  As a result of a collaboration between Jefferson Lab and niobium manufacturer
CBMM, ingot niobium was explored as a possible material for superconducting
radiofrequency (SRF) cavity fabrication. The first single cell cavity from
large grain high purity niobium was fabricated and successfully tested at
Jefferson Lab in 2004. This pioneering work triggered research activities in
other SRF laboratories around the world. Large grain niobium became not only an
interesting alternative material for cavity builders, but also material
scientists and surface scientists were eager to participate in the development
of this material. Most of the original expectations for this material of being
less costly and allowing less expensive fabrication and treatment procedures at
the same performance levels in cavities have been met. Many single cell
cavities made from material of different suppliers have been tested
successfully and several multi-cell cavities have shown the performances
comparable to the best cavities made from standard poly-crystalline niobium.
Several 9-cell cavities fabricated by Research Instruments and tested at DESY
exceeded the best performing fine grain cavities with a record accelerating
gradient of Eacc = 45.6 MV/m. Recently- at JLab- by using a new furnace
treatment procedure a single cell cavity made of ingot niobium performed at a
remarkably high Q0-value (~5x10^10) at an accelerating gradient of ~20 MV/m, at
2K. Such performance levels push the state-of-the art of SRF technology to new
limits and are of great interest for future accelerators. This contribution
reviews the development of ingot niobium technology and attempts to make a case
for this material being the choice for future accelerators.
