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51.
52.
Nanosecond lifetimes of several states in 147Nd have been studied using the reaction 146Nd(d, pγ)147Nd with 10 MeV deuterons. The following lifetimes were observed: the level at 49.9 keV, 2.5±0.5 ns; the level at 127.9 keV, ≦ 0.8 ns; the level at 190.3 keV, 1.1±0.3 ns and the level at 214.6 keV, 5.8±0.8 ns. The wave functions of the states were constructed using an axial particle-plus-rotor model. The free parameters used are compared to the systematics observed in the neighbouring heavier N = 87 isotones as well as in the N = 89 and 91 isotones. Transition rates within the and based excitations, separately, are reasonably well reproduced, but the connecting transitions indicate too strong a mixing of the shells in the calculation. 相似文献
53.
R. Katajanheimo T. Tuurnala E. Hammarén 《Zeitschrift für Physik A Hadrons and Nuclei》1978,286(1):57-63
TheΒ ?-decay of the longer-lived170Ho isomer produced through the170Er(n, p)170Ho reaction has been investigated by using a versastile detector and coincidence equipment. The half-life andΒ ?-decay energy were determined to beT 1/2=2.76±0.05 min andQ β =3.85±0.15 MeV, respectively. In addition to the ground state band and some higher energy levels, the proposed level scheme of170Er contains 11 states between 1.0 and 1.6 MeV (6 new ones), which are connected mutually by previously unknown low-energy transitions. Spin and/or parity assignments based mainly on coincidence data and multipolarity determinations are suggested for most of these states. By using systematic considerations and the nuclear projection model calculations several bands withK≧2 can be assigned tentatively. As a side result the half-life of169Ho was determined to be 4.7 ±0.2 min. 相似文献
54.
The R-tree is a well-known bounding-volume hierarchy that is suitable for storing geometric data on secondary memory. Unfortunately, no good analysis of its query time exists. We describe a new algorithm to construct an R-tree for a set of planar objects that has provably good query complexity for point location queries and range queries with ranges of small width. For certain important special cases, our bounds are optimal. We also show how to update the structure dynamically, and we generalize our results to higher-dimensional spaces. 相似文献
55.
S. Valkealahti M. Manninen E. Hammarén 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,22(2):547-551
We report molecular dynamics simulations of the impact of TiD clusters on TiD targets. In each cluster collision the total fusion probability seems to be due to a single deuterium deuterium collision. The kinetic energies of incident deuterium atoms gradually level off around the initial cluster energy, but do not reach the high energy tail of a corresponding Maxwell-Boltzmann distribution. Neither any other support for a thermonuclear fusion mechanism was observed. On the contrary, our simulations imply that the enhanced fusion rate is rather due to channeled many atom collision cascade type mechanism. 相似文献
56.
J. Mansikka-aho M. Manninen E. Hammarén 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1994,31(4):253-258
Several simple models have been used to study the effects of the surface on the electronic shell structure in metal clusters. The main results are as follows: The icosahedral clusters have the same electronic shell structure as the sphere up to about 1000 atoms. The surface roughness causes the distribution of the level spacings to be a Wigner distribution. By varying the softness of the potential we can obtain potentials where the simplest classical orbits are the five-point star or even the three-point star.This paper was originally submitted in connection with the 2nd. Int. Conference on Atomic and Nuclear Clusters held in Santorini from 28. June–2. July 1993 and is published here as a regular article after an independent refereeing procedure according to the standards of Z. Phys. D 相似文献
57.
A reaction sequence involving halogenation and replacement of the halo substituent by a nitro group using dinitrogen tetraoxide has led to a general, convenient route to 5-nitrooxazoles. Reaction schemes employing both bromine and iodine as the halo substituent have been investigated; however, the method using iodine preceded by a mercuration step affords a better overall yield in the range of 20–50%. Both 2- and 4-nitro-oxazoles can be prepared by this latter sequence, though in lower overall yields (4–12%). 相似文献
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J.Y. Andersson L. H?glund B. Noharet Q. Wang P. Ericsson S. Wissmar C. Asplund H. Malm H. Martijn M. Hammar O. Gustafsson S. Hellstr?m H. Radamson P.O. Holtz 《Infrared Physics & Technology》2010,53(4):227-230
Acreo has a long tradition of working with quantum structure based infrared (IR) detectors and arrays. This includes QWIP (quantum well infrared photodetector), QDIP (quantum dot infrared photodetector), and InAs/GaInSb based photon detectors of different structure and composition. It also covers R&D on uncooled microbolometers. The integrated thermistor material of such detectors is advantageously based on quantum structures that are optimised for high temperature coefficient and low noise. Especially the SiGe material system is preferred due to the compatibility with silicon technology. The R&D work on IR detectors is a prominent part of Acreo’s centre of excellence “IMAGIC” on imaging detectors and systems for non-visible wavelengths. IMAGIC is a collaboration between Acreo, several industry partners and universities like the Royal Institute of Technology (KTH) and Linköping University. 相似文献