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A cylindrical double Penning trap system has been installed and commissioned at the Maier-Leibnitz-Laboratory (MLL) in Garching. This trap system has been designed to isobarically purify low-energy ion beams and perform highly accurate mass measurements. Technical details of the device and the first results of the commissioning measurements will be presented. The mass resolving power achieved in the first trap for 85 Rb ions is R = 139 ( 2 ) × 10 3 , while a relative mass uncertainty of δ m / m = 2.9 × 10 − 8 was reached with the second trap (no analysis of systematic uncertainties included) when using 87 Rb as a reference ion for 85 Rb.

In-trap preparation of highly charged ions (HCIs) for precision mass measurements by cooling in a strongly coupled plasma of laser-cooled Mg 24 + ions is investigated by molecular dynamics simulations. For HCIs electrostatically decelerated below 1 eV the simulation suggests stopping times of a few 10 μ s for high charge states ( Q HCI = 40 , A HCI = 100 ). The deposited energy is found to be distributed almost over the entire crystalline plasma of N = 1 0 5 Mg 24 + ions due to collective target response. Almost all Mg 24 + ions stay within the acceptance range of the laser cooling force, thus allowing for the maintenance of the plasma conditions and efficient continuous cooling. Energy loss due to collective effects and hard binary collisions can be clearly distinguished, and can be of the same magnitude for the highest projectile charge states. While the former one can be described by the action of an effective stopping power, the latter is governed by large statistical fluctuations.

The production of 235Np and 236Pu by the reactions 236U(p,2n) 235Np and 236U(p,nβ−) 236Pu using the K-130 cyclotron of the University of Jyväskylä was investigated. The cross sections for the reactions were determined. Thick-target yield curves were derived based on the cross sections. The results are discussed and compared with previous data on other reactions leading to the formation of the same end products. The thick-target yield of 235Np in the 236U(p,2n) reaction is about 50 percent higher than the yield obtained in the 238U(p,4n) reaction leading to this nuclide at comparable particle energies. The purity of 236Pu produced in the 236U(p,nβ−) reaction is more than ten times better than for earlier known as the purest reaction 237Np(p,2n+pnβ−) 236Pu.

Masses of $^{52}$Co, $^{52}$Co$^m$, $^{52}$Fe, $^{52}$Fe$^m$, and $^{52}$Mn have been measured with the JYFLTRAP double Penning trap mass spectrometer. Of these, $^{52}$Co and $^{52}$Co$^m$ have been experimentally determined for the first time and found to be more bound than predicted by extrapolations. The isobaric multiplet mass equation for the $T=2$ quintet at $A=52$ has been studied employing the new mass values. No significant breakdown (beyond the $3\sigma$ level) of the quadratic form of the IMME was observed ($\chi^2/n=2.4$). The cubic coefficient was 6.0(32) keV ($\chi^2/n=1.1$). The excitation energies for the isomer and the $T=2$ isobaric analogue state in $^{52}$Co have been determined to be 374(13) keV and 2922(13) keV, respectively. The $Q$ value for the proton decay from the $19/2^-$ isomer in $^{53}$Co has been determined with an unprecedented precision, $Q_{p} = 1558.8(17)$ keV. The proton separation energies of $^{52}$Co and $^{53}$Ni relevant for the astrophysical rapid proton capture process have been experimentally determined for the first time. \end{abstract}, Comment: 12 pages, 13 figures, submitted to Phys. Rev. C (26.9.2016)

The MLLTRAP, presently under construction at the Maier-Leibnitz-Laboratory (Garching), is a Penning trap facility designed to combine several novel techniques to decelerate, purify, charge breed and cool the reaction products and perform high-accuracy nuclear mass measurements of highly charged, laser-cooled ions.

Atomic masses of 95-100Sr, 98-105Zr, and [corrected] 102-110Mo and have been measured with a precision of 10 keV employing a Penning trap setup at the IGISOL facility. Masses of 104,105Zr and 109,110Mo are measured for the first time. Our improved results indicate significant deviations from the previously published values deduced from beta end point measurements. The most neutron-rich studied isotopes are found to be significantly less bound (1 MeV) compared to the 2003 atomic mass evaluation. A strong correlation between nuclear deformation and the binding energy is observed in the two-neutron separation energy in all studied isotope chains.

An ion beam cooler-buncher for manipulating low-energy radioactive ion beams at the IGISOL facility is described. The cooler-buncher serves as a source of cooled ion bunches for collinear laser spectroscopy and it will be used for preparation of ion bunches for injection into a Penning trap system.

Universality of the ion guide technique allows the mass separation of isotopes of any element. However, this feature also means unselectivity in respect to chemical element number and results in severe isobaric background. Also the operation of the ion guide with the maximum yield increases the energy spread and the emittance of the ion beam. To overcome these problems, new means to cool, bunch and mass purify the ion beam will be developed. The weak radioactive ion beam will be cooled in a gas-filled radiofrequency quadrupole and further mass purified and bunched in a Penning-trap.

The MLLTRAP (Maier-Leibnitz-Laboratory TRAP) Penning trap system at the FRM-II research reactor in Munich is presented. Its planned developments to reach very high “relative atomic mass” measurement precision (e.g., below 10-10 for stable ions) are described.

The MLL-IonCatcher is a new setup for the thermalization of fusion-evaporation reaction products in highly pure helium with subsequent extraction of the stopped, singly charged ions. The setup consists of a buffer-gas stopping cell and a radio frequency quadrupole (RFQ)-based extraction system and is placed at the Tandem accelerator facility of the MLL in Garching. Test experiments were performed using the α emitter Er152 with total kinetic energies of around 180keV∕u, produced via the reaction Sb121(Cl35,4n). During the on-line measurements the number of ions entering the stopping chamber through the entrance window was determined via the detection of their specific α-decay energy. After being thermalized in the helium buffer gas at 40–140mbar the ions were guided by a combination of electric rf and dc fields towards the extraction nozzle where the ion transport was taken over by the gas flow. Subsequent to the extraction by a supersonic gas jet the ions were separated from the buffer gas and guided by t...

The ground-state branch in the beta decay of Cu-58 has been remeasured by using gamma-ray detection combined with ion-guide-based on-line mass separation. The measured value 80.8(7)% is three times more precise and in agreement with the earlier reported value. The deduced Gamow-Teller strength of this transition, to be used for the calibration of the charge-exchange reactions, is 0.0821(7). (C) 2001 Elsevier Science B.V. All rights reserved.