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!