Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse

The method of perturbed angular correlation (PAC) was applied to selected MAX phases with 211 stoichiometry. Radioactive (111)In ions were implanted in order to measure the electric field gradients (EFG) in the key compounds Ti(2)InC and Zr(2)InC to determine the strength and symmetry of the EFG at the In-site. Further PAC studies in the In-free MAX phases Ti(2)AlN, Nb(2)AlC, Nb(2)AsC and Cr(2)GeC were performed to confirm that the In probes occupy the A-site as well. The strength of the EFG, with a quadrupole coupling constant ν(Q) between 250 and 300 MHz in these phases, is quite similar to the ones found in Ti(2)InC with ν(Q) = 292(1) MHz and in Zr(2)InC with ν(Q) = 344(1) MHz, respectively. Different annealing behavior was observed whereas in all cases a linear decrease of ν(Q) with increasing measuring temperatures was found. The experimental results are also in excellent agreement with those predicted by ab initio calculations using the APW+lo method implemented in the WIEN2k code. This study shows in an exceptional manner that (111)In → (111)Cd atoms are suitable probes to investigate the local surrounding at the A-site in 211-MAX phases.

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A new digital time differential perturbed angular correlation spectrometer, designed to measure the energy of and coincidence time between correlated detector signals, here correlated gamma photons, is presented. The system overcomes limitations of earlier digital approaches and features improved performance and handling. By consequently separating the data recording and evaluation, it permits the simultaneous measurement of decays with several gamma-ray cascades at once and avoids the necessity of premeasurement configuration. Tests showed that the spectrometer reaches a time resolution of 460 ps [using a (60)Co sample and Lu(1.8)Y(0.2)SiO(5):Ce (LYSO) scintillators, otherwise better than 100 ps], an energy resolution that is equivalent to the limit of the used scintillation material, and a processing capability of more than 200,000 gamma quanta per detector and second. Other possible applications of the presented methods include nuclear spectroscopy, positron emission tomography, time of flight studies, lidar, and radar.

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