Update on SuperK Detector Failure

This note came in from Director Totsuka to the press and other scientists. Hemos and I felt it deserved more than just a regular SlashBack reference, as we feel that this is an important project. (I belive this comes form a translation from japanese, so forgive the errors) this is an update to the original post on the Super-K malfunction.

As a director of the Kamioka Observatory, which owns and is responsible to operate and maintain the Super-Kamiokande detector, it is really sad that I have to announce the severe accident that occurred on November 12 and damaged the significant part of the detector. The cause and how to deal with the lo ss in future will be discussed by newly found committees. However, even before discussing with my colleagues of the Super-K and K2K collaborations, I have decided to express my intension on behalf of the staff of the Kamioka Observatory.

We will rebuild the detector. There is no question. The strategy may be the following two steps, which will be proposed and discussed by my colleagues.

• 1. Quick restart of the K2K experiment.
  • (1) We will clear the safety measures which may be suggested by the committees.
  • (2) reduce the number density of the photomultiplier tubes by about a half.
  • (3) use the existing resources.
  • (4) resume the K2K experiment as soon as possible; the goal may be within one year.
  2. Preparation for the JHF-Kamioka experiment.
  • (1) Restore the full Super-Kamiokande detector armed with the state-of-the-art techniques.
  • (2) The detector will be ready by the time of the commissioning of the JHF machine.

To achieve our objective is formidable but we are determined to do so. But we certainly need your encouragement, advice and help. I should appreciate it very much if you could support our effort as you have kindly done so before.

Best regards,
Yoji Totsuka
director, Kamioka Observatory
On behalf of the Kamioka Observatory staff

Comments

So...

[Narag]

Just what is the SuperK?

Re:So...

[spaceyhackerlady]

Just what is the SuperK?

A detector for neutrinos. Have a look at their web page.

I attended a talk last night by one of the scientists from the Sudbury neutrino detector. One of their Big Issues at the moment is figuring out why all the best neutrino detectors only pick up a fraction of the neutrinos predicted by all the best theories on the innards of stars.

...laura

Re:So...

[SEWilco]

It is suspected that neutrinos can oscillate between several types, and the detectors are sensitive to certain types. The MINOS project will test this starting in 2003, by firing neutrinos from Fermi Lab near Chicago, under Wisconsin, to the detector in a mine near Soudan, Minnesota.

Re:So...

[spaceyhackerlady]

It is suspected that neutrinos can oscillate between several types, and the detectors are sensitive to certain types.

This was the leading theory presented the other night. It also explains why the SuperK and SNO numbers are different: SNO can only see electron neutrinos, while SuperK can (in theory, at least) see other kinds.

...laura

How long?

[Immature Bastard]

Till thier fully back up to full capacity. As far as I gather thier hoping for half capacity in a year.

Re:How long?

[Anonymous Coward]

That's a little personal isn't it? But if you insist, about this |==================| long.

If I understand this correctly...

[Tsar]

...they're going to remove the imploded detectors, then take the 4000-odd surviving detectors and redistribute them, giving them a device of roughly half the resolution of the full SuperK. Is this what they intend to have working within a year?

I surely wish them good fortune getting it back online, and eventually restoring its full capacity.

Re:If I understand this correctly...

[Anonymous Coward]

Isn't it just like chaning (big) lightbulbs? a whole year? oh how many jokes are there regarding that... how much time does to take the Japenese to change a lightbulb?

Re:If I understand this correctly...

[Tsar]

Super-K is basically a huge underground cylindrical tank, about 40 meters wide and 40 meters deep, containing 50,000 tons of very nearly pure water. The sides, top, and bottom of the tank are covered with PMT's, the photomultiplier tubes which serve as detectors in the telescope. They are all pointed inward toward the mass of water, ready to detect the slightest Cherenkov light. (And slight it is—the Cherenkov light generated by the shockwave of a single muon is about as bright to the detector as a single candle seen from the Moon.)

Fortunately, each PMT is sensitive enough to detect a single photon of Cherenkov light. How does it do this? The same way you eat an elephant—one bite at a time. First, the photon hits a photo-cathode on the inner surface of the PMT's glass bulb, and the photo-cathode, in turn, releases an electron. The electron is attracted to a dynode, which carries a high-voltage positive charge, and accelerates toward it. When it hits, its great kinetic energy causes the dynode to emit several electrons, which are attracted to a second dynode with an even higher positive charge. The process repeats once for every dynode in the detector, until the final dynode is deluged with electrons, and sends a signal indicating that it has detected a photon. Neat, eh?

As you can imagine, PMT's are expensive ($3000 each, in this case), delicate, precision instruments, and you don't move them around like lightbulbs on a Christmas tree. Especially if you've recently gone from having 11,242 of them to having only 4,000 or so in one horrific oops.

Re:If I understand this correctly...

[SEWilco]

Oh, if only these youngsters knew what a cathode and dynode were. They don't know why TUBES ROCK! Nor do they understand the mechanics behind Venus Equilateral, other than putting the experimenter in a can and the experiment outdoors in vacuum.

