National Institute of Standards and Technology

NSF: Triple Axis Spectrometer

Schematic of Neutron Spin Filter on BT-7

3He as neutron spin filter

The schematic shown above illustrates the use of NSFs on the BT-7, triple axis spectrometer. In this configuration, a NSF is used as both the polarizer and the analyzer. On the polarizer side (upstream of sample), a ³He cell is located inside a mumetal shielded box. On the analyzer side (downstream of sample), a ³He cell is located inside a mumetal shielded solenoid. The polarization of each ³He cell is monitored using in-situ NMR.

Specifications for NSF on BT-7

³He cell as polarizar and analyzer

³He polarization flipping capability

Elastic and inelastic measurements

Sample field magnitude: H ~ 10 G (P || Q or P ⊥ Q)

Four cross-section polarization efficiency correction (both horizontal and vertcal sample field)

³He transmission: ≤ 50% (for desired spin state)

Flipping ratio: ≤ 15

Scientific Application Contacts

Name Office Phone E-mail

Jeff Lynn (Team Leader) (301)975-6246 jeff.lynn@nist.gov

Ross Erwin (Polarized Beam) (301)975-6245 ross.erwin@nist.gov

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Last modified 8-25-10

Name	Office Phone	E-mail
Jeff Lynn (Team Leader)	(301)975-6246	jeff.lynn@nist.gov
Ross Erwin (Polarized Beam)	(301)975-6245	ross.erwin@nist.gov