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The Fermilab Tevatron is currently the world’s highest energy colliding beam facility. Its counter-rotating proton and antiproton beams collide at 2 TeV center-of-mass. Delivery of such intense beam fluxes to experiments has required improved knowledge of the Tevatron’s beam optical lattice. An oscillating dipole magnet, referred to as an AC dipole, is one of such a tool to non-destructively assess the optical properties of the synchrotron. We discusses development of an AC dipole system for the Tevatron, a fast-oscillating (f∼20 kHz) dipole magnet which can be adiabatically turned on and off to establish sustained coherent oscillations of the beam particles without affecting the transverse emittance. By utilizing an existing magnet and a higher power audio amplifier, the cost of the Tevatron AC dipole system became relatively inexpensive. We discuss corrections which must be applied to the driven oscillation measurements to obtain the proper interpretation of beam optical parameters from AC dipole studies. After successful operations of the Tevatron AC dipole system, AC dipole systems, similar to that in the Tevatron, will be build for the CERN LHC. We present several measurements of linear optical parameters (beta function and phase advance) for the Tevatron, as well as studies of non-linear perturbations from sextupole and octupole elements. / text

Andrea Damascelli is looking to usher in a new era of quantum computing with a groundbreaking technique that defies all nanotechnology research to date.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

This dissertation uses shocks to explain both the prevalence of radio synchroton emission and dust formation in classical novae, as well as the origin of fast radio bursts. First, we examine the radio lightcurves of nova V809 Cep and find that the peak brightness temperature exceeded 10⁵𝘒, an order of magnitude above what is expected for thermal emission. We argue that the brightness temperature is the result of synchrotron emission due to internal shocks within the ejecta. We then examine the radio lightcurves of seven novae with radio evidence for shocks (QU Vul, V1723 Aql, V5668 Sgr, V809 Cep, V357 Mus, V1324 Sco, PGIR20fbf) and IR/optical evidence for dust formation. We demonstrate that dust formation generally precedes the rise of radio non-thermal emission, and present evidence to suggest that shocks occur prior to the onset of dust formation but that the radio shock emission is initially being absorbed by a layer of photo-ionized gas ahead of the shock. We model the optical depth of the photo-ionized gas to demonstrate that the time required for the photo-ionized gas to become optically thin to radio frequencies can be longer than the time required for dust nucleation; thus, dust appears to form before the shock emission is visible. We further demonstrate that the radio spectral evolution in novae with no evidence for dust formation is markedly different from novae with evidence for shocks, suggesting that in novae without velocity or distance estimates, the radio spectral evolution could be used to constrain the presence of shocks. Finally, we demonstrate that novae with evidence for dust absorption are preferentially inclined edge, on suggesting that both shocks and dust form in the equatorial plane. Since internal shocks in nova ejecta are thought to lead to dust formation, localizing both phenomenon to the equatorial plane strengthens the connection between the two phenomena. We then use Particle-In-Cell (PIC) simulations to explore the synchroton maser instability as a potential mechanism for the formation of Fast Radio Bursts. Electromagnetic precursor waves generated by the synchrotron maser instability at relativistic magnetized shocks have been recently invoked to explain the coherent radio emission of Fast Radio Bursts. By means of two-dimensional particle-in-cell simulations, we explore the properties of the precursor waves in relativistic electron-positron perpendicular shocks as a function of the pre-shock magnetization σ ≳1 (i.e., the ratio of incoming Poynting flux to particle energy flux) and thermal spread Δᵧ ≡ 𝑘𝑇/𝑚𝑐² = 10⁻⁵−10⁻¹. We measure the fraction 𝑓𝜉 of total incoming energy that is converted into precursor waves, as computed in the post-shock frame. At fixed magnetization, we find that 𝑓𝜉 is nearly independent of temperature as long as Δᵧ ≲ 10¹·⁵ (with only a modest decrease of a factor of three from Δᵧ = 10⁻⁵ to Δᵧ = 10¹·⁵, but it drops by nearly two orders of magnitude for Δᵧ ≳ 10⁻¹. For our reference σ = 1, the power spectrum of precursor waves is relatively broad (fractional width ∼ 1−3) for cold temperatures, whereas it shows pronounced line-like features with fractional width ∼ 0.2 for 10⁻³ ≲ Δᵧ ≲ 10¹·⁵. For σ ≳ 1, the precursor waves are beamed within an angle ≃ σ -⁻¹/² from the shock normal (as measured in the post-shock frame), as required so they can outrun the shock. Our results can provide physically-grounded inputs for FRB emission models based on maser emission from relativistic shocks.

