A new neutron single-crystal diffractometer dedicated for biological macromolecules (BIX-4)

A new neutron single‐crystal diffractometer (BIX‐4) has been constructed at 1G‐B port of JRR‐3M in JAERI. Since at 1G‐B port another diffractometer for biology, BIX‐3, and a high‐resolution powder diffractometer (HRPD) coexist, the monochromator house needed to be reconstructed. The main architecture of BIX‐4 is based on that of BIX‐3. BIX‐4 uses an elastically‐bent perfect‐Si crystal monochromator and neutron imaging plates as BIX‐3. In addition, several optimizations of the monochromator and modifications from previous BIX‐3 are carried out. The final gain of the neutron intensity at the detector position is estimated to be 2.5 times larger than previous BIX‐3. That higher performance increases the opportunities to apply neutron crystallography to biological macromolecules which give only weak reflections and/or small crystals.