These tubes are vacuum tubes with metal assemblies of various shapes, each charged with various voltages. The outermost cathode is charged with electrons, but kept below the point where many electrons can flow from the cathode to the nearest dynode (which has a different charge). Part of the cathode has a light-sensitive coating which emits electrons when hit by a photon. As the previous poster mentioned, those electrons are attracted to the lesser-charged dynode. Impact of those electrons knocks loose a greater number of electrons which are attracted to the next dynode, etc. Ultimately the electrons hit an anode which is connected to electronics that detect and report the electrical pulse triggered by the photon.

Pick Up, Dust Off, Start Again

[yancey]

The Super-K has already produced some good scientific results. I'd like to see them discontinue this experiment and focus the resources on the next one.

Boy, that clears that up.

[Bowie J. Poag]

Still no formal explanation..This is beginning to sound an awful lot like, "Dad, I totalled the car..A telephone pole jumped infront of my car, and I couldn't swerve around it in time! Honest, Dad!!"

Something tells me these guys made a titanically stupid mistake, and they're afraid of letting the cat out of the bag before they have a chance to circle the wagons and defend their multi-million dollar "oops".. See, its kinda hard to rebuild the detector when your funds have been cut due to findings of gross negligence.

Again, I move we refer to it as the "Special K" detector from now on. :)

Cheers,

Re:Boy, that clears that up.

[N9VLS]

It seems more likely that the PMTs weren't manufactured to spec, and the enclosures failed as a result of pressure during the refill.

Gross negligence? Doubtful.
You don't get to spend that kind of money without at least pretending to account for possible problems. Thing is, no one expects the fscking detectors to implode like this....

Re:Boy, that clears that up.

[Anonymous Coward]

No one expects the spanish inquishion! Thats what inshurance is for.

Re:Boy, that clears that up.

[The Larch]

Crack mods, please mod the parent troll up, he's got a good point.

I'm so fucking tired of slashdot, I need to quit before I short out my keyboard with drool. And I think tonight the time has finally come. Browsing the comments on the Super-K followup, every single fucking comment at +3 or above has been "Funny" -- can you tell anything wrong with this picture?

Slashdot has degraded to the level of an irc channel. I'm off. Be good, all, and don't get horribly mauled by the schoolbus tomorrow morning.

Re:Boy, that clears that up.

[goonies]

Again, I move we refer to it as the "Special K" detector from now on. :)

We'd better refer to it as "Sushi K"

Re:Boy, that clears that up.

[goonies]

Sad thing I used my last mod point yesterday, I'd give you "+1 Funny" for that post... ;)

Re:Boy, that clears that up.

[Performer Guy]

How about they refilled too quickly, or never equalized the pressure in the sensors. It seems clear that SOMETHING went wrong here, that detector used to be filled with heavy water, second time around the enclosures implode. It beggs the question, what did they do wrong the second time that they did right before? It seems foolish to suggest that the detector enclosures were not up to spec. Besides, if they weren't they should have known about it. It would be simple to pressurize the enclosures, no need to withstand the many atmospheres of pressure at the bottom of that tank.

Re:Boy, that clears that up.

[markmoss]

It would be simple to pressurize the enclosures A photomultiplier is a vacuum tube, 20 inches long in this case. It can't be pressurized, and one end has to be transparent. So whether it's the tube itself or a glass enclosure around it, you've got to have a big glass vessel that can support the pressure. Glass is actually pretty strong in compression, so if the shape is rounded for arch-like load transfer (a sphere or a cylinder with rounded ends), the tubes would hold up quite well to static pressure. Shock is a whole different matter.

But when you have 21,000 pieces of glass, it shouldn't come as a surprise when one gets broken. Why didn't they have baffles or shock-resistant enclosures around the tubes to prevent chain-reactions?

Re:Boy, that clears that up.

[Performer Guy]

There are large enclosures which house these tubes, they aren't just floating in the drink. The load over a small tube is much less that that over a large enclosure.

And we're not talking about one breaking here, there are clearly large numbers which broke, by the sounds of it around half.

Re:Boy, that clears that up.

[Anonymous Coward]

speaking of mistakes, remove the propaganda link from your sig. You wanted to make a big deal about the fact that you were killing off the project, then let it lie dead.

you fucking retard.

Re:Boy, that clears that up.

[Anonymous Coward]

I'm Sushi K and I'm here to say
I detect neutrinos in a different way

Look out Number One in every city
Sushi K PVT has all most pretty

My special watching of remarkable novas
Is not the stereotyped scientifc way

My range is big as a galaxy
Cause I attain greater technology

Sarariman on subway listen
For Sushi K like nuclear fission

Fire-breathing lizard Gojiro
He my always big-time hero

His mutant rap burn down whole block
Start investing now Sushi K stock

It on Nikkei stock exchange
Waxes; other detectorsrs wane

Best investment, make my day
Corporation Sushi K

In pure water total immersion
English/Japanese be mergin'

Hong Kong they detect nutrinos , too
Yearn of detectors just like you

Anglophones who live down under
Sooner later start to wonder

When they get their own nutrino star
tired of data from afar

So I will get big nova traffic
When you look at computer graphic

Sushi K research statistic
Make big future look ballistic

Speed of Sushi K growth stock
Put U.S. scientists into shock

-- apoliges to Neil Stephenson and the real Sushi K --

Re:Boy, that clears that up.

