1

Absolute Cross Absolute Cross SectionsSections forforIonizationIonization, , ExcitationExcitation and and RecombinationRecombination

fromfrom InteractingInteracting--BeamsBeams ExperimentsExperiments

Research Coordination Meeting, IAEA CRP, Vienna, 14-15 November 2005

Alfred MüllerAlfred MüllerInstitutInstitut fürfür AtomAtom-- und und MolekülphysikMolekülphysik

JUSTUS-LIEBIG- UNIVERSITÄT GIESSEN

I M PA

Erhard Salzborn Erhard Salzborn representedrepresented IAMP IAMP duringduring thethe JuneJune meetingmeeting

Erhard Salzborn is retired

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OutlineOutline

1. Overview of experimental capabilities

2. Some characteristic results obtained fora) electron-ion recombinationb) photoionization of ionsc) electron-impact ionization of ions

3. Experiments relevant to the present CRP

1. 1. PresentPresentexperimental experimental capabilitiescapabilitiesof IAMP Giessenof IAMP Giessen

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OurOur specialityspeciality: : interactinginteracting beamsbeams

F1

F3

D4

D3

B 2+ES1

ES2

ES5

ALS

ASS KK

Beam crossing

Scheme adopted from H. Bräuninget al., J.Phys.B 38, 2311 (2005)

FacilitiesFacilities availableavailable at IAMPat IAMP

Electron-ion crossed-beams apparatus

see K. Tinschert et al., J.Phys.B 22, 531 (1988)

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FacilitiesFacilities availableavailable at IAMPat IAMP

Ion-ion crossed-beams apparatus

collimators

collimators

90 o magnet

17 o magnet

quadrupole

quadrupole

quadrupole

lenses

steerer

steerer

High voltage terminal

10 GHz ECR source

10 GHz ECR source

He2+ + He+ → He+ + He2+

For apparatus see H. Bräuning et al., J.Phys.B 38, 2311 (2005)

see S. Krüdeneret al., P.R.L. 79, 1002 (1997)

Versatile apparatusfor studyingatomic collisions(additional beamlines not shown)

focus is on

electron-ion crossed beams

also availablekeV atom beamscharge transfer targetselectron spectroscopy

FacilitiesFacilitiesavailableavailable at IAMPat IAMP

See J. Jacobi et al., Phys. Rev. A 70, 042717 (2004)

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FacilitiesFacilities availableavailable at IAMPat IAMP

powerful electron sources

electronsions

collectorcath

ode

See W. Shi et al., Nucl. Instrum. Methods B 205, 201 (2003)

High High currentcurrent electronelectron gungun 3 keV electrons @ beam current 1 Ademonstrated

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ESR at GSI Darmstadt

TSR Heidelberg

CRYRING Stockholm

ca. 15 m

IAMP IAMP experimentsexperiments at at heavyheavy--ionion storagestorage ringsrings

StorageStorage ring TSR at Maxring TSR at Max--PlanckPlanck--Institut für Institut für Kernphysik, HeidelbergKernphysik, Heidelberg

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ElectronElectron cooler at CRYRING, cooler at CRYRING, ManneManne--SiegbahnSiegbahn Laboratory, in StockholmLaboratory, in Stockholm

PhotonPhoton--ionion mergedmerged--beambeam experimentexperiment at at thetheAdvancedAdvanced Light Light SourceSource ALS in BerkeleyALS in Berkeley

ion source

IAMP in collaboration with R. A. Phaneuf et al., University of Nevada, Reno

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ALS at Lawrence Berkeley Laboratory

2. 2. CharacteristicCharacteristic resultsresults: :

a) a) exampleexample of of recentrecent workwork on on dielectronicdielectronic recombinationrecombination (DR)(DR)

from acceleratordipolequadrupole

septum

extractedbeam

injectionand

extraction

ion beamdirection

electron cooler

Electron target section

collision productdetectors

chargedfragmentcounting

beam profilemonitor

(hor./vert.)ion currentmonitor

Schottkypick-up

molecularfragmentimaging

5m

inductionaccelerator

TSR

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DR of ScDR of Sc18+ 18+ (1s(1s22 2s) : 2s) : TheoryTheory and TSR and TSR experimentexperiment

