Recent Results on K-Shell Ionization by Ion Collisions
The experimental K-shell ionization cross sections of 48Cd, 50Sn, 52Te, 53I and 56Ba for alpha particles, between 2.2 MeV and 2.8 MeV, and of 52Te for protons, between 1.6 and 3 MeV, are presented. The justification for making these measurements comes, on the one hand, in filling a region where, at present, data are sparse: for example, 52Te ionization cross sections by alpha particles have never been reported before, and, on the other hand, checking between previously reported and diverging sets of experimental results: for example, for alpha particles on tin. In addition, the K-shell ionization cross sections of 52Te for protons can be considered as an extension of Khelill's measurements.
Effects of coulomb repulsion in the inner-shell ionization cross-section by protons, deuterons and alpha-particles
SummaryA critical survey has been made of the currently accepted BEA theory for inner-shell atomic-ionization processes. This review has led to the introduction of an effective ion energy which accounts for the slowing-down of the ion in the nuclear Coulomb field. The effect of the ion deflection, also due to the nuclear Coulomb field, is analysed. Relativistic effects in the collision of ions withK-shell electrons have been taken into account. A tentative qualitative explanation for the experimentally observed nonexistence of a threshold energy for ionization is given in the framework of the BEA theory. Ionization cross-sections for Rb, Sr, Zr, Cd, In, Sb, W by protons in the energy range from 500 keV to 3 MeV have been measured. Also measurements of ionization cross-sections by deuterons in the energy range from 800 keV to 2.6 MeV on Rb, Sr, Zr, Cd, Sb and by He ions in the energy range from 1.4 MeV to 2.8 MeV on Cd and Sb have been performed. Results are compared with those of other authors and in the context of the corrections introduced in the BEA theory.RiassuntoÈ stata esaminata criticamente la corrente teoria BEA relativa ai processi di ionizzazione delgi strati atomici interni. Questa revisione ha condotto all'introduzione di un'energia efficace per lo ione che tiene conto del rallentamento nel campo coulombiano del nucleo. Si analizza l'effetto della deflessio dello ione, dovuta anch'essa al campo coulombiano del nucleo. Si sono considerati gli effetti relativistici nella collisione di ioni con elettroni dello stratoK. Si è cercato di fornire una spiegazione qualitativa, nell'ambito della teoria BEA, dell'osservazione sperimentale della non esistenza di un'energia di soglia per la ionizzazione. Sono state misurate le sezioni d'urto di ionizzazione di protoni nell'intervallo di energie comprese fra 500 keV e 3 MeV relativamente a Rb, Sr, Zr, Cd, Sb, In, W. Sono state inoltre eseguite misure di sezioni d'urto di ionizzazione di deuteroni nell'intervallo di energie comprese fra 800 keV e 2.6 MeV su Rb, Sr, Zr, Cd, Sb e di particelle α nell'intervallo di energie comprese fra 1.4 MeV e 2.8 MeV su Cd e Sb. I risultati sono confrontati con quelli di altri autori e nel contesto delle correzioni apportate alla teoria BEA.РезюмеПроводится критический обзор BEA теории для процессов ионизации вхчтренних оболочек атомоб. Этот подход приводит к введению эффективной энергии иона, которая позволяет объяснить замедление иона в кулоновском поле ядра. Оценивается эффект отклонения иона, обусловленный также кулоновским полем ядра. Рассматриваются релятивистские эффекты при соударении ионов с электронамиК-оболочки. Предлагается качественное объяснение экспериментально обнаруженного отсутствия пороговой энергии для ионизации в рамках BEA теории. Измерены поперечные сечения ионизации Rb, Sr, Zr, Cd, In, Sb, W протонами с энергиями в области от 500 кэВ до 3 МэВ. ъыли измерены также поперечные сечения ионизации Rb, Sr, Zr, Cd, Sb дейтронами с энергиями в области от 800 кэВ до 2.6 МэВ, а также поперечные сечения ионизации Cd и Sb ионами He в области энергий от 1.4 МэВ до 2.8 МэВ. Полученные результаты сравниваются с результатами других автров, а также в связи с поправками, введенными в BEA теорию.
Euthanasia — again: “Letting die” is not in the patient's best interests: a case for active euthanasia
Recent discussions in the Journal on the subject of euthanasia have relied on intuitive appeals to distinctions traditionally considered to be morally relevant, such as the distinction between acts and omissions (or killing and letting die), or ordinary and extraordinary means of treatment. These discussions remained inconclusive. However, the question of euthanasia no longer remains inconclusive if one adopts the perspective suggested by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research and by the World Medical Assembly – that a doctor should act in his or her patient's best interests. From this vantage point, it is argued, there will be instances when active euthanasia is the proper cause of action.