288Mc Alpha-Photon Coincidence Spectroscopy of · Alpha-Photon Coincidence Spectroscopy of...

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 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!


EDF Single-particle Diagrams


UNEDF1SOL

110

114116

108

105 115

Yue Shi et al., PRC 90, 014308 (2014)

Fermi surface


EDF Single-particle Diagrams


UNEDF1 L

105 115

Yue Shi et al., PRC 90, 014308 (2014)

Fermi surface


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


McLv

TsOg

Nh

• EC-decay – no red ”squares”!?• Always one chain per isotope!?

Alpha-decay Reminder

Note: some experimental results somewhat simplified.


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




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




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%




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%




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%



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 = –


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


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


• 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


Infrastructure: COMPEX Scanning Table

90o scatter – 12 LYCCA modules108 CsI crystals


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.


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!

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