Time reversal and the neutron

We have measured the triple correlation $D\langle\vec J_n\rangle/J_n\cdot (\vec\beta_e\times\hat p_\nu)$ with a polarized cold-neutron beam (Mumm et al., Phys Rev Lett 107:102301, 2011; Chupp et al., Phys Rev C 86:035505, 2012). A non-zero value of D can arise due to parity-even-time-reversal-odd interactions that imply CP violation. Final-state effects also contribute to D at the level of 10^???5 and can be calculated with precision of 1 % or better. The D coefficient is uniquely sensitive to the imaginary part of the ratio of axial-vector and vector beta-decay amplitudes as well as to scalar and tensor interactions that could arise due to beyond-Standard-Model physics. Over 300 million proton-electron coincidence events were used in a blind analysis with the result D?=?[???0.94±1.89 (stat)±0.97(sys)]×10^???4. Assuming only vector and axial vector interactions in beta decay, our result can be interpreted as a measure of the phase of the axial-vector coupling relative to the vector coupling, $\phi_{\rm AV}= 180.012^\circ \pm 0.028^\circ$ . This result also improves constrains on certain non-VA interactions.     

A note on constructing permutation polynomials

Let H be a subgroup of the multiplicative group of a finite field. In this note we give a method for constructing permutation polynomials over the field using a bijective map from H to a coset of H. A similar, but inequivalent, method for lifting permutation behaviour of a polynomial to an extension field is also given.     

Long-path microcells of modular design

Construction procedures are given for a long-path cell by casting the cell proper in plastic. The cast protects the cell and makes it very rigid. It also allows filling and emptying ports and end windows to become separate modules that can be easily removed for inspection and cleaning as necessary. Most importantly, casting allows the filling of the cell along the end windows, thus eliminating dead space.     

The classification of planar monomials over fields of prime square order

Planar functions were introduced by Dembowski and Ostrom in 1968 to describe affine planes possessing collineation groups with particular properties. To date their classification has only been resolved for functions over fields of prime order. In this article we classify planar monomials over fields of order with a prime.

     

Characterisation of selected drugs with nitrogen-containing saturated ring structures by use of electrospray ionisation with ion-trap mass spectrometry

The electrospray ionisation–ion-trap mass spectrometry (ESI–MS ⁿ ) of selected drugs with nitrogen-containing saturated ring structures has been investigated. Sequential product-ion fragmentation experiments (MS ⁿ ) have been performed to elucidate degradation pathways for the [M+H]⁺ ions and their predominant fragment ions. These MS ⁿ experiments result in characteristic fragmentations in which functional groups are generally cleaved from the ring systems as neutral molecules such as H₂O, amines, alkenes, esters, carboxylic acids, etc. When such a nitrogen-containing drug molecule also contains a functional group, such as an ester, that on liberation as a neutral molecule has a significantly lower –H _f° value than that of the corresponding amine then the former is preferentially liberated. Furthermore, when an aromatic entity is present in these drug molecules together with the nitrogen-containing saturated ring structure fragmentation of the latter ring occurs with the former, predictably, being resistant to fragmentation. The structures of fragment ions proposed for ESI–MS ⁿ can be supported by electrospray ionisation–quadrupole time-of-flight mass spectrometry (ESI–QTOFMS). The data presented in this paper therefore provide useful information on the structure of these heterocyclic compounds which could be used to characterise unknown drug compounds isolated from natural sources, for example.     

Bi-axial texture in Ca0.1Y0.9Ba2Cu4O8 composite wires made by metallic precursors

High filament count, silver-sheathed composite wires of Ca_0.1Y_0.9Ba₂Cu₄O₈ (Y–124) were prepared by a metallic precursor route. The ductility of the metallic precursor enabled one to manufacture tapes containing up to 962 407 filaments, with filament dimensions as fine as 0.25 μm thick and 1 μm wide. By using a thermal-mechanical treatment to texture the Y–124 grains, transport critical current densities in the oxide filaments of 69 500 A/cm² at 4.2 K in self-field were obtained. Moreover, in an applied field of 0.1 T, the samples retained 39% of their self-field critical current density. A TEM investigation revealed significant bi-axial crystallographic texture: in areas viewed, c-axis alignment of adjacent grains was within 10° and oriented perpendicular to the tape face; a-axis alignment of adjacent grains was within 15° and oriented parallel to the longitudinal direction of the filaments. Furthermore, c-axis texture alone did not adequately predict the performance of these Y−124 composite conductors. Instead, performance scaled with the degree of bi-axial texture. These wires exhibited among the best reported J_c for a polycrystalline, sintered wire of YBCO in an applied magnetic field.     

Absolute intensity of a sodium-like resonance line for temperature diagnosis of neon-like X-ray laser plasmas

Nine different neon-like ions with atomic numbers ranging from 28 to 42 have exhibited gain in various 3p—3s transitions. The temperature of the lasing plasma is critical in determining the state of ionization and the relative importance of collisional excitation and recombination pumping. In this paper we demonstrate a potentially useful new temperature diagnostic for these plasmas that works in the density range of interest for X-ray lasing: the absolute intensity of 3p—3s sodium-like lines. Due to their large collisional couplings and high optical depths, their brightness temperature approaches the actual kinetic temperature of the plasma in temperature and density regimes of importance for achieving optimal X-ray laser performance.     

Solvent effects on the nitrogen hyperfine splitting constant of the t-butyl-t-butoxy nitroxyl radical

A decrease in nitrogen hyperfine splitting constant (N-hfsc) with increasing solvent polarity is reported for $\text{t}$-butyl $\text{t}$-butoxy nitroxyl radical produced by trapping $\text{t}$-butoxyl radical with 2-methyl-2-nitrosopropane.