Spectroscopy of exotic nuclei Lecture 1 Reiner Krücken Physik Department E12 Technische Universität München Maier-Leibnitz Laboratory of TU München and LMU München for Nuclear-, Particle-, and Accelerator Physics R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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Spectroscopy of exotic nuclei Lecture 1 Reiner Krücken Physik Department E12 Technische Universität München Maier-Leibnitz Laboratory of TU München and.
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Spectroscopy of exotic nuclei
Lecture 1
Reiner Krücken
Physik Department E12Technische Universität München
Maier-Leibnitz Laboratory of TU München and LMU Münchenfor Nuclear-, Particle-, and Accelerator Physics
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
Outline
• Introduction– Central questions of the Physics of Exotic Nuclei– Production of radioactive ion beams
• Selected Topics in the Physics of Exotic Nuclei
– Nuclear Shell Structure and its Modifications in Exotic nuclei
– Halos, Skins and Pygmy Resonances
– Superheavy Nuclei
– Shape coexistence
Aim of the lectures: Discussion of current physics questions in combination with an introduction to various experimental methods
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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From QCD to atomic nuclei
u ud
Quarks,
Gluons
nucleon-nucleoninteraction
(ab-initio Models)
Light nuclei
(A10)?
QCD
Protons,
Neutrons
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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Ab-initio calculations of light nuclei
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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7500 CPU hours
From QCD to atomic nuclei
u ud
Quarks,
Gluons
nucleon-nucleoninteraction
(ab-initio Models)
Light nuclei
(A10)
?
?
Heavy nuclei
effectivenucleon-nucleon
interaction
(Mean-field theories)
QCD
Protons,
Neutrons
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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The Nuclear Landscape
Source: NUCLEUS A Trip Into The Heart of Matter
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R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
Binding energy per nucleon
Saturation of binding due toshort range of NN interaction
Maximal binding around Fe Synthesis up to Fe via fusion in stars heavy elements are produced differently (n-capture) Fission and alpha decay are possible
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Shell effects in the binding energies
Mexp –
MW
eiz
säck
er
?
?
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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Lecture 1
Central Questions in Nuclear Structure Physics
• Where are the limits of nuclear stability?• How does shell structure change far from stability?• What are the phases, relevant degrees of freedom, and symmetries of the nuclear many-body system?
• Are there new modes of collective excitation?
• How are the Heavy Elements produced? Unified theoretical framework
with predictive power
Diversified experimental strategy to understand the Structure and Dynamics of Exotic Nuclei:
Measure Ground State Properties Gamma-ray spectroscopy of excited
states Reaction studies
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Lecture 1
Valley of stability & the limits of stability
En
erg
y
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Lecture 1
r-process and shell structure
Nuclear shell structure- Defines r-process path- Imprinted in abundance pattern- maybe modified for exotic nuclei
- Fission may fill the holes- Depends on shell structure
r - process
G. Martinez-Pinedo et al.
Pfeiffer et al.
40 50 60 70 80 90-2
-1
0
1
element number
abun
danc
e lo
g(X
/H)-
12
CS22892-052 (Sneden et al. 2003)
solar r
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Lecture 1
Production of radioactive ion beams
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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15
How to produce and study Exotic Nuclei
Spectroscopic Methods:g- ray and particle spectroscopy following• Decay spectroscopy• Coulomb excitation• One- and Multi-nucleon transfer• knockout-reactions• Secondary fragmentation
Production of radioactive ion beams:• in-flight production• Isotope Separation On-Line
What can be measured? • existence of nuclei• masses, radii, half-lives • Excited states: energies, quantum numbers, transition matrix
elements , lifetimes, moments, single-particle occupations ...
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
Production of radioactive ion beams
Isotope Separation On-Line
Diffusion from thick target- depends on
chemistry- Needs time
Fragments move with beam velocity (30-90% c)
Reaction induced by light projectile (p,d,n) in thick target
Exotic nuclei are produced in thin target as fragment of heavy beam
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Lecture 1
In-flight separation
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Lecture 1
In-flight production of radioactive beams
Projectile fragmentation or fission at high energies (50 -1000 AMeV)
Both fragments are highly excited ad evaporate
nucleons
Fig. by T. Glasmacher (NSCL/MSU)
Br - DE - Br Separation Method
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Lecture 1
UNILAC
SIS
FRS
ESR
100 m
Fragment Identification
DE
DE
TOF
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R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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FAIR: Facility for Antiproton and Ion Research
Primary Beams
• 1012/s; 1.5-2 GeV/u; 238U28+
• Factor 100-1000 over present in intensity
Secondary Beams
• Broad range of radioactive beams
up to 1.5 - 2 GeV/u; • up to factor 10 000 in intensity over present
• Antiprotons 3 - 30 GeV
Storage and Cooler Rings
•Radioactive beams
•e- - A and Antiproton-A collider
100 m
UNILAC SIS 18
SIS 100/300
HESR SuperFRS
NESR
CRRESR
GSI todayGSI today
Future FacilityFuture Facility
ESR
1.4 GeV
ISOLDE at CERN
from PS Booster
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Lecture 1
REX-ISOLDE
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FRIB in the U.S. (MSU/NSCL)
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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Modifications of nuclear shell structure
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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Two-neutron separation energies
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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Fig. by R.F. Casten
Shellclosure
The extreme single-particle model
R. Krücken - XVth UK Postgraduate School in Nuclear Physics – Lecture 1
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StrongSpin-orbitFrom individual nuclei with NN interaction
to mean field with residual interaction
Penning Trap Mass Measurements
• Ingredients:– Homogeneous vertical magnetic field
® Radial trapping® cyclotron motion: wc= B q/m
– Axial electrostatic quadrupole field ® Vertical trapping® Vertical oscillation:
wz=(qU0/(md2))1/2
222
22
zcc
222
22
zcc
modified cyclotron motion:
4d2=(2z02+r0
2)
magnetron frequency:
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Lecture 1
Penning Trap Mass Measurements
yta
Vd
dx cos
22 xt
a
Vd
dy cos
22
Coupling between modes conversion to cyclotron motion
Excite cyclotron motion via quadrupole RF
Eject ions along trap axis transform radial energy to axial energy via dB/dz gradient
Measure time of flight (TOF) -the shorter TOF, the closer is the excitation frequency to the resonance
zBωμz,ωF dd
K. Blaum, Physics Reports 425 (2006) 1 – 78
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Lecture 1
ISOLTRAP
A. Herlert, et al., Int. J. Mass Spectrom. 251, (2006) 131
bunching
measurement
purification
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