1. Experiments with heavy, highly charged Ions HITRAP Project Status
Overview of Facility
Planned Experiments
The HITRAP decelerator status
Deceleration of heavy, highly charged ions from the ion storage ring ESR of the GSI accelerator facility with an rf-linear decelerator will provide ions up to bare uranium almost at rest for cutting edge experiments in atomic and nuclear physics. For this unique approach the beam has to be prepared well by electron cooling in the ESR to account for a 26 time increase of the transverse emittance during the following deceleration. An interdigital H-type (IH) structure and a radio-frequency quadrupole (RFQ) structure are operated in inverse to decelerate first from 4 MeV/u to 0.5 MeV/u and then to 6 keV/u. The quasi-continuous beam from the ESR is adapted, by using a double drift buncher, to match the longitudinal acceptance of the IH. Downstream from the IH-structure the 0.5 MeV/u beam is then fit with a spiral re-buncher to the RFQ, which finally decelerates the ions to 6 keV/u.
First commissioning beam times have shown that the bunching works well and ions have been decelerated to 0.5 MeV/u in the IH structure. Extensive measurements of transversal emittance before and after deceleration can now be compared to beam dynamics calculations.
W. Barth, D. Beck, T. Beier, M. Bevcic, E. Berdermann, M. Block, A. Bräuning-Demian, H. Brand, K. Brantjes, E. Bodewits, G. Clemente, L. Dahl, C. Dimopoulou, C. Dorn, S. Eliseev, S. Fedotova, R. Fischer, P. Forck, F. Herfurth, R. Hoekstra, M. Kaiser, O. Kester, H.-J. Kluge, S. Koszudowski, N. Kotovski, C. Kozhuharov, C. Krantz, R. Lotz, M. Maier, F. Nolden, W. Nörtershäuser, F. Peldzinski, J. Pfister, W. Quint, D. Racano, U. Ratzinger, A. Sauer, A. Schempp, M. Shaaban, A. Sokolov, M. Steck, K. Stiebing, Th. Stöhlker, W. Vinzenz, M. Vogel, H. Vormann, G. Vorobjev, C. Will, D. Winters, A. Wolf, O. Zurkan
and the HITRAP collaboration
Univ. Frankfurt, Univ. Mainz, Imperial College London, TU Darmstadt, St. Petersburg State Univ., TU Wien, Univ. Heidelberg, Jagiellonian Univ. Krakow, MPI-K Heidelberg, KVI Groningen, Univ. Stockholm, ENS Paris, Univ. Münster
Darmstadt
Frankfurt
Heidelberg
Mainz
Groningen

2. F. Herfurth "HITRAP Project Status"
GSI
Beam that will be available to users:
type A/q < 3 (U )
ions/pulse 105
energy keV/q ... meV/q
energy spread ≥ 0.3 meV
Test Ion Source - EBIT:
Up to bare K
Any element (charge breeding)
105 per pulse and second
F. Herfurth "HITRAP Project Status"

3. F. Herfurth "HITRAP Project Status"
Experiments
HCI
Elements
Isotopes
+ Matter
Charge radii
FS, HFS
g-factor
e--binding
+ surface
BW effect
a, me
QED test
Lamb-shift
Structures
+ atoms
Hollow atoms
Charge exchange
Collision dynamics
F. Herfurth "HITRAP Project Status"

4. Precision Experiments on Highly-Charged Ions
Test of quantum electrodynamics in extreme fields
g-factor of the bound electron
Electron correlations and relativistic effects
Determination of fundamental constants
Mass of the electron me
Future: fine-structure constant a
Ultra-precise mass measurements
Determination of atomic and nuclear binding energies
Fundamental
Constants R∞ α me
e+e-
£(H,n=2)
μ+e- gμ
ge bound
HFS (H,1s)
£(H,n=1)
£(U91+,n=1)
HFS (209Bi82+,1s)
GSI/Mainz data ●
Future
F. Herfurth "HITRAP Project Status"

5. Spectroscopy, Reactions and Surface Studies with HCI
Laser spectroscopy of H-like ions:
Nuclear properties (Bohr-Weisskopf effect)
isotope shift – nucl. charge radii
Reaction microscope:
Studies of reaction kinematics of slow HCI
Interaction of slow HCI up to U92+ with surfaces:
Strongly inverted systems ('hollow atoms')
Nonlinear surface modifications
F. Herfurth "HITRAP Project Status"

6. HITRAP Experimental Area
SPECTRAP
surface
experiment
MOT;
Mass Measurements
g-factor
EBIT
HITRAP
HF-platform
Click!
ready 2012
operational
F. Herfurth "HITRAP Project Status"

7. HITRAP Experimental Area
EBIT
g-factor trap
SPECTRAP
Mg CX
MOT target
Surface Chamber
F. Herfurth "HITRAP Project Status"

