Penning trap mass spectrometry

Penning trap mass spectrometry
of radioisotopes
Juha Äystö
University of Jyväskylä
V.-V. Elomaa
T. Eronen
U. Hager
J. Hakala
A. Jokinen
A. Kankainen
P. Karvonen
T. Kessler
I. Moore
H. Penttilä
S. Rahaman
S. Rinta-Antila
J. Rissanen
J. Ronkainen
A. Saastamoinen
T. Sonoda
C. Weber
Acknowledgements:
+ many collaborators around the world
AME2003, G. Audi et al., Nucl. Phys. A 729 (2003) 3
nuclear structure and nuclear astrophysics studies
Mass accuracy < 12 keV
AME2003, G. Audi et al., Nucl. Phys. A 729 (2003) 3
Accuracy required for fundamental physics
Mass accuracy < 1 keV
AME2003, G. Audi et al., Nucl. Phys. A 729 (2003) 3
Experimental approaches in
Penning trap spectrometry
TOF
z
c
⎛ δm ⎞
⎜
⎟≈
⎝ m ⎠ R ⋅ N ion
R = ν ⋅Tobs
I
ωc =
+
X
B
IMAGE
CURRENTS
AND FFT
qB
m
ωc = ω + + ω −
• RAMSEY EXCITATION
AND CLEANING
• HIGH CHARGE STATES
• OCTUPOLE EXCITATION
Cooling and bunching of low-energy RIBs
Nucl. Instr. Meth. A469, Issue 2
ISOLTRAP
JYFLTRAP
McGill at Montreal
Huge impact on:
- sensitivity in collinear laser spectrocopy (x 1055)
- optical pumping applications
- fast/efficient injection into Penning traps
Trap
Trap at
at ISOL
ISOL facility
facility
A. Herlert, et al., Int. J. Mass Spectrom. 251, (2006) 131
1 cm
B=6T
ISOLTRAP
B = 4.7 T
5 cm
1m
B u nch es,
3 k e V e n e rg y
6 0 k e V IS O L D E -
60 000 V
io n b e a m
Linear RFQ trap
Trap
Trap at
at fragmentation
fragmentation facility
facility
Low Energy Beam and Ion
Trap Facility LEBIT at NSCL/MSU
100 MeV/u
1 eV
Gas cell
1 bar He
100 MeV/u
beam
Degrader
system
Stop, extract and
select
isotope of interest
RFQ
ion guide
Beam cooler
and buncher
Mass filter
Pre-cooler
(Ne)
β,γ
9.4-T Penning trap
mass spectrometer
Trap
(He)
Test beam
ion source
Accumulate, bunch
( & break molecules)
G. Bollen, D. Davies, M. Facina, et al., Phys. Rev. Lett. 96, 152501 (2006).
Ion
detector
Cyclotron frequency
determination
FC
FC
MCP
Electrostatic
switchyard
Ion guide
Si
Si
7 T magnet
30 kV
30 kV
Purification scan
1400
101
1200
101
Counts
1000
800
Nb
TOF-resonance in Precision trap
101
Mo
Zr
600
400
200
101
120Pd
Y
0
1064700 1064750 1064800 1064850 1064900
Frequency [Hz]
Basic equations
for mass
determination
fc =
FWHM = 20 Hz
M/∆ M = 145 000
Spectroscopy
setup
}
}
FC FC
Purification
trap
Precision
trap
target
Dipole magnet
M/∆M ~ 500
Transfer line
Cyclotron beam
RFQ cooler
JYFLTRAP setup @ IGISOL
1 q
⋅ ⋅B
2π m
f c,ref
m - me
=
fc
mref - me
Storage rings and Penning traps
for high-accuracy measurements worldwide
Some highlights from TRAP facilities
SHIPTRAP
SHIPTRAP @
@ GSI:
GSI:
masses
masses of
of rp
