Ingascell laser spectroscopy of neutrondeficient 57,59Cu isotopes

1
In-gas-cell laser spectroscopy of
neutron-deficient 57,59Cu isotopes
T.E. Cocolios, A.N. Andreyev, B. Bastin, N. Bree,
J. Büscher, J. Elseviers, J. Gentens, M. Huyse,
Yu. Kudryavtsev, D. Pauwels, T. Sonoda, P. Van
den Bergh and P. Van Duppen Instituut voor
Kern- en Stralingsfysica K.U.Leuven, Belgium

• Nuclear structure around 56Ni - ZN28
• In-gas-cell laser spectroscopy
• LISOL laser ion source recent developments
• Laser spectroscopy of 57,59Cu results
• Conclusion and Outlook

Yale workshop, 18th June
2
Nuclear Structure around 56Ni (ZN28)
57Cu 199 ms

• E(2), B(E2) G. Kraus,- PRL 73 (1994) 1773
• Shell model calculations ? 56Ni (NZ28) soft
  core
• M. Honma,- PRC 69 (2004) 034335
• A. Lisetskiy,- PRC 68 (2003) 034316

56Ni 6.0 d
55Ni 209 ms
57Ni 36 h
58Ni
Z28
55Co 17 h
N28
E(2) keV
56Ni
68Ni
56Ni
68Ni
B(E22-0) e2fm4
Neutron Number N
Neutron Number N
3
Nuclear Structure of odd-A Cu isotopes (Z29)
28
24 26 28 30 32 34
36 38 40
4
Magnetic Moments of odd-A Cu isotopes (Z29)
N40
Cu Magnetic moment
57Cu 199 ms
pp3/2
N28
mSchmidt (p3/2) 3,79 mN
56Ni 6.0 d
55Ni 209 ms
57Ni 36 h
58Ni
Z28
55Co 17 h
Magnetic moment mN
54Co
Experiments
N28
Cu Mass Number

• In source laser spectroscopy at ISOLDE down to
  58,59Cu, N.J. Stone et al, PRC 77 (2008)
• Increasing deviation from the Schmidt value of
  3.79 by moving to N28

5
57-59Cu at Louvain-la-Neuve Radioactive Beam
Facility
CYCLONE 110
CYCLONE 30
CYCLONE 44
LASER ION SOURCE
LASERS
LISOL - Leuven Isotope Separator On-Line
6
Operational Principle of the LISOL Laser Ion
SourceYu. Kudryavtsev, NIMB 204, 336 (2004), M.
Facina, NIMB, 226. 401 (2004)
Fission gas cell
Fusion gas cell
238U targets
SPIG
Filament
Ar from gas purifier 500mbar
Exit hole
Laser beams
Proton beam

• Laser ion source
• Thermalisation in a buffer gas cell (500 mbar
  Ar)
• Neutralisation
• Resonant laser ionization Z-selection (isomer)
• Extraction by gas flow, transport by RF ion
  guide
• Mass separation A/Q selection

Plasma created in the cell causes recombination
of laser-produced ions
7
New development at LISOLRecoil Shadow Gas Cell
(Dual Chamber Gas Cell)
Ar, He from gas purifier

• Physical separation of stopping/ionization zone
• Efficiency not dependent on initial beam current
  up to 5 1016 e- - ion pairs/s (gt 1010 pps 58Ni
  185 MeV)
• Electrical fields selectivity gt2200 (RIB),
  10.000 (stable nickel beam)
• Higher duty cycle
• Similar on-line efficiency compared to the
  standard cell
• Y. Kudryavtsev,- NIMB arXiv0904.3635v1

Laser beams Longitudinal
Target
500 mbar
Cyclotron beam
Stopping chamber
Laser Ionization chamber
Ionization chamber
Ion collector
Ion Collector
Filament
Laser beams Transversal
Extension
Exit hole diameter 0.5 mm/1mm Stopping chamber
4 cm in diameter Laser ionization chamber 1
cm in diameter
Exit hole
Ionization in Jet
SPIG
Courtesy Yu. Kudryavtsev
8
Atomic Structure in odd-A Cu (Z29) isotopes
Cu e-
Autoionizing State
65Cu
Ionization Potential 62317.4 cm-1
?2 441.6 nm
63Cu
Atomic spin J1/2 Nuclear spin Ip3/2- Total
spin FIJ1,2
4P01/2
F2
40943.73 cm-1
F1
59Cu
?1 244.164 nm
HFSAhf
2S1/2
57Cu 6 ions/s
F2
F1
Cu gs I3/2-
Frequency GHz
Relative measurements! Simultaneous measurement
in the reference cell and 57Cu/63Cu or 59Cu/65Cu
9
57,59,63,65Cu sample HFS spectra (LISOL, November
2008) T. E. Cocolios et al. submitted to PRL,
June 2009

