Homestake Meeting Minutes, 02/20/14

Attending: Vuk, Riccardo, Gwynne, Victor, Tanner, Nelson, Eric, Shivaraj, Noah, Michael

Homestake wiki: https://zzz.physics.umn.edu/groups/homestake/home

Our agenda:

1) Homestake update (Vuk): working with 3 vendors to develop the GPS transmission system.

With Optical Zonu, purchased a transmitter/receiver for the raw GPS signal (1.5 GHz). Should be arriving soon.

With Vialite, should receive a demo setup in a couple of weeks, also for the raw signal.

With Liteway, working to develop a transmission system for the digitized signal, produced by the Q330 in master mode. Includes NMEA and 1PPS signals so may need two transmitters/receivers and fibers. They are looking into the possibility of transmitting via a single fiber, should know more in a few days.

The raw GPS signal requires high bandwidth, so would need single-mode fibers. For the digitized signals, could probably get away with multimode fibers. Will check with Bryce whether there are any restrictions on this in the mine, either in the shaft or in the drifts.

2) UMN test setup (Tanner): Building test setup at UMN. Got Antelope software installed, which will be used for data manipulation. Starting to learn about it, and will be testing some of the GPS signals when the equipment arrives. May have to use the roof location for these tests in the future. Will communicate with Gary to learn the best ways to access the data and manipulate it.

3) Analysis of existing data

  a) Frames/miniSEED files (Shivaraj, Tanner, Michael)

Shivaraj: most of the data from Homestake is in frame format, not yet converted to miniSEED. Data currently at UMN, will copy it to Caltech but needs writing permissions. Will contact Stuart.

  b) Wiener filtering (Michael, Jan)

Jan and Michael doing paper edits now, should have a draft ready by next week. Will not include the Hilbert transforms.

  c) Estimation algorithms (Shivaraj, Eric) 

Eric: added new pages on the wiki. There is also the radiometer svn

https://support.physics.umn.edu/svn/ligo/radiometer/

where we will keep the code, and any other relevant documents. There is a radiometer planning page

https://zzz.physics.umn.edu/groups/homestake/radiometer

listing things that need to be completed in the future. This page is based on a meeting between Eric and Victor - what should we include/exclude/worry about? How should we prioritize different tasks or problems to develop this algorithm? Two things that we may want to prioritize:

- assumption that P and S waves are uncorrelated is not valid: Rayleigh waves are a combination of correlated S and P waves. So we may have to weaken this assumption in the code, and could use the well-known phase relations to build this in.

- turning depth: as waves travel through the Earth will curve because of the changing refraction index (geological composition). So the wave could be changing direction as it passes through our seismometer array. At 1Hz the turning depth could be as low as 1 km, so we will have to worry about this. We should look at this in more detail and figure out what the turning depth at Homestake should be.

Eric and Victor will look into these effects and have something ready by the next telecon.

Noah: created a matlab code to generate s-waves, committed to svn now.