[habig]

Still no formal explanation?

Ok, how would you do go about doing the job of draining out ~40,000 metric tons of water, piecing together 7000 broken 1/2m diameter glass bulbs, and figuring out exactly what happened?

We've had all of three days since it happened. Do you want a quick, random guess, or do you want the right answer?

I'll opt for taking the time to come up with the right answer, thank you very much. Slashdot readers are already doing a pretty good job of supplying the quick, random, uninformed guesses.

Re:Boy, that clears that up.

[bware]

Nice.

A lot of people get paid extremely minimal amounts of money and work long, long, long, hard hours in a superclean environment to put together an amazing experiment and get a result that is staggering in its sensitivity and its implications for physics, and you want to point the fingers and talk about gross negligence.

Here's a clue. Having worked on a HEP experiment that got trashed through greed (someone wanted to steal a bunch of the expensive heavy metals for scrap), there are a many broken hearts in the SuperK researchers. HEP researchers are well known for putting in > 100 hour weeks on a regular basis, and not for the promise of stock options and early retirement at the end. Just physics data that they will spend years going through. The payoff is four pages in PRL.

Super-K's predecessor was almost denied funding because it had the nerve to obtain physics results from the neutrinos observed from SN1981A. It was designed and funded to look for proton decay, you see, and if those darn scientists can't stick to the mission, then it's gross negligence and cut their funding. Luckily wiser heads prevailed.

For what it's worth, it's a superclean environment and they probably want to continue to take steps to keep it that way. I will not speculate on why it happened, except to say that yes, it could be simple stupidity. These things happen when you are working out on the edge. No one has ever done this kind of stuff before, so there aren't rules. But not rebuilding the detector and not getting the funds to do so would be cutting off someone else's nose to spite your face - who else is going to know how to build this kind of thing better than the folks who did it, and learned from previous mistakes?

I find the chain reaction stuff unlikely though. If it's like the experiments I worked on, each PMT has it's own power supply, and any individual PMT is separate from those around it in most every way. It could be a bad HV power supply, but in general when those things go, they just stop working. Plus any individual HV card probably only supplies 12 or 25 tubes. PMTs are actually fairly robust devices. They're delicate, but we were using hand-me-downs from an experiment back in the 60s, still going strong. The original KamioKande started with hand-me-downs too.

More likely is that something went wrong with the fill in order to kill 4000 tubes all at once. But then again, it's something they've done multiple times, so what was different this time?

Who knows? All speculation. My heart goes out to the Ph.D thesis students who just had their graduation dates moved back arbitrarily, another year or more in grad school, poor bastards.

Re:Boy, that clears that up.

[autopr0n]

or never equalized the pressure in the sensors.

Do you know what a VACUUM TUBE is?

Re:Boy, that clears that up.

[Eric Sharkey]

There is *no* enclosure around the tubes. They *are* just floating in the drink. Well, not really floating. There are metal straps which wrap around them and hold them down. Since they're mostly vaccuum inside, they're much less dense then water and would float to the surface very quickly if you let them go. The theory is that the shockwave hit them at such an angle that they twisted and it was these metal straps which held them too tightly and caused enough pressure at fairly narrow places to cause them to implode.

Re:Boy, that clears that up.

[darkonc]

It seems more likely that the PMTs weren't manufactured to spec, and the enclosures failed as a result of pressure during the refill.

I'm guessing that it was only one unit which either wasn't manufactured to spec, or got hit by a worker during refill -- then the shock wave from the implosion caused a couple of it's neighbours to implode

"Then they told two friends, and they told two friends, and so on and so on....",

The problem appears to center around the fact that all of the tubes were interconnected. Thi mad it posssible to drain and refill the thousands of tubes without taking a really long time. Unfortunately, there wasn't anything (or, at least, enough) set up to dampen the shockwave in the case of a failure. It's the kind of thing that's obvious in hindsight, but only after you think of it, or it happens...

It's kinda like using box cutters to hijack a plane and use it as a suicide bomb.... We never really considered the possibility of 20 suicidal hijackers getting together to create mayhem with office implements.

Repair estimates top $30M

[Camel Pilot]

It has been estimated that the US will spend $100 Billion in a year pursuing justice in the hinterlands of Afghanistan. That comes out to approximately $300 million per day! Or we will spend what is required to fix the SuperK in 12 hours. Kind of puts things in perspective.

Re:Repair estimates top $30M

[PD]

Can't do much science when people can't safely work in office buildings or post offices.

War is immoral, and spending outrageous amounts of money on war is immoral, but it is even more immoral to ignore evil.

Hope THAT puts things into perspective.

Re:Repair estimates top $30M

[Anonymous Coward]

Yeah, what a waste of money it is to throw at Afghanistan, too.

