ISOLDE Facility at CERN: highlights and future plans

Report
Maria J. G. Borge
ISOLDE-PH, CERN
(Isotope Separator On-Line)
IEM-CSIC, Madrid
Maria J. G. Borge
, CERN,HIE-ISOLDE
PH-Dept
ISOLDE – High-lights
and
Hot Topics in Nuclear Physics
Physics at
the Femtometer scale
2
Open Questions in Nuclear Physics
How are complex nuclei built from their basic
constituents?
strong interaction in nuclear medium
• How to explain collective properties from
individual nucleon behavior?
collective versus individual
LRP2010
• How do regular and simple patterns emerge
in the structure of complex nuclei?
Observables:
symmetries
Ground-state properties:
mass, radius, J, μ, Q moments
Half-lives and decay modes
Transition probabilities
Cross sections
Main models:
Shell model (magic numbers)
Mean-field models (deformations)
Ab-initio approaches (light nuclei)
3
Production of Radiactive Beams @ ISOL Facilities
4
ISOLDE Facility
ISOLDE is the CERN radioactive beam facility
Nuclei produced via reactions of high intensity high energy proton
beam with thick and heavy targets
Provides low energy or post-accelerated exotic beams
PSB upgrade (2018)
intensity (2uA -> 6uA )
energy
(1.4 -> 2GeV)
5
ISOLDE at CERN
LHC
6
Produced Nuclei: ISOLDE 45 y Experience
Over 20 target materials and ionizers,
depending on beam of interest operated at
high temperature
U, Ta, Zr, Y, Ti, Si, …
3 types of Ion-sources: Surface, Plasma, Laser
> 700 nuclides of over 70 chemical elements
produced
Target
ISOLDE today offers the largest range
of available isotopes of any ISOL
facility worldwide.
7
ISOLDE Physics Topics
Many beams
Good beam purity and quality
Best in the World!
High intensity
Nuclear Physics
Applied Physics
Condensed matter physics and
Life sciences
Tailored Isotopes for
Diagnosis and Therapy
MEDICIS Project
Nuclear Decay Spectroscopy
and Reactions
Structure of Nuclei
Exotic Decay Modes
Fundamental Physics
Direct Mass Measurements,
Dedicated Decay Studies - WI
CKM unitarity tests, search for
b-n correlations, right-handed
currents
Atomic Physics
Laser Spectroscopy and
Direct Mass
Measurements
Radii, Moments, Nuclear
Binding Energies
f(N,Z)
Nuclear Astrophysics
Dedicated Nuclear
Decay/Reaction Studies
Element Synthesis,
Solar Processes
8
Determination of the atomic properties of Astatine
Determination of ionising potential
Identification of new atomic transitions
Comparison with atomic theory
Scan of ionizing laser: converging Rydberg
levels allow precise determination of the IP
ISOLDE collaborates
with the Short-Lived
Nuclei Laboratory
which is based on the
ISOL facility IRIS at
PNPI since 1999.
ion curre nt (p A)
30
M. Seliverstov, V. Fedoseev team
IP(At) = 9.31751(8) eV
Nature Com.
14May2013
36
10
20
10
0
16150
9
16 200
16250
16 300
-1
wa venu mber (cm )
16350
Experimental hall
Beams of 30-60 keV
Beams of 3 MeV/u
Decay spectroscopy
Coulomb excitation
Transfer reactions
Laser spectroscopy
Beta-NMR
Penning traps
Applications:
 Solide state
 Life Science
Target stations
HRS & GPS
PS-Booster
1.4 GeV protons
Mass-sep.
