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Radioactive Ion Beams: where are we now experimentally?
M. Huyse
K.U. Leuven
Moriond, March 2003
Opening page
The exploration of the chart of nuclei
284 isotopes with T1/2 > 109 yearOur beams till 1989 !
The exploration of the chart of nuclei
<1940495
The exploration of the chart of nuclei
<1940 1940 495 822
Reactors: n on U
The exploration of the chart of nuclei
<1940 1940 1950 495 822 1244
First Isotope Separator On-Line (ISOL) experimentNiels Bohr Institute 1951fast n on U: Kr and Rb isotopes
The exploration of the chart of nuclei
<1940 1940 1950 1960495 822 1244 1515
Selective detection method: decay
The exploration of the chart of nuclei
<1940 1940 1950 1960 1970
495 822 1244 1515 2010
Light-ion induced spallationHeavy-ion induced fusion
The exploration of the chart of nuclei
<1940 1940 1950 1960 1970 1980495 822 1244 1515 2010 2270
Projectile and target fragmentation+
In-flight separation
The present chart of nucleistable+ decay- decay decayp decayspontaneous fission
Around 3000 of the expected 6000 nuclei have been observed
-Explaining complex nuclei from basic constituents-The size of the nucleus: halos and skins-Isospin dependence of the nuclear force-Measuring and predicting the limits of nuclear existence-Doubly-magic nuclei and shell structure far from stability-The end of Mendeleev’s table: superheavies-Understanding the origin of elements-Testing the Standard Model-Applications in materials and life sciences
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
GeV eventually slowed down
s
meV to 100 MeV/u
ms to several s
good beam quality
gas cell
~ ms
IF versus ISOL
First generation Radioactive Beam Projects in Europe
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
First generation Radioactive Beam Projects
Location Start Driver Post-accelerator
Upgradeplanned
CRC, Louvain-la-Neuve, Belgium
1989 cyclotronp, 30 MeV, 200A
cyclotronsK = 44 and
110
SPIRAL, GANIL, Caen, France
2001 2 cyclotronsheavy ions up to 95
MeV/u6 kW
cyclotronK = 265
2 - 25 MeV/u
new driver
REX-ISOLDE, CERN, Geneva, Switzerland
2001 PS boosterp, 1.4 GeV, 2 A
linac0.8 - 2.2 MeV/u
energy upgrade
4.3 MeV/u
HRIBF, Oak Ridge, USA
1998 cyclotronp, d, , 50 -100 MeV
10 - 20 A
25 MV tandem
ISAC, TRIUMF, Vancoucer, Canada
2000 synchrotronp, 500 MeV, 100 A
linac1.5 MeV/u
energy upgrade
6.5 MeV/u
CYCLONE 110
CYCLONE 30
CYCLONE
CYCLONE 44
Ion Source
Target
CYCLONE 30
CYCLONE
CYCLONE 44
Ion Source
Target
Louvain-la-Neuve: focus on nuclear astrophysics
30 MeV p + 13C => 13N + n
13N + p => 14O +
Hot CNO cycle
Louvain-la-Neuve: nuclear physics
c.m.
