The HITRAP Project at GSI For the HITRAP collaboration: Frank Herfurth GSI Darmstadt

Content The aim is to create highly charged ions up to U 92+ at low energies (eV) or at rest Overview of the facility Deceleration and cooling Key experiments

Overview stripper target ESR electron cooling and deceleration U 73+ U 92+ UNILAC cooler Penning trap experiments for slow particles experiments with particles at rest U 92+ post- decelerator EXPERIMENTS WITH HIGHLY CHARGED IONS AT EXTREMELY LOW ENERGIES:   collisions at very low velocities ultra-accurate   surface studies and hollow-atom spectroscopy   laser and x-ray spectroscopy   g-factor measurements (tests of QED)   mass measurements SIS 6 keV /u 400 MeV /u 4 MeV /u

Overview

HITRAP in the SIS reinjection channel Experiment: Precision trap Other experimental set- ups from ESR 4 m four-gap buncher QP Tripl. x/y steerers profile grid, diagnostics QP Tripl. three-gap re-buncher x/y steerers profile grid, diagnostics Re-injection channel IH-LINAC RFQ cooler trap 4 MeV/u  0.5 MeV/u  6 keV/u wall northern wall of ESR hall solenoid diffusion valve valve 1 m diagnostics cryogenic valve x/y steerers 90 o - bender vacuum section 1vacuum section 2vac. section 3vac. section 4

HITRAP: Deceleration Cycle UNILAC and SIS: acceleration of U 73+ ions up to 400 MeV/u. Extraction towards ESR. Stripping up to uranium U 92+. ESR: Two-stage deceleration with electron cooling down to 4 MeV/u. Rebunching and fast extraction of 6·10 5 ions every 10 s towards ESR-SIS reinjection channel. HITRAP decelerator: Prebunching in four-gap buncher. Deceleration in IH-Linac down to 0.5 MeV/u. Deceleration in RFQ down to 6 keV/u. HITRAP cooler trap: Electrostatic trapping in cryogenic Penning trap. Electron cooling down to 100 eV/u. Resistive cooling to T = 4 K. From cooler trap to HITRAP experimental area: Pulsed and slow extraction of ions from cooler trap. Delivery of 10 5 highly charged ions every 10 s at energies between 1 eV/u and 20 keV/u to precision trap experiment and other experimental set-ups.

ESR deceleration cycle – Efficiency Number of ions Deceleration efficiency E = 4 MeV/u

Decelerator LINAC for HITRAP Operational Parameters:   Highly charged ions with M/q  3   Operation frequency: 108 MHz   Emittance of extracted ESR beam  1  mm mrad   Emittance of decelerated beam  100  mm mrad   Beam intensity after decelerator linac: some 10 5 ions/pulse (for U 92+ )   Repetition time: 10 s   Decelerator can be used for antiprotons

The Cooler Penning Trap trap electrodes capturing and trapping of highly charged ions electron cooling of HCI separation of HCI and electrons resistive cooling of HCI

Collision Studies With Slow HCIs HCI Reaction-Microscope   Studies of reaction kinematics of slow HCI with Reaction-Microscope   Interaction of HCI with surfaces   Development of position-sensitive and multi-hit detectors   Strongly inverted systems

Collision Studies With Slow HCIs

Surface Studies With Slow HCIs

Precision experiments High-Precision Ion Trap Techniques:   Single highly charged ion stored in Penning trap at T = 4 K   Measurement of ion cyclotron frequency and of Larmor precession frequency of the bound electron with an accuracy on the level Bound-state QED and atomic-structure investigations: g-Factor of the bound electron in hydrogen-like ions up to U 91+   Fundamental constants ( , m e )   Nuclear moments, diamagnetic shielding, charge radii   Determination of atomic binding energies via ion cyclotron frequency measurements in different charge states

Bound State QED of e - g-Factor - Dirac (Breit 1928) T. Beier, S. Karshenboim, H. Persson, V. Shabaev, V. Yerokhin, et al. all orders in Z  nuclear size Grotch et al contribution to g-factor nuclear charge Z g bound /g free  1 - (Z  ) 2 /3 +  (Z  ) 2 /4  bound-state QEDDirac theory

g-Factor of the bound electron Ion cyclotron frequency: Larmor precession frequency of the bound electron: Larmor precession frequency of the bound electron: B in hydrogen like ions

Mass Measurements High precision mass measurements:   Single highly charged ion stored in Penning trap at T = 4 K   The ion cyclotron frequency c scales with q and relative statistical mass uncertainty ~   í.e. a mass uncertainty  m/m < can be reached for stable and radioactive nuclei   Example: Comparing masses of U 92+ and U 91+ gives the electron binding energy with an uncertainty below 20 eV! No contamination, very long storage times Low statistical uncertainty Investigation of electron correlation and QED in high fields

Laser and X-ray Spectroscopy Hyperfine-Transition in H-like Ions:   Nuclear properties (charge and magnetisation distributions)   QED effects   Atomic and nuclear polarization by optical pumping X-ray spectroscopy with HCI:   Precision Measurements of Lamb shift   Isotope shift, nuclear charge radii

Conclusions GSI Future Facility: low-energy antiprotons will be available at NESR with high intensity.   HITRAP will be a unique facility for highly-charged ions up to U 92+ at very low energies.   Design of decelerator linac and cooler Penning trap is under way.   Installation of HITRAP Facility at re-injection channel in the ESR hall at GSI.   The future plans at GSI give a long-term perspective for HITRAP.