Tuesday 24 May 2011

Moving the ground tile — Part 1

As we know from the various photographs and reports, there are (were!) actually two test tiles at the site. Obviously, our recent series has focused on the destruction of the raised tile.

But what of the ground tile?

We want to move this tile off the main build area. We need to get it out of the way so we can build the main array. It is also an 'empty tile' in that there are no electronics or receiver elements embedded in it.

On the other hand, we want to keep the tile, as it is both useful as a source of parts, but also as a possible 'centre-tile' in the case we upgrade to an international station size for the KAIRA HBA.

Therefore, we decided to move the tile, pack it, and store it on the site.

The first step in this process is to remove the cover of the tile and all the solid polystyrene lids. These are stored separately. This leaves the tile vulnerable, with all the delicate parts exposed, so we need be careful now.

This is the tile with the cover removed. It clearly shows the pristine polystyrene structure.

Once the tile is ready, it can be refolded. So often, we hear about unfolding the tiles, as reported on other web sites about other LOFAR stations. However, as far as we know, this is the first time a tile has been re-folded in the field. (We'll ignore the manufacturing set-up which has the facility to fold the tiles as they are built.)

Then we prepare to lift the tile.

It is at this point that we are ready to lift the tile. Normally during unfolding, there are batons, wrapping and straps. As we are refolding, there is none of this. We didn't even have a correct centre beam, as the main LOFAR tooling is currently in use in Sweden on the SE607 build.

HBA tile being lifted

Once lifted, the tile can then be refolded and moved. We did not have the possibility to load the tile onto a pallet, nor do we have the straps or batons to secure the individual components. They are held in place at this 'unexpected' angle by gravity and gentle nudging by the team.

Nervous moments: the tile parts totter precariously in the breeze.

What happened next will be explained in tomorrow's report.

Photos: D.McKay-Bukowski

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