[en] In this paper we consider first order linear and non-linear functional differential equations with continuous distributed retarded and advanced arguments. We give some good conditions under which every solution of these equations oscillates. We generalized and improved results of Ladas and Stavroulasis [J. Diff. Egs., 44, 134(1982)] and Ruan Jiong [Chin. Ann. of Math., 5B, no. 4 (1984)]. (author)

[en] In this paper we study the nonoscillatory behaviour of even-order functional differential inequalities and equations with continuous distributed retarded and advanced arguments. For arguments we give some conditions under which these inequalities only have nonoscillatory solutions of degree 0 or n. (author)

[en] At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a single-sweep module of the Hamamatsu C5680 streak camera with an intrinsic shot-to-shot trigger jitter of 10 to 20 ps. We have upgraded the camera system with the synchroscan module tuned to 81.25 MHz to provide synchronous summing capability with less than 1.5-ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of ∼1 ps over 10s of minutes. This allowed us to measure both the UV laser pulse train at 244 nm and the e-beam via optical transition radiation (OTR). Due to the low electron beam energies and OTR signals, we typically summed over 50 micropulses with 1 nC per micropulse. We also did electron beam bunch length vs. micropulse charge measurements to identify a significant e-beam micropulse elongation from 10 to 30 ps (FWHM) for charges from 1 to 4.6 nC. This effect is attributed to space-charge effects in the PC gun as reproduced by ASTRA calculations. Chromatic temporal dispersion effects in the optics were also characterized and will be reported

[en] Excellent phase stability of the drive laser is a critical performance specification of photoinjectors such as Fermilab's A0 photoinjector (A0PI). Previous efforts based on the measurement of the power spectrum of the signal of a fast photodiode illuminated by the mode locked infrared laser pulse component indicated a phase jitter of less than 1.4 ps (technique limited). A recently procured dual sweep plugin unit and existing Hamamatsu C5680 streak camera were used to study the phase stability of the UV laser pulse component. Initial measurements with the synchroscan vertical sweep unit locked to 81.25 MHz showed that the phase slew through the micropulse train and the phase jitter micropulse to micropulse were two key aspects that could be evaluated. The phase slew was much less than 100 fs per micropulse, and the total phase jitter (camera, trigger, and laser) was approximately 300 fs RMS for measurements of 50-micropulse trains. Data on the macropulse phase stability were also obtained. A possible upgrade to achieve better phase stability will be also discussed.

[en] We report on the tunneling density of states (DOS) in strongly disordered ultrathin Be films quench condensed at 20K. Above 5K, the DOS shows the well-known logarithmic anomaly at the Fermi level. Only in a narrow temperature range near 2K is the DOS linearly dependent on energy, as predicted by Efros and Shklovskii. However, both the zero-bias conductance and the slope of the linear DOS are found to decrease drastically with decreasing temperature. Tunneling measurements at mK temperatures have revealed conclusively that a hard correlation gap opens up in the DOS

[en] The Fermilab A0 Photoinjector is a 16 MeV high intensity, high brightness electron linac developed for advanced accelerator R and D. One of the key parameters for the electron beam is the transverse beam emittance. Here we report on a newly developed MATLAB based GUI program used for transverse emittance measurements using the multi-slit technique. This program combines the image acquisition and post-processing tools for determining the transverse phase space parameters with uncertainties. An integral part of accelerator research is a measurement of the beam phase space. Measurements of the transverse phase space can be accomplished by a variety of methods including multiple screens separated by drift spaces, or by sampling phase space via pepper pots or slits. In any case, the measurement of the phase space parameters, in particular the emittance, can be drastically simplified and sped up by automating the measurement in an intuitive fashion utilizing a graphical interface. At the A0 Photoinjector (A0PI), the control system is DOOCS, which originated at DESY. In addition, there is a library for interfacing to MATLAB, a graphically capable numerical analysis package sold by The Mathworks. It is this graphical package which was chosen as the basis for a graphical phase space measurement system due to its combination of analysis and display capabilities.

[en] The current Fermilab A0 Photoinjector laser system includes a seed laser, a flashlamp pumped multipass amplifier cavity, a flashlamp pumped 2-pass amplifier system followed by an Infra-Red (IR) to Ultra-Violet (UV) conversion stage. However the current system can only deliver up to 800 pulses due to the low efficiency of Nd:Glass used inside multi-pass cavity. In this paper we will report the effort to develop a new multi pass cavity based on Nd:YLF crystal end-pumped by diode laser. We will also discuss the foreseen design of the laser system for the NML accelerator test facility at Fermilab

[en] The electric field dependence of the decay curves of 20 atm xenon excited by alpha particles has been analyzed by introducing the concept of radial charge distribution in the ionized column. A pronounced high density at the center of the track has been indicated. (orig.)

[en] The time dependence of the luminescence due to the recombination process of electrons and ions in high-pressure argon, krypton and xenon excited by ²¹⁰Po alpha-particles has been studied by considering the difference in the decay curves observed at zero field and at such a high field that all electrons are free from recombination. For argon of pressure p > 8 x 10³ Torr, the decay is well represented by the formula esup(-t/tau) - esup(-2t/Tsub(r)) for t < Tsub(r) and esup(-t/tau) for t > Tsub(r), where Tsub(r) = 6 x 10⁴psup(2.7 +- 0.3) s, tau approx. equal to 3 μs, and p is in Torr. For krypton 4 x 10³ < p < 10⁴, the decay is well represented by the formula (1 + Tsub(r)^-1t)^-2 for t > 300 ns, where Tsub(r) = 10⁴psup(-2.6 +- 0.5) s. For xenon 4 x 10³ < p < 1.5 x 10⁴, the decay is represented by a sum of an exponential decay of lifetime of about 200-300 ns for t < t₀ and a formula (1 + Tsub(r)^-1t)^-2 for t > t₀, where typical Tsub(r) and t₀ values are 2.0 μs and 1.6 μs, respectively, for 1.5 x 10⁴ Torr, and 5.6 μs and 5 μs for 4.4 x 10³ Torr. It is shown that the Coulomb interaction between the thermalized electrons and the ions in the track is strong enough to prevent electron diffusion, which results in the ambipolar diffusion. A brief consideration is given on the track structure relevant to the recombination luminescence. (orig.)

[en] The light output and the collected charge in xenon-doped liquid argon under ²⁰⁷Bi conversion electron excitation have been studied as a function of an applied electric field with the xenon concentration [Xe] less than 1.9%. With increasing [Xe], the light output was increased and was maximized at [Xe]=1.9%, having about as twice as much intensity with respect to that in pure argon. The amount of collected charge in xenon-doped liquid argon was nearly equal to that in pure argon up to 2500 ppm of [Xe], above which a slight increase was observed. The increase in light output can be explained by the difference in the conversion efficiency of the POPOP wavelength shifter for 130 nm scintillation photons in liquid argon and for 175 nm scintillation photons in xenon-doped liquid argon. (orig.)