Polarization and correlation phenomena in relativistic atomic collisions
Andrey SurzhykovUniversity of Heidelberg and GSI, Darmstadt
in collaboration withStephan Fritzsche, Nikolai Kabachnik, Alexander Gumberidze and Thomas Stöhlker
Work is supported by Helmholtz association
426. WE-Heraeus-Seminar 21 January 2009
Atomic physics of highly-charged, heavy ions
426. WE-Heraeus-Seminar 21 January 2009
During the last decade, atomic physics studies with highly-charged heavy ions have attracted much of interest both in experiment and theory.
Heavy ions provide a unique tool for investigation ultra-strong and ultra-short electromagnetic interactions.
( )2/1
1
cv=γ
−
E ≈ 1016 V/cm
Intense Laser
“structure” studies “collision” studies... and their interplay!
Characteristic x-ray emission from high-Z ions Ion storage rings Electron beam ion traps
1st step: formation of excited state
2nd step: radiativedecay
excited state
A large number of studies have been performed at the storage ring and EBIT facilities to explore projectile x-ray emission following ion-atom collisions.
Analysis the subsequent x-ray emission provides important information both on the structure and on the dynamics of highly-charged heavy ions.
426. WE-Heraeus-Seminar 21 January 2009
Alignment of excited ionic states
In ion-atom collision experiments a preferred direction for the overall system is defined by the ion direction.
Residual (excited) ion may appear to be aligned along this direction.
Example: alignmentof J=1 state
Alignment is described by set of alignment parameters.
These parameters (together with the structure parameters) determine the properties of the subsequent radiative decay.
01
012 2
2σσ
σσ+
−=
±
±A
MJ = -1 MJ = 0 MJ = +1
target atom
projectile ion
426. WE-Heraeus-Seminar 21 January 2009
Characteristic radiation: Analysis
We have performed a polarization and angle-resolved analysis of the characteristic x-ray radiation from highly-charge ions following:
426. WE-Heraeus-Seminar 21 January 2009
θ
Coulomb excitationRadiative electron capture Dielectronic recombination
1stst
ep2n
dst
ep
Radiative decay following REC of bare ions
2p3/2
fitting
)(cosP1 2 θβ+
Ani
sotr
opy
para
met
er β
E1+M2
If multipole mixing between E1 and M2 decay channels is taken into account:
Where f(E1, M2) is the “structure function”:
221 A=β )2,1(
21
2 MEfA=β
12321)2,1(EMMEf +≈
A.S. et al., PRL 88 (2002) 153001
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following REC of H-like ions
1s1/2 2p3/2
observation angle q [deg]
Ka1
Ka2
Kα1
Kα2
In contrast to Lyman-α1 decay in H-like ions, Kα1 emission in He-like ions was found to be almost isotropic.
U90+
Tp = 220 Mev/u
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following REC of H-like ions
426. WE-Heraeus-Seminar 21 January 2009
1s1/2 2p3/2
E1
M2
In contrast to Lyman-α1 decay in H-like ions, Kα1 emission in He-like ions was found to be almost isotropic.
This isotropy is the results of “E1-M2” cancellation in He-like systems:
A.S. et al., PRA 74 (2006) 052710E. Drukarev et al., PRA 74 (2006) 022717
( ) ⎟⎟⎠
⎞⎜⎜⎝
⎛−+⎟
⎠
⎞⎜⎝
⎛ +∝ )(cosP)(1451)(cosP)(
211 22
32221
1211
θθθ α PANPANW K
E1 decay M2 decay
U90+ @ Tp = 220 Mev/u
Radiative decay following REC of H-like ions
426. WE-Heraeus-Seminar 21 January 2009
E1
M2
Another sequence of the “E1-M2” cancellation is the depolarization of Kα1 radiation.
A.S., Th. Stöhlker and S. Fritzsche, NIMB in press
Tp = 10 MeV/u Tp = 220 MeV/u Tp = 400 MeV/u
+ =
M2
E1
Kα1
gas
t
arge
t
ion beam
Reacti
on plane
900
900
IIIIPL +
−=
Characteristic radiation: Analysis
We have performed a polarization and angle-resolved analysis of the characteristic x-ray radiation from highly-charge ions following:
Coulomb excitationRadiative electron capture Dielectronic recombination
θ
1stst
ep2n
dst
ep
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following excitation of He-like ions
Inte
nsity
ratio
Kα
1/Kα
2
Tp =217 MeV/u1s1/2 2p3/2
Coulomb excitation of He-like U90+
A.Gumberidze. et al., Hyperfine Int. 146/147 (2003) 133
fit of experimental data
Kα1 radiation following Coulomb excitation of He-like ions exhibits strong anisotropy.
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following excitation of He-like ions
Kα1 radiation following Coulomb excitation of He-like ions exhibits strong anisotropy.
A.S., U. Jentschura, S. Fritzsche and Th. Stöhlker, PRA 77 (2008) 042722
theoryexperiment
Tp =217 MeV/u
1s 2p3/2 21P1
1s 2p3/2 23P2
Coulomb excitation leads to an almost exclusive population of 21P1 level.
