manolis benis auger electron yields of metastable li-like projectile states repopulated by radiative...
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Manolis Benis
Auger electron yields of metastable Li-like projectile states repopulated by radiative cascades and Auger depletion
Department of Physics, University of Ioannina
SPARC workshop, Fodele, September 22-27, 2015
SPARC workshop, Fodele, September 22-27, 2015
Ion-atom Collisions
continuum
K
LM
Kcapture
K-M excitation
Ea - Auger energy
KLM Augertransition
e-e interaction
AtomicEnergylevels
Kionization
Atomic Structure: q, Zp, Zt , Ex, Ea…Collision Dynamics: b, Vp , vt …Cross section: Highly Charged Ions: Few-electrons - simpler environment for testing theories
,...),,,v,,,,( xEEZbZqV attpp
M-K radiativetransition
Ex
VpZp
Zt
b
e- e-
Ion-atom collision
vt
ProjectileIonCharge q+ Target
Atom
Highly Charged Ions
SPARC workshop, Fodele, September 22-27, 2015
Basic understanding of atomic collision processes
QED corrections
Astrophysical plasmas
Cometary X-ray emission
Fusion research
Radiation damage
HCI nano-structuring of surfaces
Guiding of HCI in insulator nano-capillaries
Accelerator physics
Instrumentation R & D
Projectile Spectroscopy
SPARC workshop, Fodele, September 22-27, 2015
Control of the number of electrons on the projectile Fewer electrons Less complicated system
Metastable ionic beams
Easy to study iso-electronic sequences C3+(1s22s), B2+(1s22s), Be+(1s22s) , …
Low-Z projectiles High Auger electron yields
Kinematic advantages Zero-degree Auger Projectile Spectroscopy (ZAPS)
T+NTE
SPARC workshop, Fodele, September 22-27, 2015
Populating the 1s2l2l' states
NTE
V
V
RTE
Target Projectile
V
T (or C)
SPARC workshop, Fodele, September 22-27, 2015
Spin statistics for 2p capture to 1s2s 3S
Sss 321 + 2p
4P : 2P- : 2P+
12
3
12
1
12
8
Final breakdown
Probability
6
4PpSss 43 2)21(
6
2PpSss 23 2)21(
Spin recoupling
6
4PPpss 43 ))22(1(
PPpss 23 ))22(1(
PPpss 21 ))22(1(
4
1
4
3
222
4
PP
PR 3
2
2
P
PR
SPARC workshop, Fodele, September 22-27, 2015
Literature Overview
Spin statistics
Strohschein et al, PRA 77 022706 (2008)
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00
1
2
3
4
5
6
7
F7+(1s2/1s2s 3S) + He
Data: Lee (1991) Tanis (2004)
Rat
io -
R =
e(
4 P)/
[e(
2 P+)
+
e(2 P
--)]
Projectile Energy (MeV/u)
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00
1
2
3
4
5
6
7
1.875
Rat
io -
R =
e(4 P
)/[
e(2P
+)
+
e(2 P
--)]
F7+(1s2/1s2s 3S) + H2
Projectile Energy (MeV/u)
Zouros et al, PRA 77 050701 (2008)
SPARC workshop, Fodele, September 22-27, 2015
Pauli exchange interaction (?)
A target electron with spin aligned to the spin of the 1s projectile:
b) cannot be captured into the 1s (or 2s) due to Pauli exclusion.
Tanis et al, PRL 92 133201 (2004)
The Pauli Exchange Interaction is reminiscent of the Transfer-Excitation mechanism, but with two identical electrons doing the Transfer and the Excitation! - Rather puzzling and difficult to calculate (not possible to date!)
New idea: So instead it interacts with the 1s (or 2s) via a Pauli Exchange Interaction with one e- transferred to the 2p forming additional 4P states
a) can be captured into the 2p directly to form the 1s2s2p 4P
SPARC workshop, Fodele, September 22-27, 2015
Radiative Cascade feeding (?)
Significant capture to higher n=3-7 indicated by CDW calculations
nl
Zouros et al , PRA 77 050701 (2008)
SPARC workshop, Fodele, September 22-27, 2015
Radiative Cascade feeding (?)
