Superheavy Element Research at the Gas-filled Separator TASCA

Superheavy Element Research

at the Gas-filled Separator TASCA

A. Yakushev; 16-th International Conference on Electromagnetic Separators, EMIS 2012, Matsue, 1-8.12.2012

Alexander Yakushev

(GSI Helmholtzzentrum für Schwerionenforschung GmbH)

for TASCA collaboration

http://th.physik.uni-frankfurt.de/~hicforfair/logo_gsi.png

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http://www.uni-mainz.de/

Outline

Introduction: TASCA – a gas-filled recoil separator for SHE

research

Status 2009: synthesis and chemical study of element 114, flerovium

TASCA research areas

Recent technical developments at TASCA

Main goal for 2011 and 2012: search for new elements with Ti-50

beam

Preliminary results of search for E120 and E119

Verification of TASCA capability: synthesis of E117 and

spectroscopy studies of E115


www.gsi.de/tasca

TransActinide Separator and Chemistry Apparatus – a

Separator for Actinide Based Reactions

M. Schädel, Eur. Phys. J. D 45 (2007) 67

A. Semchenkov et al., NIMB 266 (2008) 4153

Timeline 2002 goals defined

2003 community formed

2004 decision: gas-filled sep.

2005 start building TASCA

definition of commissioning prog.

2006 (Jan.) first beam in cave (Apr.)

first EVR measurements in FPD

2006-2008 TASCA commissioning

2008 The SHE region is reached!

2009 From ~nb (Z=104) to ~pb

(Z=114) cross section

2011-2012 Search for new elements with 50Ti


TASCA is a separator for SHE

from asymmetric reactions…

D Q1 Q2


DQhQv

HTM - High

Transmission

Mode

DQvQh

SIM – Small

Image Mode

…and a preseparator for SHE chemistry

TASCA deflects the primary beam and suppresses background from

transfer reaction products

Transmitted through a window EVRs are stopped in a gas and

transported to a chemical or detection device

EVRs Beam


Next talk by Dr. J. Even

Current International Collaboration Partners (SHE Chemistry / TASCA)

LBNL/UCB Berkeley (USA) U Lund (Sweden)

LLNL Livermore (USA) U Jyväskylä (Finland)

Vanderbilt U (USA) U Oslo (Norway)

ORNL Oak Ridge (USA) Chalmers U Gothenburg (Sweden)

UNAL Bogota (Columbia) PSI Villigen (Switzerland)

U Liverpool (UK) ITE Warschau (Poland)

U Surrey (UK) SINP Kolkata (India)

IMP Lanzhou (China)

JAEA Tokai (Japan)


2009: new focal plane detector and DAQ

48 mm

144 mm

6912 pixels

Stop detector: 144 “X” strips and 2x48 “Y” strips

Backward array: 72 mm deep, 8x 8 strips

Punch through: 2x 8 strips

In total: 320 signals from silicon

40x 8-ch. amplifiers with multiplexers

80 ADC channels + 4 32-ch. I/O registers


May June

Pre

pare

Beam

Setu

p /

Calib

rate

(48C

a+

206-2

08P

b)

48C

a+

244P

u

E*=

42

Me

V

48C

a+

244P

u

E*=

38

MeV

Beam preparation 3 days

Setup / Calibration 5 days

Element 114 Experiment 29 days

Total 30 days

Production of element 114 (HTM) (SIM)

48C

a+

244P

u

E*=

42

MeV

2009: Synthesis of 288,289114 at TASCA


HTM E* = 42 MeV

14 days of beamtime

HTM E* = 38 MeV

9 days of beamtime

a decay

SF

8 x 288114 (4n) 2 x 289114 (3n)

1 chains from 288114 (4n)

2 chains from 289114 (3n) Summary:

11x 288114

4x 289114

outside of

beam pulse HTM TASCA:

E114: (606)%

Observed decay chains


SIM E* = 42 MeV

6 days of beamtime

2 x 288114 (4n)

Error bars include statistical errors.

TASCA systematic error is estimated to 14%.

Dubna Data

Oganessian et al.,

J. Phys. G, 2008

TASCA HTM (E114): (606)%

Ch.E. Düllmann et al.,

PRL 104 (2010) 252701

Theory

V. Zagrebaev,

NPA 734 (2004) 164

10 pb! Largest s

for predicted

spherical SHE

3n

4n

Run 1 Run 2

Measured cross sections


100

120

114

162

184

108

152 N

Z

TASCA strategic areas after 2009

a

b+

EC

SF

b-


102 104 106 108 110 112 114 116 118 120

1E-15

1E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6 Projectile Target48

Ca,...,70

Zn + 208

Pb/209

Bi13

C,...,26

Mg + 238

U...249

Bk48

Ca + 238

U,...,249

Cf

cro

ss

sec

tio

n /

ba

rn

atomic number Z

Cross Sections in Hot / Cold / 48Ca Induced Fusion Reactions


100

101

102

103

104

Zagrebaev (Myers/Swiatecki)

Siwek-Wilczynksa (Muntian)

Adamian (Möller)

Adamian (Liran)

Liu (Möller)

Nasirov (Muntian)

Kuzmina (Kuzmina)

Wang (Muntian)

Exp

Ni+UFe+Pu

Cr+Cm

cro

ss

se

cti

on

/ f

b

Ti+Cf

Asymmetric

Asymmetry

(More) symmetric

Best reaction: 50Ti+249CfE120

s predicted: ~40 fb

The same is valid for E119

s predicted: ~55 fb

E120 cross sections:

current predictions from theory


293117

14 ms

289115

0.22 s

285113

5.5 s

281Rg

26 s

119 119

120 120 296120

7 ms

295120

40 ms

292118

0.3ms

291118

0.5ms

264Hs

0.5ms

271Bh

?

266Db

22min

282113

73 ms

278Rg

0.17 s

274Mt0

.45 s

270Bh

61 s

265Sg

16 s

166 168

170 172

174

270Hs

~23 s

271Hs

~4 s

269Hs

10 s

267Hs

49 ms

266Hs

2 ms

265Hs

2 ms

272Bh

9.8 s

275Mt

9.7ms

276Mt

0.73 s

263Rf

~8 s

N

271Ds

1.1ms

272Rg

1.6ms

267Db

1.2 h

261Rf

68 s

262Db

34 s

288114

0.8 s

284Cn

0.1 s

290116

29 ms

286114

0.36 s

113

109

110

112

293116

53ms

289114

2.7 s

285Cn

34 s

281Ds

9.6 s

270Ds

0.1ms

Rg

268Db

16 h

279Ds

0.3 s

275Hs

0.15 s

271Sg

2.4 m

267Rf

1.3 h

265Bh

1 s

264Bh

1 s

267Bh

15 s

266Bh

~1 s

266Mt

2 ms

267Sg

~1min

266Sg

0.4 s

264Sg

37 ms

Z

106 263Sg

1 s

262Rf

2 s?

263Db

27 s

284113

0.48 s

291116

18 ms

287114

0.5 s

283Cn

3.8 s

279Ds

0.2 s

114 114

290116

15 ms

286114

0.13 s

282Cn

0.8ms

278113

0.2ms 113 283113

0.1 s

277Cn

0.6ms Cn

288115

88 ms

287115

32 ms

279Rg

0.17 s

280Rg

3.6 s

273Ds

0.2ms

176

268Mt

42 ms

269Ds

0.2ms Ds

111

115 115

116 116

Mt

292116

18 ms

274Rg

6 ms

270Mt

5 ms

a SF

294118

1 ms 118 118

Hs

260Rf

21 ms

261Db

2 s

109

Sg 106 262Sg

15 ms

Db

Rf

Bh

50Ti+249Cf

50Ti+249Bk 292117

30ms

291117

6 ms

288116

2 ms

287116

0.4ms

Expected decay chains of E119 and E120 296119

0.2ms

295119

0.2ms

284114

0.5ms

283114

0.3ms

280Cn

0.3ms

279Cn

0.2ms

276Ds

0.3ms

275Ds

0.1ms

272Hs

0.1 s

268Sg

4 h

117 294117

78 ms

290115

16 ms

286113

20 s

282Rg

0.5 s

278Mt

7.6 s

274Bh

0.9 m

270Db

23 h

Z=120 Half-life: order of μs


Experimental challenges

1) Stable and reliable 50Ti beam

2) New target wheel for high

intensity beam

3) Production of 249Cf and 249Bk targets

4) New „fast“ electronics for μs-activities

5) Improved background suppression of TASCA

Ion source + UNILAC groups, Target lab

GSI + HIM

TASCA, GSI experimental electronics

LBNL, Berkeley; ÔRNL Oak Ridge; Inst. f.

Kernchemie, Uni Mainz; GSI target lab

GSI experimental electronics, Univ. Lund, Sweden, HIM

TASCA, GSI and LBNL, Berkeley, USA

1 pμA

J. Khuyagbaatar, 2012


A new ANalog/DIgital (ANDI) DAQ

system for µs-isotopes

PreAmp SpecAmp

ADC

Comp

MBS 1

Analog

Energy, X: Deadtime <50 μs

Preamplifiers Amplifiers ADC’s DAQ: MBS

PreAmp ADC Comp

MBS 2

Digital

Energy, Y: Trace length 50 μs

Sampling ADC

FEBEX 2

DAQ: MBS

Event Builder

EvB: MBS

0 500 1000 1500 2000 2500 30001000

1200

1400

1600

1800

2000

2200

Am

pli

tud

e

Time / channel

Sampling 65 MHz

1 ch≈17 ns

EFrontX=EbackY

EFront

Eback

J. Khuyagbaatar, 2012

Dead-time free! Lifetimes down to about 100 ns

can be measured

GSI EE


Background reduction

Efficiency loss for EVRs minimal, as confirmed in 48Ca+208Pb

J.M. Gates, 2010

Improvement compared to E114 run:

Event rate in FPD at

Br=2.28 Tm (E114 value)

Background reduction by factor ≥10

E114

312 pnA 48Ca

438 mg/cm2 244Pu

Rate: 1230 Hz

per 100 pnA / 0.5 mg/cm2

450 Hz

E120

750 pnA 50Ti

~500 mg/cm2 249Cf

Rate: 300 Hz

per 100 pnA / 0.5 mg/cm2

40 Hz


2 slits

2011: The search for E120 (50Ti + 249Cf)

August September October

Setu

p /

Ca

lib

rate

50T

i+176Y

b

Mo

un

t C

f ta

rget

50T

i+249C

f

E*=

42

MeV

Bro

ken

wate

r

pip

e W

X -

> G

SI

UN

ILA

C d

ow

n

Setup / Test / Calibrate 7 days

UNILAC operational for Cf ~39 days

Ion source service

2.4 days

Misc. breakdown

0.9 days

Standby (e.g., for SIS tuning)

0.9 days

Beam on target, data taking

~35 days


No E120 events

were found

One event cross

section limit 160 fb

2012: The 50Ti + 249Bk run to search for element 119

March 7 Arrival of 12,7 mg of 249Bk from Oak Ridge

March 25 Arrival of 249Bk target from JGU to GSI

April 4-8 Test reactions with 50Ti beam

April 13 Mounting of 249Bk target into TASCA

Sep 2 Beam dose 4,2E19

April May June

July August September

50Ti beam 750 nAp and 249Bk targets with initial thickness ≈0.44 mg/cm2.

No E119 events were found. Cross section limit 55 fb


102 104 106 108 110 112 114 116 118 120

1E-15

1E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6 Projectile Target48

Ca,...,70

Zn + 208

Pb/209

Bi13

C,...,26

Mg + 238

U...249

Bk48

Ca + 238

U,...,249

Cf

cro

ss

sec

tio

n /

ba

rn

atomic number Z

E119

E120

Search for E119 and E120: results


48Ca + 249Bk E117 48Ca + 249Am E115

Confirmation experiments

November September October

2 events in 4 weeks

Element 115: 48Ca + 243Am

25+ events in 3 weeks


Analysis is ongoing

Conclusions

• Many improvements of TASCA have been done since 2009:

new target wheel and safety system

background reduction

new digital electronics

stable and intense Ti-50 beam….

• First search for E119 and E120 with 50Ti beam 2011: 50Ti+249Cf; a cross section limit of 160 fb reached in 39 days

2012: 50Ti+249Bk; a cross section limit of 55 fb reached in 4 monts

• Confirmation experiments: synthesis of E117 and spectroscopy of E115

2 events of E117 in 4 weeks

25+ events of E115 in 3 weeks


Thank you for your attention!


On behalf of the whole TASCA collaboration

Superheavy Element Research at the Gas-filled Separator TASCA

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