Superheavy Element Studies with TASCA at

Spectroscopy of Element 115
Decay Chains288115284113

D. Rudolph, Lund University, Sweden
280Rg

10.7(1)0.16( 32 )10.3(1)0.92( 16)
12

on behalf of theTASCA/TASISpec Collaboration

276Mt

272Bh

268Db

10.15(1)4.8( 86 )γ 194,237

10.10(1)0.70( 13)9γ 362,434,…

9.21(1)10.9( 21)1525( 43 ) h

ITO International Research Center Tokyo, 2014

Outline• Superheavy Element Issues• Experiments with TASCA at• Spectroscopy of 288115 and Daughters• E115 Recoil-α(-α)-Fission Chains• Conclusions

D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Main SHE Issues at Present• Quest for new elements:

E120
E119
• Confirmation of anticipated chains from elements

E118 & E117
• Z identification of presumed Z ≥ 113 decay chains

E115• Chemistry Z ≥ 113 – placement in Mendeleev’s table

E114• Comprehensive nuclear structure information bystudying ‘lighter’ isotopes (No, Lr, Rf, Db, Sg)
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

How to Synthesize Element 120?

Most promising reaction:
50Ti + 249Cf
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

TASCA 2011: The Hunt for Element 120
Ti+Cf
4cross section / fb

10Fe+Pu
Cr+Cm
Ni+U
SHIP '11 [3]560 fb DGFRS [2]400 fb
36 d~60 d SHIP '09 [1]31090 fb
116 d

102
110010

Zagrebaev (Myers/Swiatecki)
Siwek-Wilczynksa (Muntian)Adamian (Möller)
Adamian (Liran)
Liu (Möller)
Nasirov (Muntian)Kuzmina (Kuzmina)
Wang (Muntian)
Exp

50249
249
50Ti+Bestreaction:
Ti+Best reaction:
Cf Cfσσpredicted:~40fb
fb –– 11pb
pb
pred ~ 10TASCA[1] S. Hofmann et al., GSI Sci. Rep. 2008, p. 131[2] Yu. Ts. Oganessian et al., PRC79, 024603 (2009)[3] S. Hofmann et al., TAN 11, Sochi, Russia

200 fb39 d

Asymmetric(More) symmetric

Asymmetry
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

TASCA 2012: The Hunt for Element 119
50Ti + 249Bk → Element 119

4 months!

50Ti beam 0.75 μA and 249Bk targets with initial thickness ≈0.44 mg/cm2pAprilJuneMayJulyD. Rudolph, Lund University

AugustSeptember

Advances in Radioactive Isotope Science, Tokyo, June 2014

TransActinide Separator and Chemistry Apparatus
DSSSD State-of-the-Art Stop Detector ArrayD Q Q Configuration

6900 pixels
Target Chamber
144 mm side view

48 mmdigital DAQ ⇒ access tolifetimes down to 100 ns
2200
2000

Amplitude

1800
1600
1400
1200
1000

0Eα1τ

0.44 mg/cm2, 11 mg
19 atoms
E2.5∙10α2600 GBq β,γ(T1/2 = 320 days!)

Search for Element 119:
50Ti beam

50Ti + 249Bk, integral 3.6∙1019
12/s
IN:
5∙10analysis ongoing (40 TB!)

totalrate
J. Khujagbaatar et al.

~500/s500
1000
Time / channel

www.gsi.de/tasca
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

TASCA 2012: The Hunt for Element 119
50Ti + 249Bk → Element 119

4 months!

50Ti beam 0.75 μA and 249Bk targets with initial thickness ≈0.44 mg/cm2p

April

JuneMayJuly

August

48Ca+249Bk→Element 117

September

D. Rudolph, Lund University

October

September

48Ca+243Am→Element 115

NovemberAdvances in Radioactive Isotope Science, Tokyo, June 2014

E117: 4 chains from DGFRS

2 TASCA chains

J. Khuyagbaatar et al., Phys. Rev. Lett. 112, 172501 (2014)
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Main SHE Issues at Present• Quest for new elements:TASCA at

E120: 50Ti+249Cf, 9∙1018, 2011, 6 weeks, σ < 200 fb
E119 : 50Ti+249Bk, 6∙1019, 2012, 4 months, σ < 70 fb• Confirmation of anticipated chains of elements

E117: 48Ca+249Bk, J. Khuyagbaatar et al., PRL112, 172501 (2014)• Z identification of presumed Z ≥ 113 decay chains

E115 : TASISpec, 48Ca+243Am, November 2012• Chemistry Z ≥ 113 – placement in Mendeleev’s table2010 (2014)
E114 : 48Ca+244Pu, gas-phase,
A. Yakushev et al., Inorg.Chem. 53, 1624 (2014)• Comprehensive nuclear structure information bystudying ‘lighter’ isotopes (No, Lr, Rf, Db, Sg) t.b.p.
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

The TASISpec / TASCA E115 Collaboration
111, 112502 (2013)

Special thanks to …
UNILAC

D. Rudolph, Lund University

ENSAR

Advances in Radioactive Isotope Science, Tokyo, June 2014

Identification Problem Z > 112
Separation and implantation of fusion-evaporation products
Energy, position, and time correlation of implantation and decay
Alpha-decay chains into known isotopes
120ZLvFl

114

108

BhHs

Mt

Ds

Rg

Z=115

Cn

S.G. Nilsson et al.
NPA131, 1 (1969)

End points fission!