8. Surface Modifications by HCI
SFM Topographic Picture of CaF2 surface after irradiation with 3 keV/u Xe40+
Hillock, V ~ 200 nm3
Doesn’t work for BaF2 – Why?
Kinetic or Potential Energy?
What happens for even heavier ions?
G-PAC Proposal by A.S. El-Said et al.
A. S. El-Said, et al., Nucl. Instrum. Meth. Phys. Res. B 258, 167 (2007).
A. S. El-Said, et al., Phys. Rev. Lett. 100, (2008).
F. Herfurth "HITRAP Project Status"

9. HCI – Surface Interaction
KVI – GSI – Vienna Collaboration
Xe (7·105 ms-1) on Au
ECR
HD-EBIT
HITRAP
Meissl et al., J. Surf. Sci.
Nanotech 6 (2008) 54
Bodewits et al., KVI
2010
F. Herfurth "HITRAP Project Status"

10. Laser Spectroscopy – SPECTRAP
Courtesy of Z. Andjelkovic / SPECTRAP collaboration
Laser Spectroscopy – SPECTRAP
F. Herfurth "HITRAP Project Status"

11. Laser Spectroscopy – SPECTRAP
Courtesy of Z. Andjelkovic / SPECTRAP collaboration
Trapped single and clouds of ions,
detected electrically and via fluorescence
NEXT Steps:
Pb1+
Test ion source
Ca14+
Bi80,82+
HITRAP
F. Herfurth "HITRAP Project Status"

12. F. Herfurth "HITRAP Project Status"
GSI
SIS
GeV/u
FRS
few MeV/u
ESR
UNILAC
4 MeV/u
F. Herfurth "HITRAP Project Status"

13. HITRAP – Linear Decelerator
to experiments
Beam that will be available to users:
type A/q < 3 (U )
ions/pulse 105
energy keV/q ... meV/q
energy spread ≥ 0.3 meV
matching section
and cooler trap
IH section RFQ section
DDB section 7m
F. Herfurth "HITRAP Project Status"

14. F. Herfurth "HITRAP Project Status"
Challenges
Never done before!
1 ion pulse with only 106 ions every 30 to 60 seconds
“Normal” Linac diagnostics not well suited
Unexpected behavior of decelerating accelerator
F. Herfurth "HITRAP Project Status"

15. Commissioning Summary to Date
About two weeks/year; Beam intensity ~106 ions, once a minute
2007 ESR Extraction tests / Double Drift buncher comm.
2008 DDB / IH test, first deceleration in IH seen
2009 IH retuning, RFQ mounted, Emittance measurements
ESR rebunching at 4 MeV/u, 30 MeV/u mode installed, ~40% decelerated to 500 keV/u
- Start of RFQ commissioning (transmitted 500 keV/u beam)
2011 IH Energy measurements, wide scans of RFQ parameters
~60% decelerated to 500 keV/u
F. Herfurth "HITRAP Project Status"

16. F. Herfurth "HITRAP Project Status"
ESR – From 400 to 4 MeV/u
ESR – Experimental Storage Ring at GSI with stochastic and electron cooling
ESR cycle during recent experiment
signal:
time (s)
RF amplitude
5..20
injection, stoch. cooling
3..10
deceleration 400 – 30 MeV/u
2..6
e- cooling, rebunching
2..5
deceleration 30 – 4 MeV/u
magn.dipole
field
2..5
e- cooling, ejection 3
reset magnets
ion current
40 s
F. Herfurth "HITRAP Project Status"

17. ESR – Rebunching at 4 MeV/u
March 2010
ESR – Rebunching at 4 MeV/u
Current on Farady cup (a. u.)
1 ms
F. Herfurth "HITRAP Project Status"

18. ESR – Rebunching at 4 MeV/u
March 2010
ESR – Rebunching at 4 MeV/u
Current on Farady cup (a. u.)
1 ms
F. Herfurth "HITRAP Project Status"

19. Newly developed Detectors
One-shot energy analyzer
Diamond Detector
MCP/Phosphor screen
0.1 mm slit
Beam
Mirror to CCD camera
0.5 T perm. Magnet
Sensitive single-shot
emittance meter
MCP – Screen – camera combination
MCP FC
digital camera
F. Herfurth "HITRAP Project Status"

20. Deceleration in the IH structure
~4 MeV/u
~0.5 MeV/u
Position of low energy peak vs. IH Power
Scanned Power Range:
125 … 165 kW
Theo. Value for 84Kr kW (7.55V)
F. Herfurth "HITRAP Project Status"

21. F. Herfurth "HITRAP Project Status"
Deceleration to 500 keV/u
Reached nominal efficiency (~60%)
F. Herfurth "HITRAP Project Status"

22. F. Herfurth "HITRAP Project Status"
Summary
ESR operates reliable down to 4 MeV/u
Deceleration in HITRAP to 500 keV/u commissioned
Matching IH/RFQ ongoing
RFQ offline test at MPI-K Heidelberg
Offline test cooler trap
Pilot experiments with EBIT ions
to experiments
matching section
and cooler trap
IH section RFQ section
DDB section 7m
F. Herfurth "HITRAP Project Status"