Compact femtosecond electron diffractometer with 100 keV electron bunches approaching the single-electron pulse duration limit

We present the design and implementation of a highly compact femtosecond electron diffractometer working at electron energies up to 100 keV. We use a multi-body particle tracing code to simulate electron bunch propagation through the setup and to calculate pulse durations at the sample position. Our simulations show that electron bunches containing few thousands of electrons per bunch are only weakly broadened by space-charge effects and their pulse duration is thus close to the one of a single-electron wavepacket. With our compact setup we can create electron bunches containing up to 5000 electrons with a pulse duration below 100 femtoseconds on the sample. We use the diffractometer to track the energy transfer from photoexcited electrons to the lattice in a thin film of titanium. This process takes place on the timescale of few-hundred femtoseconds and a fully equilibrated state is reached within one picosecond.Comment: 5 pages, 3 figure

Implications for (d,p) reaction theory from nonlocal dispersive optical model analysis of 40^{40}Ca(d,p)41^{41}Ca

The nonlocal dispersive optical model (NLDOM) nucleon potentials are used for the first time in the adiabatic analysis of a (d,p) reaction to generate distorted waves both in the entrance and exit channels. These potentials were designed and fitted by Mahzoon $et \text{ } al.$ [Phys. Rev. Lett. 112, 162502 (2014)] to constrain relevant single-particle physics in a consistent way by imposing the fundamental properties, such as nonlocality, energy-dependence and dispersive relations, that follow from the complex nature of nuclei. However, the NLDOM prediction for the $^{40}$Ca(d,p)$^{41}$Ca cross sections at low energy, typical for some modern radioactive beam ISOL facilities, is about 70$\%$ higher than the experimental data despite being reduced by the NLDOM spectroscopic factor of 0.73. This overestimation comes most likely either from insufficient absorption or due to constructive interference between ingoing and outgoing waves. This indicates strongly that additional physics arising from many-body effects is missing in the widely used current versions of (d,p) reaction theories.Comment: 14 pages, 15 figure

Der Akute Herzinfarkt bei Frauen : Eine Rarität oder häufig übersehen?

Bundesweit erleiden etwa 300.000 Menschen pro Jahr einen Herzinfarkt durch einen plötzlichen und kompletten Verschluß eines Herzkranzgefäßes. Prähospitale (20-30%) und hospitale (10-20%) Sterblichkeit des akuten Herzinfarktes sind hoch. Der Verlauf des Herzinfarktes ist bei Frauen, insbesondere bei jungen Frauen, komplikationsträchtiger als bei Männern. Dies gilt, wenn keine spezifische gefäßwiedereröffnende Therapie eingeleitet wird. Die Ursachen für die Übersterblichkeit der Frauen sind vielfältig: verspätete Krankenhausaufnahme, höheres Lebensalter zum Infarktzeitpunkt, bedeutsamere Begleiterkrankungen und der zögerliche Einsatz gefäßwiedereröffnender Therapieformen. Bei früher und konsequenter kathetergestützter Gefäßrekanalisation kann die geschlechtsspezifische Sterblichkeit bei Frauen aller Altersstufen aber weitgehend beseitigt werden

Pain Catastrophizing in College Athletes\u27 at Eastern Kentucky University

It is a known fact that athletes become susceptible to injuries with more athletic injury exposures, and that pain is the most common symptom paired with injury. Pain catastrophizing is a phenomenon that is caused by negative thinking that has been shown to reduce treatment outcomes in patient populations. Pain catastrophizing has been studied in different populations, usually with specific body part injuries, showing it is a relevant factor in the outcome of rehabilitation. Nobody has researched the prevalence of pain catastrophizing in highly athletic populations. In Division I athletes at Eastern Kentucky University, 291 athletes were surveyed using the Pain Catastrophizing Scale (PCS). It was found that 14% of the athletes surveyed were classified as pain catastrophizers. Athletes were also given a demographic patient identifier sheet which indicated that athletes with a current injury, previous injury, or playing with pain were at a higher risk of being a pain catastrophizer. Also, athletes with a previous injury were 3.4x more likely to be a pain catastrophizer. This can be useful when clinically rehabilitating athletes that score highly on the PCS

Improving the Dispersive Optical Model toward a Dispersive Self-energy Method

The connection between the dispersive optical potential and the irreducible nucleon self-energy from Green\u27s function theory is improved, providing a tighter link between nuclear reactions and nuclear structure. In particular, since the self-energy is inherently nonlocal, an explicitly nonlocal term is incorporated in the real part of the dispersive optical potential, which has been assumed to be local in previous parametrizations. The explicit treatment of nonlocality allows for a proper solution of the Dyson equation, and the resulting propagator can then be used to calculate experimental observables associated with ground state properties, such as the charge density, particle number, and the energy per particle. Comparison of these quantities with data suggests additional ways in which the dispersive optical model can be improved. For example, a better treatment of short-range correlations is needed, and explicitly including the nonlocality of the imaginary potential appears to be necessary for particle number conservation. Comparison of the dispersive optical potential with microscopic calculations of the self-energy is also made and suggests further improvements. Thus, increasing the correspondence between the potential from the dispersive optical model and the self-energy increases the amount of feedback from theory and experiment and provides a method for systematically improving the description of the empirical self-energy for both stable and rare isotopes. The dispersive optical model is also applied to transfer reactions, which are proving to be a useful tool for studying the nuclear structure of rare isotopes

Isospin dependence of nucleon Correlations in ground state nuclei

The dispersive optical model (DOM) as presently implemented can investigate the isospin (nucleon asymmetry) dependence of the Hartree-Fock-like potential relevant for nucleons near the Fermi energy. Data constraints indicate that a Lane-type potential adequately describes its asymmetry dependence. Correlations beyond the mean-field can also be described in this framework, but this requires an extension that treats the non-locality of the Hartree-Fock-like potential properly. The DOM has therefore been extended to properly describe ground-state properties of nuclei as a function of nucleon asymmetry in addition to standard ingredients like elastic nucleon scattering data and level structure. Predictions of nucleon correlations at larger nucleon asymmetries can then be made after data at smaller asymmetries constrain the potentials that represent the nucleon self-energy. A simple extrapolation for Sn isotopes generates predictions for increasing correlations of minority protons with increasing neutron number. Such predictions can be investigated by performing experiments with exotic beams. The predicted neutron properties for the double closed-shell 132Sn nucleus exhibit similar correlations as those in 208Pb. Future relevance of these studies for understanding the properties of all nucleons, including those with high momentum, and the role of three-body forces in nuclei are briefly discussed. Such an implementation will require a proper treatment of the non-locality of the imaginary part of the potentials and a description of high-momentum nucleons as experimentally constrained by the (e,e'p) reactions performed at Jefferson Lab.Comment: 7 pages and 7 figure