminants”
The relative energy loss in the degrader is given by:
With K: constant typical of the degrader A: nucleus mass e: thickness of the degrader Z: atomic number
Degrader
Thickness and material is chosen as a compromise between desired and undesired effects.
2qc
AvB
ENERGY STRAGGLING
ANGULAR STRAGGLING
NUCLEAR REACTIONS
INTENSITY LOSS
Wien Filter
For the selected nucleus the forces due to the two fields compensate each other:
The other ions are deviated No p dispersion
B
EvqvBqE
E
BLarge
velocity
Small velocity
Optical Coordinate System
The coordinates of each particle are defined in term of the reference particle
We need 6 variables to characterize the particle in the phase-space:
(ion-optics convention on phase space)x,y are positions or displacement from the central orbitx’ ,y’ are angles with respect to the central orbit l is the path length difference is the fractional momentum deviation from the
assumed central trajectory
ds
x’x
dxx s
Central orbit
xs plane
),,,,,( lyyxxp
VerticalHorizontal
Longitudinal
Matrix optics(I)The charge particle motion can be reduced to
a process of matrix multiplication
l
y
y
x
x
X
06661
21
1611
............
..................
..................
..................
...............
............
l
y
y
x
x
RR
R
RR
l
y
y
x
xThe action of a magnet on the particle coordinates is represented by a 66 matrix
The 6 variables are component of a vector
Each magnetic element has its own characteristic matrix TRANSFER MATRIX
The transfer matrix for a succession of magnet is the product of the transfer matrix for individual elements.
)1()2()3(...)()( RRRnRtR
Matrix optics(II)For a static magnetic system with midplane
symmetry:
0
565251
4443
3433
262221
161211
100000
100
0000
0000
000
000
l
y
y
x
x
RRR
RR
RR
RRR
RRR
l
y
y
x
x
The motion along x and y can be decomposed NO MIXED TERM
Achromatic Fragment Separator(I)
HOW TO DO IT
2 optical section (a,b) symmetric to each otherThe optic of the second section merely
compensate the dispersion caused by the first One-to-one image of the beam on target can
be obtained at the final focus
WHAT WE WANT
filter the nuclei of interest from other fragment collect as much as possible the nuclei of interest Produce an achromatic image of the primary
beam spot for further transport through other beam lines
ACHROMATIC: the total dispersion is zero
Achromatic Fragment Separator (II)
filter the nuclei with the same A/q ratio preserve the achromaticity of the separator
WEDGE SHAPED
Thicker degrader at the high velocity side Thinner degrader at the lower velocitity side
Achromatic Fragment Separator (III)
Fragment Separators
LISE
LISE at Ganil
LISE = Ligne d’Ions Super Epluchés (Super Stripped Ion Line)
secondary beam
dipole 1 wedge
Wien filtertarget
http://www.ganil.fr/lise/lise.html
dipole 2
LISE-GANIL
GSI-Darmstad
FSR@GSI
FRS of GSI
ESR - GSI
NSCL-MSU- USA
NSCL-MSU- USA
FribsIn In FFlight light RRadioactive adioactive IIon on BBeamseams
•2001-2003: RIBs Production with C(62 AMeV ), 40Ar and 58Ni (40 AMeV) and 20Ne (45 MeV) on Be target. •2004-2005: Transmission trough the LNS beam lines and First Experiment (EXPERA)
bersaglio secondario (ΔE,ToF) (x,y)
(A,Z), E
ione secondario
Si-Strip 1616
TaggingTagging
0
5
10
15
20
25
30
0 10 20 30 40N
ZNi+Al
Nuclei stabili
Ar+Be
C+Be
Ne+Be
FRIBs -LNS
RI-Beam factory: RIKENEuropean Separator On-Line
Radioactive Nuclear Beam Facility
GSI
New Projects of RIBs Facilities
EURISOL
Date: ???Site: ???
RIA-USA
Date: ???Site: ???
RIA
RIA
FAIR-GSI
2003
FAIR-GSI
FAIR-GSI
New FRS
Spectroscopy Facilities
New FRS Performances
New Storage/Cooling Rings
Mass Measurements
Mass Measurements
Mass Measurements
Mass Measurements
Mass Measurements:Why?
Pbar Production Target: Iridium 60mm thick Proton beam energy >29 GeV
Antiprotons Beam
High Energy Storage Ring and Detector Concept
High Energy Storage Ring and Detector Concept
L = 2·1032 cm-2s-1 ; p = 1.5 – 15 GeV/c
p
PANDA
6- 12 4
6 5
ΛΛ
-ΛΛ Λ
Ξ + C + He+t
He He+ π
He
p+
Very Neutron Rich Hypernuclei
•Detection and identification of Rare Nuclei•The end of Mendeleev’s table: superheavies•Measuring and predicting the limits of nuclear existence
•Explaining complex nuclei from basic constituents•Doubly-magic nuclei and shell structure far from stability•Nuclear structure, rp-process•Nuclear size and shape, r-process•The size of the nucleus: halos and skins
•Understanding the origin of elements•Nucleosynthesis (rp-process, r-process)•Lifetimes/-decay studies
•Isospin dependence of the nuclear force•Neutron stars•Nuclear Calorimetry
•Testing the Standard Model•Applications in materials and life sciences•Radioisotopes for Medical Imaging
Physics
•Interaction cross section•Elastic and Inelastic scattering •Charge exchange•Knockout or Stripping reactions •Heavy-ion collisions•Giant dipole resonance•Coulomb excitation (2+)•Direct measurements.
• Production of longer lived neutron rich isotopes
• Connection to newly synthesized elements
New Elements
19B and 22C are bound
Shell Model Calculation
16Be is not bound 16Be is not bound
No Evidence for 16Be
H. Sakurai et al., Phys. Lett. 448B, 180 (1999)
Search for 28O / Existence of
31F
-------------------