The MERIT experiment, to be run at CERN in 2007, is a proof-of-principle test for a target system that converts a 4-MW proton beam into a high-intensity muon beam for either a neutrino factory complex or a muon collider. The target system is based on a free mercury jet that intercepts an intense proton beam inside a 15-T solenoidal magnetic field. Here, we describe the design and initial performance of the 15-T, liquid-nitrogen-precooled, copper solenoid magnet.

This proposal funded the 19th Annual National Conference of Black Physics Students. This conference provided physics students with the opportunity to interact with world-class researchers and the facilities at which they work. The conference supports the well established need for the US to foster a larger and stronger scientific workforce through the recruitment and retention of science and engineering students.

Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and are not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.

In the framework of the CARE HHH European Network, we have developed a web-based dynamic accelerator-physics code repository. We describe the design, structure and contents of this repository, illustrate its usage, and discuss our future plans, with emphasis on code benchmarking.

We performed a computational and experimental analysis of fast cookoff of LX-10 (94.7% HMX, 5.3% Viton A) confined in a 2 kbar steel tube with reinforced end caps. A Scaled-Thermal-Explosion-eXperiment (STEX) was completed in which three radiant heaters were used to heat the vessel until ignition, resulting in a moderately violent explosion after 20.4 minutes. Thermocouple measurements showed tube temperatures as high as 340 C at ignition and LX-10 surface temperatures as high as 279 C, which is near the melting point of HMX. Three micro-power radar systems were used to measure mean fragment velocities of 840 m/s. Photonics Doppler Velocimeters (PDVs) showed a rapid acceleration of fragments over 80 {micro}s. A one-dimensional ALE3D cookoff model at the vessel midplane was used to simulate the heating, thermal expansion, LX-10 decomposition composition, and closing of the gap between the HE (High Explosive) and vessel wall. Although the ALE3D simulation terminated before ignition, the model provided a good representation of heat transfer through the case and across the dynamic gap to the explosive.

RHIC has been successfully operated for 5 years as a collider for different species, ranging from heavy ions including gold and copper, to polarized protons. We present a critical analysis of reliability data for RHIC that not only identifies the principal factors limiting availability but also evaluates critical choices at design times and assess their impact on present machine performance. RHIC availability data are typical when compared to similar high-energy colliders. The critical analysis of operations data is the basis for studies and plans to improve RHIC machine availability beyond the 50-60% typical of high-energy colliders.

The Embedded Fiber Optic probe directly measures detonation speed continuously in time, without the need to numerically differentiate data, and is a new tool for measuring time-dependent as well as steady detonation speed to high accuracy. It consists of a custom-design optical fiber probe embedded in high explosive. The explosive is detonated and a refractive index discontinuity is produced in the probe at the location of the detonation front by the compression of the detonation. Because this index-jump tracks the detonation front a measurement of the Doppler shift of laser light reflected from the jump makes it possible to continuously measure detonation velocity with high spatial and temporal resolution. We have employed this probe with a Fabry-Perot-type laser Doppler velocimetry system additionally equipped with a special filter for reducing the level of non-Doppler shifted light relative to the signal. This is necessary because the index-jump signal is relatively weak compared to the return expected from a well-prepared surface in the more traditional and familiar example of material interface velocimetry. Our observations were carried out on a number of explosives but this work is focused on our results on PBX-9502 (95% TATB, 5% Kel-F) and LX-17 (92.5% TATB, 7.5% Kel-F) at …

Numerous long-lived radionuclides, including {sup 99}Tc (technetium) and {sup 129}I (iodine), are present in groundwater at the Nevada Test Site (NTS) as a result of 828 underground nuclear weapons tests conducted between 1951 and 1992. We synthesize a body of groundwater data collected on the distribution of a number of radionuclides ({sup 3}H, {sup 14}C, {sup 36}Cl, {sup 99}Tc and {sup 129}I), which are presumably mobile in the subsurface and potentially toxic to down-gradient receptors, to assess their migration at NTS, at field scales over distances of hundreds of meters and for durations of more than thirty years. Qualitative evaluation of field-scale migration of these radionuclides in the saturated zone provides an independent approach to validating their presumably conservative transport in the performance assessment of the proposed geological repository at Yucca Mountain, which is located on the western edge of NTS. The analyses show that the interaction of {sup 3}H with a solid surface via an isotopic exchange with clay lattice hydroxyls may cause a slight delay in the transport of {sup 3}H. The transport of {sup 14}C could be retarded by its isotopic exchange with carbonate minerals, and the exchange may be more pronounced in the alluvial aquifer. In …