4MeV B 3+ [1s2 1S, 1s2s 3S] + H2
SPARC workshop, Fodele, September 22-27, 2015
TElnN
N
dEd
d
I
e
0
2
RTECapture
Mixed state (1s2 1S, 1s2s 3S ) beams
No lifetime/solid angle corrections
Benis et al, PRA 65 064701 (2002)
SPARC workshop, Fodele, September 22-27, 2015
Mixed state (1s2 1S, 1s2s 3S ) beams
0
2
4
6
8
10
12
14
1s2s
2 2S
1s2s
2p 4P
1s(2
s2p
3P
) 2P
1s(2
s2p
1P
) 2P
1s2p
2 2Df3S
= 25%
4 MeV B3+ + H2
150 152 154 156 158 160 162 164 166 168 170
0
2
4
6
8
10
12
14
f3S < 3%
Electron Energy (eV)
d2/
dd
(10
-20 c
m2/ e
V s
r)Practically ground state (1s2) spectrum. < 3% metastable
Ion Beam obtained by gas stripping at lower energies
Mixed state (1s2, 1s2s 3S) spectrum25% metastable
Ion Beam obtained by foil stripping
“Subtract” spectra to obtain pure metastable beam 1s2s 3S spectrum!
Mixed state (1s2 1S, 1s2s 3S ) beams
Strohschein et al, PRA 77 022706 (2008)
SPARC workshop, Fodele, September 22-27, 2015
The effective solid correction factor
TElnN
N
dEd
d
I
e
0
2 Hemispherical Deflector Analyser
12MeV C3+(1s2s2p 4PJ )
Doukas et al, Rev. Sci. Instr. 86 043111 (2015)
SPARC workshop, Fodele, September 22-27, 2015
225 226 227 228 229 230 231 232 2330.0
0.5
1.0
1.5
2.0
SIMION F = 4
4P
Ele
ctro
n S
igna
l (A
rb. U
nits
)
Auger Electron Energy (eV)
max
= kinem
= 40.3o
max
= 2.0o
max
= 1.8o
max
= 1.5o
max
= 1.0o
Benis et al, NIMB (2015) In press
101 102 103 1040
1
2
3
4
5 F = 4 s
0= 289 mm
SIMION Analytical
(max
= 2.2o)
G
VP (mm)
The effective solid angle correction factor
The lens filters out emitting angles higher than 2o
The lens also filters out electrons generated within it …
Hemispherical Deflector Analyser SIMION Monte Carlo type Calculations
SPARC workshop, Fodele, September 22-27, 2015
SIMION simulations
Doukas et al, Rev. Sci. Instr. 86 043111 (2015)SPARC workshop, Fodele, September 22-27, 2015
Revisit of older data
0
2
4
6
8
10
12
14
1s2s
2 2S
1s2s
2p 4P
1s(2
s2p
3P
) 2P
1s(2
s2p
1P
) 2P
1s2p
2 2Df3S
= 25%
4 MeV B3+ + H2
150 152 154 156 158 160 162 164 166 168 170
0
2
4
6
8
10
12
14
f3S < 3%
Electron Energy (eV)
d2/
dd
(10
-20 c
m2/ e
V s
r)
Benis et al, PRA 69 052718 (2004)SPARC workshop, Fodele, September 22-27, 2015
SPARC workshop, Fodele, September 22-27, 2015
TElnN
N
dEd
d
I
e
0
2
Tandem Parallel Plate Analyser
d L1
L2
S
x
w
l
A spectrometer with well defined solid angle
?
100 80 60 40 20 00.0
1.0x10-4
2.0x10-4
3.0x10-4
4.0x10-4
5.0x10-4
Geometrical SIMION
(
sr)
x (mm)
The effective solid angle correction factor
SPARC workshop, Fodele, September 22-27, 2015
Cascade Feeding and depletion of a state
Order
depopulation population
Curtis, Am. J. Phys 36 1123 (1968)
SPARC workshop, Fodele, September 22-27, 2015
More SIMION simulations …
Include cascade feeding theoretical calculations in the Monte Carlo SIMION simulations
Direct comparison to the experiment!
