Post on 30-Aug-2018
Thomas StöhlkerGSI and University of Heidelberg
STRONG FIELD ATOMIC PHYSICS AT GSI/FAIR:
STATUS AND OUTLOOK
Jena
Jülich
ParisGrenoble
DarmstadtCracowCaen
D. BanasG. BednarzC. BrandauS. GeyerA. GumberidzeS. HessR. MaertinR. ReuschlD. SierpowskiU. SpillmannS. TashenovM. TrassinelliS. TrotsenkoG. Weber
The Collaboration
GreenbeltMadison
Mainz Frankfurt
Lanzhou
Heidelberg
Theory: J. Eichler, S. Fritzsche, V. Shabaev, A. Surzhykov
Positive Continuum
Negative Energy Continuum
TransferExcitation Ionization
Free Pair Production
+ mc
- mc2
2
e+
e-
0
Intense Laser
HydrogenEK = -13.6 eV<E>= 1 • 1010 V/cm
Z = 1
Z = 92
H-like UraniumEK = -132 • 103 eV<E>= 1.8 • 1016 V/cm
Atomic Physics in Extremly Strong Coulomb Fields
Atomic Structure at High-Z
• bound state quantum electrodynamics (QED)
• effects of relativity on the atomic structure
• electron correlation in thepresence of strong fields
• dynamically induced strong field effectsub-attoseconds (10–22 s < t < 10–18s
• supercritical fields
1 10 20 30 40 50 60 70 80 90109
1010
1011
1012
1013
1014
1015
1016
1s
<E>
[V/c
m]
Nuclear Charge, Z
ApplicationsApplications• ion cooling techniques• storage and trapping techniques• laser and spectrometer development• photon, electron, ion detection techniques
DynamicsDynamics
• dynamically induced strong field effects,sub-attoseconds (10–22 s < t < 10–18s)
• correlated many body dynamics• elementary atomic processes at high Z• photon matter interaction, e.g. photon
polarization correlation
Positive Continuum
Negative Energy Continuum
TransferExcitation Ionization
Free Pair Production
+ mc
- mc2
2
e+
e-
0
StructureStructureStudiesStudies
• bound state quantum electrodynamics (QED)• nuclear effects on the atomic structure• effects of relativity on the atomic structure• electron correlation in strong fields• supercritical fields
Atomic Physics in Strong Coulomb Fields
Self energy Vacuum polarization
U92+ SE VP NS355.0 eV -88.6 eV 198.7 eV
∆Ε=α/π (αZ)4 F(αZ) mec2
Low Z-Regime: αZ << 1F(αZ): series expansion in αZ
High Z-Regime: αZ ≈ 1 F(αZ): series expansion in αZ not appropriate
Goal: ±1 eV
Bound-State QED: 1s Lamb Shift at High-Z
To proof the validity of QED at high-Z, a broad range of different experimental
approaches is needed
1s-Lamb shift g-factor
2s2p inHe-like
ions
two-electronQED
hyperfinestructure
Test of QED in the Strong Field Regime
massmeasurements
and ...
Production, Storage, and Cooling of HCI
Electron Cooling0.90 0.93 0.96 0.99 1.02 1.05 1.08 1.11
0.0
0.2
0.4
0.6
0.8
1.0
beam
inte
nsity
(arb
. uni
ts)
f / f0
uncooled beam
0.90 0.93 0.96 0.99 1.02 1.05 1.08 1.110.0
0.2
0.4
0.6
0.8
1.0
beam
inte
nsity
(arb
. uni
ts)
