Manolis Benis Auger electron yields of metastable Li-like projectile states repopulated by radiative cascades and Auger depletion Department of Physics,

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


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


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


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


Populating the 1s2l2l' states

NTE

V

V

RTE

Target Projectile

V

T (or C)


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


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)


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


Radiative Cascade feeding (?)

Significant capture to higher n=3-7 indicated by CDW calculations

nl

Zouros et al , PRA 77 050701 (2008)


Radiative Cascade feeding (?)

4MeV B 3+ [1s2 1S, 1s2s 3S] + H2


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)



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!


Strohschein et al, PRA 77 022706 (2008)


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)


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


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


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


Cascade Feeding and depletion of a state

Order

depopulation population

Curtis, Am. J. Phys 36 1123 (1968)


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


Spin statistics for 2p capture to 1s2s 3S


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


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


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/


Thank you for your attendance


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.

Documents

Manolis Benis Auger electron yields of metastable Li-like projectile states repopulated by radiative cascades and Auger depletion Department of Physics,