The goal of demonstrating ignition on the National Ignition Facility (NIF) has motivated a revisit of double-shell (DS) targets as a complementary path to the cryogenic baseline approach. Expected benefits of DS ignition targets include non-cryogenic deuterium-tritium (DT) fuel preparation, minimal hohlraum-plasma mediated laser backscatter, low threshold ignition temperatures ({approx} 4 keV) for relaxed hohlraum x-ray flux asymmetry tolerances, and minimal (two-) shock timing requirements. On the other hand, DS ignition presents several formidable challenges, encompassing room-temperature containment of high-pressure DT ({approx} 790 atm) in the inner shell, strict concentricity requirements on the two shells (< 3 {micro}m), development of nano-porous (<100 nm) low-density (<100 mg/cc) metallic foams for structural support of the inner shell and hydrodynamic instability mitigation, and effective control of hydrodynamic instabilities on the high-Atwood number interface between the DT fuel and the high-Z inner shell. Recent progress in DS ignition designs and required materials-science advances at the nanoscale are described herein. Two new ignition designs that use rugby-shaped vacuum hohlraums are presented which utilize either 1 MJ or 2 MJ of laser energy at 3{omega}. The capability of the NIF to generate the requested reverse-ramp pulse shape for DS ignition is expected to be comparable to …

A fusion power plant is described that utilizes a new version of the tandem mirror device including spinning liquid walls. The magnetic configuration is evaluated with an axisymmetric equilibrium code predicting an average beta of 60%. The geometry allows a flowing molten salt, (flibe-Li{sub 2}BeF{sub 4}), which protects the walls and structures from damage arising from neutrons and plasma particles. The free surface between the liquid and the burning plasma is heated by bremsstrahlung radiation, line radiation, and by neutrons. The temperature of the free surface of the liquid is calculated, and then the evaporation rate is estimated from vapor-pressure data. The allowed impurity concentration in the burning plasma is taken as 1% fluorine, which gives a 17% reduction in the fusion power owing to D/T fuel dilution, with F line-radiation causing minor power degradation. The end leakage power density of 0.6 MW/m{sup 2} is readily handled by liquid jets. The tritium breeding is adequate with natural lithium. A number of problem areas are identified that need further study to make the design more self-consistent and workable; however, the simple geometry and the use of liquid walls promise the cost of power competitive with that from fission and coal.

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This paper presents the design of two beam transport lines at the BSNS: one is the injection line from the Linac to the RCS and the other is the target line from the RCS to the target station. In the injection beam line, space charge effects, transverse halo collimation, momentum tail collimation and debunching are the main concerned topics. A new method of using triplet cells and stripping foils is used to collimate transverse halo. A long straight section is reserved for the future upgrading linac and debuncher. In the target beam line, large halo emittance, beam stability at the target due to kicker failures and beam jitters, shielding of back-scattering neutrons from the target are main concerned topics. Special bi-gap magnets will be used to reduce beam losses in the collimators in front of the target.

CO{sub 2}-fertilization affects plant growth, which modifies surface physical properties, altering the surface albedo, and fluxes of sensible and latent heat. We investigate how such CO{sub 2}-fertilization effects on vegetation and surface properties would affect the climate system. Using a global three-dimensional climate-carbon model that simulates vegetation dynamics, we compare two multi-century simulations: a ''Control'' simulation with no emissions, and a ''Physiol-noGHG'' simulation where physiological changes occur as a result of prescribed CO{sub 2} emissions, but where CO{sub 2}-induced greenhouse warming is not included. In our simulations, CO{sub 2}-fertilization produces warming; we obtain an annual- and global-mean warming of about 0.65 K (and land-only warming of 1.4 K) after 430 years. This century-scale warming is mostly due to a decreased surface albedo associated with the expansion of the Northern Hemisphere boreal forests. On decadal time scales, the CO{sub 2} uptake by afforestation should produce a cooling effect that exceeds this albedo-based warming; but if the forests remain in place, the CO{sub 2}-enhanced-greenhouse effect would diminish as the ocean equilibrates with the atmosphere, whereas the albedo effect would persist. Thus, on century time scales, there is the prospect for net warming from CO{sub 2}-fertilization of the land biosphere. Further study is …

The authors discuss a cosmology in which cold dark-matter particles decay into relativistic particles. They argue that such decays could lead naturally to a bulk viscosity in the cosmic fluid. for decay lifetimes comparable to the present hubble age, this bulk viscosity enters the cosmic energy equation as an effective negative pressure. They investigate whether this negative pressure is of sufficient magnitude to account for the observed cosmic acceleration. They show that a single decaying species in a {Lambda} = 0, flat, dark-matter dominated cosmology can not reproduce the observed magnitude-redshift relation from Type Ia supernovae. However, a delayed bulk viscosity, possibly due to a cascade of decaying particles may be able to account for a significant fraction of the apparent cosmic acceleration. Possible candidate nonrelativistic particles for this scenario include sterile neutrinos or gauge-mediated decaying supersymmetric particles.

