Integration of maXs-type microcalorimeter detectors for high-resolution x-ray spectroscopy into the experimental environment at the CRYRING@ESR electron cooler

Abstract

We report on the first integration of novel metallic magnetic (micro-) calorimeter detectors, developed within SPARC (Stored Particles Atomic Physics Research Collaboration), into the experimental environment of storage rings at GSI, Darmstadt, namely at the electron cooler of CRYRING@ESR. Two of these detector systems were positioned at the 0° and 180° view ports of the cooler section to obtain high-resolution x-ray spectra originating from a stored beam of hydrogen-like uranium interacting with the cooler electrons. While previous test measurements with microcalorimeters at the accelerator facility of GSI were conducted in the mode of well-established stand-alone operation, for the present experiment we implemented several notable modifications to exploit the full potential of this type of detector for precision x-ray spectroscopy of stored heavy ions. Among these are a new readout system compatible with the multi branch system data acquisition platform of GSI, the synchronization of a quasi-continuous energy calibration with the operation cycle of the accelerator facility, as well as the first exploitation of the maXs detectors’ time resolution to apply coincidence conditions for the detection of photons and charge-changed ions.

Application of a metallic-magnetic calorimeter for high-resolution x-ray spectroscopy of Fe at an EBIT

“…This marks an important milestone for the future deployment of maXs-series detectors, e.g., at accelerator beam lines, where typically access to the experiment setup during the beam time is limited and external sources of strong noise like pumps and beam magnets are present. Together with the coincidencebased background suppression technique demonstrated with a maXs-100 detector during a recently performed beam time at CRYRING@ESR of GSI [37], maXs-series x-ray spectrometers have come a long way towards becoming an indispensable tool for high-precision measurements in fundamental physics research.…”

X-ray Spectroscopy Based on Micro-Calorimeters at Internal Targets of Storage Rings

“…The fairly large uncertainties stemming from temperature drifts and the overlapping amplification behaviors were dramatically reduced in later experiments by continuous calibration and temperature monitoring on a per-event basis. This was demonstrated, for example, in a recently performed experiment involving the deployment of maXs detectors at the electron cooler of the CRYRING@ESR storage ring [23]. Overall, cryogenic calorimeters such as the maXs-series detectors have proven to be an excellent tool for precision X-ray spectroscopy in the hard X-ray range, and more experiments using them as spectrometers at the storage rings of the new Facility for Antiproton and Ion Research (FAIR) are already planned.…”

Radiative Recombination Studies for Bare Lead Ions Interacting with Low-Energy Electrons

“…Here, the electron cooler also serves as a target of free electrons to study the RR processes. Two dedicated X-ray detection chambers installed behind corresponding dipole magnets [11] allow us to record photon emission from the beam-target interaction volume under 0 • and 180 • observation angles with respect to the beam direction. In the experiment, two high-purity germanium detectors (Ge(i)) were used, isolated from the ultra-high vacuum of the ring via 100 µm beryllium foils.…”