G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Overview and Motivation
Mass Measurements at
ISOLDE …
… and elsewhere
Conclusions
Mass Measurements and Nuclear Structure
G. BollenNational Superconducting Cyclotron Laboratory NSCL
Michigan State University
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Rare Isotope Physics - an expedition by far not completed!
Limit of neutron-rich nuclei?
Limit of proton-rich nuclei?
Known Nuclei
HeaviestElements?
Possible
Nuclei
Binding energies determine limits of existence
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
How do mass measurements contribute?
Magic Numbers Evolution of Shell Structure
Magic Numbers Evolution of Shell Structure
Halos and SkinsHalos and Skins
Isospin SymmetryPairingExotic decaysFundamental Interactions
Isospin SymmetryPairingExotic decaysFundamental Interactions
r-processr-process
rp-pro
cess
rp-pro
cess
Stability of SHEStability of SHE
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Constraints for nuclear models
50 60 70 80 90 100 110 120 130 140
-10
-8
-6
-4
-2
0
2
4
6
8
10
Sp = 0 S
n = 0r-process
constraints for nuclear mass models
known masses
exp DusCZ Molal ComKZ SatNa Tachi SpaJo JaneMass MassJane Duflo LZe76 Pearson FRDM93 TF94 DuZu94m
odel
diff
eren
ce (
MeV
)
N (Z = 55)
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Nuclear Structure and Masses
835
840
845
850
855
860
865
In Cd Ag Pd Rh Ru Tc Mo Nb Zr Y Sr
Z (A = 100 isobars)
BIN
DIN
G E
NE
RG
Y (
MeV
) total binding energies
shell closure subshell deformationFe
Cs
50 56
two-neutron separation energies
Systematic study of masses – first indicator of new nuclear structure effectsSystematic study of masses – first indicator of new nuclear structure effects
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Tools for mass measurements on rare isotopes
Time-of-flight spectrometry
single turn: SPEG, TOFI
multi turn: cyclotrons CSS2, SARA,storage ring ESR
Conventional mass spectrometry
CERN-PS + ISOLDEChalk-RiverSt. Petersburg
Frequency measurements
storage ring ESR/GSI, future NESR, RIBF rings
RF transmission spectrometer MISTRAL/ISOLDE
Penning traps ISOLTRAP/ISOLDE, LEBIT/NSCL, JYFLTRAP/JYFL, CPT/ANLSHIPTRAP/GSI, TITAN/TRIUMF,
MAFFTRAP/Munich
c = q/m B
Out of Stock
Out of Stock
+ Q-values from reactions and decays
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
106
103
100
10-3
10-9
10-8
10-7
10-6
10-5
10-4
JYFL COOL
CPT
ESR SMS
ISOLTRAP
ESRIMS
MISTRAL
CSS2
SPEG
rela
tive
unce
rtai
nty
half life (seconds)
D. Lunney et al., Rev. Mod. Phys. 75, 1021 (2003). half life (seconds)
Time-of-Flight
TOF Schottky
RF-Spectrometer
Penning Trap
TOF Isochronous
LEBIT
Comparison of Methods
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Mass measurements far from stability at CERN
- CERN pioneered direct mass measurements far from stability- Na isotopes (SPS) discovery of island of inversion
- 11Li (SPS) first loosely bound exotic nucleus discovered
- Rb isotopes (ISOLDE) first subshell closure observed in long isotopic
chains
- ISOLDE pioneered new techniques for short-lived isotopes- Penning trap mass spectrometry + many related techniques (ISOLTRAP)
- RF mass spectrometry (MISTRAL)
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
RF
B
reference beam
MISTRAL: Mass measurements at ISOLDE with a Transmission RAdiofrequency spectrometer on-Line
ion counter ISOLDE60 kV beam
RF
1 m
magnet
slit 0.4 mm
Resolving Power R= 100000Sensitivity: 500/sFAST: very short T1/2
fc fc
frequency (kHz)
505000 505100 505200
tran
smit
ted
ion
sign
al (
coun
ts)
f = (n + ½) fc
D. Lunney/Orsay D. Lunney/Orsay
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Mass measurements of halo nuclei - 11Li
Graphics: I. Tanihata
100
150
200
250
300
350
400
450 MISTRAL2003
(preliminary)
AME95
Young93(reaction)
Wouters88(TOFI)
Kobayashi91(reaction)
Thibault75(mass spec.)
11Li
S2n
(ke
V)
MISTRAL:S2n=376(5) keV 20% higher than currently used to adjust models...
