Polarized³He cell development and application at NIST

Abstract

Over a period of well over a decade, a large number and variety of polarized 3 He cells for neutron applications have been developed and tested at the U.S. National Institute of Standards and Technology (NIST). These cells have primarily been employed for spinexchange optical pumping (SEOP), and applied to neutron scattering and fundamental neutron physics. We describe the procedures we have employed for producing these cells, as well as their characteristics and applications. Whereas our best results are for cells blown from boron-free aluminosilicate glass, we summarize results with a range of other methods. We discuss our recent work on SEOP cells for wide angle neutron polarization analysis.

Symmetry and correlations underlying hidden order inURu2Si2

“…Data were collected in both a − a (basal) plane and a−c plane geometries. Polarized neutron scattering measurements were performed using a 3 He-based apparatus 33 with open -50' -80' -120' collimation, a vertical guide field, and 14.7 meV final energy. A flipping ratio of 60 was determined from the nuclear (2, 0, 0) reflection.…”

Structure of glasses for3He neutron spin filter cells

“…Presence of such unpolarized helium atoms would limit the attainable 3 He polarization. Actually, the vitreous silica cells, which have large microscopic holes, have lower attainable 3 He polarization [22][23][24]. In the present study, it was found that blown GE180 glass has more disordered structure.…”

Spin echo small angle neutron scattering using a continuously pumped 3He neutron polarisation analyser

“…The 3 He cell (Mars) was fabricated at NIST using the procedure outlined in [29]. The cell body is made from Corning 1720 with optically flat windows made from reblown GE180 alumina silicate glass.…”

“…The windows are 8 mm thick and the cell body is 80 mm long with an inner diameter of 60 mm. The cell pressure measured by neutron transmission at NIST is 0.9 Bar [29,30]. The flat windows provide a uniform analysing path for the scattered beam because they provide for a uniform path length through the cell, compared to reblown cells.…”