Re: Design Report

  Thanks Jon,

  Yes, as you can imagine, following SuperK, we also looked at this
regarding SNO (not that we could have done a hell of a lot at that point!).
I certainly agree with all the arguments you mention. My concern was
actually more general. I'm not so worried about a repeat of the SuperK
disaster per se, it's a general concern about potential PMT problems
that could result from moving a whole, filled ~50 tonne detector with
~1000 PMTs up and down lifts and over a considerable distance - I don't
think this has ever been done before so it may raise some new issues.
Also, in a relatively small, spherical detector, how significant are shock
waves etc. ? I don't know how much of a problem this is or to what extent
this sort of thing has been studied (aside from SNO's response to occasional
blasting in the mine). But perhaps it'd be worth at least flushing out some
possible R&D tests for the upcoming proposal. Even if there is definately
no problem, I can imagine that funding agencies might like to see some sort
of explicit test anyway as they are now sensitized to this sort of thing.

                                               - Steve

Jonathan Link wrote:
>
> Hi Steve and Vic,
>
> I just wanted to comment on the possibility of Super-K-like catastrophes...
>
> Steve Biller wrote:
>
> > Any ideas for the PMT support structure? Particularly given
> > that we're actually thinking about moving these monsters
> > around, do we have to worry about SuperK-like catastrophies?
>
> After the Super-K incident, MiniBooNE investigated the possibility that
> something like that could happen in our detector. We found that several
> factors contributed to make a chain reaction event very unlikely in
> MiniBooNE.
>
> First, the lower pressure head: in Super-K most tubes within 5 meters of the
> water line were not damaged. This indicates tat the chain reaction was not
> sustainable in less than 5 meters of water. The pressure needed to establish
> a chain reaction is likely much larger. In the case of the reactor detector
> we are talking about detectors with a maximum of 6.5 meters of overhead
> liquid. Also we are also using oil which is 10 to 15% less dense.
>
> Second they used 20 inch tubes and MiniBooNE only uses 8 inch tubes. This
> difference is important because the energy stored in the vacuum (under
> pressure) of a 20 tube is significantly larger than in an 8 inch tube.
>
> I'm attaching MiniBooNE Tech Note 55 which details the full study.
>
> -Jon
>
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> Name: chain_reaction.ps
> chain_reaction.ps Type: Postscript Document (application/postscript)
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Received on Thu Jul 15 10:16:25 2004