A measurement of parity-violating gamma-ray asymmetries in polarized cold neutron capture on 35Cl, 113Cd, and 139La

An apparatus for measuring parity-violating asymmetries in gamma-ray emission following polarized cold neutron capture was constructed as a 1/10th scale test of the design for the forthcoming n+p->d+gamma experiment at LANSCE. The elements of the polarized neutron beam, including a polarized 3He neutron spin filter and a radio frequency neutron spin rotator, are described. Using CsI(Tl) detectors and photodiode current mode readout, measurements were made of asymmetries in gamma-ray emission following neutron capture on 35Cl, 113Cd, and 139La targets. Upper limits on the parity-allowed asymmetry $s_n \cdot (k_{\gamma} \times k_n)$ were set at the level of 7 x 10^-6 for all three targets. Parity-violating asymmetries $s_n \cdot k_{\gamma}$ were observed in 35Cl, A_gamma = (-29.1 +- 6.7) x 10^-6, and 139La, A_gamma = (-15.5 +- 7.1) x 10^-6, values consistent with previous measurements.Comment: 19 pages, 4 figures, submitted to Nucl. Instr. and Meth.

Internationale Bodensee-Tiefenvermessung 1990 Eine Dokumentation ueber die von 1985 bis 1990 durchgefuehrte Tiefenvermessung der Internationalen Gewaesserschutzkommission fuer den Bodensee

With 3 mapsAvailable from TIB Hannover: F94B2001 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Influence of magnetism on chemical order in a FeAl19.5 at %\mathsf{_{19.5~at\,\%}} single crystal. High temperature measurements of neutron diffuse scattering

The influence of magnetism on atomic short range order is shown in a single crystalline FeAl$_{19.5~{\rm at}\,\%}$ alloy in the disordered phase. The short range order has been measured in the paramagnetic state between 973 and 1 573 K on D7 at ILL through neutron diffuse scattering in the [110] plane. The effective pair interaction potentials $V_{1}$, $V_{2}$, $V_{3}$ and $V_{5}$ are calculated through an inverse cluster variation method. The results are compared to those obtained through X-ray diffuse scattering on the same alloy frozen in the ferromagnetic order state at 772 K. The effect of magnetic coupling on the atomic order is the most important on the 1st effective potential, which is smaller in the ferromagnetic phase than in the paramagnetic one by about a factor of 2.Nous montrons l'influence du magnétisme sur l'ordre atomique à courte distance dans un monocristal FeAl$_{19.5~{\rm at}\,\%}$ désordonné. L'ordre local a été mesuré dans le plan [110] dans l'état paramagnétique entre 973 et 1 573 K par diffusion diffuse de neutrons sur D7 de l'ILL. Les potentiels d'interaction de paires $V_{1}$, $V_{2}$, $V_{3}$ et $V_{5}$ ont été calculés par une methode de variation des amas inverses. Les résultats sont comparés à ceux que nous avions obtenus sur le même échantillon, trempé depuis 772 K dans la phase ferromagnétique, par diffusion diffuse de rayons X. L'effet du couplage magnétique sur l'ordre atomique est surtout visible sur le premier potentiel de paires effectif qui est diminué d'un facteur 2 dans la région ferromagnétique par rapport à la région paramagnétique