Status report on the GABRIELA set-up.

A. Yeremina, O. Malysheva, A. Popekoa, A. Lopez-Martensb, K. Hauschildb, O. Dorvauxc  and GABRIELA collaboration

a FLNR, JINR, 141980 Dubna, Russia ;b CSNSM, IN2P3-CNRS, F-91405 Orsay Campus, France ;c IPHC, IN2P3-CNRS, F-67037 Strasbourg, France;

eremin@jinr.ru

● Programme Advisory Committee for Nuclear Physics 18th meeting, 7-8 April 2003A.Korichi “Possible future -ray experiments at FLNR using Ge detectors array.”● Programme Advisory Committee for Nuclear Physics 19th meeting, 13-14 November 2003A.Yeremin “Activity with -rays at FLNR.”● Programme Advisory Committee for Nuclear Physics 21st meeting, 18-19 November 2004A.Yeremin “First results on -spectroscopy experiments with heavy nuclei at FLNR.”● Programme Advisory Committee for Nuclear Physics 24th meeting, 6-7 April 2006K.Hauschild “Latest results on -spectroscopy experiments with heavy nuclei at FLNR.”● Programme Advisory Committee for Nuclear Physics 25th meeting, 13–14 November 2006A.Lopez-Martens “R&D of a separator at the beam of U400MR for γ-spectroscopic investigations of heavy isotopes.”● Programme Advisory Committee for Nuclear Physics 27th meeting, 24–25 January 2008A.Yeremin “Spectroscopy of heavy nuclei at FLNR: results and plans.”● Programme Advisory Committee for Nuclear Physics 31st meeting, 25–26 January 2010A.Yeremin “Status report on the GABRIELA set-up.”

● The joint JINR – IN2P3 (France) project entitled “Study of nuclear structure and nuclear reaction mechanism of heavy and superheavy elements: Gamma and electron spectroscopy of very heavy nuclei with Z ≈ 104” started in year 2004.

GABRIELA (Gamma Alpha Beta Recoil Investigations with the ELectromagnetic Analyser)

http://flerovlab.jinr.ru/flnr/vassilissa.htmlhttp://www.csnsm.in2p3.fr/-GABRIELA-?lang=en

● The scientific aims of the collaboration were approved by the Scientific Council of IN2P3 in December 2003 and by the Scientific Council of JINR in January 2004.

● The collaboration, which includes groups from CSNSM Orsay and IPHC Strasbourg for IN2P3 and for JINR, a group from the FLNR Laboratory, has led 5 experimental campaigns since 2004.

Status of GABRIELA set up

● Beams: U400 cyclotron: complete fusion reactions, SHE, spectroscopy, chemistry of transfermium elementsEbeam 2.5 – 20 A∙MeV Abeam 12 (C) - 209 (Bi) Intensity up to 1013 pps

● Experiment: VASSILISSA electrostatic separator: ERs production cross sections, decay propertiesERs transmission 2 – 40 %, transfers suppression 104, beam suppression 1012

● Detectors: GABRIELA set up: focal plane semiconductor detectors (alpha, electron) + Ge detectors (gamma)

● Modernization of VASSILISSA - SHELS (Separator for Heavy ELement Spectroscopy): Grant from ANR (435 k€) , FLNR budget support (approx. 600 k$)

● Reconstruction of U400 cyclotron. Start at August 2010.G. Gulbekyan “Accelerator Complex of Ion Beams of Stable and Radioactive Nuclides (DRIBs-3)” Programme Advisory Committee for Nuclear Physics30th meeting, 22–23 June 2009

Present

Future

5

Total view on FLNR cyclotronsand beam lines

VASSILISSA separator

Experimental set-up VASSILISSA + (α,)-detector array

Experimental hall of the U400 cyclotron

Experimental methods: Focal plane detector assembly

anticoincidence

tflight

= (T2-T

1)

T2

T1

TOF

(E + ECE

)

ER

'Backward - Detector'

'Backward - Detector'

'-Clover-Det.''Stop-Detector'

(E)