Re:Repair estimates top $30M

[RGRistroph]

It's also been estimated that we are spending 1 billion a month:

http://www.nytimes.com/2001/11/14/opinion/14KRUG.h tml

Are you sure that you didn't get your statistic from someone who couldn't think up a number bigger than 100 billion or a period longer than a year ?

Also, if we spend 300 million in a day, then we spend 30 million in one tenth that, or 2.4 hours, a lot less than 12.

Calculators are your friend, but if you are stupid in the first place, they won't help much.

Re:Repair estimates top $30M

[Zeinfeld]

It has been estimated that the US will spend $100 Billion in a year pursuing justice in the hinterlands of Afghanistan. That comes out to approximately $300 million per day! Or we will spend what is required to fix the SuperK in 12 hours. Kind of puts things in perspective.

The estimates reported by the BBC are a billion a year. The '100 billion' figure is the amount of corporate welfare the Republican party wants to ram through Congress under the pretense it is a stimulus package.

Before anyone gives these folk any more money they should be able to explain why the previous detectors went pop. Otherwise there is every chance the replacements will fail in exactly the same way.

$30 million is a pretty large chunk of change to lose. For the same money you could fund an awful lot of interesting Comp Sci research.

Re:Repair estimates top $30M

[Anonymous Coward]

You're one of those people who keeps a rifle in each room of your house, aren't you.

Re:Repair estimates top $30M

[Anonymous Coward]

but if you are stupid in the first place, they won't help much

Woops! That must have been my problem :)

-Camel Pilot

Re:Repair estimates top $30M

[Camel Pilot]

It all depends who you believe and what they count. The $100B was mention on CNN a while back. But I did find this link which gives a good cost comparision of this and other wars. A quote from the reference link:

"Because of its global scale and long-term nature, the war on terrorism probably will cost more than the Persian Gulf War, which totaled about $80 billion in constant fiscal-year 2002 dollars"

BTW, we are little quick to call someone stupid are we not. You should show a little restraint. I am sorry i accidently fat fingered the 1 and 2.

Re:Repair estimates top $30M

[vandan]

The Bush family is in bed with the oil cartel & weapons manufacturers, not the scientific community. Anyway, you can't have too much scientific research going on, because the knowledge gained may tend to enspire people to think for themselves. ie "Why are we blowing the fuck out of Afghanistan civilians?"
War on terrorism. Yeah, right.
War on Bush's enemies, maybe..

Re:Repair estimates top $30M

[Anonymous Coward]

what's wrong with that? Better that then being a pussy that probably couldn't even stop the Little Rascals from running through your yard let alone criminals.

I keep a gun on me most of the time. You're nuts not to defend yourself. Liberals want our guns and tell us they will protect us. Well, when they can't keep planes piloted by man men that are in America illegally from crashing into buildings what makes you think they can protect us in our homes?

Do I keep a gun in every room? No that's not a good idea. Do I keep one on my person at almost all times? Yes... and I think you are a coward if you don't.

Re:Repair estimates top $30M

[astrophysics]

It's estimated to take 2 years to replace the PMTs. That's a matter of logistics not funding.

Re:Repair estimates top $30M

[Anonymous Coward]

Offtopic, but more people died on Sept. 11th from hunger than from the terrorist attacks. (Source: New Internationalist, issue 340, November 2001.) And people die from hunger everyday. Does that put things in perspective?

Re:Repair estimates top $30M

[Anonymous Coward]

Stimulus packages i.e. government spending meant to increase the demand of goods/services are famous failures. The Japanese have been trying for years and look at the success they are having.

I guess it is a sign that things are getting back to normal - we are returning to deficit spending again.

Stimulus packages get politicians and special interest groups all excited as they try to craft stimulus projects to their own predetermined and self-serving ends.

Re:Repair estimates top $30M

[volkris]

Well, have you attempted to think for yourself and answer that question? When you do, you'll find the answer very reasonable and valid.

War on terrorism is exactly what's happening, as evidenced by facts collaborated by all of the major international news networks.

You'd have to stretch quite a bit to support a charge of war on Bush's enemies.

Re:Repair estimates top $30M

[brunes69]

BBC huh? you sure thats not A British billion? In America, a Billion generally means a thousand million. (1x10^9) In England, a billion means a million million (1x10^12). So, if the BBC is reporting it as 1 billion dollars, that is really 1 trillion dollars in American terms. Now, Im not saying that it is either of these, maybe somehwer in between?

Re:Repair estimates top $30M

[Lars T.]

I recently read that the cost of the (2nd) Gulf War cost $60 billion, 90% of which was paid for by several Arabic and European States. Article in German. The article claims the Pentagon got $3.8b for the first three months of the war from Congress (not including normal cost of operations nor $20b for "special measures" after 9/11).

Re:Repair estimates top $30M

[Fyndo]

Well, they also worked to get the US out of the great depression. If they're crafted for maximum economic impact, they work, if they're turned into a big feeding trough of pork for special interests (like in Japan, and possibly the US today), then they're worse than useless.

Re:Repair estimates top $30M

[SlamMan]

Than what's a thousand million in Britain?

