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Polarized Beam Operation

A polarized beam option has been developed for BT-7, utilizing 3He polarizers immediately before and after the sample.  This gives BT-7 full polarized beam capability for experiments where a guide field (only) is applied at the sample position to control the direction of polarization, and thereby the cross sections.  The system is fully operational. The 3He itself can be inverted to achieve the alternate spin state before or after the sample.  An adjustable guide field at the sample position is under computer control to manipulate the polarization direction perpendicular or parallel to the scattering plane, or in an angular range in the scattering plane.  Spin Flippers are no longer used.

An polarized beam option with the 7 T magnet, at relatively modest fields of 2 T and below, is also availble for BT-7.

Please note that optically pumping the cells takes ~1 day to get good 3He polarization, and other instruments use the polarizers as well.  Hence the use of the polarized beam option must be requested and scheduled well in advance of an experiment. 

In addition to the BT-7 instrument publication

Double Focusing Thermal Triple Axis Spectrometer at the NCNR, J. W. Lynn, Y. Chen, S. Chang, Y. Zhao, S. Chi, W. Ratcliff, II, B. G. Ueland, and R. W. Erwin, Journal of Research of NIST 117, 61-79 (2012),

 please use the following publication to acknowledge polarized beam work on BT-7:

3He Neutron Spin Filters for a Thermal Neutron Triple Axis Spectrometer, W. C. Chen, G. Armstrong, Y. Chen, B. Collett, R. Erwin, T. R. Gentile, G. L. Jones, J. W. Lynn, S. McKenney and J. E. Steinberg, Physica B 397, 168 (2007).


Publications that have utilized the polarized beam capability on BT-7



Magnetic Order of the Iron Spins in NdOFeAs, Y. Chen, J. W. Lynn, G. F. Chen, G. Li, Z. C. Li, J. L. Luo, N. L. Wang, P. Dai, C. dela Cruz, and H. A. Mook Phys. Rev. B78, 064515 (2008).

Single Ferroelectric and chiral magnetic domain of single-crystalline BiFeO3 in an electric field, Seongsu Lee, Taekjib Choi, W. Ratcliff II, R. Erwin, S-W. Cheong, and V. Kiryukhin, Phys. Rev. B 78, 100101(R) (2008).

Spin Waves in the Magnetoelectric Effect LiCoPO4 Compound, W. Tian, J. Li, J. W. Lynn, J. L. Zarestky, and D. Vaknin, Phys. Rev. B 78, 184409 (2008)

End-compensated magnetostatic cavity for polarized 3He neutron spin filter, J.W. McIver, R. Erwin, W.C. Chen, and T.R. Gentile, Rev. Sci. Instrum. 80, 063905 (2009).

Applications of 3He neutron spin filters at the NCNR, W. C. Chen, R. Erwin, J. W. McIver III, S.Watson, C.B. Fu, T. R. Gentile, J. A. Borchers, J. W. Lynn, and G. L. Jones, Physica 404B, 2663 (2009).

Coupled Magnetic and Ferroelectric Hysteresis in Multiferroic Ni3V2O8, I. Cabrera, M. Kenzelmann, G. Lawes, Y. Chen, W. C. Chen, R. Erwin, T. R. Gentile, J. B. Leao, J. W. Lynn, N. Rogado, R. J. Cava, and C. Broholm, Phys. Rev. Lett. 103, 087201 (2009).

Nitrogen Contamination in Elastic Neutron Scattering, , Songxue Chi, Jeffrey W. Lynn, Ying Chen, William Ratcliff II, Benjamin G. Ueland, Nicholas P. Butch, Shanta R. Saha, Kevin Kirshenbaum, and Johnpierre Paglione, Meas. Sci. Technol. 22, 047001 (2011).

Antiferromagnetic order and superlattice structure in the nonsuperconducting and superconducting RbyFe1.6+xSe2, Meng Wang, Miaoyin Wang, G. N. Li, Q. Huang, C. H. Li, G. T. Tan, C. L. Zhang, H. B. Cao, Wei Tian, Yang Zhao, Y. C. Chen, X. Y. Lu, Bin Sheng, H. Q. Luo, S. L. Li,1 M. H. Fang, J. L. Zarestky, W. Ratcliff, M. D. Lumsden, J. W. Lynn, and Pengcheng Dai, Phys. Rev. B 84, 094504 (2011).

Studies of long range order and excitations in the iron arsenide superconductors, Pratt, Daniel Keith, (2011). Graduate Theses and Dissertations.

Double Focusing Thermal Triple Axis Spectrometer at the NCNR, J. W. Lynn, Y. Chen, S. Chang, Y. Zhao, S. Chi, W. Ratcliff, II, B. G. Ueland, and R. W. Erwin, Journal of Research of NIST 117, 61-79 (2012).

Carrier Localization and Electronic Phase Separation in a doped Spin-Orbit Driven Mott Phase in Sr3(Ir1-xRux)2O7, Chetan Dhital, Tom Hogan, Wenwen Zhou, Xiang Chen, Zhensong Ren, Mani Pokharel, Yoshinori Okada, M. Heine, Wei Tian, Z. Yamani, C. Opeil, J. S. Helton, J. W. Lynn, Ziqiang Wang, Vidya Madhavan, and Stephen D. Wilson, Nature Communications .5, 3377 (2014).

Discovery of a New Type of Magnetic Mode in YBa2Cu3O6+x, H. A. Mook,  J. W. Lynn, M. B. Stone, M. D. Lumsden, and A. D. Christianson, (submitted).

Spurious Peaks Arising from Multiple Scattering Events the Sample Environment in Inelastic Neutron Scattering, Lothar Pintschovius, Dmitry Reznik, Frank Weber, Philippe Bourges, Dan Parshall, Ranjal Mittal, Samrath LaI Chaplot, Rolf Heid, Thomas Wolf, Daniel Lamago, and Jeffrey W. Lynn, J. Appl. Cryst. (submitted).




General Specifications  •   Detailed Specifications   •   Operational Notes   •  

Last modified 26-April-2014 by website owner: NCNR (attn: Jeff Lynn)