CE (ECE

)

(E + ER)

ER

(E) GABRIELA: Gamma Alpha Beta Recoil Investigation with the Electromagnetic Analyser

Experimental characteristics of GABRIELA

Detection Efficiency of7 Ge detectors ~ 5 - 10 %

Focal plane strip detector – alpha detection ~ 50 %

Detection of electrons in backward hemisphere ~ 10 - 20 %

Resolution of Gamma Detectors (600 keV) ~ 2.5 keV

Resolution of Alpha detectors (5500 keV)~ 20 keV

Resolution of electron detectors (200 keV) ~ 8 keV

Decay (focal plane) studiesα- (CE) - decay measurements

transitions gs(mother) gs (daughter) Q-value transitions gs(mother) excs (daughter) followed by γ, CE E* excited levels Multipolarity of transition(s) to gs or excs spin and parity assignments Q-value (if gs not or weakly populated) ( excs (daughter) might be isomeric ) transitions isoms (mother) isoms, excs, gs (daughter) E* isomeric levels spin and parity assignments (correlation between life-times and spin/parity differences)

ER-(CE) – decay measurements transitions isoms(mother) excs, gs (mother) E* isomeric levels spin and parity assignments

Regions of interests in spectroscopy with kinematic separators

New neutron deficient isotopes in polonium region (strong change of deformation, break of G-N law, shape coexistence,…)

Isomer study in Uranium, Radium and Radon region

Spectroscopy in transfermium region (K-isomers, single particle level systematic, decay properties…)

Nuclear structure studies

Neutron number

111

112

113

114

117

115

118

116

160

164 166162 168 170 172

174 176

152 158156154

240 sm

14.0 s

Bh

Hs

Mt

Ds

Db

Sg

Pro

ton

num

ber

150

Db

Rf

Lr

Rf

Lr

No

Md

Fm

Es

Cf

Sg

a

a

a

1.8 ms

10.01 9.95

10.85 10.74

11.65

9.82

10.53

9.169.54

10.00

10.4610.59

10.12

9.75

9.71

9.02

10.37

10.33

53 ms15 ms

32 ms 87 ms

6.3 ms

0.16 s

0.1 s

4.0 s

0.17 s

0.72 s

9.8 s

1.2 h 16 h

9.7 ms

0.48 s

0.1 s

3.6 s

0.18 s 9.6 s

34 s

0.56 s 0.63 s 2.7 s

100 sm

10.6616 ms

10.20

0.5 ms

9.70

0.15 s9.30

2.3 h

8.532.4 m

344 sm11.68

9.26 ms11.15

7.16 ms10.03

2.47 s9.08

1.3 s10.31

8.84 9.30

8.201.7 m360 ms

8.3 s5.8 s 12.0 h

1.2 h7.46

7.6 m8.86

54 sm 5.6 sm

24 s7 s

11.03

2.3 ms10.18 8.84

6.9 ms

148

0.94 s9.24

17.0 s8.83?

0.51 s9.47

Heaviest SHE - limited experimental data (E, T1/2)Deformed mid-shell nuclei: opportunity for detailed nuclear structure studies

Transfermium nuclei: Z > 100Shell-stabilized nucleiLarge density of sp levels, strong Coulomb field=> Heavy nuclei: demanding theoretical testing ground

Status of the GABRIELA campaigns1. First full scale experiment: September 23d – October 25th 2004,

2. 48Ca + 207,208Pb → 255,256No*, 48Ca + 209Bi → 257Lr*A. Lopez-Martens et al., Phys. Rev. C 74 (2006) 044303

2. October 3d – November 9th 2005, 22Ne + 238U → 260No*, 22Ne + 209Bi → 231Np*,

48Ca + 208,210210PbPb → 256,258No*, 48Ca + 209Bi → 257Lr*K. Hauschild et al., Nucl. Instr. and Meth. A 560 (2006) 388-394.A. Lopez-Martens et al., Eur. Phys. J. A 32, 245 - 250 (2007)

3. October 30th - December 4th 2006 22Ne + 238U → 260No*, 40Ar + 184W → 224U*; 40Ar + 181Ta → 221Pa*

Popeko A.G. et. al., Phys. At. Nucl, 2006, vol. 69, 1183-1187K. Hauschild et al.,Phys. Rev. C 77, 047305 (2008).

