Observation of blue-shifted ultralong-range Cs2_{2} Rydberg molecules

We observe ultralong-range blue-shifted Cs$_{2}$ molecular states near $ns_{1/2}$ Rydberg states in an optical dipole trap, where $31\leq n\leq34$. The accidental near degeneracy of $(n-4)l$ and $ns$ Rydberg states for $l>2$ in Cs, due to the small fractional $ns$ quantum defect, leads to non-adiabatic coupling among these states, producing potential wells above the $ns$ thresholds. Two important consequences of admixing high angular momentum states with $ns$ states are the formation of large permanent dipole moments, $\sim 15-100\,$Debye, and accessibility of these states via two-photon association. The observed states are in excellent agreement with theory. Both projections of the total angular momentum on the internuclear axis are visible in the experiment

Space materials handbook. Supplement 1 to the second edition - Space materials experience Technical report, Oct. 1964 - Sep. 1965

Spacecraft structures and systems materials handboo

Quantum Chromodynamics Resolution of the ATOMKI Anomaly in 4He{\rm {^4He}} Nuclear Transitions

Recent observations of the angular correlation spectra in the decays ${\rm ^4He}^*\to {\rm ^4He}+ e^+e^-$ and ${\rm ^8Be}^*\to {\rm ^8Be}+ e^+e^-$ have been suggested as due to the creation and subsequent decay to an electron-positron pair of a new light particle with a mass of $\sim 17$ MeV. In this work, we present a calculation of the invariant $m_{e^+e^-}$ mass spectrum of the electromagnetic transition of an excited state of helium and estimate the differential and total width of the decay. We investigate the possibility that the source of the signal is an $e^+ e^-$ pair created by a new electromagnetic decay of $\rm ^4He$ caused by a proposed 12-quark hidden-color Fock state in the ${\rm {^4He}}$ nuclear wavefunction, the "hexadiquark.'' We find that we can fit the shape of the signal with the QCD Fock state at excitation energy ${\rm E^*}\simeq 17.9$ MeV and a Gaussian form factor for the electromagnetic decay. We address the physical issues with the fit parameters using properties of the hexadiquark state. In light of this work, we emphasize the need for independent experimental confirmation or refutation of the ATOMKI results as well as further experiments to detect the proposed new excitation of ${\rm ^4He}$.Comment: Condensed version, 8 pages, 3 figures, comments welcom

Dynamic Penetration Studies in Crushed Rock under Atmospheric and Vacuum Conditions

A device was constructed to study dynamic penetration in crushed rock both in air and a high-vacuum (10^(-5) mm Hg) condition. The apparatus is designed to drop cylindrical, metal rods, pointed on one end, into cohesion-less crushed rock material. Dynamic penetration is studied as a function of several particle sizes and mixtures of these particle sizes. Other factors considered are the density of packing, probe dimensions, vacuum pressure, and vacuum degassing rates. Experimental results show that the density of packing of the crushed rock particles is the dominant factor affecting the dynan1ic penetration. The maximum penetration occurs in air in the crushed rock with low-density packing. The 1ninimum penetration occurs in air in densely packed material. Dynamic penetration in vacuum for the low-density and high-density packing lies between the results of penetration in air for the same packing conditions. At vacuum pressures above approximately 0.1 mm Hg, all penetration values approach the air penetration measurements

Hyperspherical Description of the Degenerate Fermi Gas: S-wave Interactions

We present a unique theoretical description of the physics of the spherically trapped $N$-atom degenerate Fermi gas (DFG) at zero temperature based on an ordinary Schr\"{o}dinger equation with a microscopic, two body interaction potential. With a careful choice of coordinates and a variational wavefunction, the many body Schr\"{o}dinger equation can be accurately described by a \emph{linear}, one dimensional effective Schr\"{o}dinger equation in a single collective coordinate, the rms radius of the gas. Comparisons of the energy, rms radius and peak density of ground state energy are made to those predicted by Hartree-Fock (HF). Also the lowest radial excitation frequency (the breathing mode frequency) agrees with a sum rule calculation, but deviates from a HF prediction