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At least 1,675 records · Page 93

CLAS Database for Studies of the Structure of Hadrons in Electromagnetic Processes

The CLAS Physics Database (CLAS DB) has been developed in collaboration between SINP at MSU and Hall B at Jefferson Lab. CLAS DB contains most experimental results on inclusive, semi-inclusive, and exclusive reactions on proton and nuclei obtained with the CLAS detector. The substantial part of these experimental results represents the only data sets available in the world. The results and analysis tools provided by the CLAS DB are of particular importance for studies of the structure of the ground and excited hadron states, offering insight into strong nonperturbative QCD dynamics, which underlie the generation of hadrons from quarks and gluons.

Chesnokov, V. V.↗

Electromagnetic Launcher with Massive Light-Plasma Initiator

The results of experiments with an initiator of lithium and graphite, whose mass was 10% of the mass of the projectile, are presented. Similar initiators produce plasma with a high speed of sound and provide the initial speed of the projectile of ∼0.5 km/s. The droplet-shaped damage on the insulating wall of the accelerator channel are described. The link between the appearance of these damages and the sharp deceleration of the plasma piston (PP) is noted. A hypothesis relating the occurrence of damages to the resonant deformation of the channel under the action of a moving high-pressure front is discussed. It is shown that the hypothesis about the resonant deformation of the channel qualitatively explains the known features of the accelerator operation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Two-loop contributions of axion-like particles to electromagnetic and chromomagnetic form factors

Abstract Axions and axion-like particles emerge in many models for physics beyond the Standard Model. Thus, they have gained increasing research interest in both experimental and theoretical physics apart from their original proposition as a solution to the strong CP -problem. Among other aspects it has recently been shown that ALPs can potentially provide a solution to the long-lasting discrepancy between theory and experiment of the anomalous magnetic moment of the muon. Provided that the ALP has flavor-violating couplings to leptons, they can also mediate flavor-violating decays like $$\mu \rightarrow e\gamma $$ μ → e γ . Both processes are mediated through related form factors that we compute to two-loop order. We further show numerical implications of our calculations and how they might affect constraints on ALP couplings derived from experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

In Situ Monitoring of Direct Ink Write Process Using Electromagnetic Resonant Coupling

Additive manufacturing (AM) of multi-material objects enables the design of complex 3D architectures such as printed electronics and devices. The ability to detect the composition of multi-material printed inks in real time is an emerging need for a wide range of manufacturing applications. This study demonstrates the feasibility of using an in situ sensor to locally measure the composition of inks as they are being printed to facilitate greater control over the resulting properties and functionality of printed materials. Dielectric properties of microscale embedded metal particles in a dielectric matrix are measured and characterized as a function of particle size, shape, volume percentage and frequency. Results show that particle shape has a much greater influence on impedance measurements than the particle size. Measurements are found to agree with calculations based on an anisotropic Maxwell-Garnett dielectric function model. The resulting data can be used to generate a calibration curve correlating metal loading with impedance or capacitance and thus applied as an in situ sensor for compositional measurements during extrusion-based AM.

36 MATERIALS SCIENCE↗

High Altitude Electromagnetic Pulse Testing of Photovoltaic Modules

This report details the test setup, process, and results for radiated susceptibility testing of multicrystalline silicon photovoltaic (PV) modules as part of the EMP-Resilient Electric Grid Grand Challenge Laboratory Directed Research and Development (LDRD) project at Sandia National Laboratories. Testing was conducted over October 10-17, 2019, where 8 photovoltaic modules were exposed to E1 transient pulses with peak field levels up to 100 kV/m. Modules were terminated in a resistive load representing connected components. State of health testing conducted via I-V curve tracing of the photovoltaic modules showed no observable loss of device function due to large electric field transients. Differential mode currents were measured on the order of 10's of amps for up to a microsecond following the radiated field pulse. Common mode currents took the form of a damped sinusoid with a maximum peak of 10's to 100's of amps with a resonance near 60 MHz.

14 SOLAR ENERGY↗

Electromagnetic Pulse in Wide-Angle Gamma Shadows

Unavoidable masses external to the warhead, associated with collateral EMP scenarios of current interest, produce a gamma shadow which changes the EMP seen in the shadowed region compared to that in the absence of a shadow. Calculations with the author’s three-dimensional MACSYNC code for a ground observer under the burst show shadowed field rise times ranging from many tens to hundreds of microseconds, durations approaching a millisecond, and magnitudes similar to those of the unshadowed field, depending on gamma shadow angle. These fields are likely to be smaller for larger observer ground ranges because the source region will shift to higher altitudes with associated higher conductivity that will attenuate the field.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