The Synthesis of Super Heavy Elements (SHE) D. Ackermann, University of Mainz/GSI Future of Gamma Spectroscopy at LNL: GASP and CLARA Arrays GAMMA2004 March 3 rd 2004 requirements for the synthesis of SHE reaction mechanism studies fusion/fission excitation function SHIP, MAIALE+CORSET the CN spin distribution GASP+inner ball, GAMMASPHERE nuclear structure of the SHE: spectroscopy tools in beam (RDT + γ-γ) RITU, FMA, PRISMA(gas filled)+clara ER-α-α/-α-γ(-γ) after separation SHIP, RITU+GREAT, PRISMA(gas filled) an interesting example: 270 Ds the basic technical requirement: beam intensity CW accelerator UNILAC upgrade a first step
Shell Correction Energies Eshell in the Region of Superheavy Elements P. Möller et al. at GSI: Elements 107-112 first synthesised and unambiguously identified 107 Bh 108 Hs 109 Mt region der spherically shell stabilised nuclei ( island of stability ) element 110 recently named Darmstadtium Ds IUPAC decision - August 2003 208Pb Baptized - Decemberregion 2003 of deformed shell stabilised nuclei around Z=108 and N=162
All Chains with Z 110 GSI RIKEN Tokyo, Japan JINR/FLNR Dubna, Russia
The 2-step process Fusion - Evaporation 10 1 10-1 50 Ti + 208 Pb 258 Rf* (HIVAP calculations) fusion 1. CN formation entrance channel properties (nuclear structure, deformation ) σ [mbarn] 10-3 10-5 10-7 1n fission 2n evaporation residues 5-7 orders of magnitude 3n 10-9 220.0 230.0 240.0 250.0 260.0 E lab [MeV] F.P. Heßberger 2. ER formation survival fission competition vibration-rotation probes: Fusion-fission excitation function (fission and ERproduction) -distribution...
Fusion Dynamics and the Spin Distribution fusion evaporation fusion fission competition range of barriers σ fission survival via rotational stabilisation? ( +1) 2 E rot ( )= 2µRb 2 2n 1n 3n ER
Fusion Dynamics and the Spin Distribution V b = V Coulomb + V Nucl + V V b compound system entrance channel crit ( +1) E rot ( )= 2µRb 2 2 = crit < crit E shell 0 < < crit r 0
Experimental Approach to the Spin Distribution with GASP 1 GASP inner ball (80 BGO-crystals) 2 GASP high resolution Ge-detectors 3 statistical model (codes like PACE, EVAP, HIVAP ) E γ evaporation parameters γ-ray fold GASP response function ER identification spin removed by particles and statistical γ-rays M γ CN = (M γ - M γs ) γ + M γs γs + i M i i + gs/m ; i = p, n, α
Reactions with deformed targets leading to CN in Z = 82 Region 36 S+ 180 Hf 216 Ra* 34 S+ 168,170 Er 202,204 Po* 48 Ca+ 168 Er 216 Ra* 48 Ca+ 164 Dy 212 Rn* 48 Ti+ 150 Nd 198 Pb* 32 S+ 164 Dy 196 Pb* Features to investigate via fusion/fission excitation function and spin distribution can rotation stabilize the compound system? σ l the competition of fission and evaporation σ fus/fis +σ l the role of deformation for heavy CN σ fus/fis +σ l the effect of the shell Z=82 on fusion σ fus/fis +σ l 48 Ca+ 144,154 Sm 192,202 Pb* 48 Ca+ 150 Nd 198 Hg*
Fold Distributions with GASP for 64 Ni+ 100 Mo 4n fold 18 3n 246MeV 260MeV 20 5n 10 fold 9 4n 2n 6n 3n 246 MeV 64 Ni+ 260 MeV 100 Mo ANL/Notre Dame BGO array D.Ackermann et al., J. Phys. G 23 (1997)
Fold Distributions with GASP for 34 s+ 170 Er 204 Po * 34 S+ 170 Er GASP inner ball (80 BGO-crystals) 6,0x10 4 4,0x10 4 2,0x10 4 144 MeV 3n 4n Yield 0,0 2,0x10 5 1,5x10 5 1,0x10 5 5,0x10 4 158 MeV 3n 4n 5n 0,0 2,0x10 5 1,5x10 5 168 MeV 5n 6n 1,0x10 5 5,0x10 4 0,0 0 5 10 15 20 25 γ ray fold
Collaboration for Spin- Distribution Measurements GSI: S. Hofmann F.P. Heßberger G. Münzenberg (Uni Mainz) M. Ruan D. A. (Uni Mainz) Comenius Univ. Bratislava S. Antalic G. Berek LNL M. Axiotis L. Corradi G. De Angelis A. Gadea V. Kumar A. Latina N. Marginean T. Martinez A.M. Stefanini S. Szilner M. Trotta INFN Padova D. Bazzacco S. Beghini E. Farnea R. Menegazzo C. Rossi-Alvarez C. Ur FLNR, JINR, Dubna M.G. Itkis G.N. Kniajeva E.M. Kozulin Yu.Ts. Oganessian R.N. Sagaidak Univ. Padova G. Montagnoli F. Scarlassara
