DURATION: 2020/04/09  1:00-9:00 JST, all times posted in JST

 

operator shift : T.Yamamoto

co-operator shift : H.Yuzurihara with K.Miyo, T.Yokozawa, S.Oshino

 

CURRENT ENVIRONMENT: stable

 

shift SUMMARY : BNS range 0.5 Mpc ~ 0.7Mpc

 

time / event

1:00 / shift started. The detector was continuously locked.

 

1:59 / lock loss

2:07 / rocovered lock

 

2:19 / lock loss

2:36 / recovered lock

2:38 / observation mode

 

6:15 / green laser of Y-arm suddenly falled around GPS time = 1270415694 ~ 1270415755. We recognized  this at 6:25.

6:25 / we found the power of transmitted green laser reduced. lockloss didn't happen. At that time, the image of GIGe camera was strange.

6:29 / the power of transmitted green laser automarically recovered although we didn't touch anything.

 

9:00 / continuous locking

 

duty cycle 2020/04/09 01:00 -- 09:00 : Observation mode 91.9%

 

#####

 

We briefly used NDSCOPE to investigate the cause of the sudden drop in green laser transmission power, and didn't see any strange behavior. The value of channel K1:ALS-Y_PDH_SLOW_DAQ_OUT_DQ increases after this chaning point. Probably this is not the cause by causality.