0

1

2

3

4

5

6

7

0.00 0.05 0.10 0.15 0.20 0.250

1

2

3

4

5

6

7

j=3/

2

j=1/

2

DR

cross section ( 10-14 cm

2 )R

ecom

bina

tion

rate

coe

ff. (1

0-8 c

m3 s

-1)

Electron-ion collision energy (eV)

2s-2p Lamb shift determined with uncertainty of 1.9 meV !

S. Kieslich et al., Phys. Rev. A 70 (2004) 042714

DR of ScDR of Sc18+18+ : : ultraultra--coldcold electronelectron beambeam

In an improved experiment employing an ultra-cold electron beam, hyperfine splitting of the 2s level of Sc18+ could be observed* Energies are determined with sub-meV accuracy !

*Michael Lestinsky et al., to be published

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2. 2. CharacteristicCharacteristic resultsresults: :

b) b) exampleexample of of recentrecent workwork on on photoionizationphotoionization of of ionsions

ion source

PhotoionizationPhotoionization of Cof C3+3+ ions: ions: hhνν + C+ C3+3+ →→ CC4+4+ + e+ e

Resonance energy: 299.976(30) eV (0.01% uncertainty)

Resonance strength: 49.1±10 Mb·eV (20% uncertainty)

299.8 300.0 300.2

0

200

400

600

800

energy scan fit absolute

cross section

Cro

ss s

ectio

n (

Mb

)

Photon energy ( eV )

hν + C3+(1s2 2s 2S) → C3+(1s [2s2p 3P] 2P0) ALS

A. Müller et al., manuscript under preparation for publication in J. Phys. B

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PrinciplePrinciple of of DetailedDetailed BalanceBalance

Time-reversal symmetry relates the cross sections forphotoionization and recombination on a state-to-state basis

2Ae

2ee

f

i

ePR

AePI

)I(EcmE

gg

)(Eσ)IEhν(σ

+=

+=

eifh +↔+ν

cross section for photoionization cross section for photorecombination

photon energy electron energy

statistical weight of initial state statistical weight of final state

ionization energy of state electron rest mass

PIσ RRσ

νh eE

AIig fg

emf

Employing timeEmploying time--reversal symmetry: reversal symmetry: comparison of recombination and comparison of recombination and photoionizationphotoionization

240 250 2720

5

10

1s2p

2 2 S

1s2p

2 2 D

(1s2

s 3 S)

3p 2 Po

1s(2

s2p

1 P) 2 Po

1s(2

s2p

3 P) 2 Po

e + C4+(1s2 1S0) → C3+(1s2lnl') → C3+ + photon(s)

Mannervik et al. (CRYRING) Voigt profile-

time-reversal simulation of "dipole allowed" resonances from ALS photoionization of C3+

Cro

ss s

ectio

n (

10-2

0 cm

2 )

Electron energy ( eV )299.5 300.0 300.5

0

500

1000 resolution 47 meV Voigt-Fit

σ PI (

Mb

)

Photon energy ( eV )

C3+(1s [2s2p 3P] 2P0)photo excitation von C3+(1s22s 2S)

299.5 300.0 300.5

0.00

0.05

0.10C3+(1s [2s2p 3P] 2P0)dielectronic recombination of C4+(1s2 1S)

Ee+64.492 eV

σ DR (

Mb

)

CRYRING

ALS

A. Müller et al., manuscript under preparation for publication in J. Phys. B

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2. 2. CharacteristicCharacteristic resultsresults: :

c) c) examplesexamples of of recentrecent workwork on on electronelectron--impactimpact ionizationionization of of ionsions