Re:Repair estimates top $30M

[j-beda]

Do I keep one on my person at almost all times? Yes... and I think you are a coward if you don't.

This makes one a coward how?

Now in your mind it is safer to carry a gun than to not do so, but generally doing the more dangerous thing is not what defines a coward. In fact, it is usually the opposite.

A "classic" coward is unable to uphold their beliefs due to fear. They either act (or fail to act) in a way consistent with their beliefs because they are afraid of the consequences of that action (or not performing that action).

It seems to me that not carrying a gun would only be cowardice if the person thought that they *should* carry a gun from some philosophical reason, and yet did not due to fear. Generally this is not the case. I would say that the majority of people involved in this type of debate who do not carry guns have a philosophical reason NOT to carry a gun. Thus pointing out the danger of that decision demonstrates bravery rather than cowardice. Similarly, pointing out the dangers of carrying a gun to someone who thinks that gun possession is philosophically an important issue, might highlight the bravery of the individual in that case.

Granted, one or the other (or both for that matter) of these philosophical positions could be based on ignorance and stupidity, but nobody ever said that stupid people could not be brave.

But to get back on topic - I think it is a shame that we are so willing to invest in military strength and in environmentally unfriendly governments, businesses and practices and all those sorts of "bad" types of things and yet we spend such a relatively small amount on basic research.

Re:Repair estimates top $30M

[Anonymous Coward]

not really. the US is OUR country and we look out for our own first. It's not our fault if corrupt governments and cultures starve themselves. And there is nothing we can do (even with $$$) to fix their problem.

Re:Repair estimates top $30M

[Defiler]

A milliard.

Re:Repair estimates top $30M

[Anonymous Coward]

But it's our corrupt government that is supporting the corrupt governments that starve their people. There is pleanty we can do to fix that.

Re:Repair estimates top $30M

[Richy_T]

FWIW, billion=1000 million has pretty much become standard usage in the UK. I think the milliard is on its way out.

Rich

Re:Repair estimates top $30M

[PD]

I'm a liberal. I own no weapons. I oppose evil instead of being evil.

Re:Repair estimates top $30M

[blair1q]

And I spent $7.77 on a cheesesteak, fries, and a coke for lunch today.

--Blair
"And the student was enlightened."

Re:Repair estimates top $30M

[vandan]

My hunch is that the rate of innocent civilians killed : terrorists killed is something like 10:1
Of course, it is incredibly difficult to get statistics on these sort of things. There are live counters on the web which show the number of AMERICAN civilians killed / found / unhappy because of the towers coming down, but no such stats from the other side.
I saw on ABC (Australian) news a couple of nights ago that the US was sending in B-52s to carpet bomb the place. FUCKING B-52s AND CARPET BOMBS!!!!
That is not how to eradicate terrorism. That is responding to 1 small faction's terrorism with terrorism on the NATIONAL scale.
The sooner someone puts George Bush in the front-line the better.

Re:Repair estimates top $30M

[volkris]

I think that's very short sighted, though.
AND, there's more to this than simply human life counts. Economic and lifestyle matters have to be considered too.

But basically, simply because we're killing 10:1 right now does not mean that we won't be saving 20:1 from disuading would-be terrorists in the future. There is no way ever to know the truth behind this, but better safe than sorry.

And as for the Bush comment, I am so glad he is in his possition. I can only imagine how horrible things would be right now had Gore won the election.

Bush has been doing a really great job. It's that simple.

The Replacements

[Detroit]

Didn't they just replace a few thousand of these PMT's? Could they just put the old ones back in for the time being? Might not be as sensitive, but it's better than not getting any at all!

poof

Re:The Replacements

[SEWilco]

They replaced about 100 which were not working.

Gee, they don't have a PayPal link so we can sponsor a PMT?

Re:The Replacements

[Anonymous Coward]

Not a bad idea. They could reward contributions by publishing an article with the names of all paypal contributors (or maybe just the top 10 or 20) sorted in order of size of contribution.

Imagine having your name on a high quality (perhaps prize winning) article?

Japanese Engrish

[Robber Baron]

I know, I know, I'll probably get modded to hell for this but I've got the points to burn and simply can't resist giving in to the Dark Side and Posting a link to this site.

Re:Japanese Engrish

[Anml4ixoye]

Thanks so much for the link. That just brightened my day.

Re:Japanese Engrish

[DNS-and-BIND]

Wow, racist humor. I sure thought that stuff was dead and buried, but thanks for sharing!

Re:Japanese Engrish

[Anonymous Coward]

Oh, get a life. My *Japanese* (born and raised in Sendai) wife is the one who showed the site to me. We explored it togeather for over a half hour and wound up nearly rolling on the ground we were laughing so hard.

Re:Japanese Engrish

[Anonymous Coward]

Doesn't change the fact that it's racist humor one bit. Black people can laugh at Amos-n-Andy skits or and it's the same thing.

Re:Japanese Engrish

[chopkins1]

Actually, I beg to differ. This is merely mistranslation humor. not racist. It does not denigrate the Japanese or any other Asian in any way.

