Magnetic order in coupled spin-half and spin-one Heisenberg chains in anisotropic triangular-lattice geometry

We study spin-half and spin-one Heisenberg models in the limit where one dimensional (1-D) linear chains, with exchange constant J1, are weakly coupled in an anisotropic triangular lattice geometry. Results are obtained by means of linked-cluster series expansions at zero temperature around different magnetically ordered phases. We study the non-colinear spiral phases that arise classically in the model and the colinear antiferromagnet that has been recently proposed for the spin-half model by Starykh and Balents using a Renormalization Group approach. We find that such phases can be stabilized in the spin-half model for arbitrarily small coupling between the chains. For vanishing coupling between the chains the energy of each phase must approach that of decoupled linear chains. With increasing inter-chain coupling, the non-colinear phase appears to have a lower energy in our calculations. For the spin-one chain, we find that there is a critical interchain coupling needed to overcome the Haldane gap. When spin-one chains are coupled in an unfrustrated manner, the critical coupling is very small (~0.01J1) and agrees well with previous chain mean-field studies. When they are coupled in the frustrated triangular-lattice geometry, the critical coupling required to develop magnetic order is substantially larger (> 0.3J1). The colinear phase is not obtained for the spin-one Heisenberg model.Comment: 7 pages, 8 figure

Ultrasonic Examination of Double-Shell Tank 241-AN-102 Examination Completed July 2008.

AREVA Federal Services LLC (AFS), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic examination of selected portions of Double-Shell Tank 241-AN-102. PNNL is responsible for preparing a report(s) that describes the results of the AFS ultrasonic examinations

Ultrasonic Examination of Double-Shell Tank 241-AP-107 Examination Completed February 2008

AREVA Federal Services LLC (AFS), under a contract from CH2M HILL Hanford Group (CH2M HILL), has performed an ultrasonic examination of selected portions of Double-Shell Tank 241-AP-107. The purpose of this examination was to provide information that could be used to evaluate the integrity of the wall of the primary tank. The requirements for the ultrasonic examination of Tank 241-AP-107 were to detect, characterize (identify, size, and locate), and record measurements made of any wall thinning, pitting, or cracks that might be present in the wall of the primary tank. Any measurements that exceed the requirements set forth in the Engineering Task Plan (ETP), RPP-Plan-34301 (Castleberry 2007) and summarized on page 1 of this document, are to be reported to CH2M HILL and the Pacific Northwest National Laboratory (PNNL) for further evaluation. Under the contract with CH2M HILL, all data is to be recorded on electronic media and paper copies of all measurements are provided to PNNL for third-party evaluation. PNNL is responsible for preparing a report(s) that describes the results of the AFS ultrasonic examinations