nuclear structure studies via precision mass measurements · 2019. 5. 23. · nsd2019, venice 7...
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Nuclear structure studies via
precision mass measurements
Anu Kankainen
NSD2019, Venice 2
Nuclear structure via mass measurements
15.5.2019
Evolution of shell gaps Onset of deformation
ISOMERS
Shape coexistenceIMME, isospin symmetry Single-particle energies
In
Nucleon pairing energies
Sources: PPNP 91 (2016) 259; J. Phys. G 39 (2012) 093101 ; PRC 87 (2013) 024307
IGISOL facility in the JYFL
Accelerator Laboratory
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JYFL Accelerator Laboratory
15.5.2019
K-130 CYCLOTRON MCC-30/15 CYCLOTRON
1.7 MV PELLETRON
VARIAN cLINAC2100
University of Jyväskylä (JYU)Jyväskylä, Finland
FOUR ACCELERATORS
@jyflacclab
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IGISOL facility at JYFL Accelerator Laboratory
15.5.2019
NSD2019, Venice 6
IGISOL (Ion Guide Separator On-Line)
15.5.2019
Mass number A
RFQ Cooler& Buncher
- a fast and universal method to produce radioactive beams
K-130MCC-30
Offline ion source
Target chamber
He ~300 mbar
IGISOL-4: I.D. Moore et al., Nucl. Instrum. Meth. B 317 (2013) 208
Decayspectroscopy
JYFLTRAP:Masses and beam
purificationPost-trap decay
spectroscopy
Laser spectroscopy
J. Ärje, J. Äystö et al., PRL 54 (1985) 99
T. Eronen et al., Eur. Phys. J. A 48 (2012) 46
PRODUCTION METHODS: Fusion-evaporation Heavy-ion fusion-evaporation Proton/deuteron-induced fission Multinucleon transfer (in progr.)
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JYFLTRAP –
a cylindrical double Penning trap at IGISOL
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(1) PURIFICATION TRAP- Selecting the ions
(2) PRECISION TRAP- Mass measurements
nc
A=99 A=31
Mass-selective buffer gascooling technique
Savard et al., Phys. Lett. A 158, 247 (1991)
Time-of-Flight Ion CyclotronResonance (TOF-ICR) technique
M. König et al., Int. J. Mass Spectrom. Ion Proc. 142, 95 (1995)
7 T superconducting solenoid
(1) (2)
𝜈𝑐 = 𝜈+ + 𝜈− =𝑞𝐵
2𝜋𝒎
Ion’s cyclotronresonance frequency:
B with a reference ion:𝑚 =
𝜈𝑐𝑟𝑒𝑓
𝜈𝑐𝑚𝑟𝑒𝑓 −𝑚𝑒 +𝑚𝑒
mass
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Nuclides measured with JYFLTRAP
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JYFLTRAP:• Over 340 nuclides measured
~100 neutron-deficient~220 neutron-rich~20 stable
• More than 50 isomeric states
• Typical precisions: ~10 ppbTHIS TALK
Neutron-rich rare-earth
isotopes
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Neutron-rich rare-earth isotopes
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• 21 rare-earth isotopes measured
• 14 masses measured for the first time
• Mainly TOF-ICR, recently also PI-ICR
• Campaign I: M. Vilén et al., PRL 120, 262701 (2018)
• Campaign II: in preparation
Motivated by the rare-earth abundance peakin the astrophysical r process
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Nuclear structure motivation: N=100?
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Z. Patel et al., PRL 113 (2014) 262502
Local maximum at N=100 - deformed shell closure?Suggested by mean-field calculations [L. Satpathy and S.
Patra, Nucl. Phys. A 722, (2003) C24 & J. Phys. G 30 (2004) 771]
E.F. Jones et al, Eur. Phys. J. A 25 (2005) 467
164Gd (N=100) more rigid than 160,162GdChange in structure at N=98?
Gammasphere
EURICAat RIKEN
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Two-neutron separation energies S2n
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Onset of deformation
No change at N=100
163Gd g.s. measured
M. Vilén et al., PRL 120, 262701 (2018)
No clear indication of a subshellclosure at N=100 based on two-
neutron separation energies
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Neutron separation energies Sn
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Less odd-evenstaggering
(weaker pairing) than predicted by the
models
Lower for N = 96, 98, 100, 102Higher for N = 97, 99, 101
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Neutron pairing
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𝐷𝑛 𝑁 = (−1)𝑁+1 𝑆𝑛 𝑍,𝑁 + 1 − 𝑆𝑛(𝑍, 𝑁) = 2Δ3(𝑁)
Empirical neutron pairing gap orodd-even staggering parameter
Experimental neutronpairing weaker than
predicted by theoreticalmodels when approaching
the midshell!