(No correction factors …)
222 224 226 228 230 232 234 236 238 240 242 2440
500
1000
1500
2000
2500
3000
3500
4000
2D
2P+
2P_
4P
12 MeV C4+[1s2 1S, 1s2s 3S] + He
SIMION Second order cascades First order cascades No cascades
Ele
ctro
n C
ount
s
Auger Electron energy (eV)
2S
Calculations by T. Kirchner
!2)()(
/)(22
4
PYPY
GPY
Testing ground
SPARC workshop, Fodele, September 22-27, 2015
Spin statistics for 2p capture to 1s2s 3S
SPARC workshop, Fodele, September 22-27, 2015
Mid-Future Prospects
SPARC collaboration:Extend our studies to high(er) Z elements
Locate candidate metastable electronic configurations LS jj coupling nomenclature, theorists help
Develop a TDR Current electron spectrometer in a new setup (UHV chamber, gas jet, etc.)
Get approved and … Ask for funding …
Current and near-future prospects
In progress:• Installation of terminal gas stripper
to produce ground state beams• Installation of post strippers (foil and
gas) to produce He-like ions at lower energies
Investigation of the systematics of the 4P/2P ratio in an isoelectronic sequence study using He-like ions from Li+ , B3+ , C4+ , N5+ , O6+ , F7+ in the 0.1-2 MeV/u
Use different targets such as H2, He, Ne, Ar
SPARC workshop, Fodele, September 22-27, 2015
Ongoing Research
New calculations are needed to evaluate capture and cascade contributions for all measured collision systems
0
2
4
6
Norm.yields Norm.fit
Ne
12 MeV C4+ W=1521eV,F=4, VL4 =-684.45V,VL5=1399.32V
0
2
4
He4P
2P-2P+ 2D
0
2
4
Norm
aliz
ed e
lect
ron Y
ield
s (x
10
-11 )
(arb
.units
)
H2
2S
220 225 230 235 240 245 2500
2
4
Auger electron Energy (eV)
Ar
New targets
0
1
2
3
4
5
6
2P-
Ne (20 mTorr) Fit
18 MeV C4+ W=1966eV, F=4
2P+
Nor
mal
ized
ele
ctro
n Y
ield
s (
10-1
1)
2S
4P
2D
0
1
2
3
Ne (20 mTorr) Fit
2S
4P
2P-
2P+2D
220 225 230 235 240 245 250
0
1
2
3
4
5
6
2P-
Ar (5 mTorr) Fit
2S
4P
2P+
2D
220 225 230 235 240 245 250
0
1
2
3
2P-
Ar (5 mTorr) Fit
12 MeV C4+ W=1521eV, F=4
Auger Electron Energy (eV)
2S
4P
2P+
2D
Higher Energy – 18 MeV
SPARC workshop, Fodele, September 22-27, 2015
The People
5MV Tandem NCSRT Demokritos, Greece Dr. S. Harissopulos (Director), A. Lagogiannis, M. Axiotis, M. Andrianis
University of Crete, GreeceProf. T.J.M. ZourosA. Dimitriou (Post doc), I. Madesis (PhD), A. Laoutaris (MSc), Ch. Nounis (MSc)
University of Ioannina, GreeceProf. M. BenisS. Doukas (MSc)
ATOMKI, Debrecen, HungaryProf. B. Sulik
University of Isparta, TurkeyProf. O. Sise
York University, Toronto, CanadaProf. T. Kirchner
Universidade Nova de Lisboa, Portugal Prof. J.P. Santos, Prof. F. Parente, Prof. M.C. MartinsSorbonne Universités, Paris, France Prof. P. Indelicato
Co-financed by the European Union and Greek national funds through OP: Education and Lifelong Learning, Research Program: THALES Grant # MIS 377289
Funded by the APAPES Project: http://apapes.physics.uoc.gr/
SPARC workshop, Fodele, September 22-27, 2015
Thank you for your attendance
SPARC workshop, Fodele, September 22-27, 2015
Acknowledgement: This research has been co-financed by the European Union (European Social Fund ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) Research Funding Program: THALES. Investing in knowledge society through the European Social Fund, grant number MIS 377289.