100

Direct measurement of atomic number Z !?
152

D. Rudolph, Lund University

162

SF

184

αβ+ ECN

β-Advances in Radioactive Isotope Science, Tokyo, June 2014

X-ray Fingerprinting of an Element
Moseley’s Law, 1913
HighestK-conversion
coefficients!
0 keV
28X
257Rf115

X-ray energies predicted down to
0.1 keV precision for superheavy
elements (QED!)

α-decay
9-11 MeV
8-10E(Kα) ~ f(Kα) ~ (Z-1)2
H.G.J. Moseley, Phil. Mag. 26, 1024 (1913)~200 keVK XM1rays!
decaysγ-decay
orinternalconversion~ 200 keV
0 keV
28Y253No
113

in the Rutherfordium spirit of
R. Bemis et al., PRL31, 647 (1973)(observed 15 α-photon events)
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

“Digital” (or Sampling) Electonics
25 Ge crystals

60 MHz dead-time free sampling ADC“FEBEX” cards developed at GSI-EE.

100 MHz commercial sampling ADCs,
4x SIS3302 cards, FPGA processed:- flat-top energy- baseline- pile-up flagging

Signal height (arb. units)

96 DSSSD p-sides

α2analog electronics:
false “10-MeV” event

α1That allows to …

time (16.7ns/channel)- restore baseline in software- retain (almost) nominal Ge-detector
energy resolution… at high counting rates.

- detect summing, reduce background- software optimization (MWD)
towards best possible resolution- large dynamic range (linear within
0.1-100 MeV, time-over threshold)

An absolute MUST!

Very helpful!
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014TASISpec – in Virtual GEANT4 Space
Self-consistent crosscheck of theexperimental findings
with as many virtual
element 115 decay
chains as one likes!

“Input level”: down to pixel-by-pixel dead-layer thicknesses …
“Output level”: takes care of summing of α, CE, and Auger energies …
L.G. Sarmiento et al., NIM A 667, 26 (2011)
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Results – 288115 (3n-channel)
22 chains (out of 30) of ours are compatible with the31 chains (out of 37) associated with the 3n channel 288115
by Oganessian et al.
16 prompt α-photon coincidences
2-3 of random origin expected288115photon energy (keV)

284113500

beam off
events280Rg

300

400 ns

276Mt

100
100
200
photon time (10ns per channel)

268Db

272Bh

10.10(1)0.70( 13)909.21(1)10.9( 21)15

10.15(1)4.8( 86 )

8

1

10.7(1)0.16( 32 )QαT1/2

1

10.3(1)0.92( 16)126

E1 Case280Rg → 276Mt

X-ray Case
276Mt → 272Bh(proper candidates)25( 43 ) hD. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Results – 288115 (3n-chain)
E1 Case280Rg → 276Mt

Step 3

K X rays
194

Step 3237

6x α-photon coincidences

GEANT4 simulations: 100000 decays, normalized to number of α’s

D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Results – 288115 (3n-chain)
M1 Case280Rg → 276Mt

Step 3IF Mother Nature had provided thesetransitions as M1 transitions, this would
have been THE perfect fingerprinting case!
K X rays
194

Step 3237

6x α-photon coincidences

GEANT4 simulations: 100000 decays, normalized to number of α’s

D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Results – 288115 (3n-chain)
E1 Case280Rg → 276Mt

Step 3

The fact that these transitions are E1
transitions puts exciting contraints on
nuclear structure theory!
K X rays
194

Step 3237

6x α-photon coincidences

GEANT4 simulations: 100000 decays, normalized to number of α’s

D. Rudolph, Lund UniversityAdvances in Radioactive Isotope Science, Tokyo, June 2014

Nilsson Single-particle Diagrams
Parity-changing Δl =1 single-particle orbitals are required at β2~0.2!
The [615]11/2+ orbital is bathing in asea of NEGAtive-parity orbitals!

I. Ragnarsson, priv. comm.;
Yue Shi, PRC, in press.
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

EDF Single-particle Diagrams
UNEDF1SOL
The [615]11/2+ orbital is bathing in asea of NEGAtive-parity orbitals!
114

116
110

108

105

115

Yue Shi et al., PRC, in press.

ARIS Poster PS2-A048
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

EDF Single-particle Diagrams
UNEDF1 L
The [615]11/2+ orbital is bathing in asea of NEGAtive-parity orbitals!

105115

Yue Shi et al., PRC, in press.

ARIS Poster PS2-A048
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Results – 291-x115 (xn-channel, x=2?)
7 chains (out of 30 TASISpec) are of recoil-α(-α)-SF type.
4 chains (out of 37 DGFRS) are of recoil-α-α-SF type.
All 4 are interpreted as the 2n channel 289115.
A “brute force” mapping of all those 11 short chains and thechains presumably starting from 293117 is no longer possible!
Proper statistical assessments,nuclear structure, and thepossibility of electron-capture
decays have to be considered!

A.V. Karpov et al., Int. J. Mod. Phys. E21, 1250013 (2012)
D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014

Summary & Conclusions
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- nuclear structure theory
Rg280288115

28411310.7(1)0.16( 32 )0.92

10.3(1)0.92( 16)12

10.15(1)4.8( 86 )γ 194,237

276Mt

10.10(1)
E115 Results:
0.70( )
Bhγ 362,434,…
30 decay chains compatible withprevious reports.
9.21(1)
Two X-ray candidates compatible
with E115.
10.9( )
X-ray fingerprintingDb is25(feasible(cf. 276Mt E1) !
)h293117/289115 story is far from “trivial” …
S.G. Nilsson et al.
1392722115268

43

NPA131, 1 (1969)

D. Rudolph, Lund University

Advances in Radioactive Isotope Science, Tokyo, June 2014