Re:Japanese Engrish

[Brand X]

I'd say it's mocking bad translations, not anything about the nipponese. My mom's AJA (I think she's Gosei or Rokusei depending on how you count it... lowest possible count would be Yonsei) and while the attitudes of those of us in Hawai'i toward the nipponese (and the Mainland American Japanese, for that matter) isn't exactly that of dislocated immigrants, we still maintain ties to Japan. Heck, I know several of the products on that web page. The little chocolate sticks are actually really good, and some of the weird coffee drinks are too. I still laugh my @$$ off at the translations. I also laugh at some of the butchery of written nihongo in airports here, though we make fewer attempts, however inellegant, to accomidate those who don't speak our language. It's not just from Japan. Ever try to interpret the translated documentation on taiwanese electronics? Or, for that matter, clothing care instructions from non-name italian manufacture? And the web site had the good grace to explain the mistranslation when they could. "Emergency Trap" as an accidental mixing of english and danish, for example... The only racist element was the "Engrish" bit, that I saw, and the truth is, that's a real issue. Just as English lacks some phonemes to properly handle certain foreign languages, nihongo lacks both the "la"/"el" sound and the "ra"/"er"/"air" (We have two terminal 'r' phonemes in english. Subtle, and most people are unaware of the difference.) sound, and the substitution of the çfamily phonemes has led to more than a few confusions in translations. Look at Mitsubishi's Starion. According to one popular myth, the proposed name was Stallion, and it was misunderstood... The validity of this is uncertain, but it is a possibility. Nissan for years went by the name "Datsun" in America. They thought it sounded english, and were trying to avoid the (then) stigma of being a japanese car company. Strangely, Americans thought it sounded Japanese. It sounds neither. I'm not sure what it sounds, but it's neither of the above.

What remains true, whatever you paint over it, is this: no two dissimilar languages match well, and less than fluent translation is, has always been, and will always be, funny. It's not racism, merely something that has been associated with racism. This isn't Krusty the Clown trying to figure out why no one is laughing at his buck-toothed "Me so solly" routine...

I have a few friends who are into anime. I like watching with them, and laughing at the toned (or dumbed) down subtitles... but I can't for the life of me think of a concise way to translate the concept of some of those trisylibic expressions into english. There's too much cultural context required. Likewise with some of the funny things on the web page in question, especially the drinks.

I understand the Japanese gist, and the english-speaking side of my brain still laughs.

Wait how is this gonna work?

[jgaynor]

(2) reduce the number density of the photomultiplier tubes by about a half.

If they can up and cut the number of sensors in half will they still detect the "blue streak" of the Nuetrino if one happens to pass through? If so why were their that many photosensors in it in the first place?

Additionally - the tank will again be flooded with the same amount of water, and correspondingly, water pressure. With only half the amount of sensors - wont these sensors each have more pressure placed on them? Wasnt a collapse because of water pressure what caused the initial sensor implosion chain reaction?

This seems like a real cut-throat solution, I wish there was more of an explanation than just a few lines . . . Good to hear they're rebuilding though.

Re:Wait how is this gonna work?

[canadian_right]

I would expect that they detect half as many neutrino's with half as many detectors. The experiment will have to run twice as long to get the same quality of data.

Having half as many detectors will have NO affect on the pressure on each sensor. Only the DEPTH of the water over a particular sensor has any effect on the pressure on it.

I would guess that since they broke a great number of these expensive sensors they are are planning on making do with the sensors that didn't explode.

Re:Wait how is this gonna work?

[brainboyz]

Using double the desity of Photomultiplier Tubes allows them to get a better resolution picture of the energy released when the nutrino passes through. They won't get half the pictures, but they'll see them half as well.

It's a good solution for the time being because at least they can take pictures. If they waited until longer to get all the PMTs replaced, then they'd have less pictures overall instead of less resolution for a short period of time.

Re:Wait how is this gonna work?

[DerekLyons]

the tank will again be flooded with the same amount of water, and correspondingly, water pressure. With only half the amount of sensors - wont these sensors each have more pressure placed on them?

No, the pressure on a sensor tube is a function of the depth of water at the sensor, not of the number of tubes in the array.

Wasnt a collapse because of water pressure what caused the initial sensor implosion chain reaction?

That's the purpose of reducing the amount of sensors in the array. Increasing the spacing will reduce the chances of another chain reaction. (The strength of the shock wave falls off according to the square power law. (IIRC)) Array sensitivity will suffer a hit, but loss of half the dectectors does not always mean loss of half the capability. I suspect that angular resolution will suffer more than the absolute detection threshold.

Re:Wait how is this gonna work?

[dragons_flight]

Yes they will detect it. What you lose by reducing sensors is resolution as to direction and energy.

It's actually rather unlike that they'll miss nuetrino events because of such a change. I've had the oppurtunity to look at individual event plots and raw data, and the Cerenkov light from a single event actually registers in a considerable fraction of the tank. IIRC, typically 5-30% of detectors see each event.

