Volker Sonnenschein

Precision mass measurements beyond ^{132}Sn: Anomalous behaviour of odd-even staggering of binding energies

Atomic masses of the neutron-rich isotopes (121-128)Cd, (129,131)In, (130-135)Sn, (131-136)Sb, and (132-140)Te have been measured with high precision (10 ppb) using the Penning-trap mass spectrometer JYFLTRAP. Among these, the masses of four r-process nuclei (135)Sn, (136)Sb, and (139,140)Te were measured for the first time. An empirical neutron pairing gap expressed as the odd-even staggering of isotopic masses shows a strong quenching across N = 82 for Sn, with a Z dependence that is unexplainable by the current theoretical models.

Resonance ionization spectroscopy of thorium isotopes?towards a laser spectroscopic identification of the low-lying 7.6 eV isomer of 229Th

In-source resonance ionization spectroscopy was used to identify an efficient and selective three-step excitation/ionization scheme of thorium, suitable for titanium:sapphire (Ti:sa) lasers. The measurements were carried out in the preparation of laser spectroscopic investigations for an identification of the low-lying 229mTh isomer predicted at 7.6 ± 0.5 eV above the nuclear ground state. Using a sample of 232Th, a multitude of optical transitions leading to over 20 previously unknown intermediate states of even parity as well as numerous high-lying odd parity auto-ionizing (AI) states were identified. Level energies were determined with an accuracy of 0.06 cm−1 for intermediate and 0.15 cm−1 for AI states. Using different excitation pathways, an assignment of total angular momenta for several energy levels was possible. One particularly efficient ionization scheme of thorium, exhibiting saturation in all three optical transitions, was studied in detail. For all three levels in this scheme, the isotope shifts of the isotopes 228Th, 229Th and 230Th relative to 232Th were measured. An overall efficiency including ionization, transport and detection of 0.6% was determined, which was predominantly limited by the transmission of the mass spectrometer ion optics.

Isomeric states close to doubly magic 132Sn studied with JYFLTRAP

The double Penning trap mass spectrometer JYFLTRAP has been employed to measure masses and excitation energies for

Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

11/2^-

Enhanced γ-Ray Emission from Neutron Unbound States Populated in β Decay.

isomers in

First measurements with the BEta deLayEd neutron detector (BELEN-20) at JYFLTRAP

^{121}

Efficient, high-resolution resonance laser ionization spectroscopy using weak transitions to long-lived excited states

Cd,

Intracavity Frequency Doubling and Difference Frequency Mixing for Pulsed ns Ti:Sapphire Laser Systems at On-Line Radioactive Ion Beam Facilities

^{123}

Determination of the ground-state hyperfine structure in neutral 229Th

Cd,

Highly coherent tunable mid-infrared frequency comb pumped by supercontinuum at 1 µm

^{125}