Summary of the Superconducting RF Linac for Muon Collider and Neutrino Factory

Project-X is a proposed project to be built at Fermi National Accelerator Laboratory with several potential missions. A primary part of the Project-X accelerator chain is a Superconducting linac, and In October 2009 a workshop was held to concentrate on the linac parameters. The charge of the workshop was to "..focus only on the SRF linac approaches and how it can be used...". The focus of Working Group 2 of this workshop was to evaluate how the different linac options being considered impact the potential realization of Muon Collider (MC) and Neutrino Factory (NF) applications. In particular the working group charge was, "to investigate the use of a multi-megawatt proton linac to target, phase rotate and collect muons to support a muon collider and neutrino factory". To focus the working group discussion, three primary questions were identified early on, to serve as a reference: 1) What are the proton source requirements for muon colliders and neutrino factories? 2) What are the issues with respect to realizing the required muon collider and neutrino factory proton sources? a. General considerations b. Considerations specific to the two linac configurations identified by Project-X. 3) What things need to be done before we can be reasonably confident that ICD1/ICD2 can be upgraded to provide the neutrino factory / muon collider needs? A number of presentations were given, and are available at the workshop web-site. This paper does not summarize the individual presentations, but rather addresses overall findings as related to the three guiding questions listed above.Comment: 6 pp. Workshop on Applications of High Intensity Proton Accelerators 19-21 Oct 2009: Batavia, Illinoi

Perturbation analysis of the limit cycle of the free van der Pol equation

A power series expansion in the damping parameter, epsilon, of the limit cycle of the free van der Pol equation is constructed and analyzed. Coefficients in the expansion are computed in exact rational arithmetic using the symbolic manipulation system MACSYMA and using a FORTRAN program. The series is analyzed using Pade approximants. The convergence of the series for the maximum amplitude of the limit cycle is limited by two pair of complex conjugate singularities in the complex epsilon-plane. A new expansion parameter is introduced which maps these singularities to infinity and leads to a new expansion for the amplitude which converges for all real values of epsilon. Amplitudes computed from this transformed series agree very well with reported numerical and asymptotic results. For the limit cycle itself, convergence of the series expansion is limited by three pair of complex conjugate branch point singularities. Two pair remain fixed throughout the cycle, and correspond to the singularities found in the maximum amplitude series, while the third pair moves in the epsilon-plane as a function of t from one of the fixed pairs to the other. The limit cycle series is transformed using a new expansion parameter, which leads to a new series that converges for larger values of epsilon

Comparison of uniform perturbation solutions and numerical solutions for some potential flows past slender bodies

Approximate solutions for potential flow past an axisymmetric slender body and past a thin airfoil are calculated using a uniform perturbation method and then compared with either the exact analytical solution or the solution obtained using a purely numerical method. The perturbation method is based upon a representation of the disturbance flow as the superposition of singularities distributed entirely within the body, while the numerical (panel) method is based upon a distribution of singularities on the surface of the body. It is found that the perturbation method provides very good results for small values of the slenderness ratio and for small angles of attack. Moreover, for comparable accuracy, the perturbation method is simpler to implement, requires less computer memory, and generally uses less computation time than the panel method. In particular, the uniform perturbation method yields good resolution near the regions of the leading and trailing edges where other methods fail or require special attention

Juvenile Fish and Blue Crab Stock Assessment Program Bottom Trawl Survey Annual Data Summary Report Volume 1998

