Abstract
- We tried to change a jumper pin configuration of AA. But there is no effect on ADC noise situation.- ITMX cannot go ALIGNED just after recovering DGS racks. So we may need to wait until temperature of circuits became stable.
- ITMX is now in LOCK_ACQUISITION though coil output for GAS is around 30000ct.
Details
Because Kamiizumi-san found a difference on jumper pin configuration from LIGO's one,we measured ADC noise again with the configuration same as LIGO.
As reported in , we had already tried to change a jumper pin configuration on the filter board.
In this time, configuration on the interface board (D1909971) was changed.
'P10' is opened as a default for AA chassis made by Hitz. On the other hand, jumper pin is inserted as a default for AA chassis which are LIGO's ones and a new product lots in KAGRA.
Basically its effect may not be so large when we use ADC as differential read mode.
But it's better to short here for RTN pin on ADC board itself.
We applied this change for S2113203 and measured ADC noise again. Unfortunately, we cannot see any improvement on ADC noise situation.
After the measurement, we left jumper pins in S2113203 and we plan to insert it all other AA chassis in the future.
Just after finishing our works, ITMX cannot go ALIGNED state because GAS output saturated.
After turning ON all circuits, readout value on LVDT GAS is change o(100um) in 1hrs shown in Fig.1 (We turned ON circuits around t=-1h10m).
Drift occurs in the direction of the set point value. So after waiting for a while, DC loop can be engaged.
Because IXV room is too cold, circuit temperature is drastically changed if we turned OFF circuits during almost one day.
I guess this is not only the drift of GAS position itself, but also the stability of the temperature of circuits.
Anyway, we need to wait at least a few hours for requesting ALIGNED after such kind of work.