HRS
WITCH
REX-ISOLDE
3×1013 ppp
ISCOOL
RILIS
Travelling setups
NICOLE
Post-accelerated beams
Collection points
MINIBALL and T-REX
Travelling setups
COLLAPS
CRIS
ISOLTRAP
TAS
COLLAPS – Ne charge radii
Laser spectroscopy & Massses
Intrinsic density distributions of
dominant proton FMD configurations
Geithner et al, PRL 101, 252502 (‘08)
Marinova et al, PRC84, 034313 (‘11)
11
ISOLTRAP:
High-precision mass of 82Zn
Combined ISOLDE technical know-how:
neutron-converter, quartz transfer line, laser ionisation
Nuclear structure:
N=50 shell closure
nc 
Astrophysics:
r-process path
Astrophysics:
neutron star structure
1 q
B
2 m
Its determination is important for
modelling of the crust of neutron
stars , PRL110 (2013) 04110
CERN Courier, 53, n 3, 2013
12
D. Rodriguez, U. Granada
The Magic Number N=32
Nature 498 (2013) 346
13
WITCH
Weak Interaction Trap for Charged particles -> fundamental studies
Goal: determine bn correlation for 35Ar with (a/a)stat  0.5 %
 Energy spectrum of recoiling ions with a retardation spectrometer
 Use a Penning trap to create a small, cold ion bunch
June 2011 data
M. Beck et al., Eur. Phys. J. A47 (2011) 45
M. Tandecki et al., NIM A629 (2011) 396
14 Gorp et al., NIM A638 (2011) 192
S. Van
REX-ISOLDE
Total efficiency : 1 -10 %
1+ to A/Q = 3 – 4.5
Tested A/q = 2
15
Halo Nuclei &
Reactions
7Be 8Be 9Be10Be11Be12Be
6Li 7Li 8Li 9Li 10Li 11Li
3He 4He
1H
2H
n
14Be
6He
Common “Structural” properties



Rather inert core plus one or two barely
unbound extra neutrons
Extended neutron distribution, large
“radius”. “halo”
Very few excited states –if any.
Reaction properties at near-barrier energies:
Is the Optical Model able to describe the
scattering of the halo systems ?
r2
11
r2
9
Li
Li
= 3.71 fm
= 2.44 fm
Dobrovolsky et al, NPA766 (2006) 1
 Strong absorption in elastic channel
 Large cross section for fragmentation
 They are easily polarizable.
Reaction mechanisms and Nuclear effects
of halo nuclei need to be understood
Elastic scattering of halo nuclei near the Coulomb barrier
10,11Be+64Zn
10Be+64Zn
11Be+64Zn
Di Pietro et al. Phys. Rev. Lett. 105,022701(2010)
Catania, IEM-CSIC, Huleva, Sevilla Collaboration
CDCC calculations
Experimental elastic cross section.
reproduced only taking into account
coupling to continuum via the
Coulomb and nuclear interactions
17
Scattering of 11,9Li on 208Pb around the Coulomb Barrier
Elastic Scattering
ECM = 23.1 MeV below Coulomb Barrier
9Li
Competing process with Elastic
Scattering for loosely bound
systems
Direct Breakup
11Li
2n-Transfer
ECM = 28.3 MeV @ the Coulomb Barrier
9Li
Scattering process dominated by:
- Dipole couplings (coulomb + nuclear)
- Coupling to continuum
- Good description in a 4-body model
11Li
Cubero et al, PRL109 (2012) 262701
IEM-CSIC, Huelva, Seville Collaboration
18
18
Why to study the N=Z 72Kr Nucleus?
Nuclear structure:
o Shape coexistence in the mass region was first proposed for 72Se [Ham74].
o
72Kr
ground state is predicted to be oblate [Dic72] and [Naz85].
o First excited 0+ state in 72Kr found to be a shape isomer [Bou03].
o Possibility of study np-pairing effects as 72Kr belongs to N=Z line.
[Ham74] J.H. Hamilton et al., Phys. Rev. Lett. 32, 239 (1974)
[Dic72] F. Dickmann et al., Phys.Lett. 38B, 207 (1972)
[Naz85] W. Nazarewicz et al., Nucl. Phys. A435, 397 (1985)
[Bou03] E. Bouchez et al., Phys. Rev. Lett. 90, 082502 (2003)
Nuclear astrophysics:
o
72Kr
rp-process in N=Z nuclei & A=70-80 region
“waiting point" in rp process.
73Rb
is unbound
o β decay competes with 2p capture.
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Coulomb excitation of 72Kr
Use of submicron Y203 material for
target => Yield increase x 10
Coulex Spectra - number of counts in 710
keV peak depends on the shape of 72Kr
Oblate 72Kr expected
Doppler Corrected for
104Pd target excitation
The technique
Doppler Corrected for
72Kr projectile excitation:
150 counts in 710 keV line
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TAGS @ISOLDE: The case of 72Kr
o Conversion electron
studies to determine
the multiplicities of
the low gamma
transitions
o B(GT) obtained by measuring the intensity of the full
gamma de-excitation cascade from each fed level to
the ground state.
