status report on the gabriela set-up. a. yeremin a , o. malyshev a , a. popeko a ,
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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)
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