They use the timing of when each detector becomes active to reconstruct the path and speed of the particle generating the light. So fewer PMT tubes means less accuracy in determining the direction and energy of the nuetrino that produced the event. I would guess that it's not the case that half as many tubes means half the accuracy. If I were to make an estimate I'd say you're probably increasing the error on individual measurements by around 30-60% (as opposed to 100%, if it were doubled). This is most important on electron nuetrino events which were somewhat hard to accurately determine to begin with, compared to their muonic cousins.

With only half the amount of sensors - wont these sensors each have more pressure placed on them?

No. Hydrodynamics doesn't work that way.

Wasnt a collapse because of water pressure what caused the initial sensor implosion chain reaction?

Well the machine worked successfully for several years at the same amount of pressure, so this shouldn't be the initial cause of the accident. However it is entirely likely that the pressure facillitated the disasterous chain reaction once some faulty equipment or human error got it started.

This is an exotic size of tube and most of the replacements will have to be manufactured (which takes time), so this is probably the best solution we can expect in the near term.

Re:Wait how is this gonna work?

[astrophysics]

Since the PMTs have a vacumb inside, when the tubes are tightly packed, there's no (little) pressure tangential to the radius vector. I'd guess they'll put in "dummy detectors" or something to fill the space and keep the water from getting anywhere but on one face of the detectors.

Re:Wait how is this gonna work?

[Brett Viren]

The full 40% coverage is needed only for solar neutrinos, and to some extent possible super nova neutrinos, both of whos interactions produce far less light than other classes of neutrinos. For higher energy atmospheric and K2K neutrinos 20% coverage will translate into only slightly reduced ability to reconstruct the events and do physics.

It is a good compromise to do the most physics with the resources at hand.

Re:Wait how is this gonna work?

[dayL8]

No. Hydrodynamics doesn't work that way.

Well, at least hydrostatics doesn't, which is the useful discipline in expressing water pressure as a function of depth.

Re:Wait how is this gonna work?

[Brett Viren]

That's the purpose of reducing the amount of sensors in the array. Increasing the spacing will reduce the chances of another chain reaction.

The reason for reducing the PMT coverage is simply the lack of 50 cm PMTs this world has. The added spacing that results may, as you say, reduce the chance of another cascade implosion, but it needs to be check that it will reduce it enough to be safe.

(The strength of the shock wave falls off according to the square power law. (IIRC))

I haven't checked, but there probably is indeed a 1/r^2 falloff. But there will be another component of the fall off because the wave will disapate. Think of the first moment of implosion, the pressure wave is vacuum on one side and 3 to 4 atmosphere on the other. By the time the pressure front reaches the neighbor PMT the pressure gradient must be something less than a step function.

Re:Wait how is this gonna work?

[Brett Viren]

No. Hydrodynamics doesn't work that way.

Well, at least hydrostatics doesn't, which is the useful discipline in expressing water pressure as a function of depth.

You are both half wrong/right. The pressure at a certain depth is hydrostatic, but the implosion cascade is a hydrodynamic effect caused by the pressure wave from the first imploded PMT producing a pressure differential (and thus a net force) across the neighbor PMTs. If we assume a pressure differential of 1 atmoshphere, this translates more than 2 tons of net force (not balanced hydrostaic force) on the PMT. Those PMTs are extreamly strong, but drop a car on one and they will break.

Re:Wait how is this gonna work?

[Eric Sharkey]

It's actually rather unlike that they'll miss nuetrino events because of such a change. I've had the oppurtunity to look at individual event plots and raw data, and the Cerenkov light from a single event actually registers in a considerable fraction of the tank. IIRC, typically 5-30% of detectors see each event.

This isn't entirely true. It depends a lot on the type of event. The pictures you probably saw were either of an atmospheric neutrino event, a cosmic ray background event, or one of the K2K events. In all of these cases, the particle in the detector will have somewhere between 100 and 5000 MeV of energy (and in some cases more).

As a particle travels through matter, it loses energy as it goes. The more energy it has to start with, the longer it will go before it stops. A general rule of thumb is that a muon travelling through water loses 2MeV for every centimeter travelled. So a 100MeV muon produced by a neutrino interaction would travel for 50cm. The higher the energy, the longer the track, the longer the track, the more light produced, the more light produced, the easier it is to see.

Very high energy cosmic ray muons will produce so much light that every tube in the detector will register a hit. A typical high energy event picture is here. Would you see the pattern with half as many pixels? Of course.

The problem is that "solar neutrinos", neutrinos which come from the sun, typically have much lower energies. (Only 1-10 MeV) So low, that even before the accident, SK would miss most of them (anything below 5MeV) because they just didn't produce enough light to be distinguishable from random noise in the dector or the decay of stray radon particles. If you look at pictures of these events, normally you can't see anything by eye. There's just a few photons (5-10) which are recorded which can only be identified as a real event by their timing because you can triangulate back to a single point based on their arrival time at the PMTs. Solar neutrino physicists rarely post event display photos because there's so little to see in them. Even then, it's hard to distinguish solar neutrino events from noise. In fact, it's not possible to identify an individual event as a solar neutrino event and not a radon event that looks like a solar neutrino event. It can only be done statistically. (Radon events don't point in any particular direction, while solar events all come from the sun, so you can compare the number of events coming from the sun and the number of events apparently coming from other directions and do a background subtraction.)

