643 research outputs found
Annual Report 2004
No full textThis report documents the scientific and technical activities at the ion beam laboratory ISL. The main task of the department SF4, Structure and Dynamics are the operations of ISL but, in addition, the department s scientists run activities also at the synchrotron radiation facilities BESSY and HASYLAB and use radioactive beams at ISOLDE, CERN. Scientifically, a very successful year has passed due to the excellent performance of the accelerators in 2003 and 2004 allowing many new experiments concerning the irradiation of samples with very high doses with beams of very heavy ions. These irradiations lead to unpredicted self organisations of the surfaces and seem to open up a new dimension in the field of ion beam induced materials modifications. Other exciting new results have been obtained using the analysing power scattering and diffraction of synchrotron radiation for ion beam induced structure modifications, showing that this combination of tools is marking the steps into the right direction. Albeit the well prepared programme for the ion beam physics which has been presented together with the activities at GSI, ISL did not find the final funding. The reviewers welcomed the scientific value and the synergy of the two centres concerning the ion beam activities, but the Helmholtz Senat voted for the shutdown of the ISL facility by the end of 2007 for the following reasons The scientific perspectives had been rated low since the Hahn Meitner Institut Berlin would not foresee a future appointment of a scientific leader. In addition, though the users gave us a high ranking in terms of reliability and flexibility the official rating for ISL s commitment was low because the Hahn Meitner Institut Berlin did not agree to a rather moderate increase of the manpower to produce more hours per year of beam on target. We don t like to comment on these issues. There have been many letters of support of many institutions and high ranking individuals to all decision making institutions and individuals but so far they were all in vein. The time table for shut down has even been set forward to the end of 2006. Thus, we have to conclude that the idea of a dedicated ion beam facility producing fast ions with the appropriate equipment for ion beam applications in basic and applied research in solid state physics, materials science, and medicine could not be convincingly transferred to the decision making authorities. The readers of this report may develop their own point of view. The message for the users of ISL is that we will continue full operation until the end of 2006. Users may still send in proposals to the Meeting of the Nutzerausschuss, October 2005, and can try to finish their scientific programmes. Berlin, June 2005 Heinrich Homeye
Brief von Thirring, Hans an Meitner, Lise (Wien, 1958-11-05)
No full textOriginal Brief, Durchschlag, loses Blatt, Typoskript
Umfang: 1 Bl.1 S.; 21 cm x 30 cm
Planck, Max; Compton [Meitner-Graf], Lotte; Pugwas
Fünf Jahre Protonentherapie von Augentumoren am Hahn Meitner Institut Berlin
No full textSeit 1998 werden am Ionenstrahllabor des Hahn Meitner Instituts Berlin Deutschlands erster Einrichtung zur Protonentherapie im Rahmen eines Kooperationsvertrages mit der Charit Universitätsmedizin Berlin, Campus Benjamin Franklin, Augentumoren Aderhautmelanome, Irismelanome und Aderhauthämangiome mit 68 MeV Protonen bestrahlt. Der mittels einer Kombination aus Van de Graaff Beschleuniger und Zyklotron erzeugte Protonenstrahl wird passiv für eine konformale Bestrahlung des Tumors aufbereitet. Eine digitale Röntgenkontrolle der Lagerung des sitzenden Patienten beschränkt die Lagerungsunsicherheit auf maximal 0,3 mm. Für die Bestrahlungsplanung wird das modellbasierte Planungsprogramm EYEPLAN verwendet. In vorklinischer Erprobung befindet sich das mit dem Deutschen Krebsforschungszentrum Heidelberg entwickelte CT basierte Planungsprogramm OCTOPUS. Bisher wurden mehr als 400 Patienten bestrahlt. Erste klinische Ergebnisse entsprechen denen anderer Protonentherapiezentren. Ende 2002 ist das Universitätsklinikum Essen als weiterer Kooperationspartner hinzugekommen. Eye tumors choroidal melanomas, iris melanomas, and choroidal hemangiomas are being treated with 68 MeV protons since 1998 at the Ion Beam Laboratory of the Hahn Meitner Institute of Berlin Germany s first proton therapy center , in cooperation with the Charit University Hospital in Berlin, Campus Benjamin Franklin. The proton beam, generated via a combination of Van de Graaff accelerator and cyclotron, is prepared by passive shaping for conformal tumor irradiation. A digital X ray verification of the tumor location with the patient in sitting position limits the position uncertainties to a maximum of 0,3 mm. The treatment planning is performed using the program EYEPLAN. OCTOPUS, a CT based planning program developed in cooperation with the German Cancer Research Center of Heidelberg, is under pre clinical testing. Thus far, more than 400 patients have been irradiated. The first results are comparable to those obtained in other proton therapy centers. At the end of 2002, the University Hospital of Essen has also become a cooperation partner of the Hahn Meitner Institute
Lise Meitner, the Scientist Who Changed Medicine by Splitting Atoms
No full textThe splitting of atoms, also known as nuclear fission, produces radiation and radioactivity. Dr Lise Meitner discovered how radioactivity could be produced in 1939. She found that firing a small particle called a neutron into another atom could cause radiation to be released. Radioactive atoms created in this way can be useful for detecting cancer or checking whether the body’s organs are working properly. When radioactive atoms are injected into the blood of a patient, they travel through the body and release radiation that can be detected using special cameras, creating images or videos of the body’s tissues. In this way, radiation helps doctors to better diagnose and treat patients. Unfortunately, Dr Meitner faced many obstacles and was never credited officially for her key discovery of nuclear fission