• Production
• p and 3He induced reactions (2 mA)
• 58Ni(3He, pn)59Cu
• 58Ni(p, 2n)57Cu (T1/2199 ms)
• 60Ni(p, 2n)59Cu
• Argon buffer gas at 130 mbar
• 1 mm diameter exit hole
• Lasers repetition rate at 200 Hz

• Laser spectroscopy - resonant ionization
• reference cell (63,65Cu evaporated)
• beam intensity after mass separation
• stable 63,65Cu MCP
• radioactive mass 57,59Cu b-detection

• Simultaneous measurement in the reference cell
  and 57Cu/63Cu or 59Cu/65Cu

10
Cu HFS Scan Stability
p
p
Run Number
Courtesy T. E. Cocolios
11
Comparison of our data to previously known
Our data Literature
Ags GHz
Ags GHz
N.J. Stone,- PRC 77 (2008) 014315
12
Nuclear Magnetic Moments of the Cu (Z29) Isotopes
Magnetic moment (mN)
MSU, 2006
Honma (GXFP1)
Mass Number
13
Back to MSU data
N40
N28
Magnetic moment (mN)
Mass Number
14
Conclusions

• Laser spectroscopy in gas-cell is a reality!
• Expected magnetic moment value in 57Cu(N28)!
  (contrasting with the previous measurement by
  MSU)
• GXPF1 model describes the data for 57-69Cu well

15
THANKS!
16
65Cu In-source_at_ISOLDE versus
In-gas-cell_at_LISOL
J1/2,I3/2
F2
F1
F2
J1/2,I3/2
F1

• For s1/2 ? p1/2 electrons JJ1/2, but
  different excitation schemes, thus different
  splitting of the intermediate level (smaller in
  case of RILIS)
• Doppler broadening is dominant

17
Magnetic Moments of odd-A Cu isotopes (Z29)
N40
N28
Cu Magnetic moment
57Cu 199 ms
pp3/2
mSchmidt (p3/2) 3,79 mN
56Ni 6.0 d
55Ni 209 ms
57Ni 36 h
58Ni
Z28
55Co 17 h
Magnetic moment mN
54Co
Experiments
N28
Cu Mass Number

• In source laser spectroscopy at ISOLDE down to
  58,59Cu, N.J. Stone et al, PRC 77 (2008)
• Increasing deviation from the Schmidt value of
  3.79 by moving to N28

18
Nuclear Magnetic Moment of the 57Cu (N28) Ground
State (MSU, 2006)
19
Atomic Structure in odd-A Cu (Z29) isotopes
J1/2,I3/2
F2
F1
F2
J1/2,I3/2
F1
Odd-A Cu proton in p3/2 orbital I3/2 for s1/2
?p1/2 electrons JJ1/2
20
Gas flow calculation
Laser beams
Ar
He
The shape of the ion signal is defined by the
spatial overlapping of laser beams with the atom
flow
21
Evacuation properties of the shadow gas cell
Laser beams 100Hz
480 mbar
100
Ar
185MeV 58Ni 50ms pulse
92
400 mbar
58
300 mbar
22
Evacuation of fission products
Fission cell
Shadow cell
Exit hole 0.5mm
beam
beam
500 mbar Ar
2381 fragments of 5741 come out the exit hole
(41.5)
4860 fragments of 11896 come out the exit hole
(40.8)
23
Influence of radioactive decay on ion source
efficiency
Exit hole diameter 1 mm
Shadow cell Fission cell
Exit hole diameter 0.5 mm
24
What was done during the last years
After EURONS Laser and Trap collaboration meeting
on April 11 - April 15, 2007 in Saariselkä,
Finland.
1. On-line experiments a) 3He-induced fusion
evaporation reactions along NZ line beta decay
3He 46Ti -gt 46Cr, 47Cr , 46V, (May 2007) b)
Proton-induced fission of Uranium-238 Study of
neutron-rich 64Fe, 65Fe, 65Co, 71Co isotopes
(July 2007) 2. New ionization scheme for Ce, Pd
(2008) 3. Recoil shadow gas cell - off-line
tests - stopping of 185MeV Ni-58 beam - heavy
ion-induced fusion evaporation reaction -
proton-induced fission reaction - laser
ionization in the jet of the shadow gas cell 4.
Laser Spectroscopy in LISOL-LIST 5. Laser
Spectroscopy in gas-cell (2008, Cu isotopes)
25
Ion Collector at ON - Line conditions
Lasers longitudinal
1 euA Cyclotron beam
40Ar beam 265 MeV
500 mbar
OFF
Ion collector OFF
58Ni target
ON
Ni filament
40V, Ion collector
Ion collector-ON
Recombination of laser-produced ions only in the
elbow region
In the presence of the beam Ion collection
1000 No influence on laser ions in the shadow
zone
26
Transverse laser ionization of stable Ni atoms
Ni time profiles at different laser pulse
repetition rates
Laser pulse
No influence of ion collector voltage on ion
time profile !
Lasers transverse
27
Laser enhancement in heavy-ion induced fusion
evaporation reaction
Shadow cell
40Ar 58Ni ? 98Pd ? Rh/Ru xp yn
500 mbar
58Ni target
Ion collector
Fusion cell
28
Broadening and velocity shift of 58Ni
29
Laser enhancement in proton-induced fission
reaction

