Manolis Benis Solid angle correction factors for hemispherical and two-stage parallel plate analysers in the detection of long lived projectile Auger states

Manolis Benis

Solid angle correction factors for hemispherical and two-stage parallel plate analysers in the detection of long lived projectile Auger states

Department of Physics, University of Ioannina

9th International Physics Conference of the Balkan Physical Union, Istanbul, 24-27 August 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: HCI: Few-electrons - simpler environment for testing theoriesProjectile spectroscopy: Control # of electrons on ion by selecting its chargeSpecial interest: Two-electron processes, e- correlations and deviations from the IPM

,...),,,v,,,,( xEEZbZqV attpp

M-K radiativetransition

Ex

VpZp

Zt

b

e- e-

Ion-atom collision

vt

ProjectileIonCharge q+ Target

Atom

Ion-atom Collisions: Electron Spectroscopy

0

1

TlnN

N

d

d

PROMPT

e

PROMPT

effMETA

e

META TlnN

N

d

d

1

TlnN

N

d

d

I

e

0

effMETA

PROMPT

PROMPTMETA N

N

d

d

d

d

0


The effective solid angle correction factor

Doukas et al, Rev. Sci. Instr. 86 043111 (2015)


12 MeV C 4+ (1s2s2p 4PJ )

Hemispherical Deflector Analyser

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, submitted to NIMB


101 102 103 1040

1

2

3

4

5 F = 4 s

0= 289 mm

SIMION Analytical

(max

= 2.2o)

G

VP (mm)


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)

Hemispherical Deflector Analyser



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)

Tandem Parallel Plate Analyser

d L1

L2

S

x

w

l

Work In Progress …!

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)

Use both measurements to obtain the fractions Benis et al, Phys. Rev. A 65, 064701 (2002)

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!


TlnN

N

d

d

I

e

0

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


Application: Populating the 1s2l2l' states

Literature Overview

Spin statistics

Strohschein et al, Phys. Rev. A 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, Phys. Rev. A 77, 050701(R) (2008)


Tanis et al, Phys. Rev. Lett. 92, 133201(2004)

Pauli Exchange Interaction


Literature Overview

nl

Zouros et al, Phys. Rev. A 77, 050701(R) (2008)

Radiative Cascade feeding

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, Phys. Rev. A 65, 064701 (2002)


12 MeV C 4+(1s2s 3s) + He

Rohrbein et al, Phys. Rev. A 81, 042701 (2010)

Current and 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


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 Solid angle correction factors for hemispherical and two-stage parallel plate analysers in the detection of long lived projectile Auger states