2007/6/5 International Nuclear Physics Conference 2007 1 Experiments on Searching for the Heaviest Elements Kosuke Morita Superheavy Element Laboratory

2007/6/5 International Nuclear Physics Conference 2007 1

Experiments on Searching for the Heaviest Elements

Kosuke Morita

Superheavy Element LaboratoryRIKEN Nishina Center, RIKEN


共同研究者collaborators

K. Morimoto RIKEN

H. Haba RIKEN

A. Yoneda RIKEN

D. Kaji RIKEN

T. Ichikawa RIKEN

H. Kikunaga RIKEN

T. Akiyama RIKEN, Saitama U.

N. Sato RIKEN, Tohoku U.

A. Yoshida RIKEN

T. Suda RIKEN

T. Ohnishi RIKEN

K. Rituparna TRIUMF

K. Katori RIKEN

E. Ideguchi CNS Univ. of Tokyo

T. Yamagichi Saitama U.

S. Goto Niigata U.

H. Kudo Niigata U.

A. Ozawa Univ. of Tsukuba

K. Sueki Univ. of Tsukuba

H. Koura JAEA

F. Tokanai Yamagata U.

Y-.L. Zhao IHEP/Beijing

H.-S. Xu IMP/Lanzhou

RNC Superheavy Element Laboratory


120

119

118

117

116

115

114

113

112

Rg

Ds

Mt

Hs

Bh

Sg

Db

Rf

162 184

262

266

265264

262

261

261

260259

258

257 258 260259

260 261 262

263

262261

SHE

A

A

A

-decay

Spontaneous fission

+ or EC decay

one end of nuclear chart ‘84


120

119

118

117

116

115

114

113

112

Rg

Ds

Mt

Hs

Bh

Sg

Db

Rf

162 184

262

266

265264

262

261

261

260259

258

257 258 260259

260 261 262

263

262261 263

265 266

267266

259

264

269 270 271

267266

262

272

268

269 270 271

277

278

273

274

261

270

265

263

264

267

267 268

268

271 272

271

275 276

275

279 280

279

278

281

284 285 286

282

282

283 284

283

287 288 289 290286

287 288

290 291 292 293

294

SHE

A

A

A

-decay

Spontaneous fission

+ or EC decay

one end of nuclear chart 2007


Hs

Bh

Sg

Db

Rf

Lr

No

Md

Fm

Es

Cf

Bk

Cm

Am

Pu

Np

U

Rg

Ds

Mt

238 239

239

240 241 242 243 244

240 242

240 241 242 243 244

247

245

246

248

245 246 247

246 247242 243 244

247 248 249 250 251

248 249 250 251

249 250 251 253252 254 255

256

257

255254253

245243 244

241

255254253252251250249248247246245244

252251250249248247246245

247246245244

246245244243

242

255254253252251250 257256

255254253252 257256 258

257 259258 260

261259258 260

261260

246244 248247

250 252251247 249248

253 255254250 252251

253 255254252 256

253 255254 256 257

255 256 257 258

258 259 260 261

261 262 264

264 265 267

266

269 270 271

266

262

272

268

277

262

273

261

273

269269

265265 266

270 271

262

263

263

261

260

259

258

259

262

260

259

262

258

259

265

256 257

278

274

270

266

262

272

268

264

260

256

271

269

263

259

253

265

261

257

253

113

112

271

271

272

267

267

268

268

275

275

276

279

279

280

278

281 282

283

283

284

282 285284 286

150 162

neutron capture + -decay

cold fusion reaction

hot fusion reaction

48Ca induced reactions


116

115

114113

112111

DsMt

HsBh

SgDbRfLrNoMd

EsCf

Fm

162

152

SF+ or EC-

170

176

Reactions studied at GARIS

265Hs 10 chains

277112 2 chains

271Ds 14 chains

272Rg 14 chains

278113

New !

208Pb(58Fe, n)265Hs208Pb(64Ni, n)271Ds209Bi(64Ni, n)272Rg208Pb(70Zn, n)277112209Bi(70Zn, n)278113


Cross sections

100 102 104 106 108 110 112 114

Atomic Number

1b

1nb

10nb

100nb

100pb

10pb

1pb

0.1pb

208Pb,209Bi(HI,1n) reaction

RIKEN


Yield – Cross section (sensitivity)

Y = ×T × B ×

typical value

Y event rate /s

cross section cm2 10-36 1 p-barn

T target thickness /cm2 1.3×1018 450 g/cm2

B beam intensity /s 4×1012 0.65 particle A

efficiency 0.8

Y= 4×10-6 /s → 1 event/3days


select the nuclei of ourinterest from the unwanted

then transport to thedetector chamber

Experimental setup

標的（金属薄膜）

incident ion beam（粒子の流れ）

イオン源

加速器

分離装置 (separator)

検出器 (detectors)

nucl. reaction

remove electrons from neutral atoms

accelerate ions using electric field information of energies or positionsof incoming ions and their decayparticles are transform to electric signal

18GHz ECR ion-source

理研 original

RFQ-Linac

GARIS



RILAC Facility

18GHz ECR Ion Source

RFQ-Linac

CSM 　 Acc. Tanks RILAC Acc. Tanks

GARIS

Beam Energy Monitor


beamDifferential pumping section

D1

Bending angle 45 degreePole gap 150 mm

Radius of central ray 1200 mm

Maximum field 1.54 T

Q1, Q2

Pole length 500 mm

Bore radius 150 mm

Maximum field gradient 5.2 T/m

D2

Bending angle 10 degree

Pole gap 160 mm

Pole length 400 mm

Maximum Field 1.04 T

Magnification X -0.76Y -1.99

Dispersion 0.97 cm/%Total length 5760 mmAcceptance ±68 mrad

±57 mrad 12.2 msr

Rotating Targetr 150 mm 2000 rpm

RIKEN Gas-filled Recoil Separator GARIS

D1 Q1 Q2 D2


MCP1MCP2

SSD box

PSD

ions

Focal Plane Detectors



period 2004/4/2 ～ 2004/5/24Beam Energy 346 MeV at target half depth

Total Dose 4.4x1018

Target Thickness 450 μg/cm2

number of events 2 0.44+0.59

-0.29 pb

Irradiation time 693 Hours (28.9 Days)Beam Intensity 1.76x1012 /s (0.3 p-A)Counting rate ～ 1 cps

