We present
experimental results of the measured beam brightness generated by unbalanced
gun (fields are not equal in full and half cell). Unbalanced gun tuning
allowed us to push the gradient in the half cell to 160 MV/m while a
manufacturing imperfection limited the field gradient in the full cell
at 110 MV/m. This allows us to further improve the beam quality, achieving
another record: 1 micron RMS emittance with 0.8nC charge. Design of
the 1.6 cell gun IV allows independent control of the temperature in
the full and half cells of the gun. This opened the opportunity to conveniently
study unbalanced gun tuning that has very important applications for
high average current - high beam load injectors.