Diapositive 1

1
Laser spectroscopy studies at the DESIR facility
of SPIRAL2

• DESIR _at_ SPIRAL2

• organization scientific program

• layout of the facility

• status and perspectives

• Laser spectroscopy _at_ DESIR the LUMIERE project

• physics cases

• experimental techniques

• research program

J.C. Thomas XVth Colloque GANIL, Giens 2006
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DESIR
Désintégration, Excitation et Stockage dIons
Radioactifs
An open collaboration to promote ISOL beams at
SPIRAL2

• Results from the SPIRAL2 workshop held at GANIL
  on July 2005
• Physics with low energy beams at SPIRAL2
• http//spiral2ws.ganil.fr/2005/lowenergy/program/p
  resentations/

• Follows the earlier proposition of a low-energy
  RIB facility at SPIRAL
• - Promotors (1998) G. Auger, B. Blank, C. Le
  Brun, .
• - LIRAT facility (2005) 6He, 19Ne, 32,35Ar _at_
  30 keV

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DESIR organization
spokes-person B. Blank, blank_at_cenbg.in2p3.fr
GANIL correspondent J.-C. Thomas,
thomasjc_at_ganil.fr

• Working groups / correspondents
• - Beam handling and beam preparation /
  lunney_at_csnsm.in2p3.fr
• - Laser spectroscopy / leblanc_at_ipno.in2p3.fr
• - Decay spectroscopy / borge_at_iem.cfmac.csic.es

• Links to SPIRAL2 project management
• - Scientific program M. Lewitowitcz
• - Installation M.-H. Moscatello

4
DESIR physics program

• Decay spectroscopy
• - decay properties and nuclear structure
  studies
• - particle-particle correlations, cluster
  emission, GT strength
• - exotic shapes, halo nuclei
• Laser spectroscopy
• - static properties of nuclei in their ground
  and isomeric states
• - nuclear structure and deformation
• Fundamental interactions
• - CVC hypothesis, CKM matrix unitarity via 0 ?
  0 transitions
• - exotic interactions (scalar and tensor
  currents)
• - CP and T violation
• Solid state physics and other applications

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The DESIR facility _at_ SPIRAL2 technical
requirements

• A new experimental area of about 1500m2
• Availability from day 1
• Run in parallel with post-accelerated beams
• Fast change of the mass setting
• Neutron-rich and neutron-deficient beams
• More than one production station
• Different target-ion source assemblies including
  a laser ionization source
• Different production modes including
  fusion-evaporation and DI reactions
• Use of isotopically separated beams
• A high resolution mass separator with a
  resolution of M/?Mgt5000
• Extension of the current LIRAT beam line

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The DESIR facility _at_ SPIRAL2 layout
GANIL facility
LIRAT
7
GANIL
Ident. Station
HRS
DESIR
Exp. Area
8
DESIR building - Underground
GANIL facility today
9
DESIR building - Ground floor
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Status of the DESIR Project

• DESIR building (new experimental area)

• preliminary design study B.Blank et al., CEN
  Bordeaux-Gradignan

• High resolution separator

• preliminary design study D. Lunney et al.,
  CSNSM Orsay

• Beam preparation (cooler)

• O. Naviliat et al., LPC Caen D. Lunney et al.,
  CSNSM Orsay

• Presentation of the DESIR Project to the IN2P3
  SC in July 2006

• LoI to be submitted in October 2006 (Contact B.
  Blank)

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Synergies with other facilities

• ALTO laser ionization source, laser spectroscopy

• FAIR/NuSTAR MATS, LASPEC, NCAP, DESPEC

• RIKEN/RIBF SLOWRI

• Common issues

• beam preparation using coolers and traps

• low-energy beam diagnostics

• new types of gamma and neutron detectors

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Towards DESIR LIRAT extension

• Multi-beam facility (physics program ? 2012)

• Tests and development for SPIRAL2 DESIR

LIRAT today
b Spec.
LPC Trap
Tests
SPIRAL2
1
n
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The LUMIERE project _at_ DESIR
Laser Utilisation for Measurement and Ionization
of Exotic Radiaoctive Elements
Spokes-person F. Le Blanc, leblanc_at_ipno.in2p3.fr
Physics cases

• Nuclear structure and deformation studies far
  from stability, in the vicinity of closed shells

• from systematic measurements of the static
  properties of exotic nuclei in their ground and
  isomeric states ?ltr²gt, ?I, Qs, Ip

