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Status report on the GABRIELA set-up. A. Yeremin a , O. Malyshev a , A. Popeko a ,

Status report on the GABRIELA set-up. A. Yeremin a , O. Malyshev a , A. Popeko a , A. Lopez- Martens b , K. Hauschild b , O. Dorvaux c  and GABRIELA collaboration a FLNR, JINR, 141980 Dubna , Russia ; b CSNSM, IN2P3-CNRS, F-91405 Orsay Campus, France ;

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Status report on the GABRIELA set-up. A. Yeremin a , O. Malyshev a , A. Popeko a ,

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  1. Status report on the GABRIELA set-up. A. Yeremina, O. Malysheva, A. Popekoa, A. Lopez-Martensb, K. Hauschildb, O. Dorvauxc  and GABRIELA collaboration aFLNR, JINR, 141980 Dubna, Russia ; b CSNSM, IN2P3-CNRS, F-91405 Orsay Campus, France ; cIPHC, IN2P3-CNRS, F-67037 Strasbourg, France; eremin@jinr.ru

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

  3. GABRIELA (Gamma Alpha Beta Recoil Investigations with the ELectromagnetic Analyser) ● 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. ● 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. http://flerovlab.jinr.ru/flnr/vassilissa.html http://www.csnsm.in2p3.fr/-GABRIELA-?lang=en

  4. Status of GABRIELA set up Present ● Beams: U400 cyclotron: complete fusion reactions, SHE, spectroscopy, chemistry of transfermium elements Ebeam 2.5 – 20 A∙MeV Abeam 12 (C) - 209 (Bi) Intensity up to 1013 pps ● Experiment: VASSILISSA electrostatic separator: ERs production cross sections, decay properties ERs 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 Physics 30th meeting, 22–23 June 2009 Future

  5. VASSILISSA separator Total view on FLNR cyclotrons and beam lines

  6. Experimental set-upVASSILISSA + (α,g,b)-detector array Experimental hall of the U400 cyclotron

  7. Experimental methods: Focal plane detector assembly GABRIELA:Gamma Alpha Beta Recoil Investigation with the Electromagnetic Analyser

  8. Experimental characteristics of GABRIELA Detection Efficiency of 7 Ge detectors ~ 5 - 10 % Resolution of Gamma Detectors (600 keV) ~ 2.5 keV Focal plane strip detector – alpha detection ~ 50 % Resolution of Alpha detectors (5500 keV)~ 20 keV Detection of electrons in backward hemisphere ~ 10 - 20 % Resolution of electron detectors (200 keV) ~ 8 keV

  9. Decay (focal plane) studies α- g (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- g(CE) – decay measurements  transitions isoms(mother) excs, gs (mother)  E* isomeric levels  spin and parity assignments

  10. Isomer study in Uranium, Radium and Radon region Spectroscopy in transfermium region (K-isomers, single particle level systematic, decay properties…) 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,…)

  11. Nuclear structure studies Heaviest SHE - limited experimental data (E, T1/2) Deformed mid-shell nuclei: opportunity for detailed nuclear structure studies Transfermium nuclei: Z > 100 Shell-stabilized nuclei Large density of sp levels, strong Coulomb field => Heavy nuclei: demanding theoretical testing ground

  12. First full scale experiment: September 23d – October 25th 2004, • 48Ca + 207,208Pb → 255,256No*, 48Ca + 209Bi → 257Lr* • A. Lopez-Martens et al., Phys. Rev. C 74 (2006) 044303 Status of the GABRIELA campaigns 2. October 3d – November 9th 2005, 22Ne + 238U → 260No*, 22Ne + 209Bi → 231Np*, 48Ca + 208,210Pb → 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, 1183-1187 K. 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*

  13. Summary of results and on-going analysis 50Ti + 208Pb 22Ne + 242 Pu Year 2008, 22Ne + 238U A. Lopez-Martens et al., PRC 74 (2006) 044303 K. Hauschild, Phys. Rev. C 78 (2008) 021302(R) K. Hauschild, in progress Rf256 Rf257 Lr255 Year 2008 : 40Ar + 182W U218 Th216 Year 2008 : 40Ar + 180Hf A. Lopez-Martens et al., EPJ A32 (2007) 245

  14. Summary of results and on-going analysis Technique K. Hauschild,et. al, "GABRIELA: A new detector array for g-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 249Fm : A. Lopez-Martens et al., PRC 74 (2006) 044303 253No : A. Lopez-Martens et al., EPJ A32 (2007) 245 255Lr : K. Hauschild et al., PRC 78 (2008) 021302R 209Ra : K. Hauschild et al., PRC 77 (2008) 047305 More than 15 reports on International conferences Analysis in progress 255No → 251Fm 217Pa → 213Ac 213;214;217Th isomers

  15. 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.