Lasers on Rh Ion Collector - OFF
Lasers longitudinal
112gRh -
112mRh -



30 MeV proton beam

500 mbar Ar


U238 target

Lasers OFF Ion Collector - OFF
Ion collector, 80V
Selectivity ( 112mRh) 40 Selectivity ( 112gRh)
2

112mRh

Lasers OFF Ion Collector - ON
112gRh
Selectivity ( 112mRh) 155 Selectivity ( 112gRh)
3

30
Influence of the mother beta decay on the laser
ion source selectivity (I)
Calculated distribution of atoms sticking SPIG
rods
Distance Cell - SPIG 1.5 mm
80 in 1state 12 in 2state
112Ru
3.0 mm
31
Influence of the mother beta decay on the laser
ion source selectivity (II)
Distribution of atoms hitting SPIG rods
Argon pressure along the SPIG axis
1.5 mm
32
Transverse laser ionization of stable Ni atoms in
the jet (OFF- LINE)
50us
I.C. - OFF
I.C. - ON
Laser OFF I.C. - ON
33
Transverse laser ionization of stable Ni atoms in
the jet (ON- LINE)
40Ar beam 265 MeV, 1euA
500 mbar Ar
Ion collector, 40V
Ni filament
Vdc
Vdc210V
Lasers Transverse
SPIG
40Ar beam - ON
I.C. - OFF
40Ar beam - OFF
Formation NiAr and NiAr2 molecular ions in jet
I.C. - ON
34
Neutralization of ions in a plasma created by a
cyclotron beam
Time profiles of laser-ionized stable Ni-58 from
a filament
Ni filament
SPIG
He
1994
40 kV
mass separator



laser
cyclotron beam
Weak beam, 1nA, 1ms
Laser-produced Ni ions recombine in a plasma
created by a primary beam gt99 are
neutral We have to provide for radioactive
atoms 1. Efficient laser ionization 2. Survival
of laser-produced ions in a volume around the
exit hole
Strong beam, 1uA,20ms
4/28
35
Two-step laser ionization schemes at LISOL
80 of all elements can be ionized by the LISOL
laser system
Tunable range 225 - 800 nm
used on-line
used off-line
10/28
36

• Since 1994 the LISOL Laser Ion Source was used in
  
• Light ion-induced fusion evaporation reactions
  (Co,Ni,Mn,Cr,V) Physical Review C 59,
  2416-2421,1999
• Heavy ion-induced fusion evaporation reactions
  (Rh,Ru,Ti) European Physical Journal A 21,
  243-255, 2004
• Proton-induced fission of U-238 (Ni,Co,Fe,Cu),
  (P. Van Duppen, Wednesday, 1210) Nuclear Physics
  A 701, 145c-149c, 2002.
• Stopping of 185 MeV stable Ni beam in a gas cell
  (characterization of the gas cell) NIM B226,
  401-418, 2004, NIM B187, 535-547, 2002
• Products from spontaneous fission Californium-252
  (Rh,Ru,Mo,Pd)

Off-line studies, NIM B179,412-435,2001
10/27
37
65Cu in-source spectroscopy with RILIS_at_ISOLDEL.
Weissman et al, Phys. Rev. C65,024315(2002)
65Cu
J1/2,I3/2
F2
F1
Intensity arb. units
1 2 3 4
30534.8 30535.0 30535.2 30525.4
30535.6 30535.8
Frequency of first transition cm-1
F2
J1/2,I3/2
F1
Odd-A Cu proton in p3/2 orbital
38
Laser System
39
LISOL Laser Ion Source
Fission gas cell
238U targets
SPIG
Filament
Ar from gas purifier 500mbar
Exit hole
Laser beams
Proton beam
Pulsed operation mode
Courtesy Yu. Kudryavtsev