rp nuclei
nuclei
Proton
Proton drip-line
drip-line nuclei
nuclei
CPT
CPT @
@ Argonne:
Argonne:
46
46V,
64Ge
V, 64
Ge
heavy
heavy fission
fission products
products
82
126
LEBIT
LEBIT @
@ MSU:
MSU:
38
38Ca,
70mBr,
68Se
Ca, 70m
Br, 68
Se
50
44
44S,
65Fe
66Co
S, n-rich
n-rich 65
Fe and
and 66
Co
82
28
20
8
ISOLTRAP
ISOLTRAP @
@ CERN:
CERN:
~300
~300 isotopes
isotopes measured
measured
22
32
72
22Mg,
74Rb,
81Zn,
133Sn
Mg,32Ar,
Ar, 72Kr
Kr 74
Rb, 81
Zn, 133
Sn
50
20
28
8
TITAN
TITAN @
@ TRIUMF
TRIUMF
9,11
9,11Li,
Li, 88He
He
JYFLTRAP
JYFLTRAP @
@ Jyväskylä:
Jyväskylä:
~200
~200 isotopes
isotopes measured
measured
23
23Al,
62Ga,
92Rh,
108Te
Al, 62
Ga, 92
Rh, 108
Te
83Ga,
110Mo
fission
fission products;
products; 83
Ga, 110
Mo
Evolution of precision
-11
10
-10
10
-9
10
-8
10
RF
Spectrometers
-7
10
-6
10
-5
10
Mass
Spectrographs
Reaction Q
-4
10
1930
1940
1950
1960
1970
1980
PTMS
1990
2000
From: K. Blaum, Physics Reports 425, 1 (2006)
Nuclear structure and mass
measurements
Nuclear mass-related observables
Absolute mass --- total binding energy --- Limits of nuclear existence
Mass differencies
First order derivatives
Nucleon (s. p.) binding energy (drip-line definition)
Nucleon-pair binding energy (S2N)
Decay energy (Qβ, Qα)
Coulomb displacement energy (Isospin multiplets)
Second order derivatives
Pairing energy (odd-even staggering)
Shell-gap energy (evolution of magicity)
Energy difference of spin-orbit partner states Æ Vs0(l.s)
Valence proton-neutron interaction energy δVpn
•• Nuclear
Nuclear structure
structure (10-100
(10-100 keV)
keV)
Global
Globalcorrelations
correlations(100
(100keV)
keV)
Local
(10keV)
keV)
Localcorrelations
correlations(10
•• shell
shellstructure,
structure,spin-orbit
spin-orbitinteraction,
interaction,pairing,
pairing,collectivity
collectivity
Drip-line
Drip-linephenomena
phenomenaand
andhalos
halos(1
(1keV)
keV)
•• Nuclear
Nuclear astrophysics
astrophysics (1
(1 keV)
keV)
•• Charge
Charge symmetry
symmetry in
in nuclei
nuclei (<1
(<1 keV)
keV)
Isospin
Isospinmultiplets
multiplets
Coulomb
Coulombenergy
energydifferences
differences
•• Test
Test of
of Standard
Standard Model
Model (<
(< 100
100 eV)
eV) δm/m
δm/m << 1·10
1·10-9-9
Nuclear
Nuclearββdecay.
decay.Electroweak
Electroweakinteraction
interaction
•• CVC
CVCtheory
theoryand
andunitarity
unitarityof
ofCKM
CKMmatrix
matrix(John
(JohnHardy)
Hardy)
•• Neutrinoless
(KlausBlaum)
Blaum)
Neutrinolessdouble
double ββdecay
decay(Klaus
100
Ca
48
78
Ni
Pb
208
132
Sn
Sn
J.Dobaczewski and W.Nazarewicz
Phil. Trans. R. Soc. Lond. A356, 2007 (1998)
Shell
Shell gap
gap energy
energy and
and magicity
magicity ??