  16. GABRIELA campaign of year 2009 Tests of double sided detector and new electronics Size 60 x 60 mm2 48 x 48 strips, Resolution for a’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). It allows to increase significantly CE detection efficiency

  17. K – Isomer in 253No 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.

  18. K – Isomer in 253No Spectrum of gamma-rays observed in coincidence with the isomeric electron signal detected in the DSSD : Preliminary decay scheme of the ~700 micros isomer in 253No

  19. Isomer search in 255Lr The known low-lying a-emitting spin–isomer was confirmed. A new isomer with a half–life of t1/2=1.4(1) ms was observed

  20. 162 358 192 24.5 s 198 208Pb(48Ca,1n)255No -----> 251Fm α a– g correlation analysis

  21. Future plans: Advantage of Dubna => Acces to less neutron-deficient nuclei Present limits ≥ 3 -5 nb for decay ≥ 50 - 100 nb for prompt 78Pt,79Au,80Hg,81Tl,82Pb,83Bi targets – « cold fusion » 90Th, 92U, 94Pu, 95Am, 96Cm targets – « hot fusion » 107 262 Sg 263 Sg 106 105 104 103 102 101 100 146 148 150 152 154 156 158 160

  22. 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)

  23. Improvements to experiment: ● Improvement to experimental set up (slow ERs transmission) 1) New ion optical scheme => 2 x efficiency 2) ToF : thinner windows => less straggling ● Improvement of detector array 1) New Si detectors : larger + more strips => 2 x ERs detection efficiency, higher CE detection efficiency 2) Modified Ge detector => higher gamma detection efficiency Tx * D ~ (3-5) x

  24. 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 For asymmetric combinations – ♦ Increase of the electrostatic deflectors aperture Movable plates

  25. For asymmetric combinations – ♦Increase of the focal plane detector size Size 60 x 60 mm2 Factor of 2 in transmission Size 100 x 100 mm2

  26. Simulation of ion trajectories

  27. Calculated transmission efficiency for modernized separator. Estimated counting rates

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

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

  30. Development of the electronics 64 spectrometry channel system 4 amplifiers a, SF with 16 channel built in multiplexers 4 ADCa (8192 ch.), 4 ADC SF (4096 ch.) Conversion time 2 msec

  31. 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

  32. The people 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, France O. Dorvaux, D. Curien,, B. Gall, F. Khalfallah, M. Rousseau,L. Stuttgé IPHC, IN2P3-CNRS, F-67037 Strasbourg, France A. 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. KutsarovaInstitute for nuclear research and nuclear energy, Sofia, Bulgaria S. Antalic, S. Saro, M. Venhart Comenius University of Bratislava, Slovakia S. Hofmann, F.P. Hessberger, D. Ackermann GSI. Darmstadt, Germany D. Pantelica, R. Borcea, K. Mihai NIPNE, Roumania S. Mullins, E. Lieder, iThemba LABS, South Africa

  33. Presently Working Experimental Set Ups in the World Gas - filled Vac. V filter 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) Gas - filled Gas - filled Vac. E filter Vac. V filter Gas - filled Vac. RMS Vac. RMS Gas - filled Heavy element research Spectroscopy studies

  34. Planned set up parameters 1013

  35. Decay of the isotope 270Ds; K – isomer. Isomer – 3 decays 10.95 MeV 11.15 MeV 12.15 MeV g.s. decay – 5 events m S. Hofmann et. al., EPJ A10 (2001) p. 5.

  36. Experiment 22Ne + 242Pu →259Rf + 5n Calculated excitation functions and experimental points for the reaction 22Ne + 242Pu

  37. 22Ne + 238U → 260No* 48Ca + 244Pu → 292114* (limit for VASSILISSA)

  38. Not available now without ER energy degrading 86Kr + 180Hf → 266Hs* 136Xe + 136Xe → 272Hs*

  39. Velocity filter for asymmetric combinations(modernization of VASSILISSA)

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