15,149 research outputs found
Research and development of open-cycle fuel cells Fourth quarterly progress report, period ending Aug. 15, 1965
Digital computer program for minimizing weight of fuel cell power systems - prelaunch startup and instrumentation - mathematical model of static moisture removal process - fuel cell mode
Simulation of charged particle trajectories in the neutron decay correlation experiment abBA
The proposed neutron decay correlation experiment, abBA, will directly detect the direction of emission of decay protons and electrons as well as providing spectroscopic information for both particles. In order to provide this information, the abBA experiment incorporates spatially varying electric and magnetic fields. We report on detailed simulations of the decay particle trajectories in order to assess the impact of various systematic effects on the experimental observables. These include among others; adiabaticity of particle orbits, tracking of orbits, reversal of low energy protons due to inhomogeneous electric field, and accuracy of proton time of flight measurements. Several simulation methods were used including commercial software (Simion), custom software, as well as analytical tools based on the use of adiabatic invariants. Our results indicate that the proposed field geometry of the abBA spectrometer will be substantially immune to most systematic effects and that transport calculations using adiabatic invariants agree well with solution of the full equations of motion
The Pulse Scale Conjecture and the Case of BATSE Trigger 2193
The pulses that compose gamma-ray bursts (GRBs) are hypothesized to have the
same shape at all energies, differing only by scale factors in time and
amplitude. This "Pulse Scale Conjecture" is confirmed here between energy
channels of the dominant pulse in GRB 930214c (BATSE trigger 2193), the single
most fluent single-pulsed GRB that occurred before May 1998. Furthermore,
pulses are hypothesized to start at the same time independent of energy. This
"Pulse Start Conjecture" is also confirmed in GRB 930214c. Analysis of GRB
930214c also shows that, in general, higher energy channels show shorter
temporal scale factors. Over the energy range 100 KeV - 1 MeV, it is found that
the temporal scale factors between a pulse measured at different energies are
related to that energy by a power law, possibly indicating a simple
relativistic mechanism is at work. To test robustness, the Pulse Start and
Pulse Scale Conjectures were also tested on the four next most fluent
single-pulse GRBs. Three of the four clearly passed, with a second smaller
pulse possibly confounding the discrepant test. Models where the pulse rise and
decay are created by different phenomena do not typically predict pulses that
satisfy both the Pulse Start Conjecture and the Pulse Scale Conjecture, unless
both processes are seen to undergo common time dilation.Comment: 19 pages, 9 figures, analysis revised and extended, accepted to Ap
Line shifts in the first overtone of DF broadened by HF
Line spectra shifts in HF and in first overtone band of DF induced by HF pressure
Ultracold neutron depolarization in magnetic bottles
We analyze the depolarization of ultracold neutrons confined in a magnetic
field configuration similar to those used in existing or proposed
magneto-gravitational storage experiments aiming at a precise measurement of
the neutron lifetime. We use an extension of the semi-classical Majorana
approach as well as an approximate quantum mechanical analysis, both pioneered
by Walstrom et al. [Nucl. Instr. Meth. Phys. Res. A 599, 82 (2009)]. In
contrast with this previous work we do not restrict the analysis to purely
vertical modes of neutron motion. The lateral motion is shown to cause the
predominant depolarization loss in a magnetic storage trap. The system studied
also allowed us to estimate the depolarization loss suffered by ultracold
neutrons totally reflected on a non-magnetic mirror immersed in a magnetic
field. This problem is of preeminent importance in polarized neutron decay
studies such as the measurement of the asymmetry parameter A using ultracold
neutrons, and it may limit the efficiency of ultracold neutron polarizers based
on passage through a high magnetic field.Comment: 18 pages, 6 figure
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