Meeting Minutes 02/06/14

Attending: Riccardo, Gwynne, Vuk, Victor, Gary, Eric, Tanner, Michael

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

Our agenda:

1) Homestake update (Vuk)

Our stations preferances: https://zzz.physics.umn.edu/_media/groups/homestake/array/locations_preferences_v2.pdf

New cost estimates: https://zzz.physics.umn.edu/_media/groups/homestake/array/alcovecostestimates_surf_feb2014.pdf

Received updated cost estimates (see above) that do not include the power cables. Excluding the stations at 800 level (one is noisy and there is no rail access), and excluding the 2000-1 station (there is a location at 1700 directly above it), the costs add up to ~$110k. The battery power, assuming 10 batteries per station) adds up to $20k, which is probably an overestimate (we have AC power at several stations already). Then there is the GPS signal. Found 3 vendors that provide technology to convert the GPS signal to optical, transport it via optical fibers, and at each station convert it back to RF. It looks like the cost will be around $40k, but the details are not worked out yet. Will ask the vendors to send us samples that we could test at the UMN prototype. Will try to pursue multiple options and hopefully converge over the next two months or so.

Victor: Access issues?

Vuk: Access through Yates should be ok, probably won't have access through Ross.

Vuk: Send coordinates of stations to Gary.

Riccardo: consider to replace batteries with fuel cells? Instead of bringing batteries, you need to bring the water and the salts. At the spot, you would mix in the salts to make the acidic and basic solutions. With a large tank could last a year. Could be cheaper in the long run. There are different models. Comes as a small box with tubes to tanks from which they suck the solutions. Produce salty water and hydrogen which is burned to produce electricity. Few gallon tank, you could run for 6 month. Should be feasible in the mine, but is it useful (in terms of costs and portability) and do we trust the new technology. Two times 10 l gives 6000 W-hours, $3500 per station, cheap to extend duration.

Vuk: should look at it more, maybe we'll try to get one unit to play with in the lab. This is more expensive than what we are currently thinking for batteries, but we may have to increase the power requirements to support the GPS receivers. In that case, the fuel cell option may become more cost effective.

Gary: some groups have used similar technology in alaska, will try to contact them to get their experience.

Vuk: will speak with SURF next week. Propose to ask them to start preparing the stations (rock-bolting etc), excluding 800-1, 800-2, 2000-1, and 1700-2. Over the next 2-3 months we should converge on the GPS fiber technology, so that we can start stringing fiber cables etc.

Victor, Gary: agree


2) UMN test setup (Tanner, Gary)

Tanner: working on the software, trying to access the bailer and retrieve the data. Gary sent us the Antelope package, a software package that should help us with operation at Homestake, retrieving the data. At the moment struggling to install it. Upgraded to 64-bit OS, but now failing to find the relevant pearl library. Is ubunty system ok? Currently at the second floor, but have poor GPS access. Will try to move to the top floor to get a better access. 

Gary: PASSCAL supports this software, it is the best way to do this. And should simplify accessing data at the bailers. Ubuntu should not be a problem, others are using it. Could also try to put the antenna on the stick through the window, but roof is still the best.

Gary and Tanner should speak offline. 

3) Analysis of existing data
    a) Frames/miniSEED files (Shivaraj, Tanner, Michael)
    b) Wiener filtering (Michael, Jan)
    Michael: made some updates to the paper, now waiting for Jan to look at the paper.
    c) Estimation algorithms (Shivaraj, Eric) 
    Eric: received suggestions from Victor and Gary, will discuss them further offline. In particular, would like to understand better the statement that we can ignore vertical-going waves.
    Gary: if the field is dominated by surface-waves, you could simplify the problem and deal with two horizontal dimensions only.
    Victor: but have to worry about coupling of different wave modes.