f / f0
uncooled beam electron cooled beam
∆p/p ~ 10-5
Storage Ring
Cooling in Storage Rings
electron coolingstochastic coolinglaser cooling
Cooling in Traps
resistive coolingevaporative coolinglaser coolingelectron cooling
Storing and Cooling ist the key for precision
Traps
Precision Spectroscopy @ the ESR Storage Ring
Injection Energy400 MeV/u
Experiment @ 4 MeV/u
dece
lera
tion
Injection Energy400 MeV/u
strippertarget
ESR
electron cooling and deceleration to 4 MeV/u
U91+
400
MeV
/u
coolerPenning
trap
experiments with particles
at restU91+
deceleratorlinac
SIS
UNILAC
6 keV/u
4 MeV/u
5 keV*q
strippertarget
ESR
electron cooling and deceleration to 4 MeV/u
U91+
400
MeV
/u
coolerPenning
trap
experiments with particles
at restU91+
deceleratorlinac
SIS
UNILAC
6 keV/u
4 MeV/u
5 keV*q
U73+
11.4 MeV/u
HITRAP Schematic Overview
~105 U92+ ions~105 U92+ ions
O. Kester et al.
1990 1992 1994 1996 1998 2000 2002420430440450460470480490500510520
Dec
eler
ated
Ions
: C
oole
r (ou
r exp
.)Year
Lam
b S
hift
[eV
]
U91+
Gas
jet
Coo
ler
Dec
eler
ated
Ions
: Jet
Theory
The 1s-LS in H-like Uranium
Test of Quantum Electrodynamics (1s-LS)
80 100 120 140 160 180 2000
20
40
60
80
100
120
140
coun
ts
photon energy [kev]
Lyα1
Lyα2
K-RR
1s Lamb shift
2p3/2
2p1/2
2s1/2
1s1/2
Lyα1 (E1)
Lyα2 (E1)M1
1s-Lamb Shift
Experiment: 459.8 eV ± 4.6 eV
Theory: 463.95 eV
A. GumberidzePRL 94, 223001 (2005)
Research HighlightsNature 435, 858-859
(16 June 2005)
The 1s-LS in H-like Uranium (Exp. at GSI)
Test of Quantum Electrodynamics (1s-LS)
80 100 120 140 160 180 2000
20
40
60
80
100
120
140
coun
ts
photon energy [kev]
Lyα1
Lyα2
K-RR
1s Lamb shift
2p3/2
2p1/2
2s1/2
1s1/2
Lyα1 (E1)
Lyα2 (E1)M1
10 20 40 60 80 10010-5
10-4
10-3
10-2
10-1
1s L
amb
Shi
ft , ∆
E /
Z4 [m
eV]
nuclear charge number, Z
2005
2000
19961991
SE
VP
nuclear size
Goal: Goal: AccuracyAccuracy of of betterbetter 1 1 eVeV forfor thethe LambLamb ShiftShift in in highhigh--ZZ oneone--electronelectron ionsions
higher order
What I left out !
• Dielectronic recombination(ESR/NESR: C. Brandau, C. Kozhuharov et al.,
• Accurate mass measurements(HITRAP: K. Blaum et al.)
• g-factor measurements with HCIs(HITRAP: W. Quint et al.,)
δm/m < 1x10-11 →δmc2 ≈ 2 eV →'weighing' of Lamb shift
low-Z: most accurate determination of the electron mass
medium-Z: fine-structure constant ahigh-Z: test of QED
as tool to study bound state QED and/or nuclear radii (rare isotopes)
Hyperfine Structure
Very similar findings:
[Ho] Crespo Lopez-Urrutia et al., 1996[Re] Crespo Lopez-Urrutia et al., 1998[Pb] Seelig et al., 1998[Tl] Beiersdorfer et al., 2001
In the case of HFS, disagreementbetween
experiment and atomic structuretheory based on QED
Experimenton the HFS will be continuedin 2009 at the ESR, W. Noertershäuser et al.
20 40 60 80 100 120 140 160
1E11
1E12
1E13
1E14
1E15
1E16
1E17
1E18
<E
> V/
cm
Nuclear Charge, Z20 40 60 80 100 120 140 160
1E11
1E12
1E13
1E14
1E15
1E16
1E17
1E18
<E
> V/
cm
Nuclear Charge, Z
1s
2s
2p1/2
Critical- and Supercritical Fields
U92+ → U => U91+ + MO-X-Ray...
as function of impact parameter
RequirementsDeceleration to About 6 MeV/u
107 Slow Extracted Ions Large Solid Angle X-Ray Detectors
Monolayer Target (Uranium)Position Sensitve Particle Detectors
negative
continuum
positive
continuum+m0c2
-m0c2
0
E
boundstates
1s Lamb Shift
2eQED for He-like ions
2s-2p transitionsin He- and Li-like heavy ions
hyperfine-structure
g-factor of boundelectrons
Experiments
Self Energy VacuumPolarization
Test of Bound-State QED at high-Z
Parity admixture
( ) ( )
3 2 10 el 5 0
3 10 0
2 1 4 sin 22 2
2 2
Fw
G NP SZ
E P E S
ρ γη
⎛ ⎞− Θ −⎜ ⎟⎝ ⎠=
−
65 10η −= ⋅
GF: Fermi constant,
N: neutron number,
Θw: Weinberg angleZ: proton numberρel: electric charge density
Parity Violation in Highly Charged IonsHelium-like Uranium
( )1 1 2 1 vE M E p+
( )10 1 ,2S s s ( )3
0 1 ,2P s p
( )31 1 ,2S s s
( )10 1 ,1S s s
2 1E
1010 sτ −≈1310 sτ −≈
M1
[1s2p3/2]1P1
[1s2p3/2]3P2
[1s2p1/2]3P1
[1s2p1/2]3P0
[1s2s1/2]3S1
[1s2s1/2]1S0
First observation of the ∆n=0 3P2 → 3S1transition in He-like uranium: Experiment at the ESR
Accuracy goal: 0.5 eV
4510 eV ?PNC
e-
e-
q
qZ
Relative measurementHe-like Li-like (well-known)
U90+β = 0.25794
∆E = ElabHe - Elab
Li
U89+β = 0.29558
X-ray energy
August 2007
preliminary
M. Trassinelli et al. (2008), in preparation for PRL
Merged Beams
Supercritical fieldsSupercritical fields
U92+U91+
< 5 MeV/uFormation of a Quasi-Molecule
E(r)2pπ
1sσ
timeW. GreinerGSI-Workshop 1996
E [keV] negative continuum
2D/3D Si(Li)-Detector for Compton Polarimetry
crystall size: 4'' x 4''
Si(Li) and Ge(i) based Compton
polarimeter
energy resolution – timing - 2D/3D position sensitivity – multihit
Si(Li) Si(Li)
Ge(i)
32x32 strips2 mm pitch
128x48 strips250µm and 1167µm
Application to high precision spectroscopy based on transmission spectrometer (50 to 100 keV)
Laboratory Laboratory AstrophysicsAstrophysics
Polarization Spectroscopy
Direct insight into celestial plasmas
Spectra provide knowledge of temperature, density, element abundance, etc.