New mass measurements of fission products
55
50
132Sn
STABLE
189 NEW MASSES
45
Z
100Sn
ISOLTRAP
ISOLTRAP at
at CERN
CERN
JYFLTRAP
T1/2 ≈ 100 ms
40
92Br:
35
Sn=3.2 MeV
30
78Ni
25
30
35
40
45
50
55
N
60
65
70
75
80
Discontinuity at N~60, Z~40
S2n(N,Z) = B(N,Z) – B(N – 2,Z)
Discontinuity of S2n observed for Sr-Rb isotopes at N=60
2.2
2.0
1.8
2
2
Charge radii <r > [fm ]
22
Zr
Y
Sr
Rb
Kr
1.6
1.4
β2=0.4
20
β2=0.2
18
1.2
16
1.0
β2=0.0
0.8
0.6
14
12
0.4
0.2
10
0.0
8
-0.2
48
50
52
54
56
58
60
62
Two-neutron separation energy [MeV]
Discontinuity at N~60, Z~40 – shape effect
64
Neutron number N
Collinear laser spectroscopy at JYFL:
Zr: P. Campbell et al., PRL 89 (2002) 082501
Y:B. Cheal et al., PLB 645 (2007) 133
JYFLTRAP:
U. Hager et al. PRL 96 (2006) 042504
U. Hager et al., NPA 793 (2007) 20
S. Rahaman et al., EPJA 32 (2007) 87
N=50 gap in γ-spectroscopy
N=28 and N=50 shell gaps
N=40 sub-shell closure
Evolution of N=50 shell gap:
Spectroscopic data with comparison to shell model
calculations give some indications of the evolution of the
gap, but quantitative verification is missing.
One possibility is to compare S2n values of even isotones
close to N=50 as a function of element number.
Two-neutron separation energies in 2003
?
J. Van de Walle, PRL 99 (2007) 142501
REX-ISOLDE
Two-neutron
Two-neutronbinding
bindingenergy
energyacross
acrossN=50
N=50
Experimental
Experimental N=50
N=50 shell
shell gap
gap
26
N=46
N=48
N=50
N=52
N=54
N=56
24
22
S2n [MeV]
20
18
16
14
12
Next critical masses:
82Zn, 77,79,81Cu, 76,78,80Ni
10
8
30
32
34
36
38
40
Proton number Z
42
44
46
Density functional theories
T. Otsuka, et al., PRL 97 162501 (2006)
M. Bender et al., PRC 73 034322 (2006).
M. Stoitsov et al., PRC 68 054312 (2003).
Mass measurements for nuclear astrophysics
Mass
Masspredictions
predictionsand
andr-process
r-processabundances
abundances
R-process
R-processabundances
abundancescalculated
calculatedwith
withthe
theHFBCS-1,
HFBCS-1,ETFSI-2
ETFSI-2and
andFRDM
FRDM
mass
models
in
the
framework
of
the
canonical
model.
mass models in the framework of the canonical model.
21
−3
9
The
, ,TT==1.2
××10
21cm −3
9K and τ = 2.1 s.
n ==10
Ther-process
r-processisischaracterized
characterizedby
byNN
10
cm
1.2
10
K and τ = 2.1 s.
n
S.Goriely, Hyperfine interactions 132 (2001) 105
Rp-process path for steady-state burning,
Xe (54)
I (53)
Te (52)
H. Schatz et al., Phys. Rev.Lett. 86, 3471 (2001)
•• Sequence
Sequence of
of (p,γ)
(p,γ) and
and (α,p)
(α,p)
reactions
reactions and
and beta
beta decays
decays
•• Nuclear
Nuclear physics
physics data
data scarce:
scarce:
•• Q-values
Q-values and
and S
Spp-values
-values
needed
needed
•• Proton
Proton capture
capture rate
rate
(p,γ)
(p,γ) ∝
∝ exp(-Q
exp(-Qpp/kT)
/kT)
JYFLTRAP
SHIPTRAP
LEBIT
CPT
100 new masses
of rp-nuclei
Sb (51)
Sn (50)
In (49)
Cd (48)
Ag (47)
Pd (46)
Rh (45)
Ru (44)
5758
Tc (43)
Mo (42)
Nb (41)
Zr (40)
Y (39)
Sr (38)
56
5455
Rb (37)
Kr (36)
Br (35)
Se (34)
53
5152
4950
As (33)
Ge (32)
Ga (31)
Zn (30)
45464748
424344
41
Cu (29)
37383940
Ni (28)
Co (27)
33343536
Fe (26)
Mn (25)
3132
Cr (24)
V (23)
2930
Ti (22)
Sc (21)
25262728
Ca (20)
K (19)
2324
Ar (18)
Cl (17)
2122
S (16)
P (15)
17181920
Si (14)
Al (13)
1516
Mg (12)
Na (11)
14
Ne (10)
F (9)
11 1213
O (8)
N (7)
9 10
C (6)
B (5)
7 8
Be (4)
Waiting points !
