Re: Design Report

Hi Vic et al.,

One more point to keep in mind about building large glued acrylic structures
is the angle of the bond. One of the (many) things that Reynolds did not
take into mind before the construction of the SNO sphere was the difference
between a horizontal bond and a bond at an angle. Gravity is, indeed, an
important constraint and it took a very long time, as Steve points out,
to get to a somewhat workable protocol. A structure with a simpler set
of bonds (where "simpler" needs to be understood in great detail) would
have saved hundreds of days of construction time for SNO. There is a lot
of expertise in acrylic bonding in the industry in general (Reynolds is
a small player which makes them approachable for a small project like this
but also limits their depth of knowledge) and getting some professional
outside experience can be valuable. SNO used Jerry Stachiow (sp?) who
had lots of experience building deep sea diving spheres which helped a lot
in defining the strength of the structure and bonds but he had had no
experience with anything bigger than about two meters - as Steve also
notes, bigger implies new types of problems. SNO could probably have
benefitted from some additional outside knowledge rather than attempting
the painful (but attractive to the physicist) exercise of deriving
everything from first principles.

cheers,

Rick Van Berg

p.s. Steve, if we buy the right PMTs we do not have to worry about SK
type problems - it is specific energy vs bulb strength and, of course,
doing real tests (asking what was wrong with the SK and SNO implosion
tests is a great question for physics I).

>
>Hi Steve,
>Thanks for your comments and insights. Clearly there is a lot of R&D that
>needs to be done. We are planning on making a short trip to Reynolds in
>August. They have not been very helpful/forthcoming with information about
>constructing large structures and you provide some insight into why this is.
>We will definitely be making contact with the people you suggested to gather
>more information on the SNO experience, this will make our Reynolds trip more
>productive as well. Thanks again for your comments.
>Best regards,
>Vic
>
>Steve Biller wrote:
>
>> Hi Vic & company,
>>
>> Thanks for the nice start on the design report! Sorry for the late
>> response to this, but here are a few more notes on acrylic:
>>
>> First, one minor thing: at one point the report says SNO used
>> polycarbonate... we didn't, we used acrylic. This seems to be
>> corrected later on in the report.
>>
>> Yes, the endothermic reaction in the bonding process is a
>> very big deal... probably the central issue in putting
>> something like this together. Large pieces will not necessarily
>> make the job easier and may even make it more difficult.
>> This is because more heat is generated in larger bonds and
>> you have to make sure all the acrylic in the vicinity of the
>> entire bond is well maintained at the same elevated temperature
>> (using heating tapes etc.). You also need jigs to hold
>> each piece very carefully and securely in place during the
>> bonding procedure. I note that this whole business was one
>> of the main reasons for the delay in construction of SNO.
>>
>> By all means, go and talk to Reynolds. However, we found that,
>> while they could certainly produce the panels, even they
>> did not have the necessary expertise when it came to handling
>> the bonding. Accordingly, you should also talk to the following
>> people from SNO:
>> Peter Doe (pdoe@u.washington.edu)
>> Davis Earle (davis@surf.sno.laurentian.ca)
>> Mick Williams (m.williams1@physics.ox.ac.uk)
>>
>> I'm willing to bet such discussions will definately put you
>> off the idea of having a 3rd region! Fortunately, a consensus
>> seems to be emerging that this will likely not be necessary.
>> My understanding is that the design would then be for
>> something close to the larger of your two spheres for an
>> overall bigger fiducial volume... but we'll probably hear
>> more detail of this at the next meeting.
>>
>> The size of the neck should probably also be considered in
>> more detail. Do we want it big enough to allow manual
>> entry? Finishing/sanding the acrylic bonds might possibly be
>> one reason - could there be others? What is the maximum size
>> calibration source we may want to deploy? What are the
>> actual, quantitative disadvantages of a wider neck?
>>
>> 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?
>>
>>
>> Cheers,
>>
>> - Steve
>>
>>
>> ----- Original Message -----
>> From: "David Reyna" <reyna@anl.gov>
>> To: <mwtheta13@hep.uchicago.edu>
>> Cc: "Victor Guarino" <vjg@hep.anl.gov>
>> Sent: Thursday, July 01, 2004 2:49 PM
>> Subject: mechanical design work
>>
>> > Greetings,
>> > While at Oxford, Ed mentioned that it's been a while and we should
>> > probably have a Braidwood get together/collaboration meeting in the
>> > relative near future. With that in mind I wanted to let everyone know
>> > about a draft baseline detector design document that Vic Guarino has
>> > been assembling here at Argonne. We have been trying to look into all
>> > of the issues involved with design, assembly, installation and operation
>> > of a baseline detector and intend to present this for more detailed
>> > review and revision at the next collaboration meeting. At this
>> > time, the document is still a work in progress with several sections
>> > still needing to be fleshed out, but we would like to encourage any
>> > interested parties to take a look now and provide feedback or comments.
>> > The document can be found at
>> > http://www.hep.anl.gov/vjg/Reactor-Baseline1.doc
>> >
>> >
>> > Regards,
>> > -Dave
>> >
>> >
Received on Thu Jul 15 09:46:52 2004