Diapositive 1

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The DESIR facility at SPIRAL2

• DESIR Désintégration, excitation et stockage
  dions radioactifs
• (Decay, excitation and storage of
  radioactive ions)
• Result of a SPIRAL2 workshop in July 2005 on
  ISOL beams at SPIRAL2
• - Decay spectroscopy Maria José Garcià
  Borge (Madrid)
• - LASER spectroscopy François Le Blanc (IPN
  Orsay)
• Gerda Neyens (KU Leuven)
• Paul Campbell (Manchester)
• - Atom and ion traps Dave Lunney (CSNSM)
• Oscar Naviliat-Cuncic (LPC Caen
• Frank Herfurth (GSI)
• Spokes-person Bertram Blank
• GANIL liaison Jean-Charles Thomas

Bertram Blank, SAC SPIRAL2, 19-20 October 2006
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Why another ISOL facility?

• close to stable beam intensities for exotic
  nuclei
• much higher intensities than at ISOLDE or Oak
  Ridge
• not too far from EURISOL intensities
• key nuclei like 78Ni, 100Sn, 132Sn with high
  intensities
• fusion-evaporation to access high-spin states

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Conclusions of the SPIRAL2 Workshop (july 2005)
Low energy RIB
1. A new experimental area of about 1500m2
located at the ground floor, dedicated to the
experiments with low-energy beams from SPIRAL2 is
strongly requested. The new building includes
areas for the experimental equipments,
acquisition and control rooms. 2. A High
Resolution mass Separator (HRS) with a resolution
of M/?Mgt5000 with a dedicated identification
station is absolutely necessary. A separation
scheme Low Resolution mass separator ? RFQ cooler
? HRS is proposed. 3. The low energy radioactive
beams should be available for experiments already
at the beginning of the operation of SPIRAL 2.
The physics program requires both neutron-rich
and neutron-deficient beams. 4. More than one
production target ion source station is
required to ensure flexible schedule and a
possibility for fast change of the mass of
radioactive beams. 5. An extension of the current
LIRAT beam line in order to take full advantage
of the SPIRAL 1 beams is proposed.
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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
• - deformation
• Fundamental interactions
• - CVC hypothesis, CKM matrix unitarity via 0 ?
  0 transitions
• - exotic interactions (scalar and tensor
  currents)
• - CP (or T) violation with e.g. Radium
• Solid state physics and other applications

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SPIRAL 2 LAYOUT
GANIL facility
LIRAT
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Underground
J.C. Thomas, GANIL
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DESIR Ground-floor
LUMIERE
general purpose spec
Paul trap
laser
MOT
trap
BESTIOL
neutrons
buncher
Ion sources
x
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Beam handling methods
Magnetic separation (HRS)
PENNING TRAP
A. Jokinen, JYFL
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Beam handling RFQ cooler and buncher
RFQ-cooler 3 p mm mrad, 0.5 eV, 10 ms, 60
D. Lunney et al., CSNSM
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Beam handling Implementation
F. Varenne, GANIL
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Summary of decay spectroscopy experiments The
BESTIOL facility (BEta decay STudies at the
SPIRAL2 IsOL facility)

• Decay studies with halo nuclei
• Clustering studies in light nuclei
• Super-allowed b decays and the standard model of
  electro-weak interaction
• Angular correlation measurements and standard
  model of electro-weak interaction
• Cases of astrophysical interest
• New magic numbers
• Transition from Order to Chaos
• Shape coexistence, deformation and Gamow-Teller
  distribution
• High-spin isomers
• Test of isospin symmetry combined with charge
  exchange reactions
• Beta-delayed charged-particle emission e.g.
  proton-proton correlation

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Decay properties of exotic nuclei

• 1916 Rutherford Wood ?? Philos. Mag. 31 (1916)
  379
• 1963 Barton Bell identified 25Si as ?p
  emitter

• Global properties

?-delayed particle emission

• Very Selective probe

E, ? Level density Spin, Isospin ?-decay
properties
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Search for exotic interactions
e
nucleus
q
ne