Example:
68Se(pp,γ)70Kr
68Se β+
Li (3)
5 6
He (2)
3 4
H (1)
0 1 2
59
λpp vs. λβ ?
Mass Measurements for Nuclear Astrophysics at LEBIT
68 69 70
29
30
31
32
37
Kr
36
Br
35
Se
34
66 67 68
As
33
65
64
Ge
32
Ga
31
Zn
30
N
Z
33
34
35
36
37
38
39
40
41
Æ 68Se poses a greater delay
60
68
Se
50
40
teff[s]
70 71
Rb
30
This Work
AME'03
20
N=Z
10
Network Calculation of Type I X-Ray Burst
0
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Temp. (GK)
Æ
are
largely
due
ÆThe
Theremaining
remaininguncertainty
uncertainty
are
largely73
dueto
tothe
the
65
69
unmeasured
masses,
e.g.
As,
Br
and
Rb
65
69
73
unmeasured masses, e.g. As, Br and Rb
P. Schury et al., PRC75(2007)055801
J. Savory et al., in preparation
New
Newdata:
data:SHIPTRAP
SHIPTRAPand
andJYFLTRAP
JYFLTRAP
N=Z
stable nucleus
Xe (54)
I (53)
JYFLTRAP 2007
Te (52)
JYFLTRAP 2006
Sb (51)
Sn (50)
JYFLTRAP 2005
In (49)
Half-life > 10 ms
Mass precision > 10 keV
Cd (48)
Ag (47)
Pd (46)
Half-life > 10 ms
Unknown mass
Rh (45)
Ru (44)
Tc (43)
Mo (42)
Nb (41)
Zr (40)
Y (39)
Sr (38)
N
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
9 32S beam impinging on 54Fe or natNi target
9 12 QEC and Sp values were improved (80-83Y, 83-86,88Zr and 85-88Nb)
9 Mass of 84Zr for the first time as well Sp-energies of 84Zr and 85Nb.
Mass excesses of Nb-isotopes
Proton separation energies
JYFLTRAP
AME2003
Sp(AME)-Sp(exp.) [keV]
800
600
400
200
0
-200
Large deviations compared to compiled
values [AME2003], which are based on the
beta-endpoint measurements.
88Nb
87Nb
86Nb
85Nb
88Zr
86Zr
85Zr
84Zr
83Zr
83Y
82Y
81Y
80Y
-400
9 Large discrepancies for for Nb-isotopes
9 Need to revise Sp-values, and thus the location
of the rp-process path
A. Kankainen, EPJA 29 (2006) 271
SHELL-GAP ENERGY AT N = 50
24000
AME2003
JYFLTRAP/ SHIPTRAP
ISOLTRAP
N
2
4
=
N
0
5
=
S2n / keV
20000
16000
N
8
5
=
12000
8000
29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
PROTON NUMBER Z
Charge symmetry effects in nuclear structure
Mirror nuclei and states
Isospin multiplets
Test of charge (in)dependence in nuclear interaction
Example of T=3/2 isospin multiplet
Mass energy
23Al
10
23Ne
23Mg
11
23Na
T=3/2, 5/2+
13
T=1/2, 3/2+
12
Switch on Coulomb interaction !
