Experiments

Note: for current information please also visit the corresponding experiment pages of the new installed "Stored and Cooled Ion Division" at MPIK Heidelberg.

In the working group MATS different projects are currently carried out, which are explained briefly in the following. More details can be found on the respective sub-pages:

Precision Mass Spectrometry

Penning Trap mass-spectrometry experiments for radio-nuclides are presently all based on the time-of-flight (TOF) cyclotron resonance detection technique. A microchannel plate is used to detect the TOF with an efficiency of about 30%. In order to increase the efficiency up to 100%, a novel detector set-up is being constructed in which ions are accelerated by approximately -20 keV towards a conversion dynode where secondary electrons are produced and traced by a combination of a scintillator and a photomultiplier. This new conversion electrode detector is to be applied first of all at the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN (Geneva, Switzerland). More details can be found here

An alternative method of cyclotron resonance measurement is being investigated. This method - the Fourier Transform-Ion Cyclotron Resonance (FT-ICR) - is based on the non-destructive detection of mirror currents induced in the trap electrodes by oscillating ions. Considering the rarity of transuranic species produced, it is planned to transfer the FT-ICR technique to SHIPTRAP at GSI. Prior to experiments at GSI, the double-Penning trap mass spectrometer will be installed as TRIGA-TRAP at the research reactor TRIGA Mainz to perform mass measurements on exotic and heavy elements. For this purpose, the thermal noise is mainly a critical factor, which requires the cooling of the trap and detection electronics down to at least the temperature of liquid helium (4.2 K). Details are provided here 

The accuracy of the current precision mass spectrometry at ISOLTRAP and other Penning trap mass spectrometers is limited by the fluctuations in temperature and pressure of the helium as well as nitrogen reservoirs of the superconducting magnet. Pressure fluctuations are causing temperature fluctuations, which have an effect on the magnetic susceptibility of the materials, which are located around the precision trap. Thus, the constancy of the magnetic field is affected. The fluctuations in the magnetic field can be reduced substantially by means of temperature and pressure stabilization. In addition to higher accuracy, a more effective utilization of beam time is achieved because fewer calibration measurements of the magnetic field have to be performed.

In order to enhance the accuracy of on-line mass measurements of radionuclides with ISOLTRAP we intend to excite the ion motion inside the Penning trap using the Ramsey method, i.e. temporally separated oscillating fields. Besides elaborating on the theoretical line shape of the energy absorption and the time-of-flight resonance curve resulting from the Ramsey excitation, the technical implementation of this method will be realized and the enabled enhancement in accuracy determined.

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g-Factor of the Proton

Currently, the magnetic moment of the proton can be determined with a precision of 1E-8. We intend to improve the current value by a factor of 10. To this end, a novel Penning trap design is being developed. With regard to the GSI future project, where antiprotons will be available, it will be possible to increase the accuracy in measuring the magnetic moment of the antiproton. Until now, the magnetic moment has been derived from antiprotonic atoms with an accuracy of 3E-3. We intend to increase this value by more than a factor of 1E6 and to perform a CPT test for hadrons. At present, the experiment is under construction. Read the details here

g-Factor of the Electron in calcium

Determination of the g-factor of the bound electron in hydrogen-like calcium (40Ca19+). This experiment is an important step in the chain of increasing nuclear charge towards the final goal to measure the g-factor of hydrogen-like uranium in the HITRAP project at GSI. Hydrogen-like calcium has several advantages, especially its doubly-magic nucleus with 20 neutrons and 20 protons which results in a better accuracy of the theoretical calculation of the g-factor. We designed a novel double Penning trap system for this experiment, which is currently under construction. Read more details about the measurement principle, the experimental setup and the current status

Future Experiments

The MATS collaboration proposes a novel, innovative Penning trap system at the GSI future project FAIR. The experiment allows performing high precision mass measurements and decay spectroscopy on short-lived highly charged radionuclides. Details concerning the setup and the experimental outline can be found here

The limits in accuracy of the g-factor apparatus for high-precision mass measurements are explored for the HITRAP project at GSI. A mass resolution of m/δm = 1.0E9 for 12C5+ has already been achieved in preliminary experiments. Thus, an accuracy of mass determination for a single highly charged ion of 1.0E-10 or better can be expected. If an uncertainty of 1.0E-11 could be reached, the determination of the 1s Lamb shift of 2 eV is possible by comparing the mass of a bare uranium nucleus with the mass of the hydrogen-like ion. This corresponds to the present uncertainty of theoretical predictions except for a factor of 2 and would allow testing QED in the electric sector with the strongest fields available in laboratories. Read the details here