• d/d (mb/sr)
• 4He(6He,6He)4He
• Ec.m. = 11.6 MeV
6He + 238U
4He + 238U
6Li + 238U
4He + 238U
6He + 238U fusion-fission 6He + 4He elastic scattering
J. L. Sida et al. PRL84 (2000) 2342 R. Raabe et al. PLB458 (1999) 1
E (keV)
Neutron pick-up of 30Mg (T1/2=0.3 s)
30Mg + 2H 31Mg + 1H
10.000 atoms/sec
2.23 MeV/u31Mg
16N (from beam contamination)
REX-ISOLDE - CERN + MINIBALL array
76Kr + 208Pb
500.000 atoms/sec
2.6 - 4.4 MeV/u
Coulomb excitation of 76Kr (T1/2=14.6 h)
SPIRAL - GANIL + EXOGAM array
First results from SPIRAL and REX-ISOLDE
Mass measurements
N=Z
Ge70 Ge72 Ge73 Ge74
Se74
As75
Ge76
Se76 Se77 Se78
Kr78
Br79
Se80
Kr80
Br81
Kr82
Sr84
P
P
P
Ge62 Ge63 Ge64 Ge65
As65
Se65
Ge66
As66
Se66
Ge67
As67
Se67
Ge68
As68
Se68
Ge69
As69
Se69
As70
Se70
Br70
Kr70
Ge71
As71
Se71
Br71
Kr71
As72
Se72
Br72
Kr72
As73
Se73
Br73
Kr73
Sr73
As74
Br74
Kr74
Rb74
Sr74
Ge75
Se75
Br75
Kr75
Rb75
Sr75
As76
Br76
Kr76
Rb76
Sr76
Ge77
As77
Br77
Kr77
Rb77
Sr77
Ge78
As78
Br78
Rb78
Sr78
Y78
As79
Se79
Kr79
Rb79
Sr79
Y79
Br80
Rb80
Sr80
Y80
Kr81
Rb81
Sr81
Y81
Rb82
Sr82
Y82
Rb83
Sr83
Y83 Y84 Y85
34
35
36
37
38
Z = 39
(H. Schatz et al. Phys. Rep. 294 (1998) 167)
possible waiting points
possible rp - process main path
mass excess not yet measured (AME95)
ISOLTRAP measurements2000 - 2002
before 2000
As63 As64
rp-process
Super-allowed Fermi -decay74Rb (T1/2=65 ms)
m = 4.5 keV (m/m = 6 10-8)
0
ISOLTRAP
AME95
CSS2 (GANIL)A.S. Lalleman et al., Hyp. Int. 132 (2001) 315
Rare Isotope Accelerator: RIA
RI-Beam factory: RIKEN
GSI
European Separator On-LineRadioactive Nuclear Beam Facility
• Experimental aim of the second generation facilities figure of merit for the study of exotic nuclei x > 1000
• Technological challenge increase the global selectivity and sensitivity increase the secondary beam intensity
The new generation of Radioactive Beam Facilities
RIA expected yields
1,0E+00
1,0E+02
1,0E+04
1,0E+06
1,0E+08
1,0E+10
Ni Cu Zn Ga
yiel
d (a
t/s)
A=78
79
80
7776
78Ni
RIA expected yields78Ni: 70 at/s
100Sn: 8 at/s
Intensity and Selectivity
secondary = productionNtarget beam x release – transport
x ionization
x transport - storage - post-acceleration
Isecondary/Itotal
Intensity
Purity
Event rate
Icounts(reaction) = Isecondary branching reaction Nsecondary target
x spectrometer
x detector
Icounts(decay) = Isecondary branching
x detector
Peak to background
Rresolving power
(suppression of background, identification of events)
Figures of Merit (in first approximation)
78Ni @ 3-5 MeV/uEx(2+-0+) = 4 MeV
B(E2)=500 e2fm4
(Coulex) 100 mbNsecondatytarget
(58Ni)= 3mg/cm2
Ntarget (238U, = 100 pbarn) = 100 g/cm2
Countrate estimate
“Ideal (realistic?)”
Icounts(2+-0+) (minimum)
10 cts/day
x spectrometer 10 %
Isecondary(78Ni) 375 at/s
post-accelerator 50 %
ionization 50 %
release 50 %
Ibeam (p, 1 GeV) 19 A needed!!
needs pure conditions
modestintensity!
An example: Coulomb excitation of 78Ni at an ISOL system
“Ideal (realistic?)”
Now Gain factor
Ibeam (p, 1 GeV) 100 A direct(5000 A indirect)
10 A 10(> 500)
release 50 % 0.1 % 500
ionization 50 % 10 % 5
post-accelerator 50 % 10 % 5
Isecondary(78Ni) 2000 at/s 58 at/h 105
x spectrometer 10 % 1 % 10
104
beam purity?