4. February 1st – March 10th 2008:40Ar + 182W → 218U+ 4n; 40Ar + 180Hf → 216Th+ 4n; 22Ne + 238U → 255No + 5n

K. Hauschild et al.,Phys. Rev. C 78 (2008) 021302(R)Yeremin A.V. et. al., NIM B 266 (2008) 4137-4142

5. February 9th – March 14th 2009:48Ca + 207Pb → 255No*, 40Ca + 159Tb → 199At*

48Ca + 181Ta → 224,225Np*

253

No

279

129

58

0

279

221 150

58

71

8280

129

Fm249

8001

5/2+ 167 31.0 sm

255Lr

110

60

0

8420

Md251

8470

502.5 sec

030 sec

8530

8320

8370160

14

Published results

In progress

Future experiment

Failure from 210Pbtarget

A. Lopez-Martens et al., PRC 74 (2006) 044303

A. Lopez-Martens et al., EPJ A32 (2007) 245

K. Hauschild, in progress

22Ne + 242 Pu

U218

Lr255

Year 2008 : 40Ar + 182W

K. Hauschild, Phys. Rev. C 78 (2008) 021302(R)

Summary of results and on-going analysis

Th216

Year 2008 : 40Ar + 180Hf

50Ti + 208Pb

Rf256Rf257

Year 2008, 22Ne + 238U

Summary of results and on-going analysis

249Fm : A. Lopez-Martens et al., PRC 74 (2006) 044303253No : A. Lopez-Martens et al., EPJ A32 (2007) 245255Lr : K. Hauschild et al., PRC 78 (2008) 021302R209Ra : K. Hauschild et al., PRC 77 (2008) 047305

255No → 251Fm217Pa → 213Ac213;214;217Th isomers

TechniqueK. Hauschild,et. al, "GABRIELA: A new detector array for -ray and conversion electron spectroscopy of transfermium elements." NIM A 560 (2006) 388

A. Yeremin, et. al., "Project of the experimental setup dedicated for gamma and electron spectroscopy of heavy nuclei at FLNR JINR.“ NIM B 266 (2008)4137

Physics

Analysis in progress

More than 15 reports on International conferences

GABRIELA campaign of year 2009

Improvements to Ge set-up + VASSILISSA transmission

Spectrum of gamma-rays in 249Fm obtained during the 2004 (blue) and 2009 (black) campaigns. The spectra correspond to the same beam dose on target.

GABRIELA campaign of year 2009

Size 60 x 60 mm2

48 x 48 strips,Resolution for ’s – 17 keV

The back face of the detector was equipped with 3 pre-amplification ranges, which allows it to be sensitive to low-energy conversion electrons (0-2 MeV), alpha's (0-20 MeV) and fission fragments (0-200 MeV).

Tests of double sided detector and new electronics

It allows to increase significantly CE detection efficiency

Plot of the logarithmic time difference between an implant signal in the DSSD and a decay signal in the same pixel of the DSSD as a function of decay energy. The alpha particle energies of 253No and 252No are indicated as well as the low-energy signal given by the isomeric decay of 253No.

K – Isomer in 253No

: Preliminary decay scheme of the ~700 micros isomer in 253No

Spectrum of gamma-rays observed in coincidence with the isomeric electron signal detected in the DSSD

K – Isomer in 253No

Isomer search in 255LrThe known low-lying -emitting spin–isomer was confirmed.

