The nuclear magnetic moment of "Ir and the directional distribution of gamma rays in "Os
Angular distributions of gamma transitions between levels in I9OOs fed in the decay of I9'Ir aligned in a rhenium single crystal have been measured at temperatures down to 2 mK. Multipole mixing ratios in both gamma and electron-capture transitions are deduced and compared with various nuclear models. The angular distribution coefficients are applied to interpret very small anisotropies observed when I9'Ir is polarised in an iron host matrix, cooled to 2.5 mK. The deduced magnetic dipole moment of the 4 + ground state of I9'Ir is Ip(I9'Ir; GS)~ = 0.04( l)pN. Possible single-particle descriptions compatible with this result are suggested. NUCLEAR MOMENTS: I9'Ir (from Re(a, n)): measured I,(@ from oriented nuclei in single crystal Re and polycrystalline Fe: deduced I9OOs S(E2/M1), Jp in electron capture, lpl(1901r ground state).
Mixed magnetic dipole and electric quadrupole hyperfine interactions studied by nuclear orientation with and without nuclear magnetic resonance
This paper considers the effect on both conventional nuclear orientation, and on the combined nuclear magnetic resonance/nuclear orientation (NMR/ON) techniques, when a small electric quadrupole interaction is added to a simple magnetic nuclear hyperfine hamiltonian. It is shown that such an addition is difficult to detect by conventional nuclear orientation and can lead to substantial misinterpretation of experimental results. Quantitative examples are given. The effect of such an addition on the NMR/ON resonance line spectrum is discussed in detail and it is shown that, for the linewidths found in ferromagnetic metals, this combined technique can detect electric quadrupole couplings eQVzz of order 0.1% of the magnetic dipole coupling. A discussion of possible sources of such quadrupole interaction and dilute impurities in ferromagnetic metals is included.
Pedagogy of the “Not”: Negation, Exodus, and Postdigital Temporal Regimes
Postdigital capitalist time is an incessant acceleration that acts to homogenize time and wed us to the present, to which we have to constantly catch up. While the impulse of this is no doubt economic (the realization of value), it is crucially undergirded by a pedagogical logic wherein we have to perpetually learn and re-learn the latest apps, social media configurations, operating systems, and so on. Political strategies of resistance thus need to be bolstered by an alternative mode of educational life, and I propose a pedagogy of the “not” as one possibility. Such a pedagogy is an act of suspension that sustains a detachment from the present, clearing out oppositions and thereby exposing us to a radical indeterminacy and potentiality that is always untimely. Suspension is the praxis of negation, which means that negation operates by keeping sense indeterminate to meaning and signification. Rather than suppressing, disavowing, or annihilating the stated content, negation retains even that which is negated. While this would appear as a form of exopedagogy, which withdraws from the dialectic of the private/public, I instead argue that it redefines the terms of any dialectic, redefining the very categories exopedagogy withdraws from. Before concluding, I spend some time with Sandy Grande’s important critiques of Eurocentrism and progress in Western critical education, demonstrating how negation as suspension circumvents these errors through its accommodation of—or, better, insistence on—variegated temporalities and forms of life.