Experimental condition 208Pb(70Zn, n)277112

J. Phys. Soc. Jpn., Vol. 76, No. 4, p.043201(2007)


277112

273Ds

269Hs

265Sg

261Rf

CN

11.09 ± 0.07 MeV1.10 ms23.57 mm

11.14 ± 0.04 MeV0.52 ms23.45 mm

9.17 ± 0.04 MeV14.19 s23.34 mm

8.71 ± 0.04 MeV23.02 s23.45 mm

197.3 MeV2.97 s23.41 mm

34.42 MeV23.33 mm

16-April-2004E (70Zn) = 349.5 MeV

Observed events at RIKENin 208Pb + 70Zn reaction

277112

273Ds

269Hs

265Sg

261Rf

CN

11.32 ± 0.04 MeV1.22 ms18.31 mm

11.15±0.07MeV (2nd trig. PSD+SSD)39.9 s20.18 mm

9.25 ± 0.07 MeV(PSD+SSD)0.270 s19.03 mm

8.70 ± 0.04 MeV79.9 s18.05 mm

156.3 MeV8.3 s18.50 mm

35.13 MeV18.45 mm

22-May-2004E (70Zn) = 349.5 MeV

Strip #8 Strip #11


277112

273Ds

269Hs

265Sg

261Rf

257No

253Fm

CN

11.45 MeV280 s17.85 mm

11.08 MeV110 s17.77 mm

9.23 MeV19.7 s17.81 mm

4.60 MeV7.4 s17.57 mm

8.52 MeV4.7 s17.96 mm

8.34 MeV15.0 s17.91 mm

32.04 MeV18.06 mm

277112

273Ds

269Hs

265Sg

261Rf

CN

11.17 MeV1406 s26.03 mm

11.20 MeV310 s26.01 mm

9.18 MeV22.0 s26.16 mm

0.2 MeV18.8 s27.33 mm

153 MeV14.5 s26.70 mm

24.09 MeV26.06 mm

09-Feb-1996E(70Zn) = 343.8 MeV

05-May-2000E (70Zn) = 346.1 MeV

Observed events at GSIin 208Pb + 70Zn reaction


ref.1 Hofmann S. et al., Z. Phys. A354, 229 (1996) 208Pb + 70Zn → 277112 + n2 Hofmann S. and Münzenberg G., Rev. Mod. Phys. 72, 733

(2000)

208Pb + 70Zn → 277112 + n

3 present 208Pb + 70Zn → 277112 + n4 present 208Pb + 70Zn → 277112 + n5 Lazarev Yu. A. et al., Phys. Rev. C54, 620 (1996) 244Pu + 34S → 273Ds + 5n6 Lazarev Yu. A. et al., Phys. Rev. C62, 064307(2000) 244Pu + 22Ne → 261Rf + 5n

GSI RIKEN FLNRref. 1 2 3 4 5 6

277112 11.45 11.17 11.09±.07 11.32±.040.28 ms 1.41 ms 1.10 ms 1.22 ms

273Ds 11.08 11.20 11.14±.04 11.15±.07 11.350.11 ms 0.31 ms 0.52 ms 0.04 ms 0.39 ms

269Hs 9.23 9.18 9.17±.04 9.25±.0719.7 s 22.0 s 14.2 s 0.27 s

265Sg 4.60 0.20 8.71±.04 8.70±.04 8.6374.0 s 18.8 s 23.0 s 79.9 s 158 s

261Rf 8.52 153 197 156 8.30±0.064.70 s 14.5 s 2.97 s 8.30 s 54+8

-4 s257No 8.34 8.22 8.24, 8.34

15.0 s 384 s 17 s


10s 1ms 0.1s 10s 1000s

277112 = 1.0 ms

273Ds = 0.24 ms

269Hs = 14 s

265Sg = 32 s

261Rf = 7.6 s

T_decay/s

RIKEN

GSI

N=165

N=163

N=161

N=159

N=157


0.25

14

1.0

32

7.6

277112273Ds269Hs265Sg261Rf

ms+0.25-0.08

s+14-5

ms+1.0-0.3

s+32-11

s+7.6-2.5

0.69 ms+0.69-0.23

9.7 s+9.7-3.2

0.17 ms+0.17-0.06

22 s+22-8

5.3 s+5.3-1.8

T1/2


period 2003/9/5 ～ 2006/5/15Beam Energy 5.03 AMeV

348 MeV at target half depth

Total Dose 6.2x1019

Target Thickness 1.3x1018 /cm2 (0.45 mg/cm2)_GARIS 0.8(2-ev.) 3.1x10-38 cm2

31 +40-20 fb

Irradiation time 5776 Hours (241 Days)Beam Intensity 3.0x1012 /s (0.5 p-A)

Summary of 209Bi + 70Zn experiment




year start stop hours

/days

dose/sum[x　1019]

[fb]

error+ error-

2003 9/5 12/29 1389/57.9 1.24/1.24 75.3(upper limit)

2004 7/8 8/2 526/21.9 0.51/1.75 55 130 45

2005 1/20 1/23 72/3.0 0.07/1.82 52 120 43

3/23 4/22 650/27.1 0.71/2.53 75 100 49

5/19 5/21 48/2.0 0.05/2.58 74 98 48

8/7 8/25 386/16.1 0.45/3.03 63 83 40

9/7 10/20 937/39.0 1.17/4.20 45 59 29

11/25 12/15 469/19.5 0.63/4.83 39 51 25

2006 3/14 5/15 1300/54.2 1.37/6.20 31 40 20

5776/241Total 2　events

2004 4/2 5/24 694/28.9 0.44 440 590 290

Z=112

Z=113


Masses of Beams & TargetsAudi & Wapstra, Nucl. Phys A565, 1 (1993)

