Formation of magnetic minerals at hydrocarbon-generation conditions

In this paper, we report the pyrolysis and formation of magnetic minerals in three source rock samples from the Wessex Basin in Dorset, southern England. The experimental conditions in the laboratory recreated the catagenesis environment of oil source rocks. Magnetic analysis of both the heated and the unheated samples at room temperature and at very low-temperatures (5 K), coupled with transmission electron-microscopy imaging and X-ray analysis, revealed the formation of nanometre-sized (<10 nm), magnetic particles that varied across the rock samples analysed, but more importantly across the pyrolysis temperature range. Magnetic measurements demonstrated the formation of these magnetic minerals peaked at 250 °C for all rock samples and then decreased at 300 °C before rising again at 320 °C. The newly formed magnetic minerals are suggested to be primarily pyrrhotite, though magnetite and greigite are also thought to be present. The sizes of the magnetic minerals formed suggest a propensity to migrate together with oil potentially explaining the magnetic anomalies observed above and within oil fields

Fixing the conformal window in QCD

A physical characterization of Landau singularities is emphasized, which should trace the lower boundary N_f^* of the conformal window in QCD and supersymmetric QCD. A natural way to disentangle ``perturbative'' from ``non-perturbative'' contributions to amplitudes below N_f^* is suggested. Assuming an infrared fixed point persists in the perturbative part of the QCD coupling even below N_f^* leads to the condition \gamma(N_f^*)=1, where \gamma is the critical exponent. Using the Banks-Zaks expansion, one gets 4<N_f^*<6. This result is incompatible with the existence of an analogue of Seiberg duality in QCD. The presence of a negative ultraviolet fixed point is required both in QCD and in supersymmetric QCD to preserve causality within the conformal window. Evidence for the existence of such a fixed point in QCD is provided.Comment: 10 pages, 1 figure, extended version of a talk given at the QCDNET2000 meeting, Paris, September 11-14 2000; main new material added is evidence for negative ultraviolet fixed point in QC

High-Efficiency Neutron Detectors

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Energy Dependence of Cross Sections for Stretched States Excited in (p,n) Reactions

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

High-Spin States Excited Via (p,n) Reactions

This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

Stretched State Excitations in the 26-Mg(p,n)26-Al Reaction at 134 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Performance of Large-Volume, Mean-Timed Neutron Detectors

This work was supported by the National Science Foundation Grants NSF PHY 78-22774 A03, NSF PHY 81-14339, and by Indiana Universit

Performance of Large-Volume Mean-Timed Neutron Detectors

Supported by the National Science Foundation and Indiana Universit

High-Spin "Stretched" States Excited in (p,n) Reactions

This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit