Transcript INVESTIGATION OF THE NON-STATISTICAL PRODUCTION RATIO OF 1S2S2P 4P AND 1S2S2P 2P STATES BY e- CAPTURE TO THE 1S2S 3S STATE OF.

INVESTIGATION OF THE NON-STATISTICAL PRODUCTION RATIO
OF 1S2S2P 4P AND 1S2S2P 2P STATES BY
e- CAPTURE TO THE 1S2S 3S STATE OF He-LIKE IONS:
A PROGRESS REPORT
Theo J.M. Zouros
Dept. of Physics, University of Crete,
Heraklion, Crete, GREECE
Atomic Collisions & Electron Spectrometry Laboratory
Institute of Nuclear and Particle Physics,
Demokritos, Athens
XXIV ISIAC Barcelona July 19-21, 2015
Production of
1s2s2p 4P and 1s2s2p 2P states by
e- capture to the 1s2s 3S state of He-like ions
0.1 – 2 MeV/u
𝑋
𝑍−2 +
1𝑠2𝑠 3S + 𝑇 𝑒 − → 𝑋
He-like Ion Beams:
𝑋 𝑍−2 + : C4+, F7+, B3+
Also want to do Li+, N5+, O6+
𝑍−3 +
1𝑠2𝑠𝟐𝒑 4,2P +
Gas targets
𝑇: H2, He, Ne, Ar, …
@ the 5 MV Tandem of Demokritos
Athens, Greece
APAPES project
(http://apapes.physics.uoc.gr)
ISIAC Barcelona July 19-21, 2015
1s2s2p 3-electron spectrum resulting
from e- capture to He-like beam
e- Analyzer
12 MeV C4+
W=1521eV, F=4 (VL4=-684.45V,VL5=1399.32V)
14
4P
4
1s2p2 2D
8
1s(2s2p1P)2P+
R = P/(2P+ + 2P-)
10
6
Ne (20mTorr)
4
1s(2s2p 3P)2P-
ion
12
1s2s2 2S
F6+ (1s2s 3S2p)
Normalized electron Yields (x 10-11)
1s2s2p 4P
2
0
1480
1500
1520
Laboratory Energy (eV)
2P
±
Interest in ratio
4P/2P
ISIAC Barcelona July 19-21, 2015
1540
What’s in a Ratio? R=4P/2P
12 MeV C4+ W=1521eV, F=4 (VL4=-684.45V,VL5=1399.32V)
• Independent of most
instrumental parameters
14
Normalized electron Yields (x 10-11)
4
P
Ne (20mTorr)
12
R = 4P/(2P+ + 2P-)
10
8
6
2
2
S
4
2
2
P-
(i.e. detector efficiency, number of ions,
target pressure, etc.)
P+
D
2
0
1480
1500
1520
Laboratory Energy (eV)
1540
• Obey spin statistics
• Unexpected value could reveal
existence of underlying
processes
ISIAC Barcelona July 19-21, 2015
Ratio R=4P/2P
12 MeV C4+ W=1521eV, F=4 (VL4=-684.45V,VL5=1399.32V)
14
Normalized electron Yields (x 10-11)
4
P
Ne (20mTorr)
12
R = 4P/(2P+ + 2P-)
10
8
6
2
2
S
4
2
P+
2
P-
D
2
Expected ratio from
spin statistics
After subtraction of
Ground state
“contamination”
0
1480
1500
1520
1540
Laboratory Energy (eV)
2P= 2P
2P+
+
Additional new check:
R= 4P/2P = 2
2P /2P+
ISIAC Barcelona July 19-21, 2015
=3
Obtaining pure metastable beam contributions
Pure metastable state
Ratio of 4P/2P
WMU
So why the big
discrepancy!?
Spin statistics
Strohschein et al PRA 2008
ISIAC Barcelona July 19-21, 2015
First explanation: Pauli exchange interaction?
WMU
Alternative hypothesis: Cascade feeding
UoC
ISIAC Barcelona July 19-21, 2015
Alternative hypothesis: Cascade feeding
nl
Overlooked channel:
Radiative cascade Feeding!
Tanis et al considered
capture only to n=2
Significant capture to higher
n=3-7 indicated by our CDW
calculations
Cascade feeding 1s2s2p 4P analysis
Order
For a state p:
depopulating
populating
transitions
E1Selection Rules:
Quartet  Doublet
NOT allowed!