The recognition criterion for discovery of a new chemical element includes two aspects, the characterization properties and the assignment properties. In this paper, we will discuss the status of element 115 experiments that have been performed in Dubna, Russia, highlighting the characterization and assignment properties as they specifically relate to a recent experiment. After discussing the status of what is known about the decay properties of element 115 [1], observed previously using the Dubna Gas-Filled Recoil Separator, we will discuss the prior chemical studies that have been performed on the Db descendant of element 115 [2]. Following the success of that experiment, some additional chemical information was desired. Two separation chemistries were then developed at LLNL and JINR. LLNL utilized reversed phase chromatography and JINR utilized anion exchange chromatography to perform not only +4/+5 separations, but also intra-group separations, where Nb-like and Ta-like fractions were eluted. The results from an experiment using these chemistries for the first time during December 2005 in Dubna, Russia, will be compared with prior chemical results. We will conclude with a discussion of possible enhancements to the work already performed and the current status of the future experimental plans.

The China Spallation Neutron Source (CSNS) is a newly approved high-power accelerator project based on a H{sup -} linear accelerator and a rapid cycling synchrotron. During the past year, several major revisions were made on the design including the type of the front end, the linac frequency, the transport layout, the ring lattice, and the type of ring components. Here, we discuss the rationale of design revisions, status of the R&D efforts, and upgrade considerations.

We discuss criteria for designing an optimal 'green field' proton driver for a neutrino factory. The driver parameters are determined by considerations of space charge, power capabilities of the target, beam loading and available RF peak power. A neutrino factory may be the best experimental tool to unravel the physics involved in neutrino oscillation and CP violation phenomena [1]. To have sufficient neutrino flux for acceptable physics results within 5 years requires about 10{sup 22} protons on target per year, which corresponds to 1-4 MW of proton beam power from the proton driver depending on the beam energy. In the past, there were individual proposals from different laboratories of a particular design of proton driver capable of delivering beam power from 2 to 4 MW, without consistent attention paid to the needs or requirements from the downstream systems. In this study, we try to identify the requirements from those down stream systems first, then see whether it is possible to design a proton driver to meet those needs. Such a study will also assist site specific proposals to further improve on their designs to better serve the need of a proton driver for neutrino factory applications.

The rate capabilities of LiFePO{sub 4} composites are dependent on the structure of the carbon that coats the powders, formed during co-calcination with carbon containing precursors. The addition of readily decomposed pyromellitic acid and graphitization catalysts such as ferrocene during synthesis results in coatings with low D/G (disordered/graphene) ratios, while maintaining the carbon content of the powders below 2 wt. %. This is important to avoid adversely affecting the tap density. The good correlation between the pressed pellet conductivities of the LiFePO{sub 4}/C composites and their rate capability in lithium cells is further confirmation of the importance of the carbon structure, because graphitic carbons generally have higher conductivities than disordered ones.

The COBRA-IE computer code is a thermal-hydraulic subchannel analysis program capable of simulating phenomena present in both PWRs and BWRs. As part of ongoing COBRA-IE assessment efforts, the code has been evaluated against experimental data from the NUPEC BWR Full-Size Fine-Mesh Bundle Tests (BFBT). The BFBT experiments utilized an 8 x 8 rod bundle to simulate BWR operating conditions and power profiles, providing an excellent database for investigation of the capabilities of the code. Benchmarks performed included steady-state and transient void distribution, single-phase and two-phase pressure drop, and steady-state and transient critical power measurements. COBRA-IE effectively captured the trends seen in the experimental data with acceptable prediction error. Future sensitivity studies are planned to investigate the effects of enabling and/or modifying optional code models dealing with void drift, turbulent mixing, rewetting, and CHF.

Multi-bunch instabilities degrade beam quality through increased beam emittance, energy spread and even beam loss. Feedback systems are used to suppress multi-bunch instabilities associated with the resistive wall of the beam ducts, cavity-like structures, and trapped ions. A new digital transverse bunch-by-bunch feedback system has recently been commissioned at the Taiwan Light Source, and has replaced the previous analog system. The new system has the advantages that it enlarges the tune acceptance and improves damping for transverse instability at high currents, such that top-up operation is achieved. After a coupled-bunch transverse instability was suppressed, more than 350 mA was successfully stored during preliminary commissioning. In this new system, a single feedback loop simultaneously suppresses both horizontal and vertical multi-bunch instabilities. Investigating the characteristics of the feedback loop and further improving the system performances are the next short-term goals. The feedback system employs the latest generation of field-programmable gate array (FPGA) processor to process bunch signals. Memory has been installed to capture up to 250 msec of bunch oscillation signal, considering system diagnostics suitable to support various beam physics studies.

The Double Bend Achromatic (DBA) and the Triple Bend Achromatic (TBA) lattice have been studied rather extensively for use for the NSLS-II storage ring. The advantage of the TBA compared to the DBA in terms of emittance per period is well known. However, the DBA has the advantage of greater number of ID straight sections for the users and maybe easier to tune the dispersive section for reduced chromatic sextupole strength. We present a comparison of these lattices based on optimization of the non-linear driving terms using high order achromatic cancellation of driving terms of the nonlinear lattice.

Low-mass stars, {approx} 1-2 solar masses, near the Main Sequence are efficient at producing {sup 3}He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of {sup 3}He with the predictions of both stellar and Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus we are able to remove the threat that {sup 3}He production in low-mass stars poses to the Big Bang nucleosynthesis of {sup 3}He.

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