1,031 research outputs found
Enhancement of the Deuteron-Fusion Reactions in Metals and its Experimental Implications
Recent measurements of the reaction d(d,p)t in metallic environments at very
low energies performed by different experimental groups point to an enhanced
electron screening effect. However, the resulting screening energies differ
strongly for divers host metals and different experiments. Here, we present new
experimental results and investigations of interfering processes in the
irradiated targets. These measurements inside metals set special challenges and
pitfalls which make them and the data analysis particularly error-prone. There
are multi-parameter collateral effects which are crucial for the correct
interpretation of the observed experimental yields. They mainly originate from
target surface contaminations due to residual gases in the vacuum as well as
from inhomogeneities and instabilities in the deuteron density distribution in
the targets. In order to address these problems an improved differential
analysis method beyond the standard procedures has been implemented. Profound
scrutiny of the other experiments demonstrates that the observed unusual
changes in the reaction yields are mainly due to deuteron density dynamics
simulating the alleged screening energy values. The experimental results are
compared with different theoretical models of the electron screening in metals.
The Debye-H\"{u}ckel model that has been previously proposed to explain the
influence of the electron screening on both nuclear reactions and radioactive
decays could be clearly excluded.Comment: 22 pages, 12 figures, REVTeX4, 2-column format. Submitted to Phys.
Rev. C; accepte
Temperature cycling tests on a mixed Be/Li₄SiO₄ pebble bed in the HEBLO facility. (Final report)
The 198Au beta-half-life in the metal Au revisited
The half-life of the beta-decay of 198Au has been measured for room
temperature and 12 K. The resulting values of T(RT) = 2.684 +- 0.004 d and T(12
K) = 2.687 +- 0.005 d agree well within statistical uncertainties. An evidence
for a temperature dependence of the half-life was not observed.Comment: accepted for publication in Eur. Phys. J.
Single Particle Tracking for Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring
A scheme where 1.5 ps and 15 ps long bunches rms can be stored simultaneously in the BESSY II storage ring has recently been proposed BESSYVSR . This paper presents simulations of single particle beam dynamics influenced by superconducting cavities used for the strong longitudinal beam focusing. The effect of RF jitter on very short bunches is investigated and results are discussed. Furthermore, possible effects on beam dynamics during ramp up and ramp down of the high gradient fields in the cavities are studied. The primary goal is to reveal preliminary design specifications for RF jitter on the basis of single particle dynamic
Order Parameter at the Boundary of a Trapped Bose Gas
Through a suitable expansion of the Gross-Pitaevskii equation near the
classical turning point, we obtain an explicit solution for the order parameter
at the boundary of a trapped Bose gas interacting with repulsive forces. The
kinetic energy of the system, in terms of the classical radius and of the
harmonic oscillator length , follows the law , approaching, for large , the
results obtained by solving numerically the Gross-Pitaevskii equation. The
occurrence of a Josephson-type current in the presence of a double trap
potential is finally discussed.Comment: 11 pages, REVTEX, 4 figures (uuencoded-gzipped-tar file) also
available at http://anubis.science.unitn.it/~dalfovo/papers/papers.htm
Ground-State Properties of a Rotating Bose-Einstein Condensate with Attractive Interaction
The ground state of a rotating Bose-Einstein condensate with attractive
interaction in a quasi-one-dimensional torus is studied in terms of the ratio
of the mean-field interaction energy per particle to the
single-particle energy-level spacing. The plateaus of quantized circulation are
found to appear if and only if with the lengths of the plateaus
reduced due to hybridization of the condensate over different angular-momentum
states.Comment: 4 pages, 2 figures, Accepted for publication in Physical Reveiw
Letter
Influence of Transient Beam Loading on the Longitudinal Beam Dynamics at BESSY VSR
BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches rms can be stored simultaneously in the BESSY II storage ring has recently been proposed [1]. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal phase space which is different for each bunch. The result are variations along the fill pattern in synchronous phase, synchrotron fre quency and bunch shape. This paper presents investigations of transient beam loading and depicts the consequences on bunch length, phase stability and longitudinal multi bunch oscillations for the projected setup of BESSY VS
Lipid, detergent, and coomassie blue G-250 affect the migration of small membrane proteins in blue native gels:Mitochondrial carriers migrate as monomers not dimers
Background: Mitochondrial carriers were thought to be dimeric based on their migration in blue native gels. Results: The high molecular mass species observed in blue native gels are composed of protein monomers, detergent, lipid, and Coomassie stain. Conclusion: The mitochondrial carriers are monomeric not dimeric. Significance: The apparent mass of small membrane proteins in blue native gels requires significant correction
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