78Ni produced at an ISOL system: rates
Now(1) Proposed Gain factor
Ibeam (238U, 1 GeV/u) 1010 at/s 1 1012 at/s 100
in-flight separator 3 - 6 % ( 5%)
30 – 60 % ( 50%) (2) 10
Isecondary(78Ni) 35 at/h 10 at/s (3) 1000
(1) based on the first identification of 78NiC. Engelmann et al., Z. Phys. A352 (1995) 351
* I(238U) = 2 107 at/s* in-flight separator = 1.6%
* I(78Ni) = 0.5 at/day
(2) GSI: Conceptual Design Report
(3) RIA: I(238U) = 2 1013 at/s @ 400 MeV/u I(78Ni) = 70 at/s
! ! !Nsec. target
(IF) = 100 x (ISOL)but
Low energy backgroundand
Doppler correction
78Ni produced at an IF system: rates
Stopping of fragments in a gas cell (I)
100 cm
30 cm0.5 – 1 bar
Delay(ms)1000
100
10
1
0.1
Argon
Helium
0.01 0.1 1 10 E/N(10-17 V . cm2)
G. Savard @ ANL
Heavy-Ion Beam
High-power target
Range bunching
Gas catcher
Low energy beam
• range bunching• stopping of reaction products in buffer gas• electrical fields (AC and DC)
• remove electrons (neutralization)• drag ions towards exit hole
1
10
100
1000
10000
1,E+03 1,E+06 1,E+09 1,E+12 1,E+15
Q (ion-e pairs/cm3s)
Sat
ura
tion
fie
ld (
V/c
m)
Sugaya
Ahmed
Sato
0.1 cm
1 cm
10 cm
50 cm
1
2
3
4
5
heavy-ion ion guide
fission ion guide
Shiptrap
RADRIS
RIA
M. Huyse,- Nucl. Instr. Meth. B
• what is the intensity limit?
Stopping of fragments in a gas cell (II)
He (1 atm)
• laser ionization after the plasma has decayed• increased selectivity!
FragmentationG. Savard ,- @ ANL and GSIG. Bollen ,- @ MSUM. Wada ,- @ RIKEN
Laser ion source at ISOLDE
Energy (eV)
0
4
• efficiency up to 10 %• selectivity: depending on the implementation• applicable for many elements (universal)
high-temperature cavity
laser++
++
+
photo ionssurface ions
Laser Ion Source
• -decay of 78Cu at ISOLDE
78Ni0.2 s
78Cu0.34 s
78Zn1.5 s
78Ga5.5 s
78Ge88 m
78As1.5 h
78Se
N=50
Z=28
1
102
104 relative
J.M. Daugas et al. Phys. Lett. B476 (2000) 213
0+
(2+)
(8+)(6+)
(4+)
78Zn
908 keV
890 keV
730 keV
• p(1 GeV) + Ta-rod neutron• neutron + 238U 78Cu no deep spallation
The problem of selectivity: an example from ISOL
• laser ionization of Cu isotopes• -gated gamma decay spectrum
600 700 800 900 1000Energy (keV)
105
104
103
78Ga
78Cu
730 keV
890 keV
laser on
laser off
700 800 900 Energy (keV)
Production rates:
J.M. Daugas et al. Phys. Lett. B476 (2000) 213
0+
(2+)
(8+)(6+)
(4+)
78Zn
908 keV
890 keV
730 keV
)(
)(10
/4600)(
/6.0)(78
784
78
78
Ga
Cu
satGaP
satCuP
The decay of 78Cu
-200
0
200
400
600
800
1000
1200
30534,6 30534,8 30535 30535,2 30535,4 30535,6 30535,8 30536
Frequency of first transition (cm-1)
Inte
nsity
(arb
. uni
ts)
1+
3-
6-
(1+)
(3-)
(6-)
70Cu4
1
29
6.6(2) s
33(2) s
44.5(2) s0
100
200
(keV)
V. Fedoseev, U. Koster,J. Van Roosbroeck et al., ISOLDE
• laser ionization in a hot cavity• different hyperfine splitting for the different isomers• enhancement of specific isomers
• increase selectivity of laser ion sources• reduce power, pressure and Doppler broadening
Production of isomeric beams: 70Cum1,m2,g
production
ionization
purification
measurement:• identification• reaction / decay / g.s. properties• ...
acceleration / deceleration / storage
• high-power targets• geometrical optimization• radiation safety
• laser ionization (selectivity, isomeric beams)• release optimization, chemistry• gas cell (space-charge limit, laser re-ionization)• charge-state breeding vs. 1+ acceleration
• RF-coolers, traps(intensity limit, high-resolution mass separator)
• -identification• fast tracking of particles
• high-power accelerators
Outlook