A new isomer with a half–life of t1/2=1.4(1) ms was observed

208Pb(48Ca,1n)255No -----> 251Fmα

-6 -5 -4 -3 -2 -1 00

2

4

6

8

10

12

14

Cou

nts

ln()

Alpa - correlationsTime differeence for

251Fm isomer, E = 198 keV Random

T1/2

= 24 msecPrompt

0 50 100 150 200 250 300 350 4000

5

10

15

20

Co

unts

Energy (keV)

115 keVK

121 keVK

135 keV137 keVK

198 keV24 msec isomer

219 keV

correelations for 251Fm

– correlation analysis

24.5 s 198

192

162358

Future plans: Advantage of Dubna

244Md

245Md

243Fm

244Fm

246Md

247Md

245Fm

246Fm

248Md

249Md

247Fm

248Fm

250Md

251Md

249Fm

250Fm

252Md

253Md

251Fm

252Fm

254Md

255Md

253Fm

254Fm

256Md

257Md

255Fm

256Fm

258Md

259Md

257Fm

258Fm

260Md

261Md

259Fm

260Fm

249Lr

250Lr

248No

249No

251Lr

252Lr

250No

251No

253Lr

254Lr

252No

253No

255Lr

256Lr

254No

255No

257Lr

258Lr

256No

257No

259Lr

260Lr

258No

259No

261Lr

262Lr

260No

261No

263Lr

264Lr

262No

263No

251Db

252Db

250Rf

251Rf

253Db

254Db

252Rf

253Rf

255Db

256Db

254Rf

255Rf

257Db

258Db

256Rf

257Rf

259Db

260Db

258Rf

259Rf

261Db

262Db

260Rf

261Rf

263Db

264Db

262Rf

263Rf

265Db

266Db

264Rf

265Rf

253Bh

254Bh

252Sg

253Sg

255Bh

256Bh

254Sg

255Sg

257Bh

258Bh

256Sg

257Sg

259Bh

260Bh

258Sg

259Sg

261Bh

262Bh

260Sg

261Sg

263Bh

264Bh

262Sg

263Sg

265Bh

266Bh

264Sg

265Sg

267Bh

268Bh

266Sg

267Sg

78Pt,79Au,80Hg,81Tl,82Pb,83Bi targets – « cold fusion »

90Th, 92U, 94Pu, 95Am, 96Cm targets – « hot fusion »

100

101

102

103

104

105

106

107

146 148 150 152 154 156 158 160

Present limits ≥ 3 -5 nb for decay≥ 50 - 100 nb for prompt

=> Acces to less neutron-deficient nuclei

263Sg

262Sg

Way to the asymmetric combinations

• Achievement: neutron rich isotopes, that could not be reached in more symmetric combinations.

• Disadvantage: very broad energy and angular distributions of recoils => low transmission of kinematic separators

Possible solutions

• Modernization of the kinematic separator, design for asymmetric combinations

• Alternative experimental installations (gas jet, gas jet + ISOL)

Improvements to experiment:

2) Modified Ge detector => higher gamma detection efficiency

1) New Si detectors : larger + more strips => 2 x ERs detection efficiency, higher CE detection efficiency

2) ToF : thinner windows => less straggling

Tx * D ~ (3-5) x

● Improvement to experimental set up (slow ERs transmission)

1) New ion optical scheme => 2 x efficiency

● Improvement of detector array

Velocity filter for asymmetric combinations(modernization of VASSILISSA)

High transmission for asymmetric combinations (beams of 12C, 14,15N,16,18O, 20,22Ne) movable plates of electrostatic deflectors

Availability for symmetric combinations (136Xe + 136Xe → 272Hs*) 50 cm long plates, high electrostatic field strength

0

1

2

3

4

5

6

7

8

9

10

11

12

Target W heel

Quadrupole Lenses I

Quadrupole Lenses II

Beam

Electric Deflector I

E lectric Deflector II

M agnetic Deflector II

M agnetic Deflector I

Beam Stop

Tim e of Flightdetector

Position-sensitivedetector array Magnetic

Deflector III

For asymmetric combinations – ♦ Increase of the electrostatic deflectors aperture

Movable plates

Size 100 x 100 mm2

Size 60 x 60 mm2

For asymmetric combinations – ♦ Increase of the focal plane detector size

Factor of 2 in transmission

Simulation of ion trajectories

Calculated transmission efficiency for modernized separator.