Masses of Compound NucleiMyers & Swiatecki, Nucl. Phys. A601, 141 (1996)

Calculated threshold of fission after 1n emission

5 10 15 20Ex of C.N. (MeV)

20

10

4

2

1

0.5

0.3

0.20.1

(p

b)272Ds

273111

278112

279113


Sn

(A – n) + n

A

B + T

B + T + EcmSn

saddle point

DeformationBf

Second chance fissionsreshold

saddle point

Deformation

Energy diagram of 1n emission

Ecm

Ex(

CN

)



278113

274111

270Mt

266Bh

CN11.68 MeV (PSD)344 　 μs30.49 mm

11.15 MeV6.149+5.003 (PSD+SSD)9.260 ms30.40 mm

10.03 MeV 1.136+8.894(PSD+SSD)7.163 ms29.79 mm

9.08 MeV (PSD)2.469 s30.91 mm

36.75 MeVTOF 44.61 ns30.33 mm

23-July-2004 18:55 (JST)

1st chain

262Db

204.05 MeV(PSD)40.9 s30.25 mm

278113

274111

270Mt

266Bh

CN11.52 MeV (PSD)4.93 　 ms30.16 mm

0.88+10.43=11.31 MeV(PSD+SSD)34.3 ms29.61 mm

2.32 MeV (escape)1.63 s29.45 mm

9.77 MeV (PSD)1.31 s29.65 mm

36.47 MeVTOF 45.69 ns30.08 mm

2-April-2005 2:18 (JST)

209Bi + 70Zn → 278113 + n

262Db

192.32 MeV(PSD)0.787 s30.47 mm

2nd chain

s.f.s.f.

= 31 fb


10s 1ms 0.1s 10s 1000s

278113 = 2.6 ms

274Rg = 21.8 ms

270Mt = 0.82 s

266Bh = 1.89 s

262Db = 20.8 s

T_decay/s

RIKEN

N=165

N=163

N=161

N=159

N=157


10s 1ms 0.1s 10s 1000s

277112 = 1.0 ms

273Ds = 0.24 ms

269Hs = 14 s

265Sg = 32 s

261Rf = 7.6 s

T_decay/s

RIKEN

GSI

N=165

N=163

N=161

N=159

N=157


0

5

0

5

0

5

0

5

0

5

Cou

nts

/ bi

n 0

5

0

5

0

5

Cou

nts

/ 10

0 ke

V

E α / MeV

0

5

8 9 10 11 120

5

4

5

1

2

3

4

5

10000s100s1s10ms100s

Tdecay

252Md ← 256Lr ← 260Db ← 264Bh ← 268Mt ← 272111

=5.5ms

=30ms

=1.3s

=2.2s

=27s

　 α ３α ５ α ４ α ２ α １

(sec)

α １ α １

α ２ α ２

α ３ α ３

α ４α ４

α ５α ５

=27s

Journal of Physical Society of Japan (JPSJ) Vol. 73, (2004) 1738 - 1744


1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

156 158 160 162 164 166

112113113-2

Hin

dra

nce

Fac

tor

(Te

xp/T

calc)

dcZQbaZTcalc 10log

112DsHs

SgRf

113

RgMtBh

neutron number

1661641621601580.1

156

1

10

100

1000


Summary I

• 208Pb(58Fe,n)265Hs, 208Pb(64Ni,n)271Ds,209BiPb(64Ni,n)272Rg, 208Pb(70Zn,n)277112, and 209Bi(70Zn,n)278113 reactions have been studied.

• Independent confirmations of synthesis of elements 108, 110, 111, and 112

• Optimum reaction energies for (HI,n) reactions were studied

• New synthesis of an isotope of 113th element


Summary II

• 278113 was produced by 209Bi(70Zn,n) reaction.