Ideal Cities
No full textErika Meitner discusses her new book: Ideal Cities. This collection of autobiographical narrative and lyric poems explores the relationship between body and place—specifically the pleasures and dangers of women’s corporeal experiences. Ideal Cities is guided by an epigraph from Song of Songs, and the metaphorical idea of bodies as cities, and cities as bodies. How do women’s bodies become sites of inscription via sex, childbirth, and other highly physical acts? These poems also investigate urban, suburban, and rural borderlands. Who do we leave behind or look past? What do we discard, as purposeful markers or accidental refuse? How can these people, places, and objects be woven into larger ideas about nature, sense of place, home, exile, and both personal and collective memory?Video. 39:34
Transient Resonant Auger-Meitner Spectra of Photoexcited Thymine [Elektronisk resurs]
No full textWe present the first investigation of excited state dynamics by resonant Auger-Meitner spectroscopy (also known as resonant Auger spectroscopy) using the nucleobase thymine as an example. Thymine is photoexcited in the UV and probed with X-ray photon energies at and below the oxygen K-edge. After initial photoexcitation to a ππ* excited state, thymine is known to undergo internal conversion to an nπ* excited state with a strong resonance at the oxygen K-edge, red-shifted from the groundstate π* resonances of thymine (see our previous study Wolf et al.,Nat. Commun., 2017,8, 29). We resolve and compare the Auger-Meitner electron spectra associated both with the excited state and ground state resonances, and distinguish participato rand spectator decay contributions. Furthermore, we observe simultaneously with the decay of the nπ* state signatures the appearance of additional resonant Auger-Meitner contributions at photon energies between the nπ* state and the ground state resonances. We assign these contributions to population transfer from the nπ* state to a ππ* triplet state via intersystem crossing on the picosecond timescale based on simulations of the X-ray absorption spectra in the vibrationally hot triplet state. Moreover, we identify signatures from the initially excited ππ* singlet state which we have not observed in our previous study
Brief von Schrödinger, Erwin an Meitner, Lise (Dublin, 1952-04-03)
No full textOriginal Brief, Abschrift, Typoskript, Handschrift des Verfassers, lose Blätter
Umfang: 3 Bl. 3 S. : 20,9x26,5 cm
Ausführliche Stellungnahme zum letzten Absatz von L. Meitners "Spaltung und Schalenmodell des Atomkerns". Hinweis auf Schrödingers ["Are There Quantum Jumps"], wo er sich kurz vor Erhalt der Arbeit von Lise Meitner über eine gleiche Frage äußert. Einladung nach Dublin. Ankündigung eines interessanten Kollegiums
Option-Style Multi-Factor Comparable Company Valuation for Practical Use
No full textClassical single-factor comparable company valuation (CCV) like e.g. valuation using the price-earnings ratio is associated with several shortcomings. The two most important are the non-applicability of negative values in the basis of reference and the high requirements to the qualitative characteristics of comparable companies. This paper develops a multi-factor CCV model based on substance and performance related accounting attributes that largely overcomes these drawbacks. Additionally, the model allows to depict expected future earnings development economically sounder than single-factor models. Furthermore, by accounting for management?s option to adapt firm assets differently or to liquidate the company the model can conclusively assign positive stock prices to currently negatively performing companies. --Valuation,Multiples,Real Options
Influence of Selective Carbon 1s Excitation on Auger–Meitner Decay in the ESCA Molecule
No full textTwo-dimensional spectral mapping is used to visualize how resonant Auger–Meitner spectra are influenced by the site of the initial core–electron excitation and the symmetry of the core-excited state in the trifluoroethyl acetate molecule (ESCA). We observe a significant enhancement of electron yield for excitation of the COO 1s → π* and CF3 1s → σ* resonances unlike excitation at resonances involving the CH3 and CH2 sites. The CF3 1s → π* and CF3 1s → σ* resonance spectra are very different from each other, with the latter populating most valence states equally. Two complementary electronic structure calculations for the photoelectron cross section and Auger–Meitner intensity are shown to effectively reproduce the site- and state-selective nature of the resonant enhancement features. The site of the core–electron excitation and the respective final state hole locality increase the sensistivity of the photoelectron signal at specific functional group sites. This showcases resonant Auger–Meitner decay as a potentially powerful tool for selectively probing structural changes at specific functional group sites of polyatomic molecules
Time-resolved Auger-Meitner spectroscopy of the photodissociation dynamics of CS2
No full textThe photodissociation dynamics of UV excited CS
2 are investigated using time-resolved Auger-Meitner (AM) spectroscopy. AM decay is initiated by inner-shell ionisation with a femtosecond duration x-ray (179.9 eV) probe generated by the FERMI free electron laser. The time-delayed x-ray probe removes an electron from the S(2p) orbital leading to secondary emission of a high energy electron through AM decay. We monitor the electron kinetic energy of the AM emission as a function of pump-probe delay and observe time-dependent changes in the spectrum that correlate with the formation of bound, excited-state CS
2 molecules at early times, and CS + S fragments on the picosecond timescale. The results are analysed based on a simplified kinetic scheme that provides a time constant for dissociation of approximately 1.2 ps, in agreement with previous time-resolved x-ray photoelectron spectroscopy measurements (Gabalski, et al 2023 J. Phys. Chem. Lett. 14 7126-7133).</p
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