• b-n angular correlation

requires to measure the recoil ion b particle

• within the SM

x Fermi fraction r GT/F mixing ratio

• beyond the SM

a contains quadratic S and T contributions
O. Naviliat-Cuncic et al., LPC Caen
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Search for exotic interactions Production and
preparation of 6He
candidate
(pure GT transition)
deduce bn angular correlation from measurement
of b-recoil (recoil with very low energies lt 1
keV)
6He production at SPIRAL
cooling in H2 gas / bunching
trapping/measuring
LIRAT low energy beam line
O. Naviliat-Cuncic et al., LPC Caen
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Search for exotic interactions Setup and first
results

• TOF of ions extracted from trap

• first time difference for b-decay

(V-A theory)
RF ON/OFF
O. Naviliat-Cuncic et al., LPC Caen
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CVC, CKM, exotic currents 0 ? 0 b decays
3073.5 (12) s (1) 3074.4 (12) s
(1,2)
Measurements - Q value
- T1/2 - branching
ratios
? Vud00 0.9738(4) (1)
0.9736(3) (1,2,3) VusK 0.2200(23)
(PDG) 0.2254(21) (4) VubB
0.00367(47) (PDG) ?
0.9987(11)
( 2? shift)

• (1) Towner and Hardy, PRL 94 (2003) 092501, PRC
  71 (2005) 055501
• (2) Savard et al., PRL 95 (2005) 102501
• (3) Marciano Sirlin, PRL 96 (2006) 032002
• (4) E865, KTeV, NA48, KLOE
• (PDG) Particle Data Group, S. Eidelman et al.,
  PLB 592 (2004) 1

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0 ? 0 b decays Physics output

• 1. Vud matrix element (? test of unitarity)
• 2. test of CVC (constancy of Ft0? 0 values)
• 3. right-handed currents
• -0.0005 lt ? lt 0.0015 (90 C.L.)
• 4. scalar currents

Ad 3 Left Right Symm.-models W1 WL cos? - WR
sin? W2 WL sin? WR cos? ? m12 / m22
0.011
Ad 4 scalar currents
N. Severijns et al.
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0 ? 0 b decays Future studies

• further improve results for classical isotopes
  
• determine Ft-values for new isotopes of
  interest
• Tz -1 isotopes 18Ne, 22Mg, 26Si, 30S, 34Ar,
  38Ca, 42Ti
• Tz 0 isotopes 62Ga, 66As, 70Br, 74Rb, 78Y,
  82Nb, 86Tc, 90Rh, 94Ag, 98In
• stronger limits for new physics
• test and improve reliability of isospin
  corrections
• extend CVC test to higher mass region
• ? needs
• - relatively pure beams (? 103 at/s) of
  classical and new 0 ? 0 isotopes
• - precision spectroscopy techniques (for
  t1/2 and BR)
• - Penning traps (mainly for QEC/mass)

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Study of GT strength via b-delayed proton decay
21Mg
21Mg
J.C. Thomas
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Mirror symmetry studies
? ?nuc ?SCC

• Allowed Gamow-Teller transitions
  (log(ft)lt6)

• 17 couples of nuclei
• 46 mirror transitions

Average asymmetry d
11 (1) in the 1p shell (Alt17)
0 (1) in the (2s,1d) shell (17ltAlt40)
J.C. Thomas, J. Giovinazzo et al. (GANIL/CENBG)
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Search for p-p correlation in b2p decay

• Two possible decay schemes
• sequential ? no angular or energy correlation
• 2He type decay ? angular and energy correlation
• ? pairing correlations, nucleon-nucleon
  interaction, final-state interactions.

Possible candidates 22Al, 23Si, 26P, 27S, 31Ar,
35Ca, 43Cr, 50Ni .