Reaction Ep1/2 MeV Target thickness mg/cm2

Transmission

22Ne(238U,5n)255No 115 U3O8 – 0.2 0.09 (now – 2%)

22Ne(238U,5n)255No 115 Met – 0.2 0.12

22Ne(197Au,5n)214Ac 110 Met – 0.2 0.14

40Ar(181Ta,4n)217Pa 182 Met – 0.3 0.28

40Ar(162Dy,7n)195Po 198 DyO2 – 0.3 0.28

48Ca(174Yb,4n)218Th 200 YbO2 – 0.35 0.48

48Ca(208Pb,2n)254No 216 Met – 0.4 0.42

Estimated counting rates

ReactionCross section Transmission

%ERs counting rate per day

242Pu(22Ne,5n)259Rf 3.0 nb 7 110244Pu(22Ne,5n)261Rf 5.0 nb 7 180248Cm(18O,5n)261Rf 13 nb 4 270243Am(22Ne,5n)260Db 2.0 nb 7 70243Am(22Ne,4n)261Db 1.5 nb 7 55248Cm(22Ne,5n)265Sg 0.3 nb 6 10208Pb(54Cr,1n)261Sg 0.5 nb 50 90

Manufacturing of the dipole magnets at St. Petersburg (ANR money, 105 k€)

New power supplies for quadrupole lenses (FLNR money, 180 k$)

Development of the electronics

64 spectrometry channel system4 amplifiers , SF with 16 channel built in multiplexers 4 ADC 8192 ch.), 4 ADC SF (4096 ch.)Conversion time msec

Realization period (execution plan)

• 1. Stage 1: Month 1 – 3. Detailed ion optical calculations of the separator itself. Design of dipole magnets and vacuum tanks for electrostatic deflectors.

• 2. Stage 2: Month 4 – 12. Manufacturing of the 2 dipole magnets, vacuum system of the separator, purchase of 3 turbo pumps, 1 fore pump and accessories, power supplies for dipole magnets. Required stage costs : 325 kEuros

• 3. Stage 3: Month 7 – 18; Manufacturing of the 2 high voltage vacuum chambers, the electrostatic plates and the insulators, purchase of 2 high voltage power supplies. Required stage costs : 260 kEuros

• 4. Stage 4; Month 10 – 21; purchase of the focal plane Silicon detectors (Canberra, Micron), the control system, spectroscopic electronics. Assembling, tests, mounting of the equipment. Required stage costs : 240 kEuros

• 5. Stage 5; Month 19 - 24; Assembling of the separator, beam line and the beam diagnostics at the experimental hall of U400 cyclotron, tuning of the experimental set up, tets experiments. Required stage costs : 20 kEuros

A.V. Yeremin, M.L. Chelnokov, V.I. Chepigin, A.V. Isaev, I.V. Izosimov, D.E. Katrasev, A.N. Kuznetsov, O.N. Malyshev, A.G. Popeko, E.A. Sokol, A.I. Svirikhin, FLNR, JINR, Dubna, Russia

K. Hauschild, A. Lopez-Martens, J. Robin CSNSM, IN2P3-CNRS, F-91405 Orsay Campus, FranceO. Dorvaux, D. Curien,, B. Gall, F. Khalfallah, M. Rousseau,L. Stuttgé IPHC, IN2P3-CNRS, F-67037 Strasbourg, FranceA. Goergen, Ch. Theisen G.De France, Ch. Stodel DAPNIA/SPhN, CEA-Saclay, France GANIL, France

M. Guttormsen, A-C Larsen, S. Siem, N. Syed Department of Physics, Oslo University, 0316 Oslo, Norway

F. Hanappe, V. Bouchat Université Libre de Bruxelles, 1050 Bruxelles, Belgium

A. Minkova, T. Kutsarova Institute for nuclear research and nuclear energy , Sofia, BulgariaS. Antalic, S. Saro, M. Venhart Comenius University of Bratislava, SlovakiaS. Hofmann, F.P. Hessberger, D. Ackermann GSI. Darmstadt, GermanyD. Pantelica, R. Borcea, K. Mihai NIPNE, Roumania

