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

-------------------