Wednesday, November 26, 2014

Guess what this means

From the sys-ops chat this morning:
Joseph_Schlitz_rc1 has become a Jedi release that has killed sndaq Beer_Trooper ... The force is so strong that there is not even data showing up at 2ndbuild at all unfortunately that seems to be a more serious thing

Is there anyone in @channel that can look into this? Otherwise I would ask WO's for rollback

A clue:

XXX yes, but for some reason, there were no alerts

YYY run was taken as "TestData"

XXX ah, ok

YYY 8 doesn't that mean online alert systems ignore it?

XXX AM yes
this is a precaution
ok, so everything is fine

YYY well, outside the SNDaq mysteries

I'll look up the details and post the answers later.


As I wrote earlier, IceCube found it useful to give each DOM a unique name; not just a number. Numbers are too easy to transpose. The DOMs are programmed with data acquisition software, which is rarely perfect, and updated from time to time. New software releases are also given names, and by tradition these are named after bars. SNDAQ stands for a special piece of software: SuperNova Data AcQuisition. It works by looking not for individual neutrinos, which from a supernova are plentiful but of too low an energy to stand out, but for a general brightening of all the DOMs by thousands and thousands of small interactions.

The "_rc1" means that this is test release 1.

"@channel" is, of course, the tag for the chat software being used for this conversation. "WO" stands for Winter Overs--a pair who work on our experiment during the antarctic winter (11 month tours--they get started now).

Not all data acquisition taking is for physics: some of the "runs" are tests; hence the TestData run.

A supernova is a very interesting thing to observe, and since SN1987A we now know that neutrinos escape the blast well before the visible light is finally generated. Therefore there is a communications network designed to alert all the participating systems to look out if one of them detects something that might be a supernova. Obviously you don't want the alert to go out if you're just running a test.

A "DOM" is a "Digital Optical Module" with a large phototube, a couple of small computers and a couple of fast signal converters (one less sensitive so it can see large signals), which transmits its measurement of light received to collection computers at the surface. These are all carefully coordinated so we can tell what time light arrived at a DOM on one "string" relative to the time it arrived on another, so we can tell what direction the original particle came from.

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