Ionization of Tetramethyltin in a Molecular Beam Injected Near a Metal Substrate in Vacuum with Laser Irradiation on the Substrate

Abstract

Increased accuracy in radiation delivery to a patient provided by scanning particle beams leads to high demands on quality assurance (QA). To meet the requirements, an extensive quality assurance programme has been implemented at the Heidelberg Ion Beam Therapy Center. Currently, highresolution radiographic films are used for beam spot position measurements and homogeneity measurements for scanned fields. However, given that using this film type is time and equipment demanding, considerations have been made to replace the radiographic films in QA by another appropriate device. In this study, the suitability of the flat-panel detector RID 256 L based on amorphous silicon was investigated as an alternative method. The currently used radiographic films were taken as a reference. Investigations were carried out for proton and carbon ion beams. The detectors were irradiated simultaneously to allow for a direct comparison. The beam parameters (e.g. energy, focus, position) currently used in the daily QA procedures were applied. Evaluation of the measurements was performed using newly implemented automatic routines. The results for the flat-panel detector were compared to the standard radiographic films. Additionally, a field with intentionally decreased homogeneity was applied to test the detector's sensitivities toward possible incorrect scan parameters. For the beam position analyses, the flat-panel detector results showed good agreement with radiographic films. For both detector types, deviations between measured and planned spot distances were found to be below 1% (1 mm). In homogeneously irradiated fields, the flatpanel detector showed a better dose response homogeneity than the currently used radiographic film. Furthermore, the flat-panel detector is sensitive to field irregularities. The flat-panel detector was found to be an adequate replacement 0031-9155/12/010051+18$33.00

Gas-Phase Organolanthanide (Ln) Chemistry: Formation of Ln+−{Benzene} and Ln+−{Benzyne} Complexes by Reactions of Laser-Ablated Ln+ with Cyclic Hydrocarbons

“…5,7 Two primary experimental approaches for studying metal ion-molecule reactions are Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) 1,5,7,12 and guided ion beam mass spectrometry. 3,4 In addition, Sato et al have described the laser ablation-molecular beam (LAMB) technique 25,26 and applied it to a variety of M + + R reactions 27 including some with R ) benzene. 16,21 The LAMB technique entails injecting neutral reactants into the path of nascent laserablated M + and characterizing the collision product ions with a mass spectrometer.…”

“…Two primary experimental approaches for studying metal ion−molecule reactions are Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) 1,5,7,12 and guided ion beam mass spectrometry. , In addition, Sato et al have described the laser ablation−molecular beam (LAMB) technique , and applied it to a variety of M + + R reactions including some with R = benzene. , The LAMB technique entails injecting neutral reactants into the path of nascent laser−ablated M + and characterizing the collision product ions with a mass spectrometer. A potential complication is that laser ablated metal ions can be produced with a broad distribution of translational and internal energies; the kinetic energy (e.g., ∼1−10 eV) is generally substantially greater than the internal energy (e.g., 0.1−1 eV) .…”