[en] For boron neutron capture therapy, a promising cancer therapy under development, knowledge about the subcellular boron distribution is important. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and nonresonant laser secondary neutral mass spectrometry (NR-Laser-SNMS) have been used for examining freeze-fractured, freeze-dried human melanoma cells incubated with sodium mercaptoundecahydro-closo-dodecaborate (Na₂¹⁰B₁₂H₁₁SH,BSH), a ¹⁰B containing drug. With both techniques, elemental and molecular images were obtained from the cancer cells with very high sensitivity and subcellular resolution. The measurement of the K/Na ratio demonstrated that the preparation technique used was appropriate for preserving the chemical and structural integrity of living cells. The boron images showed that the intensity of intracellular and extracellular boron signals was clearly different after incubation of cells in different boron concentrations

[en] Short communication

[en] We have examined atomic and molecular distributions in freeze-fractured freeze-dried primary osteoblasts and cancer cells using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and non-resonant laser secondary neutral mass spectrometry (NR-Laser-SNMS). A pulsed Ga primary ion beam with a diameter of approximately 200 nm was employed to bombard the sample. Ion-induced electron-images were used to identify individual cells. High resolution elemental and molecular images were obtained from cell cultures. From these data the K/Na ratio was determined. It shows a higher K-concentration inside individual cells demonstrating that the chemical and structural integrity of living cells were preserved by the applied preparation technique. Consecutive presputtering of the sample with different primary ion dose densities was used to move the analysis plane toward the inside of the cell. It can be concluded that TOF-SIMS and Laser-SNMS are well suited for imaging trace element and molecule concentrations in biological samples

No abstract available

No abstract available

No abstract available

[en] In general a decay with a missing (not detected) particle cannot be fully reconstructed apart from a few exceptions. For example, if the momentum of the decaying particle is known or if the missing energy in an event is measured precisely, then the missing particle 4-momentum can be determined. Here a new method is proposed that utilizes additional information about the topology of a decay: the direction from the primary to the secondary vertex combined with momentum conservation allows the determination of the missing particle momentum up to a twofold ambiguity. The semileptonic decay of the B_s⁰ mesons is considered as an example to illustrate this method and to compare its performance against conventional approaches

No abstract available

[en] Parametric x-ray or quasi-Cherenkov radiation is produced by the passage of an electron through a crystal. A critical absorber technique has been employed to investigate its linewidth. Experiments have been performed with the 855MeV electron beam from the Mainz Microtron MAMI. Thin absorber foils were mounted in front of a CCD camera serving as a position sensitive photon detector. Upper limits of the linewidth of 1.2 and 3.5eV were determined for the (111) and (022) reflections of silicon at photon energies of 4966 and 8332eV. These limits originate from geometrical line broadening effects that can be optimized to reach the ultimate limit given by the finite length of the wave train. copyright 1997 The American Physical Society

No abstract available