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Experiments with polarized beams at ISOLDE
Dimiter L. Balabanski, INRNE
• the Bulgarian involvement at ISOLDE • alignment and polarization of exotic nuclei• collinear laser spectroscopy @ ISOLDE
• alignment of isomers in transfer reactions• tilted-foil polarization of exotic post-accelerated beams
• overlap with the ESFRI Spiral2 project• on the road to the EURISOL facility
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The Bulgarian participation at ISOLDE
1. Bulgaria is not a member of ISOLDE! 2. The participation in the experiments is based on personal
contacts and is financed by individual research grants. 3. Bulgarians at ISOLDE
• early 1990s Prof. Krasimira Marinova – COLLAPS experiments in collaboration with Univ. Mainz
• early 2000s Prof. Balabanski – COLLAPS and REX-ISOLDE experiments in collaboration with Univ. Leuven
• 2005 – 2006 Dr. Georgi Georgiev – CERN fellow• since 2009 Dr. Deyan Yordanov – CERN fellow
4. FP6 EWON report (within EURONS) reporting on Bulgarian activities at ERI submitted to EC
5. in 2010 four experiments at ISOLDE with Bulgarian participation
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Nuclear moment measurements
magnetic moment () quadrupole moment (Q)
single-particle configuration (configuration mixing)
collective properties(deformation, effective charges)
Spin-orientedbeams
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Spin-oriented beams
some definitions
m-2 –1 0 +1 +2
spin-alignment
m-2 –1 0 +1 +2
spin-polarization
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classical view quantum-mechanical view
Pop
ula
tion
I = 2
E
m =2m =1
m =0m =-1
m =-2
I=2 ensemble
Necessary to induce polarization of the beam prior the measurement
ISOL beamsISOLDE – CERN SPIRAL2
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Part III: Halo nuclei
The Li chain
Why is 11Li so big?
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Part III: Halo nuclei
The COLLAPS beam line at ISOLDE
know how: Univ. Mainz
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Part III: Halo nuclei
Quadrupole moments of Li isotopes: 11Li vs 9Li(U. Leuven – U. Mainz experiment) 9Li 11Li
scan = RF – L,fix (kHz)
1992
LiNbO33 LiNbO3
ASYMMETRY (%)
2003
-.4
0
.4
.8
10 15 20
0 15 20 25(b) Li
-8.0
-7.0
-6.0
-5.0
-4.0
10 15 20 25
ZnZn
scan = RF – L,fix (kHz)
2004
0,050
0 ,052
0 ,054
0 ,056
0 ,058
0 ,060
0 ,062
0 ,064 9 Li
Asy
mm
etry
10 12 14 16 18 20 22
0 ,030
0 ,035
0 ,040
0 ,045
0 ,050
0 ,055
0 ,060
0 ,065
0 ,070
0 ,075
0 ,080 11 Li
Asy
mm
etr
y
scan
[kH z]
10 16 22
ASYMMETRY (%)
5.2
5.8
6.0
6.2
5.6
5.4
5.0
0,050
0 ,052
0 ,054
0 ,056
0 ,058
0 ,060
0 ,062
0 ,064 9 Li
Asy
mm
etry
10 12 14 16 18 20 22
0 ,030
0 ,035
0 ,040
0 ,045
0 ,050
0 ,055
0 ,060
0 ,065
0 ,070
0 ,075
0 ,080 11 Li
Asy
mm
etry
scan
[kH z] 10 16 22
ZnZn7.0
5.0
4.0
6.0
Q(11Li)Q(9Li) = 1.090(14)
Quadrupole Splitting
15,5
16
16,5
17
17,5
18
0 2 4 6 8 10Measurement nr.
(9
,11 L
i)9Li
11Li
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Part III: Halo nuclei
Did we learn something from the Li chain ?
We think: YES
• A precision measurement of the electric quadrupole moments of 9,11Li reflects the charge distribution in these nuclei. The quadrupole moment of 11Li is found 9 ± 1% larger than that of 9Li.
• This small difference supports the interpretation of the two-neutron halo.
• The small but significant difference between both moments is a first direct proof that correlations between the halo and the core exist.
D. Borremans, D.L. Balabanski, K. Blaum, W. Geithner, S. Gheysen, P. Himpe, M. Kowalska, J. Lassen, P. Lievens, S. Mallion, R. Neugart, G. Neyens, N. Vermeulen, and D. Yordanov
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Can we measure nuclear static moments with post-accelerated
ISOL beams ?
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REX - ISOLDE @ CERN
REX - ISOLDE
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Why transfer reactions ?
