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Precision spectroscopy of HCI in a reaction microscope. C. Dimopoulou. Max-Planck-Institut für Kernphysik, Heidelberg. HITRAP Meeting, 26-28 May 2005, Munich. MPI-K Heidelberg @ HITRAP. Goal: study charge transfer processes in collisions between HCI and atoms/molecules/clusters.

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Precision spectroscopy of HCI in a reaction microscope

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Precision spectroscopy of

HCI in a reaction microscope

C. Dimopoulou

Max-Planck-Institut für Kernphysik,

Heidelberg

HITRAP Meeting, 26-28 May 2005, Munich


MPI-K Heidelberg @ HITRAP

Goal: study charge transfer processes in collisions

between HCI and atoms/molecules/clusters

Task: develop a reaction microscope

(COLTRIMS spectrometer)

Milestone: tests of the reaction

microscope with light HCI


Extraction of HCI from the HD-EBIT

example: 3104 Kr30+ ions/s

count rate

magnetic field  sqrt(M/q), [arb.units]

ion beam size: ~5 mm (FWHM)


Target Jet

HCI Beam

Ion

Detector

Cold atomic/molecular

target

HCI beam

E~keV/u

position sensitive

detectors

E-field

recoil target

ions

E-field

Scattered

projectile

Projectile detector

Reaction Microscope

Coincident measurement of

momentum vectors of charged collision fragments


He target

HCI beam

EBIT

Target Jet

HCI beam

PSD

E-field

Projectile

detector

Extraction of HCI

(e.g. Ne10+, Ar18+,

Kr34+, U64+,Xe54+)

recoil ions

E-field

recoil ion detector

PSD

t

  • TOF:

  • target ion charge

  • state

  • long. momentum

He+

  • Position:

  • trans. momentum

He2+

Tests with HCI from the EBIT: The electron capture experiment


He target

HCI beam

PSD

E-field

recoil ions

E-field

PSD

t

  • TOF:

  • target ion charge

  • state

  • long. momentum

He+

  • Position:

  • trans. momentum

He2+

Tests with HCI from the EBIT: The electron capture experiment


Ne6+

f

p

9 keV/q Ne7+

p

p

i

D

p

p

Q

p

vP = 0.36 a.u.

He+

Q ppi

p

^

r

p

r

=

-

p

= Q /

v

-

v

/2

p

r||

p

p

r

Electron capture: Precision spectroscopy


0,4

mrad

0,3

mrad

/

Q

0,2

scattering angle

Scattering angle /

0,1

HITRAP: ultimate Q-value resolution

pr|| Q /vp

0,0

10

20

30

40

50

60

70

Q

-

value /

eV

Q

-

value /

eV

capture into n=4

1500

1500

3

2s4s

S

1,3

1

2s 4

L

l

2s4p

P

x10

1000

1000

Projectile excitation

counts

2p 3

l

counts

counts

counts

3

2s4d

D

FWHM 0.72

eV

1

2s4d

D

1

500

2s4s

S

500

2s 3

l

0

0

10

20

30

40

50

60

70

15

16

17

18

19

20

21

22

23

24

25

Q

-

value /

eV

Q

-

value /

eV

Q value /

eV

Q value /

eV

Electron capture: Precision spectroscopy

  • excellent resolution: 0.7eV FWHM

  • excellent precision: 3-100 meV

  • many states resolved simultaneously

  • no selection rules


Q value (eV) :

Q = Ebf - Ebi

Single electron capture in

12 keV/q Ar16+-He collisions

cross section (arb.u.)

scattering angle (mrad)

Dynamics

cross section (arb.u.)

Structure

Q-value (eV)


From light to heavy HCI

?


First capture experiment with U64+ ions

Q value (eV) :

Q = Ebf - Ebi

14 keV/q U64+

(103-104 ions/s)

on He

cross section (arb.u.)

scattering angle (mrad)

Dynamics

cross section (arb.u.)

Structure


The HITRAP reaction microscope

Increased Acceptance for recoil ions:

large ion detector (MCP) with hole in preparation


Summary & Outlook

EBIT

Target: gas-jet

HCI beam

Projectile

detector

  • Reaction microscope:

  • ready and tested in EC

  • experiments with HCI

  • from the EBIT

recoil ion detector

  • Systematic study of EC for bare noble gas ions up to Xe54+ on He

  • Collaboration with S.Knoop, Groningen

  • Future:

  • Installation at HITRAP


Auger cascades

X-rays

E~keV/u

<~~~~~~~~~

Reaction

microscope

HCI

Target

Studies with HCI at HITRAP

HCI from HITRAP

Formation of ”hollow atoms”

t ≈ 1 fs

Questions:

  • Precision Spectroscopy

  • Dynamics of formation:

  • many-electron flux

  • 3. Rearrangement processes

 Coincident detection of ions, electrons and photons


People

Max-Planck Institut, Heidelberg

R. Moshammer, J. R. Crespo Lopez-Urrutia,

D. Fischer, C. Dimopoulou, T. Ferger, G. Sikler,

H. Tawara, A. Gonzalez, R. Soria,

G. Brenner, J. Braun, H. Bruhns, B. Feuerstein, J. Ullrich

Former collaborators

V. Mironov, C. Osborne, A. Lapierre, M. Trinczek

KVI, Groningen

S. Knoop, R. Hoekstra


People


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