C. Kleffner’s research while affiliated with GSI Helmholtz Centre for Heavy Ion Research and other places

An experiment addressing electron capture (EC) decay of hydrogen-like $^{142}$Pm$^{60+}$ ions has been conducted at the experimental storage ring (ESR) at GSI. The decay appears to be purely exponential and no modulations were observed. Decay times for about 9000 individual EC decays have been measured by applying the single-ion decay spectroscopy method. Both visually and automatically analysed data can be described by a single exponential decay with decay constants of 0.0126(7) s$^{-1}$ for automatic analysis and 0.0141(7) s$^{-1}$ for manual analysis. If a modulation superimposed on the exponential decay curve is assumed, the best fit gives a modulation amplitude of merely 0.019(15), which is compatible with zero and by 4.9 standard deviations smaller than in the original observation which had an amplitude of 0.23(4).

An experiment addressing electron capture (EC) decay of hydrogen-like Pm60+142 ions has been conducted at the experimental storage ring (ESR) at GSI. The decay appears to be purely exponential and no modulations were observed. Decay times for about 9000 individual EC decays have been measured by applying the single-ion decay spectroscopy method. Both visually and automatically analysed data can be described by a single exponential decay with decay constants of 0.0126(7)s−1 for automatic analysis and 0.0141(7)s−1 for manual analysis. If a modulation superimposed on the exponential decay curve is assumed, the best fit gives a modulation amplitude of merely 0.019(15), which is compatible with zero and by 4.9 standard deviations smaller than in the original observation which had an amplitude of 0.23(4). Keywords: Two body weak decay, Orbital electron capture, Single particle decay spectroscopy, Heavy ion storage ring

As part of the accelerator chain for antiproton production of the FAIR facility, a special high-intensity short pulsed 325 MHz Proton Linac is being developed [1], [2]. The Proton Linac is designed to deliver a beam current of 70 mA with an energy of 68 MeV. A 2.45 GHz ECR source designed for the generation of 100 mA beams with an energy of 95 keV is currently being tested at CEA/Saclay. The production of the structure of the IAP ladder RFQ is nearly completed. All parts of the RFQ vacuum chambers have been successfully copperplated at the GSI. Seven Thales Klystrons have been delivered to GSI at the beginning of 2018 and are nearly ready for use. The completion of the setup of the HV modulator is expected mid of the year 2019. The state of procurement Figure 2: Proton Linac Interface Wall with the construction area for the Proton Linac in front.

For the Facility for Antiproton and Ion Research (FAIR) a compact proton linac will produce proton beams with energy of 68 MeV that will be injected into upgraded Heavy Ion Synchrotron (SIS 18), accelerated to 4 GeV, and further accelerated to 30 GeV in SIS 100. The commissioning of the proton injector which would serve for the injection into the proton linac has already started at CEA/Saclay. The ion source operating with a microwave frequency of 2.45 GHz based on Electron Cyclotron Resonance (ECR) plasma production with two coils each with 87.5 mT magnetic field, will deliver a 100 mA proton beam at 95 keV of energy. The Low Energy Beam Transport (LEBT) including two short solenoids system and integrated steerers will transport the proton beam to the RFQ entrance with an expected emittance lower than 0.3π mm mrad (normalized, rms). After the LEBT an electrostatic chopper will be mounted in front of RFQ to shorten the beam pulse to 36 µs. This paper presents the status of the commissioning phases including first results of proton injector.

HADES is a fixed target experiment using SIS18 heavy-ion beams. It investigates the microscopic properties of matter formed in heavy-ion, proton and pion-induced reactions in the 1-3.5 GeV/u energy regime. In 2014 HADES used a secondary pion beam produced by interaction between high-intensity nitrogen primary beam and a beryllium target. In these conditions beam losses, generated by slow extraction and beam transport to the experimental area, led to activation of the beam line elements and triggered radiation alarms. The primary beam intensity had to be reduced and the beam optics modified in order to keep radiation levels within the allowed limits. Similar beam conditions are requested by HADES experiment for upcoming run in 2018 and in the following years. Therefore, a number of measures have been proposed to improve beam transmission and quality. These measures are: additional shielding, additional beam instrumentation, modification of beam optics and increase of vacuum chambers' apertures in critical locations. The optics study and preliminary results of FLUKA simulations for optimization of location of loss detectors are presented.

Once operational, CRYRING@ESR will store and decelerate ions delivered by the experimental storage ring ESR at energies well below those of ESR. In addition to that, CRYRING@ESR has an electron cooler operating with an ultracold electron beam, allowing to provide cooled ion beams for precision experiments. These ions will be delivered to a broad range of experiments presently in preparation; either in-ring or extracted to a dedicated beamline for experiments. An overview and status report of the installation and commissioning of the CRYRING-@ESR storage ring for highly charged ions at the GSI Helmholtzzentrum für Schwerionenforschung is presented. The installation of this storage ring started in 2014 and was completing end of 2016, when this publication was written.

We report on the resonant coherent excitation (RCE) of the 2s-2p3/2 transition in Li-like U89+ with an enhanced energy resolution, which was achieved by reducing the projectiles momentum spread. The kinetic temperature of the beam was decreased by electron cooling in the ESR, and the collisional momentum broadening in the target was suppressed by the use of thin crystal (1.0 and 2.5 μm-thick). The resonance width was observed to be ~1.4 eV in FWHM, which is three-times narrower than that from the previous work.

A radioactive 56Ni beam was successfully accumulated for an experiment with an internal hydrogen target at the storage ring ESR of GSI, Germany. The radioactive beam was produced and separated at the GSI fragment separator from a stable 58Ni beam. About 8 · 10456Ni28+ions were injected into the ESR on a high relative momentum orbit. The beam was subjected to stochastic precooling, bunched and transported to a low relative momentum orbit. Slightly below this deposition momentum, the beam was accumulated and continuously cooled by means of electron cooling. After accumulating about 60 shots, this beam was prepared to overlap with the ESR internal gas jet target for a nuclear physics experiment. Data acquisition was started with a stored beam of roughly 4.8 · 10 6 particles in the beginning.

The CNAO (Centro Nazionale di Adroterapia Oncologica), located in Pavia (Italy), is a dedicated clinical synchrotron facility for cancer therapy using high energy proton and Carbon beams. The 400 MeV/u synchrotron is injected by a 216.8 MHz 7 MeV/u linac composed by a low energy beam transport (fed by 2 ion sources), a 400 keV/u 4-rod type RFQ and a 20 MV IH-DTL. The commissioning of the two ECRIS ion sources and the low-energy line was successfully completed at the end of January 2009 reaching the proper beam conditions for injection into the RFQ. After installation and conditioning, the RFQ was commissioned with beam by the GSI-CNAO-INFN team in March 2009. The beam tests results are presented and compared to the design parameters.