After several months of recovery work since the earthquake, we succeeded in taking the proton beam from Dec.24,2011 as scheduled and successfully confirmed the functionality of the beam line components and the reproducibility of neutrino production.
However, on Dec.22, during the final operation test, switching devices called IGBTs in the horn power supply were broken. The cause is being identified in detail.
Therefore, the beam operation during December was made without horn operation.
We are working to recover the power supply and aim to restart the full experiment with the horn operation from March.
During January we plan to take beam with the horn off in order to make beam studies for high power operation and various systematic studies using near neutrino detectors.