• 278113()→274Rg()→270Mt()→266Bh()→262Db(SF)

• Identification was based on– connected to the known decays 266Bh()→262Db(SF)– reaction energy systematics– cross section systematics

• Z & A of 278113 are largest ones among the isotopes whose Z & A were determined experimentally.


・ Research in future ー Science of heavy elements ー

1)Searching for new elements

2)Spectroscopic study of heaviest elements

3)Chemistry of heaviest elements

4)Development of the new detectors for SHE study


Thank you for your attention.



1)Searching for the new elemets

Z=113 cont. 209Bi + 70Zn → 278113 + n

Z=114 start 208Pb + 76Ge → 283114 + n

Z=115 start 209Bi + 76Ge → 284115 + n ???

Z=120 start 238U + 64Ni → 299120 + 3n GARIS upgrade

cf. DUBNA 244Pu + 58Fe → 299120 + 3n


Cross sections

-8

-7

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

8

9

98 100 102 104 106 108 110 112 114 116 118 120

Z

log

(sig

ma/

nb

)

系列1

系列2

系列3

系列4

系列5

系列6

系列7

Uniform 2005.9Chart 1

Projectile

Projectile

Target

Target Pb Bi Pb

Bi

Pb Pb Pb Bi Pb Pb Pb Bi Pb Bi Pb Bi Pb Bi48Ca 48Ti

50Ti

51VPb

52Cr

Pb Pb54Cr

55Mn

Bi

58Fe 62Ni

Pb64Ni

65Cu

Bi

70Zn 76Ge 82Se 86Kr

STICK

STICK*DIFFUSE

STICK*DIFFUSE*SURVIVE

s(inj)=0, asymmetry drift f=0.47 f=0.47

Shell+2 MeV

Shell+2 MeV

Upperpoints

Lowerpoints

Calculated by Wladek Swiatecki Dec. 2005


122

121

120

119

118

117

116

115

114

113

112

111

110

109

108

107

106

105

104

103

102

101

100

99

98

186185184183182181180179178177176175174173172171170169168167166165164163162161160159158157156155154153152151150149

278

274

270

266

262

277

273

269

265

261

272

271

268

267

264

263

260

259

256

255

265

261

257

294

293292291290

288287

286 288 289 290

284283

282 283 284 285 286

280279

279 281 282

276275

275 278

272

271

267

267

268

268

287

296

302

308

299

293

305

272

232Th+40Ar

238U+58Fe

238U+64Ni

238U+70Zn284283

Z=120N=184

Magic number?

208Pb+76Ge


122

121

120

119

118

117

116

115

114

113

112

111

110

109

108

107

106

105

104

103

102

101

100

99

98

278

274

270

266

262

277

273

269

265

261

272

271

268

267

264

263

260

259

256

255

265

261

257

294

293292291290

288287

286 288289290

284283

282283284285286

280279

279 281282

276275

275 278

272

271

267

267

268

268

287

296

302

308

299

293

305

272

284283


2)Spectroscopic study of the heaviest elements

113 278

111 274

Mt 270

Bh 266Bh 265

α 線 γ 線の同時測定による励起状態の研究


3)Chemistry of the heaviest elements

Using GARIS as a pre-separator for chemistry experiments

excellent!! →Dr. Haba’s talk today

New GARIS for ONLY Chemistry experiment use??


4)New Detector for SHE Search

Independent Identifications of A & Z from decay-chain

High resolution E measurement

High resolution total-E detection ??


RILAC + GARIS + Chemistry

AVF + newGARIS + Chemistry

as a research center of Heavy Element’s Science in Asia


young powers!


0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

330 335 340 345 350

Elab　(MeV)

　(pb)

GSIRIKEN


Rotating Target = 300 mm, = 3000 rpm

Documents

2007/6/5 International Nuclear Physics Conference 2007 1 Experiments on Searching for the Heaviest Elements Kosuke Morita Superheavy Element Laboratory