• Setup Cube-silicium
• 6 DSSSD
• 6 large-area
• silicon det.
• g detection
• beam catcher
• or fast tape

I. Matea et al., CEN Bordeaux-Gradignan
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Study of decay of 31Ar at SPIRAL/LIRAT
Proton spectrum

• Production rate 0.5 1 31Ar per second
• strong contamination from 33Ar

I. Matea et al., CEN Bordeaux-Gradignan
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One- and two-proton emission from isomers 94Ag
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One- and two-proton emission from isomers 94Ag
Relative energy spectra for p-p
3-body
0.39(4)s
1.9 keV
Si-Si-?? (92Rh)
I. Muhka, Nature 439 (2006) 298
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LUMIERE Laser Utilisation for Measurement and
Ionization of Exotic Radioactive Elements

• Collinear Laser spectroscopy
• - spins
• - magnetic moments
• - quadrupole moments
• - change of charge radii
• N50, N64, N82, etc.
• b-NMR spectroscopy
• - nuclear gyromagnetic factor
• - quadrupole moment
• monopole migration of proton and neutron
  single particle levels around 78Ni
• persistance of N50 shell gap around 78Ni
• persistance of N82 shell gap beyond 132Sn
• Microwave double resonance in a Paul trap
• - hyperfine anomaly and higher order momenta
• (octupole and hexadecapole deformation)

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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 and nuclear moment measurements
178Hf isomer at Orsay F. Le Blanc et al.
101Zr at JYFL P. Campbell et al.
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Isotope shift measurements

• previous experiments

N82
N104
F. Le Blanc et al., IPN Orsay
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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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The physics case for b-NMR on polarized 60 keV
beams

• polarized 60 keV beams are obtained using
  resonant laser excitation.
• with I 5.103 pps, T½ from 1 ms to 10 s, beam
  purity gt 50 .
• b-NMR is a sensitive and precise method to
  measure g-factors and quadrupole
• moments of exotic nuclei (ground states,
  isomers) with lifetimes from 1 ms up
• to several seconds.
• combination with hyperfine structure
  measurements yields a unique determination
• of the spin (e.g. PRL 94, 022501 (2005)).
• Systematic precise measurements of g-factors
  reveal deviations from normal
• behaviour and provide information on
  configuration mixing or onset of deformation
• (breaking of shell closures).
• N50 g factor of neutron-rich Ga and Cu
  isotopes to determine where
• the inversion of the pp3/2 and pf5/2 orbitals
  occurs.
• N82 g.s. configuration from gI measurements.

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The physics case for b-NMR on polarized beams
nuclear structure towards and beyond 78Ni
Kr
Produced at SPIRALII with d-induced fission
Se
Ge

• Evolution of n orbits
• from Z40 to Z28
• ground state spins and moments
• of 83Ge, 81Zn, 79Ni and
• of 81Ge, 79Zn, 77Ni
• g-factors can reveal erosion
• of N50 shell closure

Zn
Ni
Lifetime OK for b-NMR studies
G. Neyens et al., KU Leuven
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Collinear laser spectroscopy and b-NMR

• 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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Estimated budget

• Building 6000 kEuros
• - DESIR hall 3000 kEuros
• - Basement 1000 kEuros
• - Crane 1000 kEuros
• - 20 overhead 1000 kEuros
• HRS 816 kEuros
• - RFQ cooler 150 kEuros
• - 2 magnets power supplies 400 kEuros
• - pumps, beam lines, diagonstics 130
  kEuros
• - 20 overhead 136 kEuros
• Beam handling 1640 kEuros
• - off-line source 60 kEuros
• - RFQ cooler/buncher and switch yards 650
  kEuros
• - Preparation Penning trap 460 kEuros
• - in-trap decay detection system 195
  kEuros
• - 20 overhead 275 kEuros

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The DESIR Collaboration
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Summary

• solid physics case
• very promising intensities for exotic nuclei
  (e.g. fusion-evaporation)
• almost 100 co-authors the  DESIR  LOI
• with its installations a unique facility
• preliminary study of building at CENBG
• study of cooler/buncher and HRS at CSNSM
• installation of collinear laser spectroscopy at
  ALTO
• to be built it has to be included in  reference
  solution 
• synergies with FAIR DESPEC, LASPEC, MATS, NCAP