XX--rayray emissionemissionstudiesstudies forfor ionsions in in
well well defineddefinedchargecharge--statesstates QQ
XX--rayray emissionemission of of hot hot plasmasplasmas producedproducedbyby intenseintense laserlaser and and
ionion beamsbeams
FeQ+
Crab nebula
Radiative processes: Main photon matter interaction processes exhibit distinct photon polarization features (Synchrotron Radiation, Bremsstrahlung, Recombination, Inverse Compton Scattering)
∆E
E∆+= 'ωω hhenergy recoil electron :E∆
hω
hω ´θ
ϕ
E
Polarization Measurement via Compton Scattering
0
30
60
90
120
150
180
210
240
270
300
330
ϕ
E
)cos θsin2'
'()'(21 2
c222
0 ϕωω
ωω
ωωσ
−+=Ω h
h
h
h
h
hrdd
Klein-Nishina equationLinearly polarized radiation
hωe-
θc
Si(Li) 2D-strip
-180 -135 -90 -45 0 45 90 135 1800
100
200
300
400
500
600
inte
nsity
azimuthal angle (φ)0 30 60 90 120 150 180
0,0
0,2
0,4
0,6
0,8
1,0
pola
rizat
ion
frac
tion
observation angle, θLAB(deg)
S. Hess et al.,2008(Poster II39)
Stored Ions (Z=Q)
Dipole Magnet
Gas Jet
Experiments at the Jet-Target Electron transferfrom the target atominto the HCI
Particle Counter(MWPC)
50 100 150 200 250 300 350
0
200
400
Lyα1 K-R
EC
8-RE
C
M-R
EC L-R
EC
Lyβ
Lyα2
coun
ts
photon energy (keV)
Coincidence
...ωZ
eZ1)(Q
Q
++→
++−
−+
h
Si(Li) 2D-strip
Ψion beam
E
S
Spin Polarized Ion Beams
for spin polarized ions, thepolarization plane and scattering plane are not equal for spin aligned ionbeams
predictions by A.Surzhykov et al., PRL 94, 203202 (2005)
control over the spin-polarization of storedions:required for EDM and PNC experiments
spin-polarized
Recombination: spin polarization of particles Recombination: spin polarization of particles (ion or electron beam)(ion or electron beam)
Simulation
ψ degree of beampolarization⇒
LaserLaser--Acceleration of Electrons Acceleration of Electrons
typical setup for electronlaser acceleration studies:
Nature 431 (Sept. 2004):3 groups report on laser accelerationof (low-emittance) electron beams with (quasi-monochromatic) 70-200 MeV
E.g. Ex-ray (360keV) = 4 · γ2(for 150MeV e-) · EPhoton(1eV)
x-ray pulse (fs)MeV electron beam
electron pulse∼50 MeV,
(energy spread (2 to 4%)
Laser pulse1 TW, τ = 50 fs, λ=800 nm
X-ray pulse~60 keV, ~10 psωh
10mrad divergence
laser Pulse
First phase of experiment• determination of x-ray background• optimization of x-ray signal, e.g.
laser intensity, target density, pulse duration
Second phase of experiment• determination of the x-ray polarization
Hard x-ray generation using Thomson scattering off laser accelerated electron bunches
Collaboration with the l'OASIS Group@LBNL(supported by NSF,DAAD)
Time Profile
High Intensity Laser PHELIX
• UNILAC ion beam: 5 MeV/u S15+
• heating laser: Phelix,15 ns, 150 J