Quartet  Quartet
allowed!
Strong cascade feeding
of 1s2s2p 4P !
Cool!
ISIAC Barcelona July 19-21, 2015
Cascade feeding 1s2s2p 4P analysis
Order
c0
c2
t
σN4P4P(t)
c2
0.0005
0.0004
1 MeV/u
C4+ + He
c1
0.0003
0.0002
0.0001
c0
Strong cascade
Feeding!
For t >10-11s
10 14
10 12
10 10
10 8
10 6
t s
t 10(s)
4
New plots based on the work of
Röhrbein et at Phys. Rev. A 2010
ISIAC Barcelona July 19-21, 2015
c1
But wait a minute!
Shouldn’t the cascades also feed the 2P states too
Thus also enhancing the denominator
of the 4P/2P ratio?
Indeed! But …
ISIAC Barcelona July 19-21, 2015
Cascade feeding 1s2s2p 2P analysis
Order
c0
c2
Same E1 selection rules!
However now
Auger transitions
to ground state
much stronger!
They rapidly deplete
higher lying levels!
Minimal cascade
feeding
of 1s2s2p 2P !
ISIAC Barcelona July 19-21, 2015
c1
Cascade feeding 1s2s2p 2P analysis
Order
c0
c2
2P(t)
t
σN2P
0.00015
0.00010
1 MeV/u
C4+ + He
c2
c1
c0
0.00005
No cascade
Feeding!
State depleted
for t >10-12s
10 14
10 12
10 10
10 8
10 6
t s
t 10(s)
4
New plots based on the work of
Röhrbein et at Phys. Rev. A 2010
ISIAC Barcelona July 19-21, 2015
c1
Similar results also presented for C4+
Röhrbein, Kirchner,
Fritzsche PRA 2010
This selective
Cascade feeding
mechanism
accounts 70%
for about 50%
of the observed
enhancement
Strohschein et al PRA 2008
So what is the rest due to?
EXCELLENT QUESTION!
2013 - APAPES
Proposal granted!



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
Ideally suited to the Demokritos tandem
accelerator energy range of 0.8-5 MV.
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
ISIAC Barcelona July 19-21, 2015
New results
2014-2015
APAPES
Comparison
150
Mixed (1s2 + 1s2s 3S)
Gaussian fits
4
P
2
100
P+
12 MeV C4+
Normalized Yields (arb.units)
C4+ + Ne
2
P-
2
S
50
2
D
0
12 MeV C4+
12
C4+ + He
10
8
6
4
2
0
220
225
230
235
240
245
250
Electron Energy (eV)
Similar energy resolution
ISIAC Barcelona July 19-21, 2015
Strohschein 2008
More New results
2014-2015
Higher Energy – 18 MeV
New targets
6
6
W=1521eV,F=4,
VL4 =-684.45V,
VL5=1399.32V
Normalized electron Yields (x10-11) (arb.units)
4
Ne
2
0
4
2
4
P
He
2
S
2
2
P- P+ 2D
0
4
3
4
5
Normalized electron Yields ( 10-11)
12 MeV C
4+
Norm.yields
Norm.fit
P
2
18 MeV C4+ W=1966eV, F=4
Ne (20 mTorr)
Fit
4
4
P
2
P+
2
2
2
2
2
P-
S
1
1
D
2
2
S
0
6
P-
P+
2
D
0
3
5
Ar (5 mTorr)
Fit
4
P
Ar (5 mTorr)
Fit
4
P
2
4
3
2
2
P+
2
S
P-
1
2
2
2
S
2
P-
D
P+
2
D
1
0
220
0
225
230
235
240
245
250
0
220
225
230
235
240
245
250
Auger Electron Energy (eV)
4
Ar
2
0
220
Ne (20 mTorr)
Fit
2
3
2
H2
12 MeV C4+ W=1521eV, F=4
225
230
235
240
245
Auger electron Energy (eV)
250
New calculations are needed
to evaluate capture and cascade
contributions for all measured
collision systems
ISIAC Barcelona July 19-21, 2015
Zero-degree Auger Projectile spectroscopy setups:
1s2s2p 4P yield correction for long-life times
APAPES -12 MeV C4+
WMU
-1
Temporal Term FT (mm )
-1
10
J=1/2 =3.7 ns
J=3/2 =13.2 ns