C. Bachelet, Ph.D. thesis (2004), EPJ A direct DOI: 10.1140/epjad/i2005-06-005-5
MIS RAL
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
New Paul-trapBeam cooler
Test run (Sept. 2005) :new mass for 12Be (T1/2 = 21 ms)
Test run (Sept. 2005) :new mass for 12Be (T1/2 = 21 ms)
11Be, 12Be, towards 14Be
MIS RAL
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
How magic are magic numbers?
H. Savajols et al., Eur. Phys. J. A direct (2005)
DOI: 10.1140/epjad/i2005-06-189-6
Island of Inversion
SPEG/GANILSPEG/GANIL
MISTRAL: n-rich Na and Mg isotopes with high precision
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
ISOLTRAP – triple trap spectrometer
G. Bollen et al., NIM A 368 (1996) 675H. Raimbault-Hartmann, NIM B 126 (1997) 378F. Herfurth et al., NIM A 469 (2001) 254
accumulation & bunching of ISOLDE
60 keV beam
coolingisobar separation
Rm
m
1 105
determination of cyclotron frequency
Rm
m
5 106
1m
B unc hes,3 keV ene rgy
60keV ISOLDE-
ion beam
1 cm
5 c
m
6 0 0 0 0 V
B = 4.7 T
B = 6 T
Linear RFQ trap
Mass measurement via determination of cyclotron frequency
c = (q/m)B
PRINCIPLE
0 1 2 3 4 5 6 7 8 9240
270
300
330
360
390
63Ga T1/2 = 32.4 s
Mea
n tim
e of
flig
ht /
s
Excitation frequency RF
- 1445125 / Hz
A. Herlert, K. Blaum A. Herlert, K. Blaum
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
32Ar32Ar
17Ne17Ne
74Rb74Rb
72Kr72Kr
216Bi216Bi
147Cs147Cs
232Ra232Ra
In 2002-2004
131 masses measured ()
rel. accuracy m/m 1·10-7
mean improvement: factor 40
33,34Ar33,34Ar
70Cu70Cu
~1000 / s
Highlights 2003 / 2004
Nuclide Half-life Uncertainty Yield
17Ne
32Ar
72Kr
74Rb
109 ms
98 ms
17.2 s
65 ms
~300 eV
1.8 keV
8.0 keV
4.5 keV
~1000 / s
~100 / s
~500 / s
22Na 2.6 y 160 eV ~106 / s
22Mg22Mg
ISOLTRAP harvest
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
0 10 20 30 40 50 60-60
-40
-20
0
20
40
60
A
1
-1
0
0 10 20 30 40 50 60-60
-40
-20
0
20
40
60
A
1
-1
0
0 10 20 30 40 50 60-60
-40
-20
0
20
40
60 Ground state quartets Excited state quartets Ground state quintets
x10
d /
ke
V
A
d /
ke
V
A = 33, T = 3/2 quartet:
A = 32, T = 2 quintet:
d = -0.13(45) keV
d = -0.11(30) keV
33Ar m = 0.44 keV32Ar m = 1.8 keV
33Ar m = 0.44 keV32Ar m = 1.8 keV
32,33Ar - most stringent test of IMME M = a + bTz + cTz
2 (+ dTz3)?
K. Blaum et al., PRL 91, 260801 (2003)
-40 -30 -20 -10 0 10 20 3080
100
120
140
160
180
200
220 32Ar T1/2 = 98 ms Y=100/s
Me
an
TO
F
(s)
RF - 2842679 (Hz)
Search for Scalar Currents from -delayed p-decay of 32Ar
E. G. Adelberger, A. Garcia et al., PRL 83 (1999) 1299 and 3101
Motivated by: Limits for Scalar Currents from -delayed p-decay of 32Ar can now be put on purely experimental ground
a = 1.0050 ± 0.0052(stat) ± (syst)
Limits for Scalar Currents from -delayed p-decay of 32Ar can now be put on purely experimental ground
a = 1.0050 ± 0.0052(stat) ± (syst)
ISOLTRAPISOLTRAP
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
35 40 45 50
10
12
14
16
18
Mn
SeAs
GeGaZn
FeCo
CuNi
S2n
(M
eV
)
NIs N = 40 magic? More measurements are required!
