ISABELLE superconducting power distribution system

Research during the period June 1980 through May 1981 is described. Areas studied include: radioactive decay of /sup 199/Po and /sup 201/Po, /sup 202/At, /sup 189/Tl energy levels from Pb decay, /sup 192/Pb ..-->.. /sup 192/Tl ..-->.. /sup 192/Hg, and Ba decays; high spin states; inelastic scattering and reactions of heavy ions from deformed nuclei; and nuclear structure theory. (GHT

The Muonium Atom as a Probe of Physics beyond the Standard Model

The observed interactions between particles are not fully explained in the successful theoretical description of the standard model to date. Due to the close confinement of the bound state muonium ($M = \mu^+ e^-$) can be used as an ideal probe of quantum electrodynamics and weak interaction and also for a search for additional interactions between leptons. Of special interest is the lepton number violating process of sponteanous conversion of muonium to antimuonium.Comment: 15 pages,6 figure

Design of the Source Development Lab bunch compressor

The accelerator at the Source Development Lab at BNL consists of a 1.6 cell RF photocathode electron gun followed by a 230 MeV SLAC-type linac that includes a magnetic chicane bunch compressor. The nominal specifications call for a 10 ps FWHM bunch of 2nC charge to be compressed in time by a factor of 25 at an energy of 85 MeV. The design of the compressor magnets and the beam dynamics from the gun through the magnetic chicane are described

Performance of magnesium cathode in the S-band RF gun

In this paper, the authors present the preliminary results of the performance of magnesium cathode in a high frequency RF gun. The quantum efficiency of Mg showed a dramatic improvement upon laser cleaning, increasing from 10{sup {minus}5} to 4 {times} 10{sup {minus}4} after two hours of cleaning, and to 2 {times} 10{sup {minus}3} after systematic cleaning. The cleaning procedure for this increase is described in detail. Charge measured as a function of the laser injection phase relative to the RF phase indicates that the temporal variation of the field on the cathode both due to the RF and the shielding effect of the emitted electrons play a critical role in the emission and extraction of electrons. A model that includes this variation is numerically fitted to the measured charge and the results are presented. The unexpected outcome of the fit was the low field enhancement factor (0.1) predicted by the model for the photoemission. The physical origin of this is still under investigation

Commissioning results of the next generation photoinjector

The Next Generation Photoinjector (NGP) developed by the BNL SLAC / UCLA collaboration was installed at the Brookhaven National Laboratories Accelerator Test Facility (ATF). The commissioning results and performance of the photocathode injector are present. The Next Generation Photoinjector consists of the symmetrized BNL/SLAC/UCLA 1.6 cell S-band Photocathode RF gun and a single solenoidal magnet for transverse emittance compensation. The highest acceleration field achieved on the cathode is 150 m V, and the RF guns normal operating field is 130 MV/m. The quantum efficiency of the copper cathode was measured to be 4.5 x 10{sup -5}`. The transverse emittance and bunch length of the photoelectron beam were measured. The optimized rms normalized emittance for a charge of 300 pC is 0.77 {pi} mm mrad. The bunch length dependency of photoelectron beam on the RF gun phase and acceleration fields were experimentally investigated

Effect of Liposome Characteristics and Dose on the Pharmacokinetics of Liposomes Coated with Poly(amino acid)s

Long-circulating liposomes, such as PEG-liposomes, are frequently studied for drug delivery and diagnostic purposes. In our group, poly(amino acid) (PAA)-based coatings for long-circulating liposomes have been developed. These coatings provide liposomes with similar circulation times as compared to PEG-liposomes, but have the advantage of being enzymatically degradable. For PEG-liposomes it has been reported that circulation times are relatively independent of their physicochemical characteristics. In this study, the influence of factors such as PAA grafting density, cholesterol inclusion, surface charge, particle size, and lipid dose on the circulation kinetics of PAA-liposomes was evaluated after intravenous administration in rats. Prolonged circulation kinetics of PAA-liposomes can be maintained upon variation of liposome characteristics and the lipid dose given. However, the use of relatively high amounts of strongly charge-inducing lipids and a too large mean size is to be avoided. In conclusion, PAA-liposomes represent a versatile drug carrier system for a wide variety of applications

The Sensitivity of HAWC to High-Mass Dark Matter Annihilations

The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC will observe gamma rays and cosmic rays with an array of water Cherenkov detectors. The full HAWC array is scheduled to be operational in Spring 2015. In this paper, we study the HAWC sensitivity to the gamma-ray signatures of high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be sensitive to diverse searches for dark matter annihilation, including annihilation from extended dark matter sources, the diffuse gamma-ray emission from dark matter annihilation, and gamma-ray emission from non-luminous dark matter subhalos. Here we consider the HAWC sensitivity to a subset of these sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the Galactic center. We simulate the HAWC response to gamma rays from these sources in several well-motivated dark matter annihilation channels. If no gamma-ray excess is observed, we show the limits HAWC can place on the dark matter cross-section from these sources. In particular, in the case of dark matter annihilation into gauge bosons, HAWC will be able to detect a narrow range of dark matter masses to cross-sections below thermal. HAWC should also be sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The constraints placed by HAWC on the dark matter cross-section from known sources should be competitive with current limits in the mass range where HAWC has similar sensitivity. HAWC can additionally explore higher dark matter masses than are currently constrained.Comment: 15 pages, 4 figures, version to be published in PR

Sheddable Coatings for Long-Circulating Nanoparticles

Nanoparticles, such as liposomes, polymeric micelles, lipoplexes and polyplexes are frequently studied as targeted drug carrier systems. The ability of these particles to circulate in the bloodstream for a prolonged period of time is often a prerequisite for successful targeted delivery. To achieve this, hydrophilic ‘stealth’ polymers, such as poly(ethylene glycol) (PEG), are used as coating materials. Such polymers shield the particle surface and thereby reduce opsonization by blood proteins and uptake by macrophages of the mononuclear phagocyte system. Yet, after localizing in the pathological site, nanoparticles should deliver their contents in an efficient manner to achieve a sufficient therapeutic response. The polymer coating, however, may hinder drug release and target cell interaction and can therefore be an obstacle in the realization of the therapeutic response. Attempts have been made to enhance the therapeutic efficacy of sterically stabilized nanoparticles by means of shedding, i.e. a loss of the coating after arrival at the target site. Such an ‘unmasking’ process may facilitate drug release and/or target cell interaction processes. This review presents an overview of the literature regarding different shedding strategies that have been investigated for the preparation of sterically stabilized nanoparticulates. Detach mechanisms and stimuli that have been used are described