16,955 research outputs found

### Transient effects on electron spin observation

In an earlier publication we addressed the problem of splitting an electron beam in the Stern-Gerlach experiment. In contrast to arguments put forward in the early days of quantum theory, we concluded that there are no issues of principle preventing the observation of electron spin during free flight. In that paper, however, we considered only a sudden switch off of the separating magnetic field. In this work we consider the possible effects of finite switching times at the beginning and the end of the interaction period. We consider a model where the coupling between the electron and the field is time dependent. As a result of the time dependence, the field also acquires an electric component, but this seems to cause no significant change of our conclusions. On the other hand, the smooth change of the interaction enforces the same longitudinal velocity on the electron both at the beginning and end of the interaction period because of conservation laws; this effect was missing in our earlier calculations. As the electrons are supposed to travel as a beam, this feature helps by restoring the beam quality after the interaction

### Manifestation of transient effects in fission induced by relativistic heavy-ion collisions

We examine the manifestation of transient effects in fission by analysing
experimental data where fission is induced by peripheral heavy-ion collisions
at relativistic energies. Available total nuclear fission cross sections of
238U at 1 A GeV on gold and uranium targets are compared with a
nuclear-reaction code, where transient effects in fission are modelled using
different approximations to the numerical time-dependent fission-decay width: a
new analytical description based on the solution of the Fokker-Planck equation
and two widely used but less realistic descriptions, a step function and an
exponential-like function. The experimental data are only reproduced when
transient effects are considered. The deduced value of the dissipation strength
depends strongly on the approximation applied for the time-dependent
fission-decay width and is estimated to be of the order of 2x10**21 s**(-1). A
careful analysis sheds severe doubts on the use of the exponential-like
in-growth function largely used in the past. Finally, we discuss which should
be the characteristics of experimental observables to be most sensitive to
transient effects in fissionComment: 18 pages, 2 figures, background information on
http://www-w2k.gsi.de/kschmidt

### Elastohydrodynamics for soft solids with surface roughness: transient effects

A huge number of technological and biological systems involves the lubricated
contact between rough surfaces of soft solids in relative accelerated motion.
Examples include dynamical rubber seals and the human joints. In this study we
consider an elastic cylinder with random surface roughness in accelerated
sliding motion on a rigid, perfectly flat (no roughness) substrate in a fluid.
We calculate the surface deformations, interface separation and the
contributions to the friction force and the normal force from the area of real
contact and from the fluid. The driving velocity profile as a function of time
is assumed to be either a sine-function, or a linear multi-ramp function. We
show how the squeeze-in and squeeze-out processes, occurring in accelerated
sliding, quantitatively affect the Stribeck curve with respect to the steady
sliding. Finally, the theory results are compared to experimental data

### Transient effects in fission evidenced from new experimental signatures

A new experimental approach is introduced to investigate the relaxation of
the nuclear deformation degrees of freedom. Highly excited fissioning systems
with compact shapes and low angular momenta are produced in peripheral
relativistic heavy-ion collisions. Both fission fragments are identified in
atomic number. Fission cross sections and fission-fragment element
distributions are determined as a function of the fissioning element. From the
comparison of these new observables with a nuclear-reaction code a value for
the transient time is deduced.Comment: 6 pages, 2 figures, background information at
http://www-w2k.gsi.de/kschmidt

### Research Laboratory of Electronics Quarterly status report, 16 Feb. - 15 May 1969

Computer program for calculating large signal nonlinear transient effects in avalanche diod

### Transient effects in the backscattered current of a Luttinger liquid

We study the backscattered current in a Luttinger liquid in the presence of a
point like weak impurity switched on at finite time, taking into account
finite-temperature effects. We show how the well-known results for a static
impurity are distorted. We derive a dimensionless parameter $\tau_{R}$ as
function of the electron-electron interaction and the temperature, such that
for $\tau_{R} 1$) the switching process is relevant (irrelevant). Our
results suggest the possibility of determining the value of the Luttinger
parameter $K$ through time measurements in transport experiments at fixed
voltage.Comment: 8 pages, 3 figures. To appear in Physical Review

### Non-linear vortex dynamics and transient effects in ferromagnetic disks

We report a time resolved imaging and micromagnetic simulation study of the
relaxation dynamics of a magnetic vortex in the non-linear regime. We use
time-resolved photoemission electron microscopy and micromagnetic calculations
to examine the emergence of non-linear vortex dynamics in patterned Ni80Fe20
disks in the limit of long field pulses. We show for core shifts beyond ~20-25%
of the disk radius, the initial motion is characterized by distortions of the
vortex, a transient cross-tie wall state, and instabilities in the core
polarization that influence the core trajectories.Comment: 11 pages, 3 figures, submitted to Phys. Rev. Let

### Metastability and Transient Effects in Vortex Matter Near a Decoupling Transition

We examine metastable and transient effects both above and below the
first-order decoupling line in a 3D simulation of magnetically interacting
pancake vortices. We observe pronounced transient and history effects as well
as supercooling and superheating between the 3D coupled, ordered and 2D
decoupled, disordered phases. In the disordered supercooled state as a function
of DC driving, reordering occurs through the formation of growing moving
channels of the ordered phase. No channels form in the superheated region;
instead the ordered state is homogeneously destroyed. When a sequence of
current pulses is applied we observe memory effects. We find a ramp rate
dependence of the V(I) curves on both sides of the decoupling transition. The
critical current that we obtain depends on how the system is prepared.Comment: 10 pages, 15 postscript figures, version to appear in PR

### Evaluation of commercial ADC radiation tolerance for accelerator experiments

Electronic components used in high energy physics experiments are subjected
to a radiation background composed of high energy hadrons, mesons and photons.
These particles can induce permanent and transient effects that affect the
normal device operation. Ionizing dose and displacement damage can cause
chronic damage which disable the device permanently. Transient effects or
single event effects are in general recoverable with time intervals that depend
on the nature of the failure. The magnitude of these effects is technology
dependent with feature size being one of the key parameters. Analog to digital
converters are components that are frequently used in detector front end
electronics, generally placed as close as possible to the sensing elements to
maximize signal fidelity. We report on radiation effects tests conducted on 17
commercially available analog to digital converters and extensive single event
effect measurements on specific twelve and fourteen bit ADCs that presented
high tolerance to ionizing dose. Mitigation strategies for single event effects
(SEE) are discussed for their use in the large hadron collider environment.Comment: 16 pages, 8 figure

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