Only E1 transition contributes to Ka1 decay:
( ) )()( 22111θθθ α MEK WNWNW +∝
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following excitation of He-like ions1s 2p3/2 21P1 Calculations of the alignment of the He-like ions
following Coulomb excitation have been performed by taking full interaction into account:
Vector-potential term gives rise to magnetic interactions
1s2 1S0
1s 2p3/21P1
MJ =0
MJ =0 MJ =-1 MJ =+1
Alig
nmen
t par
amet
er A
2
426. WE-Heraeus-Seminar 21 January 2009
( ) ( ) 2
3220
2e1
)(0
ii
fq qq
dqq ψβαψβ
σ µqr−
−∝ ∫
∞
MJ = -1 MJ = 0 MJ = +1
MJ = -1 MJ = 0 MJ = +1
A.S., U. Jentschura, S. Fritzsche and Th. Stöhlker, PRA 77 (2008) 042722
Characteristic radiation: Analysis
We have performed a polarization and angle-resolved analysis of the characteristic x-ray radiation from highly-charge ions following:
426. WE-Heraeus-Seminar 21 January 2009
θ
Coulomb excitation Dielectronic recombinationRadiative electron capture
1stst
ep2n
dst
ep
Radiative decay following K-LL DR
K-LL DR of (initially) H-like U91+
Angular analysis of the characteristic radiation has been performed both the hypersatellite (HS) and satellite (S) transitions.
Discrepancy has been found for the anisotropy of the Kα1 HS line following K-L1/2L3/2 DR.
X. Ma et al., PRA 68 (2003) 042712
2s1/2 2p3/2 : 22p1/2 2p3/2 : 12p1/2 2p3/2 : 22s1/2 2p3/2 : 1
1s1/2 2p3/2 : 11s1/2 2p3/2 : 21s1/2 2p1/2 : 01s1/2 2s1/2 : 01s1/2 2p1/2 : 11s1/2 2s1/2 : 1
L 1/2
L 3/2
reso
nanc
e gr
oup
Kα1,2 HSnon-dipole effects were not included!
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following K-LL DRDetailed theoretical analysis has been performed for each individual line by taking into account multipole-mixing and many-body phenomena.)(cosP1)( 222 θθ AfW +∝
Photon angular distribution:
alignmentstructure function
2s 2p3/2: 2 1s 2s: 1 2s 2p3/2: 1 1s 2s: 1
electric dipole (E1)all multipoles
...12
1~ 22 ++EM
f ifα
S. Fritzsche, A.S. and N. Kabachnik., PRA 78 (2008) 032703
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following K-LL DR
Detailed theoretical analysis has been performed both for every individual line by taking into account multipole-mixing and many-body phenomena...
...and for resulting Kα1,2 radiation.
2s1/2 2p3/2 : 22p1/2 2p3/2 : 12p1/2 2p3/2 : 22s1/2 2p3/2 : 1
1s1/2 2p3/2 : 11s1/2 2p3/2 : 21s1/2 2p1/2 : 01s1/2 2s1/2 : 01s1/2 2p1/2 : 11s1/2 2s1/2 : 1
L 1/2
L 3/2
reso
nanc
e gr
oup
Kα1,2 HS
...))(cosP1()( 2)(
22,1++∝ ∑ θβθα
k
kkK NW
+ + .... =
2s 2p3/2: 2 1s 2s: 1 2s 2p3/2: 1 1s 2s: 1 all multipolesE1 only
S. Fritzsche, A.S. and N. Kabachnik., PRA 78 (2008) 032703
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following K-LL DR
DR/RTE provides a tool to investigate magnetic (Breit) terms in the electron-electron interaction.
Strong effect was found for the resonant strengths (total cross section).
What is the effect for differential properties which are more sensitive to magnetic interactions?
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following K-LL DR
We have investigated effect of Breit interaction on the population of doubly-excited ionic states and, hence, on the subsequent decay radiation.
( )( ) ⎟⎟⎠
⎞⎜⎜⎝
⎛∇∇+−+
=+=
122
122211
12
1221
12
coscos
1
rr
rr
rVVV BC
ee
ωωααωααK-LL DR of (initially) H-like U91+
Example: alignment of 2s 2p1/2 : 1 level is strongly affected by Breit interaction effects.
2s 2p1/2: 1 1s 2s: 0
only CoulombCoulomb + Breit
Breit interaction strongly affects angular distribution of the subsequent decay!
only Coulomb Coulomb + Breit
MJ = -1 MJ = 0 MJ = +1
A2 = -0.516MJ = -1 MJ = 0 MJ = +1
A2 = +0.374
S. Fritzsche and A.S., PRA to be submitted
426. WE-Heraeus-Seminar 21 January 2009
Radiative decay following K-LL DR
We have investigated effect of Breit interaction on the population of doubly-excited ionic states and, hence, on the subsequent decay radiation.
( )( ) ⎟⎟⎠
⎞⎜⎜⎝
⎛∇∇+−+
=+=
122
122211
12
1221
12
coscos
1
rr
rr
rVVV BC
ee
ωωααωααK-LL DR of (initially) H-like U91+
Example: alignment of 2s 2p1/2 : 1 level is strongly affected by Breit interaction effects.
2s 2p1/2: 1 1s 2s: 0
only CoulombCoulomb + Breit
.... and its linear polarization!
only Coulomb Coulomb + Breit
MJ = -1 MJ = 0 MJ = +1
A2 = -0.516MJ = -1 MJ = 0 MJ = +1
A2 = +0.374
S. Fritzsche and A.S., PRA to be submitted
426. WE-Heraeus-Seminar 21 January 2009
Characteristic radiation: Analysis
We discussed the characteristic x-ray emission from highly-charge ions following:
Coulomb excitationRadiative electron capture Dielectronic recombination
The angle-and polarization-resolved studies may reveal unique information about:
interplay of many-body and multipole-mixing effects
magnetic interactions in electron-nucleus and electron-electron interactions
dynamics of relativistic ion-atom collisions
426. WE-Heraeus-Seminar 21 January 2009