Demokritos March 11, 2009

1

High resolution High resolution AugerAuger projectileprojectile e e-- spectroscopy spectroscopy: : A state-selective tool to study A state-selective tool to study

highly charged ionhighly charged ion - atom collisions - atom collisions

Theo J.M. ZourosTheo J.M. Zouros

Department of PhysicsDepartment of PhysicsUniversity of Crete - HeraklionUniversity of Crete - Heraklion

LIBRA kick-off meetingLIBRA kick-off meeting

Ion – Atom/electron CollisionsIon – Atom/electron Collisions

Ion beamZ ~ 1-12I ~ 1-100 nAq ~ 1-12E ~ 0.5-2 MeV/uV ~ 3-6 a.u.gs or metastable

t = -t = -∞∞ t = -t = -∞∞∆∆t = 10t = 10-17-17 s sPreparationPreparation

Ionization ExcitationTransfercombinations

RelaxationRelaxation

e-

e-

e-

γ

γ

Black box?!

Non radiative: Auger electronsRadiative: Photon decay

Atom/Molecule Targetq = 0 (neutral)Gas/Solidgs or excited staten ~ 1012-1020 #/cm3

InteractionInteraction

Detectorsprojectile, recoil, photon, electroncoincidencesΔΩ – solid angleε - efficiency

e- beam Targetq = -1 I ~ 1-50 μAn ~ 106-108 #/cm3

UoC HEMISPHERICAL ANALYZER UoC HEMISPHERICAL ANALYZER WITH 2-D PSD 0WITH 2-D PSD 0oo ELECTRON SPECTROMETER ELECTRON SPECTROMETER

UoC HEMISPHERICAL ANALYZER UoC HEMISPHERICAL ANALYZER WITH 2-D PSD 0WITH 2-D PSD 0oo ELECTRON SPECTROMETER ELECTRON SPECTROMETER

Ion Beam

Gas in Pressure Gauge

Gas Cell

PSDX-PositionY- Position

Timing

4-element lens

Faraday Cup

Inner hemisphere

electrons

Outerhemisphere

θ e-

IonResolution ~ 0.1%ΔΩ = 1.8 x 10-4 sr

00 dgrs

Experimental Setup at the 7MV tandem of Experimental Setup at the 7MV tandem of J R Macdonald Laboratory – Kansas State universityJ R Macdonald Laboratory – Kansas State university

1997

2003

Dedicated experimental Dedicated experimental setup 1990 – 2007setup 1990 – 2007

Now have moved all to Now have moved all to DemokritosDemokritos Tandem Tandem

Demokritos 13, 2003 5

0 1000 2000 3000 4000

10-22

10-21

10-20

10-19

10-18

00

inelastic scattering

Bin

ary

En

cou

nte

r

(

v e =

2V p)

1800

elastic scattering

1800

3l3

l' 2

s

3ln

l'(n>

3)

2

s

cu

sp

v e =

Vp

3l3

l' 2

s

2p2

1

s

30.04 MeV F8+

+ H2

00 electron spectra

DD

CS

(cm

2 /eV

sr)

LAB Electron Energy (eV)

High resolution ion Auger electron spectraHigh resolution ion Auger electron spectra

E.P. Benis – PhD thesis, UoC 2001E.P. Benis – PhD thesis, UoC 2001

Elastic Scattering of Quasi-free Electrons on BElastic Scattering of Quasi-free Electrons on B4+4+ Ions Ions

180 190 200 2100

1

2

3

4

5

6

230 240 250 2600

1

2

3

Electron Energy (eV)

2l2l'

d2

/dd

(

10 -

20 c

m2 /e

V s

r)

2p2

1 S

2s2p

1P

2s2p

3P

2s2

1 S

2p2

1 D

220

2lnl

' Ser

ies

Lim

it

2l5l'

2l4l'

2l3l'

3.91 MeV B4+ + H2

Doubly Excited stateszp

z

freee

freequasie

2

vV

)J(v)(E

dΩ

dσ

dEd

σd

180 190 200 210 220 230 240 250 260

1

10

R - Matrix

e- + B4+

d/d

(10 -

18 c

m2 /s

r)

Electron Energy (eV)

Zouros, Benis, Gorczyca, PRA68, 010701(R) (2003)

Elastic Scattering of Quasi-free Electrons on BElastic Scattering of Quasi-free Electrons on B3+3+ Ions Ions

150 155 160 165 170 1750

3

6

9

12

15

180 185 190 195 200 2050

1

2

3

4

5

6

7

1s2p

2 2 S

1s2l2l'