98Mo 99Mo
100Tc
100Mo 101Mo
102Tc
63Cu 64Cu
65Zn
65Cu 66Cu
67ZnP P
• populate low-spin (single-particle) states• go a step further in the Nuclear Terra Exotica
Principle investigators: Georgi Georiev (Orsay) and DLB (Sofia)
Part IV: The future: Transfer reactions with RIBs
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The 63m,65mNi experiment (I = 9/2+)
(d,p) reactions
Tandem at IPN-Orsay
• pulsed 6 MeV 1 nA D beam
• enriched 64Ni/62Ni (ferromagnetic)
targets
• known g(63mNi) = - 0.269(3)Muller et al. PR B40, 7633 (1989)
• HF field of Ni(Ni) = 6.90(5) TRiedi et al. PR B15, 5197 (1977)
Part IV: The future: Transfer reactions with RIBs
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63mNi 65mNi
gexp. = -0.296 (3)
G. Georgiev et al, J.Phys.(London) G31, S1439 (2005)
Ni exp.2004
Bg N
L
Larmor frequency
)}(2cos{4
3
),2(),(
),2(),()(
22
22
tBA
BA
tItI
tItItR L
HF field Ni(Ni) = 6.90(2) T
Experimental results
~ 15% alignment in transfer reactions at the Coulomb barrier (3 MeV/u)
Part IV: The future: Transfer reactions with RIBs
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Polarized beams at HIE-ISOLDE – from dreams to reality
G. Georgiev1, M. Hass2, A. Herlert3, D.L. Balabanski4, L. Hemmingsen5, K. Johnston3, M. Lindroos3, K. Riisager6, J. Van de Walle3, D. Voulot3, F. Wenander3, W.-D. Zeitz7
1. CSNSM, Orsay, France; 2. The Weizmann Institute, Rehovot, Israel; 3. ISOLDE, CERN, Geneva, Switzerland; 4. INRNE, BAS, Sofia, Bulgaria; 5. IGM, LIFE, University of Copenhagen, Denmark; 6. Department of Physics and
Astronomy, University of Aarhus, Denmark; 7. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany
Polarized beams – WHY?
p
dd
pdd
dd
dd
Ay
Precise test of the nuclear models for exotic nuclei: • transfer reactions(analyzing power)• Coulomb excitation – spin/parity;multiplicity assignments etc.• nuclear moments – proton/neutron character, angular momentum j
21 j
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Can one do it and how?
M. Hass et al., NPA 414, 316 (84)
Tilted Foils - the principles: • atomic polarization nuclear polarization• higher nuclear spins higher polarization (>10% achieved so far)• strong velocity dependence (poorly studied up to now)
•Can one post-accelerate the ions after polarizing them?done for stable beams - noble-gas like charge states + LINAC J. Bendahan et al., ZPA 331, 343 (88)
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- unique opportunity
What do we need to achieve it?
-NMR setup from HMI Berlin transferred to ISOLDE
• gain of complete control on the TF polarization
• nuclear structure (moments, reactions …),
nuclear methods in the solid-state physics,
biophysics etc. …
3 MeV/u and 0.3 MeV/u
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SPIRAL 2
SPIRAL2 is a new European facility to be built at GANIL laboratory in Caen, France. The project aims at delivering stable and rare isotope beams with intensities not yet available with present machines. SPIRAL2 will reinforce the European leadership in the field of nuclear physics based on exotic nuclei.
The scientific programme proposes the investigation of the most challenging nuclear and astrophysics questions aiming at deeper understanding of the nature of matter.
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The SPIRAL 2 project
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SPIRAL2 EFFORT
MoU between GANIL and INRNE, BAS
• participation in the Spiral2PP project (FP7 Infrastructures);
• production of prototypes for the superconducting LINAC;
• participation in the construction of the PARIS spectrometer;
• declared interest in the Spiral2 scientific programme.
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EURISOL: The Main Challenges
• Design a 5MW; 1GeV proton driver with additional capability of 200 AMeV deuterons and A/Q=2 Heavy Ions; build and test prototypes of the cavities.
• Design a liquid Hg converter which will accept 5 MW of beam power.
• Design a UCx target which will make the most efficient use of the neutrons produced.
• Evaluate the safety constraints of the above set up.• Design an efficient multi-user beam distribution system.• Design a superconducting HI LINAC capable of accelerating 132Sn
up to 150 AMeV• Investigate technologies for the instrumentation of the future• Provide a conceptual study for a beta-beam neutrino facility.
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EURISOL layout
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