E.P. Wigner 1957 / pure Coulomb
New
New JYFLTRAP
JYFLTRAP data:
data:
23
23Al
23Mg
Al and
and 23
Mg ++ E
Eγγ(T=3/2)
(T=3/2)
IMME: M(A,T,Tz) = a + b Tz + c Tz2
± 310 eV
23Al
10
± 620 eV
± 150 eV
± 100 eV
± 370 eV
23Mg
11
23Ne
± 2.7 eV
23Na
12
13
A=23 is the most accurately known isospin multiplet
PR
A
N
I
M
I
L
E
!
Y
R
IMME:
Tzz ++ cc T
Tzz22 ++ dd T
Tzz33
IMME: M(A,T,T
M(A,T,Tzz)) == aa ++ bb T
?
A=
A= 23
23 quartet:
quartet: dd == 0.15
0.15 ±± .32
.32 keV
keV
perfect
perfect quadratic
quadratic fit
fit !!
ISOLTRAP
32Ar,33Ar,35K,36Ca
Weak interaction studies:
beta and double beta decays
Superallowed β Decay
Conserved-vector-current hypothesis:
– Vector part of weak interaction is constant
– Decay rate only a function of the vector coupling constant GV and the
matrix element
– For 0+ Æ 0+ (T=1) decays
Ft ≡ ft (1 + δ R )(1 − δ C ) =
K = product of fundamental constants
K
2GV (1 + ∆ R )
2
V
Corrections:
δC – isospin symmetry breaking correction
δR – radiative correction
∆R – nucleus independent radiative correction
ft = ft (Q , T1/ 2 , b, PEC )
5
Q
– Decay energy ⇔ mass m – δm/m<10-9
T1/2 – Half-life - δT1/2/T1/2 < 10-4
b
– Branching ratio - δb/b < 10-4
PEC – Electron capture fraction
Latest news: Ramsey cleaning applied in
54
54Co and 50
50Mn
QEC
value
measurements
of
EC
229 keV
1.75 min
290 ms
0+
50
197 keV
5+
β+
gs
1.48 min
7+
193 ms
0+
Mn
54
β+
gs
Co
β+
β+
0+ gs
stable
50
stable
Cr
T.
T. Eronen
Eronen et
et al.,
al., Phys.
Phys. Rev.
Rev. Lett.
Lett. 100
100 (2008)
(2008) 132502
132502
0+ gs
54
Fe
Ramsey method
Theory:
Martin Kretzschmar, IJMS 264 (2007) 122-145
Experimental:
Sebastian George et al., IJMS 264 (2007) 110121
T. Eronen, Piaski School, Poland, 2007
”Normal method”
”Ramsey method”
54mCo
54Co
QEC(50Mn)=7634.48(7) keV
(gs)
QEC(54Co)=8244.54(10) keV
Situation today
Q-value Half-life
62Ga
@ TRIUMF (2006-2008)
T1/2=116.100(22)ms, BR=99.858(8)%
Branching Ratio
34Ar, 34Cl
@TAMU (2006)
T1/2=843.8(4) ms,1.5268(5)s
38mK
@TRIUMF (2008)
BR=99.967(4)%
46V
@ ANL (2005)
Q=7052.90(40) keV
38mK
46V
@ Jyväskylä (2006)
Q=7052.72(31) keV
50Mn,54Co
@Jyväskylä (2007)
Q=7634.48(7), 8244.54(10) keV
26mAl,42Sc
@Jyväskylä (2006)
Q=4232.83(13),6426.13(21) keV
www.phys.utk.edu/witek/Talks/APS08.v5.ppt
Conclusions
•
Penning trap mass spectrometry has opened a new avenue in (mass)spectrometry of
exotic nuclei.
•
About 700 atomic masses measured with Penning traps to precision <10 keV
•
Mass differences are found sensitive probes of nuclear structure (deformation, shell gaps).
Evidence observed for the persistence of the neutron shell gap towards 78Ni.
•
Applications in nuclear astrophysics gain from precision.
•
Weak interaction studies profit from highest precision as well. (CKM unitarity test)
•
Improved binding energy data is hoped to assist theories to develope towards better
quantitative description of exotic nuclei.
•
JYFL mass data available now at: http://research.jyu.fi/igisol/JYFLTRAP_masses/
•
Comparison between AME95 and present data!!!