Superheavy Element Studies
Sub-task members:
Paul Greenlees
Rodi Herzberg, Peter Butler, RDP
Christophe Theisen
Fritz Hessberger
Christelle Stödel
Michael Sewtz
Krunoslav Subotic
Jyväskylä
Liverpool
CEA Saclay
GSI
GANIL
LMU München
INN Vinca
Synthesis & Decay Spectroscopy
120
114
112
110
108
S. Hofmann, Nucl. Phys. News Intl
EURISOL intensities at least 10x lower than stable beams
Produce & study neutron-rich nuclei?
What can be done with
X+
132Sn?
132Sn
N=82
Study region around
end of Dubna chains
Example reactions
132Sn
+
132Sn
137Cs
+
(t1/2 = 30 years) →
132,134,136Xe
267Db*
→ 264,266,268Rf*
132Sn + 138Ba → 270Sg*
132Sn + 139La → 271Bh*
132Sn + 140,142Ce → 272,274Hs*
132Sn + 142-150Nd → 274-282Ds*
90,92Kr
+ 181Ta → 271,273Mt*
90,92Kr + 186W → 276,278Ds*
44Ar
+ 232Th → 276Hs*
44Ar + 238U → 282Ds*
High spin states in SHE
48Ca
+
208Pb

256No*
Ex = 21 MeV
92Kr
+
164Dy

256No*
Ex = 24 MeV
Egido & Robledo
PRL 85 1198
Predicted simultaneous alignment of pi13/2 and nj15/2 around 30ħ
In-beam spectroscopy - which cases?
Already Done
Proton Number
Potentially doable
Neutron Number
Feasibility depends on the specifics of each and every case!
Example reactions
92Kr
132Sn
+
50Ca
+
164Dy
130-136Xe
→
→
256No*
262-268Rf*
+ 204Hg → 254Fm*
50Ca + 205Tl → 255Md*
50Ca + 208Pb → 258No*
50Ca + 209Bi → 259Lr*
Gamma-ray Spectrometer
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
Dominant channel is constant ~0.1 - 1b
fission. This limits Ge rate!
Target wheel spokes need beam sweeping
High efficiency, granularity and energy
resolution (AGATA!)
“Conventional” alternative array when
AGATA is elsewhere?
Electron Spectrometer
Fission does not readily produce CE
SHE produce more CE than Gamma
High (>10%) efficiency up to 0.5 MeV
Energy resolution 1 keV to resolve L & M CE
Couple to recoil separator and/or g array
SAGE
Recoil separator or spectrometer









Mass resolution not essential if tagging, but could
be useful in certain cases?
High transmission efficiency (>40%) & beam
suppression (>1012) for all reactions.
Momentum acceptance >10%
Angular acceptance > ±10°
Focal plane size matched to detection system
Focal plane system to measure all decays (a, b, g,
p, e-, fission) with high efficiency
Flexible DAQ for correlations (triggerless TDR?)
Rotating or cooled targets
Radioactive targets
Resonance Ionization Spectroscopy
Buffer gas cell + optical resonator
High repetition rate, high power laser systems
PIPS detectors
Z & A selective detection?
Entrance Foil
Development of an On-Line Spectrometer
Ion mobility measurements
Drift Time Cell (100 mbar Ar Buffer Gas)
Electric Field ( 50 V/cm)
254No
Ion
Beam
Parallel
Plate
Counter
Channeltron
+ 1.5 kV
Ion Guide
+
QMS
HI+
+
Dynode Foils
- 1.5 kV
a-Detector Wheel
30 cm
QMS :
40 u
e-
Fixed
QMS :
254 u
a-Detectors
Counts
Ion mobility is related to ion’s size
Direct Measurement of
Need:
Ion Mobility Spectrometer
TbD
Direct mass separation (QMS) or
magnet
Ta,bD = TaD - TbD
Position sensitive parallel plate trigger counter
PIPS detector
39
40 wheel
TD [ms]
Build on HV platform to extract 60keV beam out of buffer gas
cell and allow subsequent mass analysis in magnetic separator?
Beam Requirements
Narrow excitation functions  <1% energy resolution
Emittance <5p mm rad (as presently available)
Wobbling system in addition to target wheel?
Stable beam operation for calibration (10-100pnA)
Campaigns of experiments for efficient use of beam time
Required floor space
Largely dictated by separator (e.g., SHIP is 12m long)
Shielding for electrostatic elements & beam dump
Space around target for g-ray & electron spectrometers
Space at focal plane for spectrometer, atomic physics
& chemistry set-ups
20m x 20m is probably reasonable
Room background needs to be low!!
Future work
Cross section calculations are needed!
Rate of scattered beam particles in target chamber
(132Te t1/2 = 70h)
Future work
Cross section calculations are needed!
Rate of scattered beam particles in target chamber
(132Te t1/2 = 70h)
Design of separator, target chamber, spectrometers, …
Shielding of beam dump in separator
…
In-beam g-ray spectroscopy
Lighter neutron-rich nuclei?
Compound nuclei
48Ca
+ 124Sn  172Yb*