4,889 research outputs found
Discovery of Long-Lived Shape Isomeric States which Decay by Strongly Retarded High-Energy Particle Radioactivity
The reaction 28Si + 181Ta has been studied at E(Lab) = 125 and 135 MeV.
Coincidences between high energy particles and various X- and gamma-rays from
abnormally long-lived states were observed. e.g. 7.8 - 8.6 MeV alpha-particles
with gamma-rays of a superdeformed band, 5.1 - 5.5 MeV alpha-particles with X-
and gamma-rays of W, Re, and Pt, and 3.88 MeV particles (interpreted as
protons) with 185.8 keV gamma-rays. The data are interpreted in terms of the
production of long-lived (t(1/2) of several months) high spin isomeric states
in the second well of the potential in the parent nuclei, which decay to the
normal states in the daughters, and in the third well of the potential, which
decay to the second well.Comment: 25 pages including 11 figures and 3 table
Strongly Enhanced Low Energy Alpha-Particle Decay in Heavy Actinide Nuclei and Long-Lived Superdeformed and Hyperdeformed Isomeric States
Relatively low energy and very enhanced alpha-particle groups have been
observed in various actinide fractions produced via secondary reactions in a
CERN W target which had been irradiated with 24-GeV protons. In particular,
5.14, 5.27 and 5.53 MeV alpha-particle groups with corresponding half-lives of
3.8(+ -)1.0 y, 625(+ -)84 d and 26(+ -)7 d, have been seen in Bk, Es and Lr-No
sources, respectively. The measured energies are a few MeV lower than the known
g.s. to g.s. alpha-decays in the corresponding neutron-deficient actinide
nuclei. The half-lives are 4 to 7 orders of magnitude shorter than expected
from the systematics of alpha-particle decay in this region of nuclei. The
deduced evaporation residue cross sections are in the mb region, about 4 orders
of magnitude higher than expected. A consistent interpretation of the data is
given in terms of production of long-lived isomeric states in the second and
third wells of the potential-energy surfaces of the parent nuclei, which decay
to the corresponding wells in the daughters. The possibility that the isomeric
states in the third minimum are actually the true or very near the true ground
states of the nuclei, and consequences regarding the production of the
long-lived superheavy elements, are discussed.Comment: 27 pages including 8 figures and 4 table
Exact Evolution Operator on Non-compact Group Manifolds
Free quantal motion on group manifolds is considered. The Hamiltonian is
given by the Laplace -- Beltrami operator on the group manifold, and the
purpose is to get the (Feynman's) evolution kernel. The spectral expansion,
which produced a series of the representation characters for the evolution
kernel in the compact case, does not exist for non-compact group, where the
spectrum is not bounded. In this work real analytical groups are investigated,
some of which are of interest for physics. An integral representation for the
evolution operator is obtained in terms of the Green function, i.e. the
solution to the Helmholz equation on the group manifold. The alternative series
expressions for the evolution operator are reconstructed from the same integral
representation, the spectral expansion (when exists) and the sum over classical
paths. For non-compact groups, the latter can be interpreted as the (exact)
semi-classical approximation, like in the compact case. The explicit form of
the evolution operator is obtained for a number of non-compact groups.Comment: 32 pages, 5 postscript figures, LaTe
Coherent Description for Hitherto Unexplained Radioactivities by Super- and Hyperdeformed Isomeric States
Recently long-lived high spin super- and hyperdeformed isomeric states with
unusual radioactive decay properties have been discovered. Based on these newly
observed modes of radioactive decay, consistent interpretations are suggested
for previously unexplained phenomena seen in nature. These are the Po halos,
the low-energy enhanced 4.5 MeV alpha-particle group proposed to be due to an
isotope of a superheavy element with Z = 108, and the giant halos.Comment: 8 pages, 2 figures, 1 table, to be published in Int. J. Mod. Phys.
New Outlook on the Possible Existence of Superheavy Elements in Nature
A consistent interpretation is given to some previously unexplained phenomena
seen in nature in terms of the recently discovered long-lived high spin super-
and hyper-deformed isomeric states. The Po halos seen in mica are interpreted
as due to the existence of such isomeric states in corresponding Po or nearby
nuclei which eventually decay by gamma- or beta-decay to the ground states of
210Po, 214Po and 218Po nuclei. The low-energy 4.5 MeV alpha-particle group
observed in several minerals is interpreted as due to a very enhanced alpha
transition from the third minimum of the potential-energy surface in a
superheavy nucleus with atomic number Z=108 (Hs) and atomic mass number around
271 to the corresponding minimum in the daughter.Comment: 8 pages, 8 figures, 5 tables. Paper presented at VII Int.
School-Seminar on Heavy Ion Physics, May 27 - June 1, 2002, Dubna, Russi
Rail Marketing, Jobs and Public Engagement
The chapter briefly explains the marketing mix in a rail context and then discusses marketing strategies to promote rail from two perspectives. Firstly, rail is perceived as a transport service offered to potential users and various marketing tools are used to maximise rail companies’ profit. Secondly rail is seen as a career path and variety of marketing, skills training and public engagement actions are targeting potential talents, already within the industry as well as those beyond the railway sector. The pool of talented individuals includes students, graduates, academics and professionals who are exposed to recruitment and retention activities of the railway sector. Various activities and projects run by the rail industry, targeting audience at school, university, professional and general public’s levels, are presented with their success stories as well as challenges some of the initiatives faced. Also, results of a survey focusing on skills and jobs for rail (and transport sector) of the future are presented and commented on
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