Jenne, Wanda V, Gizem K

Wanda and Gizem arrived today to help set up the DAS (distributed acoustic sensing) system that we're going to test for a few months.  We're borrowing DAS interregators from EarthScope, and using spare dark fibers that go down the arms.  The DAS will measure strain changes in the fibers.  We've got 2 models of DAS interregator on site, however only commissioned one today.  Both models are eye-safe, and have been registered with the LHO LSO.  

Since we need to connect to the fibers that are buried along the inside of the arms, the interregators are set up in the MSR close to the fiber junction box. 

Fil did the actual connection to the LIGO fiber box, connecting some short 10m fibers that Wanda brought.  We're using fiber #24 on Xarm (the fiber junction box calls this Right) and fiber #24 on the Yarm (the junction box calls this Left).  Gizem took OTDR (optical time delay reflectrometry) measurements of each of our 4km fibers (one on the Xarm, one on the Yarm).  The reports are attached here.  One of the connectors (likely at the junction box) on one of the arms is a little lossy (0.6 dB loss), but since it's the junction box we're just going to live with it. Also, one of the splices at the midstation is better than the other (I think it's the Yarm that is better).  More details are in the attached pdfs from the OTDR measurements.

We elected to just use rack 120V, rather than the UPS 120V, since we don't have long enough UPS-specific power cables.  The power here on site is plenty good quality for the DAS.  

We watched the data live on the monitor that is set up with the interregator in the MSR, and indeed it's working!  We're going to leave it running overnight and have a look tomorrow at the data, particularly to see the quiet time in the middle of the night.  

The attached photo is of the setup we've got on the far side of the MSR.  The black case is the Febus DAS interregator, and we've got a 21 TB hard drive attached to collect the data. The fibers go up in the overhead tray, then down to the junction boxes which are at the very top of that first rack. 

Tomorrow we will start work on the following to-do items:

• Connect one of the arms instead to the other model of DAS interregator (should be very quick), to see if there's a difference.
• Work with Nyath to set up remote access via the GC network to the DAS' internal computer.  Wanda and Gizem will find from their IT folks what their IP address ranges are, and then we'll only allow access from those IP access ranges.  
• Walk the first few hundred meters of each end of the fibers (from the corner, and from the end), and do a 'tap test' from known locations to see where in the fiber length those show up.  We've got a work permit in and have talked to both Mike and Richard about outdoor hazards (heat, animals, etc).  Once that's signed we'll go for a walk in the morning, probably bringing a sledgehammer with us for ground 'tapping'. 
• Go to each end station, to have a look at the other end of the fibers.  We will likely ask Fil to connect a jumper cable to the end of the cable in the end station, and then will put a terminator or something on the end to reduce the losses there.