S. Mullins, E. Lieder, iThemba LABS, South Africa

The people

35

Presently Working Experimental Set Ups in the World

Dubna Gas Filled Separator (Russia) SHIP (Darmstadt, Germany)Berkeley Gas Filled Separator (USA)GARIS (Saitama, Japan)VASSILISSA (Dubna, Russia)LIZE3 (GANIL, France)RITU (JYFL, Finland)FMA (Argonne, USA)JAERI-RMS (Tokai, Japan)TASCA (Darmstadt, Germany)

Heavy element research Spectroscopy studies

Gas - filled

Gas - filled

Gas - filled

Gas - filled

Gas - filled

Vac. V filter

Vac. E filter

Vac. V filter

Vac. RMS

Vac. RMS

Planned set up parameters 1013

Decay of the isotope 270Ds; K – isomer.

Sf Hs266

Ds270

0+2+

4+6+

8+

10+

12+

14+

16+

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

Е MeV/

0+2+4+6+

8+229 218

10+

12+

14+

16+10-

9-

6.0 msecMeV1.13

Theory Exp

MeV Q46 ---- msec T83 6.9 msec T

.

9.60 ----

.

1/21/2sf

Sg262

Theory Exp

10 2 10.34 MeV Q 2.3 msec T > 6.9 msec T

.

. 0

. 1/2

1600 1/2sf

Theory Exp.

11 24 11.20 MeV Q6 100 msec T

> 0.2 msec T

. .

540

7 1/2

1/2sf

0+ 2+4+

6+

8+

10+

12+9-10-

E=

10.95 MeV

11.15 MeV

12.15 MeV

Isomer – 3 decays

S. Hofmann et. al., EPJ A10 (2001) p. 5.

g.s. decay – 5 events

m

Experiment 22Ne + 242Pu → 259Rf + 5n

Calculated excitation functions and experimental points for the reaction 22Ne + 242Pu

22Ne + 238U → 260No*Nucl. Е(МeV) B (vac. Т∙m) B (He. Т∙m) B (H2. Т∙m) V (cm/ns) E/qvac (MV)

22Ne 112.4 0.76 0.76 0.76 3.14 11.7260No 9.5 0.74 1.82 2.45 0.26 0.99238U 34.8 0.72 1.89 2.01 0.53 1.934He 58.5 1.1 5.31H2 18.7 0.62 6.0

48Ca + 244Pu → 292114* (limit for VASSILISSA)Nucl. Е(МeV) B (vac. Т∙m) B (He. Т∙m) B (H2. Т∙m) V (cm/ns) E/qvac (MV)

48Ca 236 0.88 0.94 0.94 3.1 13.0292114 38.8 0.79 2.0 2.18 0.51 2.0244Pu 129.7 0.83 1.65 1.49 1.0 4.24He 67 1.2 5.71H2 18.8 0.62 6.02

86Kr + 180Hf → 266Hs*Nucl. Е(МeV) B (vac. Т∙m) B (He. Т∙m) B(H2. Т∙m) V (cm/ns) E/qvac (MV)

86Kr 400 0.96 1.12 1.12 3.0 14.3266Hs 130 0.82 1.60 1.50 0.97 3.95180Hf 350 0.92 1.23 0.92 1.94 8.964He 68.0 1.2 5.71H2 18.2 0.6 5.9

136Xe + 136Xe → 272Hs*Nucl. Е(МeV) B (vac. Т∙m) B (He. Т∙m) B (H2. Т∙m) V (cm/ns) E/qvac (MV)

136Xe 600 1.1 1.38 1.38 3.0 15.7272Hs 300 0.95 1.39 1.21 1.46 6.85136Xe 600 1.1 1.38 1.38 3.0 15.74He 66.6 1.2 5.71H2 17.4 0.6 6.0

Not available now without ER energy degrading

Velocity filter for asymmetric combinations(modernization of VASSILISSA)