TRIUMF Summer Institute, 2015 Precision Measurements of Nuclear - - PowerPoint PPT Presentation
TRIUMF Summer Institute, 2015 Precision Measurements of Nuclear Masses Klaus Blaum 113 th -25 th July 2015 Klaus.blaum@mpi-hd.mpg.de Content Motivation for precision mass data 1 Production of short-lived exotic ions 2 How to weigh an
Klaus.blaum@mpi-hd.mpg.de
Klaus Blaum 113th-25th July 2015
Content
1 3 4
Motivation for precision mass data How to weigh an atom Nuclear structure and astrophysics
5
Tests of fundamental symmetries
2
Production of short-lived exotic ions
6
Neutrino physics applications
Some useful literature
Books and review articles:
L.S. Brown and G. Gabrielse: Physics of a single electron
Lecture Notes in Physics, 651, 169-210 (2004) F.G. Major et al.; Charged Particle Traps, Volume I and II Springer, Vol. 37, Berlin (2005)
with radioactive beams; Physica Scripta T152, 014017 (2013)
1 Atomic masses: Motivation
mn,p ≈ 1 GeV/c2 = 1.000.000.000 eV/c2 ≈ 0,0000000000000000000000000017 kg
H2 C60
(nuclear) astrophysics, astrochemistry, production of heavy elements, atomic and molecular binding energies
Fields of applications
nuclear structure, nuclear forces
T C P
fundamental interactions and their symmetries, fundamental constants
particle antiparticle
Atomic and nuclear masses
MAtom = N•mneutron + Z•mproton + Z•melectron
= N · – binding energy + Z · + Z ·
Masses determine the atomic and nuclear binding energies reflecting all forces in the atom/nucleus.
δm/m < 10-10 δm/m = 10-6 – 10-8
Why measuring atomic masses?
δm/m General physics & chemistry ≤ 10-5 Nuclear structure physics
≤ 10-6 Astrophysics
≤ 10-7 Weak interaction studies ≤ 10-8 Metrology - fundamental constants Neutrino physics ≤ 10-9 CPT tests ≤ 10-10 QED in highly-charged ions
≤ 10-11
N · – binding energy + Z · + Z ·
Sources: Accelerator or reactor based radioactive beam facilities and electron beam ion traps. CERN IMP/GSI MPIK TRIGA
KATRIN-TRAP TRIGA-TRAP THe-TRAP PENTA-TRAP Experimental setups CSRe/ESR ISOLTRAP/TITAN SHIPTRAP
The liquid drop model
2 3 / 1 3 / 4 2 2 3 / 1 ,
) ( 5 3 / I A a a A Z r e A a a A E
OberfSymm Symm Oberf Vol Kern B − − −
+ + + + =
A = N + Z, neutron number N, proton number Z and elementary charge e Nuclear Radius: R ≈ r0A1/3 Symmetry: I2 = (N – Z)2/A2
Volume Surface Coulomb Symmetry Parity
Comparison Bnucl: Theory-experiment
Nuclear structure effects like shell closures become visible.
1949: The shell model and magic numbers (Göppert-Mayer + Jensen).
Nuclear structure effects like shell closures become visible.
Test of nuclear mass models
Cs (Z=55)
2 Production of short-lived exotic ions
Radioactive ion beam production
nuclear reaction Primary beam Secondary beam
I0 IRIB
Reaction rate
C i 1 b 10 b
ion beam preparation, separation, acceleration/deceleration, ...
Principle
R = σreaction · φprimary · Ntarget
Cross sections 1 pb – > 10 b Beam flux 1011 – 1015 /cm2 /s Target thickness 0.1 – 100 g/cm2
RIB intensity
IRIB = ε · R ε = f ( )
Transmission, element, half-life, ionization, ...
0.1 / day - > 1012 / s
Proton-induced reactions (ISOLDE, ISAC)
protons p n + Spallation + + Fragmentation + + Fission
201Fr 11Li
X
143Cs
Y
238U
1 GeV
before
Protons 8 V 500 A 9 V 1000 A
http://isolde.web.cern.ch/isolde
after
ISOLDE target
Target- station 1 GPS Target- station 2 HRS
ISOLDE target robots
Ionization possibilities
H Li Na Be Mg Cs Rb K Fr Ba Sr Ca Ra La Y Sc Ac Hf Zr Ti Rf Ta Db W Sg Re Bh Os Hs Ir Mt Pt Ds Au Rg Hg
112
Al Tl Si Pb P Bi S Po Cl At Nb V
Mo
Cr
Tc
Mn
Ru
Fe
Rh
Co
Pd
Ni
Ag
Cu
Cd
Zn In Ga
Sn
Ge
Sb
As
Te
Se I Br
Xe
Kr Ar Rn B C N O F Ne He Th Ce
Pa
Pr U Nd
Np
Pm
Pu
Sm
Am
Eu
Cm
Gd
Bk
Tb
Cf
Dy
Es
Ho
Fm
Er
Md
Tm
No
Yb
Lr
Lu
+ SURFACE –
hot PLASMA cooled
LASER ION SOURCE:
113 114 115 ~80 elements ~1300 isotopes
ISOL: Isotope Separation On-Line
ISOL principle
3 How to weigh an atom
νc,2 νc,1 νc,1 νc,2
How to weigh atoms/ions?
By capturing and storing of ions and comparing with other masses! Nobel Prize in Physics in 1989 to Hans Dehmelt und Wolfgang Paul „for the development of the ion trap technique“.
Wolfgang Paul (1913 - 1993) Hans Dehmelt (1922 - ... )
Storage and cooling techniques
particles at nearly rest in space relativistic particles ∗ ion cooling ∗ long storage times ∗ single-ion sensitivity ∗ high accuracy
Storage ring
ESR
0 2.5 5 m
Penning trap
0 0.5 1 cm
z
r
The Penning trap
particle moves with cyclotron frequency → bound in radial direction
z c
B m q = ω
) ( 2 ) , (
2 2 1 2 2
ρ ρ − = z d U z V
DC
F = −e0(∇φ(r) + v × B) + mr = 0
··) 2 (
2 2 2 1 2
ρ + = z d
Geometry parameter Equation of motion in a Penning trap
F = −e0∇φ(r) + v × B
plus Lorentz force: equation of motion:
F = −e0(∇φ(r) + v × B) + mr = 0
··axial oscillation
2
2
= + ⋅ z m z md U e
m z = 0 ··
2
2 md U e
z =
ω z or axial frequency radial oscillation
2 4 2
2 2 z c c
ω ω ω ω − + =
+
2 4 2
2 2 z c c
ω ω ω ω − − =
−
modified cyclotron frequency magnetron frequency
iy x u + =
B m e
c
= ω
( )
t i
e u t u
ω −
= u u 2 u i
2 z c
= + ω − ω
substitution:
·
u -
·
u =
Storage of ions in a Penning trap
Ion q/m Charge q Mass m
U
B
The free cyclotron frequency is inverse proportional to the mass of the ions!
m qB
c
/ = ω
L.S. Brown, G. Gabrielse, Rev. Mod. Phys. 58, 233 (1986).
ωc
2 = ω+ 2+ω- 2+ωz 2
ωc = ω+
+ ω-
An invariance theorem saves the day:
End of lecture 1
What did we learn? 1) Motivation for precision mass data 2) Liquid drop model and nuclear binding energy 3) Production of radioactive ions 4) Storage of charged particles 5) Penning trap technique What comes next? 1) Manipulation of stored ions 2) Frequency measurement techniques 3) Experimental setup 4) Applications of precision nuclear mass data * Nuclear physics and astrophysics