Electron Energy (eV)

1s2lnl' (n>2)

1s2s

2 2 S

1s(2

s2p

1 P) 2 P

1s(2

s2p 3 P

) 2 P 1s2p

2 2 D

1s2s

2p 4 P

d2 /dd

(1

0 -20 c

m2 /e

V s

r)

4.0 MeV B3+ + H2

Doubly Excited states

----

- 2s

2p 3 P

----

- 2s

2p 1 P

150 155 160 165 170 175 180 185 190 195 200 2050.1

1

10

100

R - Matrix

e- + B3+

d/d

(10 -

18 c

m2 /s

r)

Electron Energy (eV)

Zouros, Benis, Gorczyca, PRA68, 010701(R) (2003)

Ion-atomIon-atom//electron interactions: electron interactions: Investigation of the Coulomb forceInvestigation of the Coulomb force

• Force is Force is CoulombCoulomb:: Potential usually known - can write down a HamiltonianPotential usually known - can write down a Hamiltonian• Calculate emission or Calculate emission or interactioninteraction cross sections cross sections• Difficulties: Difficulties: manymany particles, particles, long rangelong range force, force, correlationcorrelation effects effects• Model calculationsModel calculations• Develop theoretical and experimental techniquesDevelop theoretical and experimental techniques• Test approximationsTest approximations

Interest in ion-electron/atom collisions Interest in ion-electron/atom collisions ApplicationsApplications• TokomakTokomak and and AstrophysicalAstrophysical Plasmas Plasmas

• Accelerator technology - Storage ringsAccelerator technology - Storage rings• Radiation damage – Radiation damage – cancer therapycancer therapy• Basic atomic collisionsBasic atomic collisions

• Use HCI and simple targets – few-electron systems• Study ion excitation rather than target excitation:

Control charge state q of ion – N number of electrons Isoelectronic sequence study – same N different Z

In preparation for PHYSICS REPORTS In preparation for PHYSICS REPORTS Zero-degree Auger spectroscopy of Projectile Ions in atomic collisionsZero-degree Auger spectroscopy of Projectile Ions in atomic collisions

in collaboration with in collaboration with N. StolterfohtN. Stolterfoht (HMI-Berlin) (HMI-Berlin)

Dept. of Physics, University of Crete-Heraklion, Crete

Theo J.M. Zouros (Θεόδωρος Τζούρος - tzouros@physics.uoc.gr)

Project: Investigation of one- and two-electron processes in energetic ion-atom collisions using high resolution Auger projectile electron spectroscopy

Goal: State-selective cross section measurements of basic atomic collision processes and the investigation of their collisional energy dependence. Processes include capture, excitation, ionization and combinations such as transfer-excitation, transfer-loss, double-electron capture etc. Investigation of dynamic electron correlation effects.

Scientific domain: Atomic collision physics (Basic Research)

Beams: p, Li, B, Be, C, N, O, F and possibly higher Z

Charge-states: bare, one-, two-, three- and four electron ions, i.e. F6-9+ etc.

Intensities: 10 nA

Setup: installed at INP permanently, modifications necessary.

Spectrometer: Electrostatic energy analyzer in magnetically shielded chamber.

Detectors: MCP or channeltron

Targets: differential pumped gas target using H2, He, Ne, Ar etc.

Personnel: 1 Senior scientist, ideally 1 post-doc and or 1 or 2 students

Man-power support by INP (Yes/No – No. of scientists – Mech. Workshop etc.) :

Other details: Will need basic NIM electronic support, 3-4 3-5kV power supplies, 2-3 turbo pumps and data acquisition and control programs – possibility of collision chamber and spectrometer exists

Is the project part of an international collaboration ? : Yes (Kansas State U., ATOMKI, ITS-LEIF EU network)

Is the project a preparatory work for expmts. abroad ? : Not necessarily but could be

1st TANDEM users meeting, Feb. 3, 2006, INP/Demokritos, Athens

Looking forward to a mutually profitable Looking forward to a mutually profitable collaboration/use of the facilitycollaboration/use of the facility

Thank the Thank the LIBRALIBRA organizers organizers and the and the DEMOKRITOS tandem staffDEMOKRITOS tandem staff for their help so far for their help so far

And in the future to come And in the future to come

Will need help setting up and running experiments Will need help setting up and running experiments all interested parties (particularly students) all interested parties (particularly students)

are invited to joinare invited to join

tzouros@physics.uoc.grtzouros@physics.uoc.gr