this morning during the maintenace we performed several activities, reported below.

-  investigations about the fast unlocks. We went in the injection electronic room (where  the rack of the rampeauto is situated). Like in the past it has been noticed that some IMC unlocks are related to the circuit in this room (for example some unlocks are produced when switching on/off the oscilloscope near the rampeauto, when switching on/off the lights,... ).

We closed the rack for the rampeauto to be shielded, but unlocks were still produced.

We then plugged an antenna on the oscilloscope next to the rampeauto and we found out an oscillation at 43 kHz, whose amplitude increases a lot next to the neon lights. We then tried to swtich off the light system from the circuit breaker but it doesn't disappear, on the other hand it is less noisy. However, we cannot let the lights circuit off since it is the same circuite as the one for the badge system.In conclusion, for the moment we have observed this possible noise source, which is somehow increased by the neon lights, but we still haven' t identified its source.

We also found out that the rampeauto rack is not connected to the ground. We then connected it, but unlocks still occurred.

Mrs Flowers installed a magnetometer close to the rampeauto in order to monitor related magnetic perburbations.

- verification of the 56 MHz tuning. We unplugged the 56 MHz RF source and with a spectrum analyzer we directly verified the tuning on the EOM. The resonant circuit it's well centered on 56.437MHz with a Q of about 55.

Note : a piezoelectric resonances of the crystal is located on the modulation frequency

- measurement of the gain margin of the IMC locking loop. We can at present lock with a gain margin of 4 dB (from 16 to 20 dB) that is really weak.

- PMC perturb on the slave laser :

In order to be able to unlock the laser before the EIB without going in the laser lab, we plugged the PMC pertub DAC on the Slave Perturb with 10dB attenuation.

With 8V sent to the PMC offset the, the slave laser unlocks.

- recentering of the quadrants in the diagnostic box.

From the DMS alarm laser ampli we found a bad centering of the quadrants of the diag box on the laser bench, probably moved by mistake while touching the 14 MHz EOM. We recentered them (plot 2)

- reduction of the correction on the BPC. We did it by remote using picomotors (plot 1)