Yesterday we continued the installation the SFP cavity on EPRB. The interferometer was locked in PRITF with MICH offset = 0.3.

In order to acquire the signals from the SFP the INJ_dboc_EER config file has been updated.

2 lines have been added.

DBOX_ADC2378_CHANNEL    INJ_SFP_RAMP     5    100000    "" 2    0        "V"
DBOX_ADC2378_CHANNEL    INJ_SFP_PD     6    100000    ""    2 0        "V"

Those signals have been then downsampled in the INJ_moni process.

The 2 signals are then named INJ_SFP_B4_PD and INJ_SFP_B4_RAMP.

The old DAC channel used to apply offset on the SFP installed on the EIB has been reused (ISYS_dac_EER).

The channel 0 of the DAC is now connected to the SFP driver ramp offset input.
Note that this setup has been prepared in a short time and cabling as well as naming of the channels will be cleaned up soon. A picture of EPRB is shown in figure 1.

The cavity alignment was improved and the SFP cavity length re-tuned. However, we could not obtain a very clean and defined peak. It makes it difficult to extract the 6 MHz sidebands from the carrier shoulder in a reliable way.

Moreover, the ramp appears to be very noisy, but it is probably only a matter of readout, since the actuation which is actually sent to the piezo looks good as seen on the oscilloscope. (figure 2)