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Alpha-Photon Coincidence Spectroscopy of
Superheavy Nuclei
on behalf of the
TASCA & TASISpec Collaborations
20th Colloque GANIL, October 2017, Amboise, France
D. Rudolph, Lund University, Sweden
9.21(1) MeV10.5( ) s
288Mc
284Nh
280Rg
276Mt
272Bh
268Db
10.10(1) MeV 0.68( ) sγ 362, …
10.15(1) MeV4.4( ) sγ 237, …
10.2(1) MeV0.97( ) s
10.7(1) MeV0.17(2) s
27(3) h
1210
54
97
1511
Outline
• Introduction• Nuclear Structure Issues• Spectroscopy Tools• Future Efforts• Summary
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
100
120
114
162
184
108
152N
Z
α
β+ EC
SF
β-
Z=115?
108
100
114
120
152 162
184
Qα
Shell gap at Z=114?
E1Structure constraint!
Few atoms/nuclei per day – at most!
Where is the Island of Stability?Does it Exist in the First Place?
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
D. Rudolph et al., PRL 111, 112502 (2013)Top Ten APS Physics Newsmakers 2013
Probe & Guide Nuclear Structure Theory
I. Ragnarsson, priv. comm.;Yue Shi, PRC 90, 014308 (2014)
The [615]11/2+ orbital is bathing in a sea of NEGAtive-parity orbitals!
Parity-changing Δl =1 single-particle orbitals are required at β2~0.2!
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
EDF Single-particle Diagrams
The [615]11/2+ orbital is bathing in a sea of NEGAtive-parity orbitals!
UNEDF1SOL
110
114116
108
105 115
Yue Shi et al., PRC 90, 014308 (2014)
Fermi surface
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
EDF Single-particle Diagrams
The [615]11/2+ orbital is bathing in a sea of NEGAtive-parity orbitals!
UNEDF1 L
105 115
Yue Shi et al., PRC 90, 014308 (2014)
Fermi surface
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
100
120
114
162
184
108
152
(Reasonably) Current Status
Cn
N
Z
DsMt
HsBh
α
β+ EC
SF
β-
Rg
Fl
Z=119Z=120Z=118
Chemistry: Fl, Z=114
108
100
114
120
152 162
184
New Elements:50Ti + Actinides
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
McLv
TsOg
Nh
• EC-decay – no red ”squares”!?• Always one chain per isotope!?
Alpha-decay Reminder
Note: some experimental results somewhat simplified.
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Cn 2840.10 s
sf 100%
Fl 2880.64 s
α 9.93(3)
Even-even nuclei …
0+
288Flα
Qα,exp = Qα,theo
0+
284Cn bα hugeHF small
Alpha-decay Reminder
Note: some experimental results somewhat simplified.
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Cn 2840.10 s
sf 100%
Fl 2880.64 s
α 9.93(3)
Nh 285
Mc 289
Rg 281
sf 100%
115
114
113
112
111
Odd-even nuclei …
Ji289Mc
αQα,exp = Qα,theo
Jf=Ji285Nh bα huge
HF small
Alpha-decay Reminder
Note: some experimental results somewhat simplified.
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Cn 2840.10 s
sf 100%
Fl 2880.64 s
α 9.93(3)
115
114
113
112
111
Odd-even nuclei …
Ji289Mc
αQα,exp = Qα,theo
Jf=Ji
Jf≠Ji285Nh bα small
HF large
Nh 285
Mc 289
Rg 281
sf 100%
Alpha-decay Reminder
Note: some experimental results somewhat simplified.
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Cn 2840.10 s
sf 100%
Fl 2880.64 s
α 9.93(3)
115
114
113
112
111
Odd-even nuclei …
Ji289Mc
αQα,exp ≠ Qα,theo
Jf=Jiγ, CE, x rays
J~Jf285Nh
Alpha-photon coincidences!
Nh 285
Mc 289
Rg 281
sf 100%
Alpha-decay Reminder
Note: some experimental results somewhat simplified.
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Cn 2840.10 s
sf 100%
Fl 2880.64 s
α 9.93(3)
115
114
113
112
111
Odd-even nuclei …
Ji289Mc
αQα,exp ≠ Qα,theo
Jf=Jiγ, CE, x rays
ΔJ»2285Nh
X
Nh 285
Mc 289
Rg 281
sf 100%
Alpha-decay Reminder
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Cn 2840.10 s
sf 100%
Fl 2880.64 s
α 9.93(3)
115
114
113
112
111
Odd-even nuclei …
IiJi
285Nh α1Qα,exp ≠ Qα,theo α2
Jf=Ji
If = Ii281Rg
J ≠ I:Two parallel α-decay branches!
COMMON ACROSS the nuclidic CHART!