• Hyperfine anomaly and high-order components of
  the hyperfine interaction

• from precise measurements of the hyperfine
  structure constants

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Atomic hyperfine structure
Interaction between an orbital e- (J) and the
atomic nucleus (I,mI,QS)

• results in a hyperfine splitting (HFS) of the e-
  energy levels

n
J
with
F
DEHFS

• Hyperfine structure constants

and

• Collinear laser spectroscopy DmI/mI 10-2,
  DQS/QS 10-1 for heavy elements

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Isotope shift measurements
Frequency shift between atomic transitions in
different isotopes of the same chemical element

• related to the mass and size differences

J2, F2
dnA,A
J2, F2
J1, F1
J1, F1

• mean square charge radius variations with a
  precision 10-3

• study of nuclei shape (deformation)

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Isotope shift measurements

• previous experiments

N82
N104
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Isotope shift measurements at DESIR

• with I 103-104 pps

• N50

• neutron skin in N gt 50 Ge isotopes (neutron star
  studies)

• deformation in N 50 Ni isotopes (collectivity
  vs magicity)

• N82

• shape evolution for Z 50 (Ag, Cd, In, Sn)

• N64

• strongly oblate shapes predicted in Rb, Sr and Y
  for N gt 64

• Z40

• shape transitions predicted in the Zr region
  (Mo, Tc, Ru)

• Rare earth elements

• large deformation and shape transitions
  predicted (Ba, Nd, Sm)

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b-NMR spectroscopy
b-asymmetry in the decay of polarized nuclei in a
magnetic field

• Zeeman splitting related to gI and QS

MI
I
M-I
with
and

• resonant destruction of the polarization (i.e.
  b-asymmetry) by means of an additional RF
  magnetic field

• DgI/gI 10-3, DQS/QS 10-2

• complementary technique to collinear laser
  spectroscopy

• suitable for light elements (low QS values)

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Collinear laser and b-NMR spectroscopy

• previous experiments at COLLAPS

• from the position of hyperfine transitions spin
  assignment and sign of gI for the g.s. of 31Mg

HFS 31Mg1
b asymmetry
nRF (MHz)

• from b-NMR precise measurement of gI

• strongly deformed intruder Ip 1/2 g.s. of
  31Mg, G. Neyens et al, PRL 94, 022501 (2005)

• from QS measurements via b-NMR QS(11Li) gt
  QS(9Li) ? p-n interaction halo n orbitals, D.
  Borremans, Ph.D. Thesis, 2004, KU Leuven, R.
  Neugart et al.

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b-NMR spectroscopy at DESIR

• with I 5.103 pps, T½ from 1 ms to 10 s, beam
  purity gt 50

• in combination with collinear laser spectroscopy
  whenever the spin and the configuration of the
  state is not known

• in case QS is to small to be measured by
  collinear laser spectroscopy

• N50

• g factor of neutron-rich Ga and Cu isotopes to
  determine where the inversion of the pp3/2 and
  pf5/2 orbitals occurs

• persistence of the N50 shell gap from the g.s.
  configuration of N49 (ng9/2) and N51 (nd5/2)
  even Z nuclei (81,83Ge, 79,81Zn, 77Ni)

• N82

• g.s. configuration from gI measurements

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Double laser and RF spectroscopy in traps

• RF scan of hyperfine transitions between Zeeman
  levels

• No Doppler effect ? accurate measurements

• In a Penning trap (high magnetic field)

• precise determination of the hyperfine constant A

• high precision on gI (DgI/gI 10-4)

• hyperfine anomaly (nuclear magnetization
  extension) constraining the computation of the
  nuclear wave function

• looking at different isotopes neutron radius
  variations PNC

• In a Paul trap (low magnetic field)

• precise determination of the hyperfine constants
  A, B as well as C (magnetic octupole moment) and
  D (electric exadecapole moment) high-order
  deformation parameters

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Double laser and RF spectroscopy in traps

• Previous results O. Becker et al., Phys. Rev.
  A48, 3546 (1993)

• at DESIR (Igt100 pps, T½gt100 ms)

• hyperfine anomaly Au, Eu, Cs

• high-order deformation in the actinide region
  Rn, Fr, Ra, Am

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The LUMIERE collaboration
F. Le Blanc, G. Neyens (b-NMR), P. Campbell, K.
Flanagan , S. Franchoo, C. Geppert, M. Kowalska,
I. Moore, R. Sifi, C. Theisen, J.-C. Thomas,
and others are welcome !!!