P. Sarriguren,
Phys. Rev. C 79, 044315 (2009)
Briz, ISOLDE Workshop 2012
IEM-CSIC, Strasbourg, Surrey, Valencia
The B(GT)
21 distribution favours oblate deformation!
Searching for pear-shaped nuclei at ISOLDE
Quadrupole deformation
Coulomb excitation to directly
access E3 transition strengths
λ=2
Oblate (Earth)
λ=2
Prolate (Rugby ball)
B(E3) ≳ 30 s.p.u. gives significant
β3
Octupole correlations enhanced at
numbers: Z or N=34, 56, 88, and
N= 134.  Observed Z≈88 &
N≈134
Microscopically driven...
Intruder orbitals of opposite
parity and ∆J, ∆L = 3 close
to the Fermi level
22
L. P. Gaffney, et al. (2013). Nature, 497(7448), 199–204. doi:10.1038/nature12073
Hangout with CERN: Going pear-shaped (http://www.youtube.com/watch?v=x8Jdu9O2RhU&feature=emuploademail) MORE than 1000 viewers
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Physics program @ REX
REX-ISOLDE started in 2001
72 different beams already used at REX- ISOLDE of 700 available!
20
40
82
50
222,224Ra; 220,222Rn
184,186,188Hg
Probing Pear Shape
Nature 497 (2013)199
Probing shape coexistence
82
The Limitations of REX-ISOLDE (E 3.1 MeV/u)



Evolution of collectivity

Extension
to
higher
energy
is
difficult
Xe
Se, shape coexistence, Hurst PRL 2007
around Sn
110Sn;
Cederkäll, PRL 2007
Very limited energy flexibility
106,108Sn, Cederkäll, PRL 2008
Operation restricted to pulsed mode
50
122,124,126Cd
Bunch length is not flexible
70
138,140,142,144
96Sr, 88Kr, 92Kr
28
132
140,148,150Ba
74,76,78,80Zn Probing large scale shell model, Van der Walle, PRL2007
67,69,71,73Cu,
Stefanescu et al., PRL 2008
68,70Cu, isomeric 68Cu, Stefanescu , PRL 2007
30,31,32Mg,
20
Niedermaier PRL2005, H. Scheit
d(30Mg,p)31Mg, K. Wimmer, PRL 2010
Halos & clusters
d(8Li,p)9Li*; d(9Li,p)10Li…
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Near Future: HIE-ISOLDE project
•
•
•
•
Energy Upgrade:
The HIE-ISOLDE project
construction of the SC
LINAC to upgrade the
energy of the postaccelerated radioactive
ion beams to 5.5 MeV/u in
2015 and 10 MeV/u by
2017
25
Approved Dec 2009
Offically started Jan 2010
Yacine Kadi project Leader
Budget 40 M$
Intensity Upgrade:
The design study for the
intensity upgrade, also part of
HIE-ISOLDE, started in 2011,
and addresses the technical
feasibility and cost estimate
for operating the facility at
10 kW once LINAC4 and PS
Booster are online.
Physics addressed with HIE-ISOLDE / IS564
Study of the unbound proton-rich nucleus 21Al with resonance elastic and
inelastic scattering using an active target (USC, IEM, MAYA Collaboration)
26
Experiment
To measure resonant elastic, 20Mg(0+), and inelastic, 20Mg(2+),
scattering using MAYA to determine energy, spin and parity of
the 21Al excited states.
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Summary and outlook
The future of ISOLDE is bright. It will restart in June 2014 with the
low energy program.
With more than 40 year of operation ISOLDE remains as the pioneer
ISOL-installation both at the level of designing new devices and
production of frontier Physics.
Post accelerated beams up to 5.5 MeV/u for the wide range of nuclei
produced at ISOLDE will be available from Autumn 2015.
HIE-ISOLDE will be the only next-generation radioactive beam facility
(as identified by the NuPECC LRP) available in Europe in 2015, and
the most advanced ISOL facility world-wide.
Welcome to propose challenging experiments!
Thanks for your attention !
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