The Virginia Institute of Marine Science (VIMS) has conducted a trawl survey dating back to 1955. Over the years methods and objectives have varied according to funding sources and state and/or federal mandates.· The present thmst of the program is to provide juvenile indices of relative abundance for recreationally, commercially, and ecologically important fish and invertebrates. These measures of juvenile abundance are widely used as a key element in the management of the Atlantic States\u27 coastal fishery resources. Estimates of juveniles (age-0) have proven to be a reliable and early indicator offuture year-class strength. A review of previously available indices of juvenile abundance for important fishery resource species of the Chesapeake Bay by the Chesapeake Bay Stock Assessment Committee (CBSAC), a federal/state committee sponsored and funded by the National Oceanic and Atmospheric Administration (NOAA), resulted in the recommendation that, a unified, consistent trawl program should be one of the primary monitoring tools for finfish and crab stock assessment. (Chesapeake Bay Program Stock Assessment Plan, Chesapeake Executive Council 1988). Several comments should be noted for the 1998 sampling year. In May, mega-invertebrates (2: 5mm) began to be sampled. For most species only presence was noted at each trawl location. For selected species, counts were also collected. Habitat data began to be recorded in May as well. Categories were selected based on samples obtained in the trawl or attached to the tickler chain. Habitat types include: sponge, hydroids, sea squirts, submerged aquatic vegetation, shell, etc. These habitats were categorized for each sample based on volume. In July, sampling began on some of the · smaller secondary water systems. The Pocomoke Sound, Mobjack Bay, and Piankatank River were sampled on only a limited basis over the past 40 years. The Great Wicomico River had never been sampled by the program. Information from these water systems should help better understand species distribution and essential habitat for target species. Species with marked increases in catch rates included spadefish and Atlantic croaker. Species with decreasing catch rates included scup, spot, and blue crabs. The program suffered a setback in August when the engine of the research platform, RIV Fish Hawk, failed. The vessel could not be repaired in time and a portion of the Rappahannock River and the entire Chesapeake Bay were not sampled. This marked the first time in over 15 years the survey was not, or could not, be completed as scheduled

Estimating relative abundance of young of year American eel, Anguilla rostrata, in the Virginia tributaries of the Chesapeake Bay March 2000 - June 2001

Measures of juvenile recruitment success have long been recognized as a valuable fisheries management tool. In the Chesapeake Bay, these measures have provided reliable indicators for future year class strength for blue crabs (Lipcius and van Engel, 1990), striped bass (Goodyear, 1985), and several other recreationally important fishes (Geer and Austin, 1999). The American eel, Anguilla rostrata, is a valuable commercial species along the entire Atlantic coast from New Brunswick to Florida. Landings along the U.S. Atlantic coast have varied from 290 MT in 1962 to a high of 1600 MT in 1975 (NMFS, 1999). In recent years there seems to be declining harvest, with similar patterns seen in the Canadian maritime providences. The Mid-Atlantic states (New York, New Jersey, Delaware, Maryland, and Virginia) have comprised the largest portion of the East Coast catch (88% of the reported landings) since 1988 (NMFS 1999). The Chesapeake Bay jurisdictions of Virginia, Maryland, and Potomac River Fisheries Commission (PRFC) alone represent 30, 15, and 18% respectively, of the annual United States (Gulf and Atlantic coast states) commercial harvest for the years 1987-1996 (ASMFC, 1999). Some fishery-independent indices have shown a decline in abundance in recent years as well (Richkus and Whalens 1999; Geer in review). Hypotheses for the decline include shifts in the Gulf Stream, pollution, over-fishing, parasites, habitat loss, and barriers to passage (Castonguay et al. 1994). more ..

New electron source concept for single-shot sub-100 fs electron diffraction in the 100 keV range

We present a method for producing sub-100 fs electron bunches that are suitable for single-shot ultrafast electron diffraction experiments in the 100 keV energy range. A combination of analytical results and state-of-the-art numerical simulations show that it is possible to create 100 keV, 0.1 pC, 20 fs electron bunches with a spotsize smaller than 500 micron and a transverse coherence length of 3 nm, using established technologies in a table-top set-up. The system operates in the space-charge dominated regime to produce energy-correlated bunches that are recompressed by established radio-frequency techniques. With this approach we overcome the Coulomb expansion of the bunch, providing an entirely new ultrafast electron diffraction source concept

Concept of a laser-plasma based electron source for sub-10 fs electron diffraction

We propose a new concept of an electron source for ultrafast electron diffraction with sub-10~fs temporal resolution. Electrons are generated in a laser-plasma accelerator, able to deliver femtosecond electron bunches at 5 MeV energy with kHz repetition rate. The possibility of producing this electron source is demonstrated using Particle-In-Cell simulations. We then use particle tracking simulations to show that this electron beam can be transported and manipulated in a realistic beamline, in order to reach parameters suitable for electron diffraction. The beamline consists of realistic static magnetic optics and introduces no temporal jitter. We demonstrate numerically that electron bunches with 5~fs duration and containing 1.5~fC per bunch can be produced, with a transverse coherence length exceeding 2~nm, as required for electron diffraction