34,336 research outputs found
Hydrogen maser oscillation at 10 K
A low temperature atomic hydrogen maser was developed using frozen atomic neon as the storage surface. The maser has been operated in the pulsed mode at temperatures from 6 K to 11 K and as a self-excited oscillator from 9 K to 10.5 K
Hyperbolic Unit Groups and Quaternion Algebras
We Classify the rational quadratic extensions K and the finite groups G for
which the group ring R[G] of G over the ring R of integers of K has the
property that the group of units of augmentation 1 of R[G] is hyperbolic. We
also construct units in a non-split quaternion algebra over R.Comment: 15 pages, this work is part of the PHd. Thesis of the third author.
The paper was accepted in Proceedings Mathematical Science
Effects of geometric constraints on the nuclear multifragmentation process
We include in statistical model calculations the facts that in the nuclear
multifragmentation process the fragments are produced within a given volume and
have a finite size. The corrections associated with these constraints affect
the partition modes and, as a consequence, other observables in the process. In
particular, we find that the favored fragmenting modes strongly suppress the
collective flow energy, leading to much lower values compared to what is
obtained from unconstrained calculations. This leads, for a given total
excitation energy, to a nontrivial correlation between the breakup temperature
and the collective expansion velocity. In particular we find that, under some
conditions, the temperature of the fragmenting system may increase as a
function of this expansion velocity, contrary to what it might be expected.Comment: 16 pages, 5 figure
Statistical multifragmentation model with discretized energy and the generalized Fermi breakup. I. Formulation of the model
The Generalized Fermi Breakup recently demonstrated to be formally equivalent
to the Statistical Multifragmentation Model, if the contribution of excited
states are included in the state densities of the former, is implemented. Since
this treatment requires the application of the Statistical Multifragmentation
Model repeatedly on the hot fragments until they have decayed to their ground
states, it becomes extremely computational demanding, making its application to
the systems of interest extremely difficult. Based on exact recursion formulae
previously developed by Chase and Mekjian to calculate the statistical weights
very efficiently, we present an implementation which is efficient enough to
allow it to be applied to large systems at high excitation energies. Comparison
with the GEMINI++ sequential decay code shows that the predictions obtained
with our treatment are fairly similar to those obtained with this more
traditional model.Comment: 8 pages, 6 figure
Inclusive Breakup Theory of Three-Body Halos
We present a recently developed theory for the inclusive breakup of
three-fragment projectiles within a four-body spectator model
\cite{CarPLB2017}, for the treatment of the elastic and inclusive non-elastic
break up reactions involving weakly bound three-cluster nuclei in
/ collisions. The four-body theory is an extension of the
three-body approaches developed in the 80's by Ichimura, Autern and Vincent
(IAV) \cite{IAV1985}, Udagawa and Tamura (UT) \cite{UT1981} and Hussein and
McVoy (HM) \cite{HM1985}. We expect that experimentalists shall be encouraged
to search for more information about the system in the elastic
breakup cross section and that also further developments and extensions of the
surrogate method will be pursued, based on the inclusive non-elastic breakup
part of the spectrum.Comment: 8 pages, 3 figures, Contribution to the Proceedings of Fusion17:
"International Conference on Heavy-Ion Collisions at Near-Barrier Energies",
20-24 February 2017 Hobart, Tasmania, Australi
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