Nh 28522.6 s
α 9.58(5)
Mc 2892.35 s
α 10.37(5)
Rg 281 60.2 s
sf 100%
U. Forsberg et al., NPA 953, 117 (2016); PLB 760, 293 (2016); PhD thesis, Lund University
Nh 285
Mc 289
Rg 281
sf 100%
Nuclear Structure Theory 289Mc-285Nh-281Rg
Ene
rgy
(MeV
)0.4
0.2
0.0
energy density functional UNEDF1SO
ß2 0.08 0.13-0.15 0.20
[606]13/2
[615]11/2
[615]11/2
[521]1/2
[505]9/2[510]1/2
[512]3/2[512]3/2[512]3/2
[510]1/2
[510]1/2[505]9/2
[550]1/2
[550]1/2
[503]7/2
[503]7/2
α+ α+
α- α-
0.4
0.2
0.0
macroscopic microscopic #2
ß2 0.067 0.132 0.147
[606]13/2
[615]11/2
[615]11/2[521]1/2
[505]9/2
[510]1/2
[512]3/2
[512]3/2
[512]3/2 [510]1/2
[510]1/2
[503]7/2[550]1/2
[541]1/2
[503]7/2α+α+
α- α-
0.4
0.2
0.0
energy density functional UNEDF1
ß2 0.12 0.15 0.19
[615]11/2
[615]11/2
[615]11/2
[521]1/2
[505]9/2
[510]1/2
[512]3/2 [512]3/2[512]3/2[510]1/2
[510]1/2
[550]1/2[550]1/2
[503]7/2
[505]9/2α+
α+
α-
α-
0.4
0.2
0.0
macroscopic microscopic #1
ε2 0.057 0.045 0.082
[606]13/2
[615]11/2[615]11/2
[521]1/2[512]5/2
[503]7/2
[512]3/2
[521]1/2[510]1/2
[505]9/2
[512]5/2
[521]1/2
[503]7/2
[503]7/2
α+
α+
α-
α-
Ene
rgy
(MeV
)E
nerg
y (M
eV)
[606]13/2
[624]9/2
[606]13/2
I. Ragnarsson et al.
Yue Shi et al.
[606]13/2
[615]11/2
Ene
rgy
(MeV
)
A. Sobiczewski et al.
It is not about which model fits best:Pattern recognition!
Two separate α–decay sequences,high-Ω π = + and low-Ω π = –
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Generalized, i.e. model independent PATTERN predicted/expected:ALL hitherto observed decay chains startingfrom odd-A ISOTOPES of Fl, Mc, Lv, and Ts(Z = 114 - 117) should reveal at least
TWO INDEPENDENT DECAY CHAINS!
Where are they ?
• Insufficient data?• (Over)simplified interpretation?
9.21(1) MeV10.5( ) s
288Mc
284Nh
280Rg
276Mt
272Bh
268Db
10.10(1) MeV 0.68( ) sγ 362, …
10.15(1) MeV4.4( ) sγ 237, …
10.2(1) MeV0.97( ) s
10.7(1) MeV0.17(2) s
27(3) h
1210
54
97
1511
E115 – “Summary & Conclusions”
0.92
Open the modern spectroscopy toolbox …- fully pixelized Si detector system- complement with Ge array for photons- employ “digital” sampling electronics- cross-check with Geant4 simulations:
self-consistency physics-observations
~100 chainsDubna, GSI, LBNL
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Yu.Ts. Oganessian et al., PRC 87, 014302 (2013)J.M. Gates et al., PRC 92, 021301(R) (2015)
Results Decay Step 1: 288Mc→ 284NhStep 1 Step 1
10.3
0
Cou
nts
per c
hann
el
Z=114 gap!??
β2 ~ 0.2
GEANT4 simulations: 100000 decays, normalized to number of α’s
Cou
nts
per c
hann
el
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
• Optimize (new, 1.5 M€!) Ge solid-angle coverage x 1.4• Move into nominal TASCA focal plane x 1.4• Increase segmentation of the implantation DSSSD• Add & optimize active (ACS!) and passive shielding• (Increase primary beam intensity – cw-LINAC x ~5)
order of magnitude in sensitivity! nuclear spectroscopy on 1 pb level!
Future: “LUNDIUM” Chamber
Z=115
Z=114
Z=11X
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Infrastructure: COMPEX Scanning Table
90o scatter – 12 LYCCA modules108 CsI crystals
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Heavimet absorbers
3x 2-mm slits
32-channel Cologne preamplifiers + FEBEX3 read-out
x-y-arm, automated
Heavimet source canister (~1 GBq)Collimator: 100mm long, 1mm diameter
x yz
120
1st COMPEX test crystal
Summary & OutlookLUNDIUM Chamber & COMPEX Germaniums:- start: Q3 2016; test crystal: 1/2017; design fixed 9/2017; 1st test
capsule: 11/2017; 1st COMPEX: 1/2018; segm. COMPEX: 11/2018- construction of vacuum chamber and DSSSD upgrade: < 9/2018 - first experiment behind TASCA at GSI: 2019 (with some ACS)
Alpha-photon (γ rays and/or x rays) coincidence spectroscopy in the superheavy element regime itself is decisive for any nuclear-structure based understanding of the shell structure
of the heaviest elements.
D. Rudolph, Lund University 20th Colloque GANIL, October 2017, Amboise
Some problems:- Sensitivity for electron conversion (EC) decays?- Isotopic assignments / multiple chains from the same isotope:
Conclusive mass, A, (in progress) and proton number, Z , (feasible) measurements highly desirable!