Search results for "ROMP"
showing 10 items of 117 documents
Brief an Garlieb H. Merkel
1799
Ms. 930a, Nr. 8, Bl. 22r-23v Böttiger, Karl August. Brief an Garlieb H. Merkel, Weimar, d[en] 13. November 1797 Autora rokraksts / Autograph, vācu, angļu un latīņu val. / Deutsch, Englisch und Latein [4] lpp. / S. Attēlu numuri / Bildnummern: 930a-008-1 – 930a-008-4 Der Verfasser nennt in diesem inhaltsreichen Brief zahlreiche Namen und hält nicht nur die Verbindung mit Merkel, die aus dessen erstem Aufenthalt in Weimar resultierte, aufrecht, sondern gibt ihm weitere Hinweise und Empfehlung für seinen weiteren Aufenthalt in Dänemark. So rät er zur Übersetzung dreier Romane aus dem Englischen, darunter Jane Wests „A gossip's story“ (London 1796). Ferner bittet der Verfasser Merkel um Gefälli…
Perspective on Curved Surfaces in the Age of Pozzo: The Nuova Pratica di Prospettiva of Paolo Amato
2016
The study focuses an almost unknown treatise on perspective, The Nuova Pratica di Prospettiva, written by the priest Paolo Amato (1634–1714) in the last years of his life and published posthumously in 1733. The main points of interest of the Nuova Pratica is the perspective projection on cylindrical surfaces, which exceeds the coeval ‘practical’ treatises on perspective. A detailed resume of Amato’s treatise is accompanied by geometric schemes illustrating the perspective method proposed by the author. None of the paintings made by Amato has come down to us, but the vault covering a hall added to a Norman church in Palermo shows a trompe l’oeil that was painted by one of his favorite discip…
Probing the small- x nuclear gluon distributions with isolated photons at forward rapidities in p+Pb collisions at the LHC
2014
Inclusive direct photon production in p+Pb collisions at the LHC is studied within the NLO perturbative QCD. Our aim is to quantify the dominant $x$ regions probed at different rapidities and to identify the best conditions for testing the nuclear gluon parton distribution functions (nPDFs) at small $x$. A comparison to the inclusive pion production reveals that from these two processes the photons carry more sensitivity to the small-$x$ partons and that this sensitivity can be further increased by imposing an isolation cut for the photon events. The details of the isolation criteria, however, seem to make only a small difference to the studied $x$ sensitivity and have practically no effect…
New Beta-delayed Neutron Measurements in the Light-mass Fission Group
2014
A new accurate determination of beta-delayed neutron emission probabilities from nuclei in the low mass region of the light fission group has been performed. The measurements were carried out using the BELEN 4π neutron counter at the IGISOL-JYFL mass separator in combination with a Penning trap. The new results significantly improve the uncertainties of neutron emission probabilities for {sup 91}Br, {sup 86}As, {sup 85}As, and {sup 85}Ge nuclei.
The Generalized Model for the Description of Prompt Neutrons in the Low-energy Fission
2013
Abstract The generalized model for the description of neutron emission from the spontaneous and neutron-induced fission in the energy interval up to 20 MeV is developed. For accurate calculations of nucleon composition and excitation energy of the fissioning nucleus at the scission point, the time-dependent statistical model including the pre-equilibrium neutron emission and nuclear friction effects is used. For each member of the compound nucleus ensemble at the scission point, the primary fission-fragment characteristics such as kinetic and excitation energies and yields are calculated using the scission-point fission model with nuclear shell and pairing effects, and based on the multimod…
Mass and charge distributions in the very asymmetric mass region of the neutron induced fission of
2001
Abstract The mass-separator Lohengrin was used to measure the yields of the light fission products with A=74−85 and their nuclear charge and kinetic energy distributions from the odd- Z compound nucleus 239 Np ∗ formed by double capture of thermal neutrons. The mass yield distribution reveals an influence of the fragment shell with N=50 affecting also the nuclear charge and kinetic energy distributions. An odd–even effect for protons is found in the very asymmetric mass division, increasing from 4% to 35% with increasing fission asymmetry. This is in contrast to findings in normal asymmetric fission (region of high fission yields) where no odd–even effect for protons was observed. An odd–ev…
The neutron long counter NERO for studies of neutron emission in the r-process
2010
Abstract The neutron long counter NERO was built at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, for measuring β -delayed neutron-emission probabilities. The detector was designed to work in conjunction with a β -delay implantation station, so that β decays and β -delayed neutrons emitted from implanted nuclei can be measured simultaneously. The high efficiency of about 40%, for the range of energies of interest, along with the small background, are crucial for measuring β -delayed neutron emission branchings for neutron-rich r-process nuclei produced as low intensity fragmentation beams in in-flight separator facilities.
A facility for fast-neutron irradiations at Jyväskylä and its use for nuclide cross-section measurements in fission
2013
Abstract An efficient and reliable transport system for fast-neutron irradiations has been built at the Physics Department, Jyvaskyla, Finland. It is constructed from commercial bicycle components and is driven by a computer-controlled stepping motor. It can be operated in single or cyclic mode. The neutron irradiated targets are moved within 1.2 s (full stop to full stop) to a well-shielded position 3 m away where they can be removed or directly investigated by γ spectroscopy. The system has been built with the aim to experimentally verify the calculated production rates of neutron-rich nuclei in the SPIRAL2 uranium target. However, the facility can be used for various kinds of fast-neutro…
Poly(phosphonate)s via Olefin Metathesis: Adjusting Hydrophobicity and Morphology
2014
Olefin metathesis step-growth (acyclic diene metathesis (ADMET)) and chain-growth (ring-opening metathesis) polymerization was used to prepare linear poly(phosphonate)s with variable hydrophilicity. The first phosphonate monomer, i.e., di(undec-10-en-1-yl) methylphosphonate, for ADMET polymerization was developed, and potentially degradable and biocompatible, unsaturated poly(phosphonate)s were prepared with molecular weights up to 23 000 g mol–1 with molecular weight dispersities Đ < 2. These polymers were studied with respect to their interaction with a calcium phosphate bone substitute material from an aqueous nanoparticle dispersion that was prepared by a solvent evaporation miniemulsio…
Synthesis and characterization of amphiphilic comb-polymers via ring-opening metathesis polymerization of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[…
1994
A number of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[2.2.1]hept-2-enes (exo,exo-5,6-bis(alkoxymethyl)-7-oxanorbornenes) with long alkyl chains were prepared by reduction of the Diels-Alder adduct of furan and maleic anhydride, followed by alkylation with a series of different n-alkylbromides. These monomers were polymerized via ring-opening metathesis polymerization (ROMP) catalyzed by ruthenium trichloride in ethanolic solution. Contrary to a helical conformation as it was predicted by a previous molecular model study the poly(7-oxanorbornenes) adopt a coil conformation in solution. In bulk the materials show side chain crystallization.