TripleTriple--IonizationIonization of of BeBe--LikeLike BB++

500 600 700 800 900

0

1

2

3

4

5

6

7 energy scan measurement absolute cross sections fit formula

K-shell double ionizationwith subsequent Auger decay

direct triple ionization

σ 1→ 4 (

10-2

2 cm

2 )

Energy ( eV )

B+(1s22s2) → B3+(2s2) threshold energy

J. Jacobi et al., ICPEAC 2003, Stockholm, Abstracts of Contributed Papers, p. Fr086

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IonizationIonization in in ComplexComplex SystemsSystems

100 10000

5

10

H. Knopp et al., Giessen, to be published

e + Ba4+(3d104s24p64d105s25p4) → Ba5+ + 2eC

ross

sec

tion

( 10

-17 cm

2 )

Energy ( eV )

SixfoldSixfold IonizationIonization of Baof Ba4+4+

700 750 800 850

0.0

5.0

10.0

15.0

Cro

ss s

ectio

n σ

4,10

( 1

0-22 c

m2 )

Energy ( eV )

750 7600

2

4

H. Knopp et al., Giessen, to be published

7 e- ejected afterdielectr. captureof incoming e-

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3. 3. Experiments relevant to Experiments relevant to the present CRPthe present CRP

Giessen proposal for CRP:cross sections for electron-impact single and multiple ionization of Xeq+ ions

rate coefficients for radiative and dielectronic recombination of ions such as Fe8+, Fe13+, Fe14+, Fe16+, Sc18+ , Cu26+, Si3+ , Si11+, Mg11+

Xenon Xenon ionsions producedproduced byby ECR ECR sourcesource

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ElectronElectron--impactimpact ionizationionization of Xeof Xe10+10+ ionsions

0 100 200 300 400 500 600 700 8000.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

580 600 620 640 660 680 700

5.1

5.2

5.3

5.4

5.5

5.6

120 140 160 180 200 220 2400.0

0.1

0.2

0.3

0.4

absolute data energy scan data

Cro

ss s

ectio

n σ 10

→11

( 10

-18 c

m2 )

Electron energy ( eV )

A. Müller et al., to be published

DielectronicDielectronic recombinationrecombination of Cuof Cu26+26+ ionsions at TSRat TSR

E. Schmidt et al. to be published

An improved experiment was carried out to study DR of Li-like Cu with very accurate calibration of the energy scale. Energy resolution much superior to that of our previousexperiment at the Heidelberg storage ring was observed

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DielectronicDielectronic recombinationrecombination of Feof Fe13+13+ ionsions at TSRat TSRE. Schmidt et al. to be published

DR of Al - like iron was studied in the energy range 0-60 eVNumerous strong resonances were found.

SummarySummary

Highest priority right now: single and multiple ionization of Xeq+ ions

Storage ring recombination experiments are underway

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ScientificScientific personnelpersonnelat IAMP, Giessenat IAMP, Giessen

Prof. Dr. Alfred MüllerPD Dr. Stefan SchippersDr. Kurt HuberPD Dr. Harald BräuningDipl.Phys.Eike SchmidtDr. Jörg JacobiDipl.Phys. Sebastian BöhmM.Sc. Alexander BorovikDr. Dejang YuDr. Sandor RiczJan JungPatrick LöfflerAlexander TitteDietrich BernhardtKristof Holste

Collaborating with:Atomic Physics Groups at

GSI, DarmstadtMPI-K, HeidelbergUniversity of StockholmPhysics Department, University of Nevada, RenoColumbia University, Astronomy& Astrophysics, New York

Scientific Support Groups atTSR, MPI-K, HeidelbergESR, GSI, DarmstadtALS, LBL, BerkeleyCRYRING, MSL, Stockholm

Atomic Theory Groups atGiessen UniversityUniversity of StockholmUniversity of StrathclydeQueen‘s University, BelfastAuburn University

And others occasionally