J=5/2 =117.2 ns
-2
10
-3
10
-4
10
-5
10
1
10
-1
10
-2
10
 = max
0(s0-z) (sr)
0
10
-3
10
C4+
-4
10
-2
0(s0-z) FT(z) (sr/mm)
10
-3
10
-4
10
-5
10
-6
10
τ1/2 = 2.8 ns
-7
10
0
50
100
150
200
250
300
1 MeV/u
τ3/2 = 7.3 ns
Z (mm)
τ5/2 = 120 ns
28.9cm
5.8cm
ISIAC Barcelona July 19-21, 2015
Zero-degree Auger Projectile spectroscopy setups:
1s2s2p 4P yield correction for long-life times
WMU
c0
C4+
For C4+1s2s2p 4P
correction factors:
7.3, 8.8, 10.2
for 6, 9, 12 MeV
Strohschein PRA 2008
τ1/2 = 2.8 ns
1 MeV/u
τ3/2 = 7.3 ns
τ5/2 = 120 ns
5.8cm
ISIAC Barcelona July 19-21, 2015
1s2s2p 4P metastable solid angle correction factor –
WMU – two-stage parallel plate Analyser (2PPA)
Comparison for c0 and c2
2PPA
entry
dN/dz Detected e-
Norm dN dz J 1 2
Lost e-
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.1
1
10
100
z (mm) – distance from target
ISIAC Barcelona July 19-21, 2015
1000
z mm
z = Vp t
1s2s2p 4P metastable solid angle correction factor –
WMU – two-stage parallel plate Analyser (2PPA)
No cascade
correction
New point!
With cascades
c2 correction
Röhrbein, Kirchner, Fritzsche PRA 2010
ISIAC Barcelona July 19-21, 2015
Summary and Conclusions
• c2 Cascades included
in the solid angle correction factor
Now Corrected 4P/2P ratio for C4+
in much better agreement with theory!
• More measurements still needed
for different collision systems to
better check systematics (APAPES)
• Follow up cascade calculations
• Tests of solid angle correction factors to 4P
• Can someone please calculate the
Pauli Exchange Interaction?
ISIAC Barcelona July 19-21, 2015
In April 2015 joined the APAPES collaboration
Tom Kirchner
York University
Toronto, Ontario, Canada
THEORY – Capture calculations
and Analytic Cascade formulation
Curtis,
AJP 1968
ISIAC Barcelona July 19-21, 2015
APAPES
Main team
• Dept. of Physics, Univ. of Crete, Heraklion
Theo
Zouros
(Prof & PI)
Anastasios Ioannis Angelos
Dimitriou Madesis Laoutaris
(PostDoc)
(PhD student) (MS student)
ISIAC Barcelona July 19-21, 2015
APAPES
important participants
Measurements
Manolis
Benis
(Prof)
Bela
Sulik
(Prof)
Dept of Physics
Univ of Ioannina
Greece
ATOMKI
Debrecen
Hungary
Spiros
Doukas
U. Ioannina
SIMION
Omer
Sise
(Prof)
Univ of Isparta
Turkey
Genoveva
Martinez-Lopez
(Prof)
Jose
Paulo Santos
(Prof)
Dept Fisica
Aplicada Madrid,
Dept de Fisica
Univ Nova de Lisboa
Spain
CPO simulations
Zoom lenses
ISIAC Barcelona July 19-21, 2015
Portugal
Atomic
Structure
calculations
APAPES
Support Team
5MV Tandem, Institute of Nuclear and Particle Physics
NCSRT Demokritos
Dr. Sotiris
Dr. Tasos
Dr. Michalis
Harissopulos Lagoyannis Axiotis
(Director)
(Res.)
(Res.)
Miltos
Theo
Andrianis Mertzimekis
(Accel. Eng.) (Prof.)
Univ. of
Athens
ISIAC Barcelona July 19-21, 2015
The end
thank you for listening
Recent publication: Doukas et al. RSI 84 (2015) 043111
More info? Please Contact me: [email protected]
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.
ISIAC Barcelona July 19-21, 2015