Towards exotic doubly magic nuclei - 78Ni
Evolution of nuclear binding towards doubly-magic 78Ni is not known nuclear structure – r-process
ISOLTRAPISOLTRAP
C. Guenaut PhD 2005EPJA direct 2005
81Zn
BRAND NEWBRAND NEW
+ n-rich tin isotopes up to 135Sn
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
270
300
330
360
390
Mea
n T
OF
/
s
270
300
330
360
390
Mea
n T
OF
/
s
0 2 4 6 8 10 12
270
300
330
360
390
Mea
n T
OF
/
s
c - 1300610 / Hz
16%
4%
80%
Intensity ratio:
with cleaning of 6– state
Unambiguous state
assignment!
Unambiguous state
assignment!
(6–) state = gs
(3–) state = 1.is
1+ state = 2.is
101(3) keV101(3) keV
242(3) keV242(3) keV
Identification of triple isomerism in 70CuISOLTRAPISOLTRAP
J. Van Roosbroeck et al., PRL 92, 112501 (2004)
c=q/m·B
RILISRILIS
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Mass measurement programs outside ISOLDE
TRAPS LEBIT NSCLat MSU
Fragmentation,
In-flight fission
Short-lived, non-ISOL elements
SHIPTRAP GSI Fusion-Evaporation Superheavies
p-rich
CPT ANL Fusion-Evaporation
Fission
p-rich and n-rich (selected regions)
JYFLTRAP JYFL IGISOL, Spallation, Fission
Non-ISOL elements
Storage Ring ESR GSI Fragmentation
In-flight fission
Schottky (large surveys T1/2>10s)TOF: short-lived
Spectrometer TOF
SPEG GANIL Fragmentation Short-lived, very exotic
Cyclotron TOF CSS2 GANIL Fragmentation Short-lived
+ reactions (unbound states, beyond the dripline) and decays
New projects: TITAN at ISAC (highly-charged ions), MAFFTRAP (n-rich)
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
SHIPTRAP – Towards SHE
precision measurements with heavy ions produced at SHIP/GSI
Fusion-evaporation reactionsFusion-evaporation reactions
M. Block/GSIM. Block/GSI
146Ho(#), 147Ho, 147Er(#), 148Er(#), 147Tb, 147,148Dy, 148Tm(#)
732216 732220 732224 732228 732232
120
122
124
126
128
130
me
an
TO
F /
us
excitation freq. / Hz
147Ho600ms exc. timeBRAND NEWBRAND NEW 147Ho
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
beam from A1900
9.4 T Penningtrap system
Low Energy Beam and Ion Trap Facility at NSCL/MSU
1 cm1 cm
~ 100 MeV/u~ 1 eV
Low-energyexperiments
1 cm
Gas stopping
LEBIT
Mass measurementsLaser spectroscopyPost Acceleration
Mass measurementsLaser spectroscopyPost Acceleration
Gas stopperBeam Buncher
Precision experiments at low-energies with rare isotopes from fast-beam fragmentation
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Secondary Beam 38Ca (92 MeV/u)
Statistical uncertainty m 80 eV
Expected final uncertainty m < 300 eV
• First successful nuclear physics
experiment with a thermalized beam
from fast beam fragmentation.
• 38Ca is a 0+ 0+ beta emitter: new
candidate for CVC tests.
• First successful nuclear physics
experiment with a thermalized beam
from fast beam fragmentation.
• 38Ca is a 0+ 0+ beta emitter: new
candidate for CVC tests.
Precision Mass Measurement of Fast Beam Fragments
m(38Ca++)/m(H30+)
37Ca++
T1/2 = 181 ms
67As+
… and more to come&
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Conclusions
Mass measurements are key to a better understanding of nuclear structure and important to other fields of research with radioactive isotopes
ISOLDE has a very strong mass measurement program- Experiments related to key topics: halos, evolution of shell structure, nuclear astrophysics, fundamental interaction tests- Two excellent experimental devices with significant development potential
Complementary programs exist worldwide– different techniques (PTMS, TOF, ESR) – different production methods
… still a lot to be done!
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Mass Measurements at RIA
Known masses
PTMS m < 50 keV
TOFMS m > 300 keV
RIA-TRAPwith 21 TeslaRIA-TRAPwith 21 Tesla
G. Bollen, INTC-NUPAC Meeting, CERN, Geneva, October 2005
Masses close to Z=82
Discussion within IBM & microscopic-macrosopic modelR. Fossion et al., NPA 697 (2002) 703
S. Schwarz et al., NPA 693 (2001) 533
ISOLTRAPISOLTRAP
Region of shape-coexistence with
interesting nuclear structure effects