M. Vilén et al., PRL 120, 262701 (2018)
Nuclei close to 78Ni
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Mass measurements close to N=40 and N=50
15.5.2019
Measured several new isotopes close to N=40 and N=50 at JYFLTRAP
L.C. Canete, S. Giraud, A. Kankainen, B. Bastin et al., in preparation
N=40 N=50
75Ni+
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Phase-Imaging Ion Cyclotron Resonance
technique (PI-ICR): resolving low-lying isomers
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ME = -50976(7) keV
Jπ = (3,4) T1/2 = 637.7(55) ms
E* = 0#(200#) keV
Jπ = (1,3) T1/2 = 1.27(30) s
JYFLTRAP: PI-ICR, tacc = 200 ms
cyclotron motion
g.s.m1
center
E*
?NUBASE
2016
Two half-lives (TRISTAN):J. A. Winger et al, PRC 42, 954 (1990).
Mass of 76Cu (638 ms state; ISOLTRAP):C. Guenaut et al., PRC 75, 044303 (2007);A.Welker et al., PRL 119, 192502 (2017).
76Cu+
JYFLTRAP: TOF-ICR, TRF = 1120 ms
76Cu+
m1 g.s.
76Cu
JYFLTRAP: estimate for T1/2
There are two states!
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Systematics of Cu isotopes
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Vingerhoets et al., PRC 82 (2010) 064311
76Cu?
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Shape coexistence in the 78Ni region: 79Znm
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Collinear laser spectroscopy at ISOLDE
X. F. Yang et al. PRL 116, 182502 (2016)
Large!
Isomeric state with an exceptionally largeroot-mean-square radius and spin 1/2+
Excitation energy from masses:Ex= [m(isomer)-m(g.s.)]c2
JYFLTRAP TOF-ICR measurements
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Systematics of N=49 isotones
15.5.2019
X. F. Yang et al., PRL 116, 182502 (2016)
Shell evolution when moving further away from stability
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N=40 subshell closure
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Measurements of 67Fe and 69,70Co at JYFLTRAP
N=40 subshell closure below 68Ni weak
Previous measurements of 68Co and 69Co [Izzo et al., PRC 97, 014309 (2018)] most likelymeasured the isomer, not the ground state anomaly in the S2n plot
Ground and isomeric states determined for 69Co at JYFLTRAP location of the 1/2- intruder state at N=42
L. Canete, S. Giraud, A. Kankainen, B. Bastin et al., submitted
Nuclei close to 132Sn
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Neutron-rich silver isotopes
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ENSDF
Measurement campaign at the IGISOL facility 2018 - 2019 Excitation energies and more accurate ground-state mass values (PI-ICR) Spins of the states (laser spectroscopy)
Z=40 subshell closure Comparison to shell
model predictions
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128In and 130In studied with TOF-ICR and PI-ICR
15.5.2019
All three states in 130In resolved and measured with PI-ICR
TOF-ICR PI-ICR
𝜋0𝑔9/2−1
𝜈0ℎ11/2−3
𝜋0𝑔9/2−1
𝜈0ℎ11/2−1
128In:
130In:
Close to 132Sn
Isospin symmetry
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Isobaric Multiplet Mass Equation at A=52
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Charge-independence
D. A. Nesterenko, AK et al., J. Phys. G: Nucl. Part. Phys. 44 (2017) 065103
JYFLTRAP:52Co (g.s.+m)
52Fe, 52Mnd=6.0(32) keV
Conclusions:Compatible with d=0No big changes above A=40
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Isospin symmetry in the heavier mass region
• Precision measurements of TZ=+1 nuclei: 82Zr, 84Nb, 86Mo, and 88Tc
• 88Tcm and 89Ru (TZ=+1/2)measured for the first time
• 89Ru more bound than predicted in AME16
• MDE predictions for 82Mo and 86Ru alsomore bound and more precise than AME16 extrapolations
15.5.2019
M. Vilen et al., to be submitted
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Summary and outlook
• Penning traps are versatile tools to study nuclear
structure via nuclear binding energies
• PI-ICR method opens new possibilities to study low-lying
isomeric states unreachable with other techniques
• MR-TOF to be installed before JYFLTRAP later this year
decay spectroscopy with purified beams (MONSTER)
mass measurements
15.5.2019
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Acknowledgements
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ERC CoG MAIDEN
This work has been supported by the Academy of Finland under grants No. 275389, 284516, 312544 and the Finnish Centre of Excellence Programme 2012-2017
(Nuclear and Accelerator Based Physics Research at JYFL). This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 771036 (ERC CoG MAIDEN). We thank for the bilateral
mobility grant from the Institut Francais in Finland, the Embassy of France in Finland, the French Ministry of Higher Education and Research and the Finnish Society of Science and Letters. We are grateful for the mobility support from PICS
MITICANS (Manipulation of Ions in Traps and Ion sourCes for Atomic and Nuclear Spectroscopy).
IGISOL group in Jyväskyläand all experimental and theoreticalcollaborations related to the presented work!
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