No / Multi-pellet formulations are advantageous for the controlled release of drugs over single-unit dosage forms. To understand the diffusion controlled drug release mechanism, the pellet structure and drug release from a single pellet (not at dose level) were studied using synchrotron radiation X-ray computed microtomography (SR-muCT) and a sensitive LC/MS/MS method. The purpose of this article is to introduce a powerful, non-invasive and quantitative technique for studying individual pellet microstructures and to investigate the relationship between the microstructure and drug release from single pellets. The data from the single pellet dissolution measurements demonstrated that the release profile of capsules containing approximately 1,000 pellets per unit dose was the summation of the release profiles of the individual pellets. The release profiles of single tamsulosin hydrochloride (TSH) pellets formed three groups when a cluster analysis was performed, and the dissolution rate of the individual pellets correlated well with the combined effects of the drug loading, volume and surface area of the pellets (R(2) = 0.9429). In addition, the void microstructures within the pellet were critical during drug release. Therefore, SR-muCT is a powerful tool for quantitatively elucidating the three-dimensional microstructure of the individual pellets; because the microstructure controls drug release, it is an important parameter in the quality control of multi-pellet formulations.

Spider pulsars are compact binary systems consisting of a millisecond pulsar and a low-mass companion. Their X-ray emission, modulated on the orbital period, is interpreted as synchrotron radiation from high-energy electrons accelerated at the intrabinary shock. In this dissertation, we conduct global two-dimensional particle-in-cell simulations of the intrabinary shock, assuming the shock wraps around the companion star. When the pulsar spin axis is nearly aligned with the orbital angular momentum, the magnetic energy of the relativistic pulsar wind, composed of magnetic stripes of alternating field polarity, efficiently converts to particle energy at the intrabinary shock via shock-driven reconnection. The highest energy particles accelerated by reconnection can stream ahead of the shock and be further accelerated by the upstream motional electric field. In the downstream, further energization is governed by stochastic interactions with the plasmoids or magnetic islands generated by reconnection. Our results show that the synchrotron spectrum is nearly flat, 𝐹_𝜈 ∝, and the light curve displays two peaks just before and after the pulsar eclipse (superior conjunction), separated in phase by approximately 0.8 rad, with the peak flux exceeding that at inferior conjunction by a factor of ten. Additionally, we consider radiative losses in the form of synchrotron cooling using the reduced Landau-Lifshitz model. We examine three cooled scenarios, with a synchrotron burnoff limit (𝜰_rad) of 120, 60, and 30, comparing these simulations to an uncooled case to understand the impact of radiative losses on particle acceleration and emission.

19 Dec 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 1993" Ning Yang. 12/19/2004. Report is also available in paper and microfiche from NTIS.

Thesis (Ph.D.); Submitted to The University of California at Berkeley, Berkeley, CA (US); 1 Sep 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--55022" Prilliman, Gerald Stephen. USDOE Director. Office of Science. Office of Basic Energy Sciences (US) 09/01/2003. Report is also available in paper and microfiche from NTIS.

Thesis (Ph.D.); Submitted to Univ. of California, Davis, CA (US); 17 Sep 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "UCRL-TH-207378" Gibson, D J. 09/17/2004. Report is also available in paper and microfiche from NTIS.