ER-α-γ Spectroscopy behind SHIP
Nuclear Structure of the Heaviest Nuclei I: ER-α-α Coincidences: 251 No F.P. Heßberger et al., submitted to EPJ A
Nuclear Structure of the Heaviest Nuclei II: ER-α-α Coincidences: 257 Db F.P. Heßberger et al., Eur. Phys. J. A 12, 57-67 (2001) S. Cwiok, S. Hofmann And W. Nazarewicz NPA A575 (1994) Experiment: α-α-coincidences
Nuclear Structure of the Heaviest Nuclei III: ER-α-γ Coincidences: 255 Rf/ 253 No F.P. Heßberger, Symposium on Nuclear Clusters, Rauischholzhausen Germany, August 2002
The even-even isotope 270 Ds 270 Ds 266 Hs 262 Sg
The even-even Isotope 270 110 and its decay products 266 Hs und 262 Sg 8 decay chains: 2 types with different τ α ( 270 110): 0.15ms and 8.6 ms 3 out of 4 chains complete of the typ: α-α-fission 1 γ-ray (218 kev) coincident to the mother decay in chain #7 7 days of irradiation σ= (13±5) pbarn (for comparison σ( 269 110) = 15 pbarn) S. Hofmann et al., Eur. Phys. J. A 10, 2001
k-isomer and Tentative Decay Scheme for 270 110 162 162 neutrons Fermi level ν[725] 11/2- ν[615] 9/2+ ν[613] 7/2+ ν[725] 11/2- ν[615] 9/2+ ν[613] 7/2+ 1.34 MeV I = 10-1.31 MeV I = 9 - S. Ćwiok and P.-H. Heenen tentative decay scheme S. Hofmann et al., Eur. Phys. J. A 10, 2001 270 110 266 Hs
Project for a superconducting CW-linac U.Ratzinger et al., University of Frankfurt dc beam 1 < A/q < 7 E beam : 4-7.5 MeV/u E beam < ± 3keV/u Intensity gain: Duty cycle 30% 100% 3.5 28 GHz ECR-source 5-10 increased stability (65% 85)% 1.3 shorter shutdowns (107 d/y 47 d/y) 1.2 Total gain 25-55 RFQ, 108 MHz IH DTL, 108 MHz CH DTL, supercond. QWR Cavities 324 MHz 108 MHz Debuncher Energy MeV/u normal conducting super conducting super conducting 0.003 0.3 1.4 1.8 2.4 3.3 4.2 5.2 6.1 7.1 ECR source 0 5 10 15 20 25 30 Z / m
New 28 GHZ ECR Ion Source Goals : Increasing the average beam intensity on target Higher intensity in high charge states Higher duty factor in linac Semi-empirical scaling law: I(A q+ ) ω ECR 2 increase of microwave frequency higher magnetic flux density (superconducting) 1000 100 28 GHz SC-ECRIS (2007) (extrapolated) intensity (eµa) 10 1 0,1 14 GHz GSI-CAPRICE II (1990) 20 25 30 35 40 45 50 Xe charge state
New Front-end for the High Charge State Injector 50% duty factor intensity-gain factor x2 New RFQ-structure: gain of the duty factor higher injection energy increased acceptance Additional 28 GHz-ion-source: intensity gain of factor two higher charge states for increased duty factor LEBT Laminated magnets: redundance for ion sources preparation for future pulse to pulse operation with different ion-species
High Duty Cycle RF-Operation of the GSI- High Charge State Injector (HLI) and the Alvarez-accelerator Rebuncher Presently: duty factor (beam)= 25 % (rf: 35 %), A/ξ 8 Upgrade: (new RFQ-structure, higher charge state from 28 GHz-ECR) A/ξ 6.5, duty factor = 50 % (rf: 60 %) Performance of all rf-tube-amplifiers (Alvarez@1.5 MW, IH+RFQ+Single Gap@200 kw, Rebuncher@ 4 kw) is sufficient to meet the requirements Alvarez Rebuncher
The SHIP group GSI: The collaboration JINR-FLNR Dubna, Russia: S. Hofmann F.P. Heßberger R. Mann G. Münzenberg (Univ. Mainz) P. Kuusiniemi (Postdoc) B. Sulignano (Ph.D. student) D. A. (Univ. Mainz) B. Lommel (targetlab) B. Kindler (targetlab) H.-G. Burkhard (mechanics) H.-J. Schött (elektronics) A.G. Popeko A.V. Yeremin University Bratislava, Slovakia Š. Šaro S. Antalic (Ph.D. student) G. Berek (Ph.D. student) B. Streicher (Ph.D. student) University Jyväskylä, Finland: M. Leino J. Uusitalo