It's these types of events which will be hurt most by the loss of the extra tubes.

Re:Wait how is this gonna work?

[DoctorNathaniel]

No, it's not quite that good. By reducing the number of phototubes by 1/2, your energy resolution drops by 1/4 (1/sqrt(N)). However, your noise wall only drops by a factor of 2, so you're left with a much worse signal/noise ratio, and you have to raise your trigger threshold.

Basically, this will kill Super-K's solar neutrino project.. they likely will have to raise their thresholds by several MeV (over their current 5.5 MeV limit). However, their high-energy measurements won't be nearly so hurt; they simply will lose some reconstruction efficiency.

Somewhere in the Japan....

[zulux]

Mr. Tanaka: You have failed the SuperK - Dr. E.! Our German contacts are not pleased with the latest ramifications of the 'device.'
Dr. E.: Wah! But the Gaia force was in alignment, this can not be!
Mr. Tanaka: Your latest failure is being undue attention to our cause.
Dr. E.: Wah! But Pretty-Girl likes to SCUBA in the detector. Makes fresh-wind in water and boom - becomes divine-wind chain reaction.
Mr X.: Doctor, your failure is now at hand!
Dr. E: Wah! I give my body to the Emperor! Pretty-Girl, be saying Goodbye! (Slice) (Slice)

No need to ask forgiveness

[The Pim]

I belive [sic] this comes form [sic] a translation from japanese, so forgive the errors

Don't be ashamed, Chris! We're quite used--indeed endeared--to the editors' barely intelligible brand of English. For Taco, that would be a good post.

Oh, you meant the quoted part ...

Re:No need to ask forgiveness

[Anonymous Coward]

Don't you mean "indeered"? and "enteligible"?

geez man, get a spellchecker already...

Re:No need to ask forgiveness

[Anonymous Coward]

Also:

This note came in from Director Totsuka to the press and other scientists.

I guess other scientists must mean scientists other than Director Totsuka, but at first glance it reads as scientists other than the press, which of course doesn't make sense because the members of the press are not in general scientists.

Can this work?

[jdevons]

I really like things that work.....

The world revolves around the sun??

[pjbass]

I just got through reading through the description of the super-k and what it is supposed to do, and found myself hitting dictionary.com quite a bit. I was very impressed and excited about this project, but came across something that I read a few times and it still doesn't make any sense to me:

If the problem of solar neutrinos would be caused by the oscillation of neutrinos, it is predicted that the number of solar neutrinos is
different in the day and at night ; however, there is not much difference in intensity of
solar neutrinos between the day and night.

So the assertion (or hypothosis) is that the amount of neutrinos emitted from the sun's core is different during night than day?? If I'm missing something, please someone let me know. I find this difficult to understand, since the sun really doesn't give a damn what earth is doing, especially when you're talking about night in Japan vs. night in America. I honestly welcome clarification on this if anyone has any. Thanks!!

Re:The world revolves around the sun??

[i_am_nitrogen]

Actually, what it's suggesting is that during the night there would be fewer solar neutrinos due to the earth being in the way. Perhaps what is being discovered is that neutrinos are (for the most part anyway) not blocked or slowed down by the earth itself in any significant way, or that solar neutrinos really aren't caused by direct emission from the sun. At any rate though, I am not a theoretical physicist, I just like to think about this kind of stuff a lot, so I could be totally off the wall.

Re:The world revolves around the sun??

[Anonymous Coward]

Where is the Sun at night? Somewhere below your feet .... So, at night the solar neutrinos have to pass through the Earth, before they can hit the detector. According to some theories, this should give a detectable change in the neutrino signal.

Re:The world revolves around the sun??

[merlin_jim]

Actually, according to current theory, neutrinos pass through normal matter without interacting with it (much)... that's why you need such a big and delicate detector to find them at all; they are practically inert as far as normal matter is concerned.

So, I don't know why this statement was made, except to say that the neutrino's rate of interaction with matter is one of the more hotly debated questions in science right now. Its rate of interaction and its mass are two variables that play an important role in all of cosmology (for details, lookup Mach's theory, Ober's Sky, Missing Mass, and the Omega constant, sometimes referred to as the Hubble constant)

Re:The world revolves around the sun??

[asterisk_man]

IANAP but i believe the oscillation of neutrinos refers to the theory that they switch forms as they travel through space. In theory, at night they will travel a different distance to the detector than they will during the day and possibly have changed to a more or less detectable form in the meantime. Though in comparison to the distance already traveled the distance traveled through the earth would seem to be insignificant to the supposed period of oscillation (some small number of oscillations between the sun and earth if i remember correctly). I think they're just going down a long list of theories and crossing off anything that they can.

Re:The world revolves around the sun??

[Brand X]

IANAP but i believe the oscillation of neutrinos refers to the theory that they switch forms as they travel through space.

I used to be a student of one of the American Physicists more heavilly involved in Super-K. Spent a lot of time learning this theory. You have it mostly right. They don't so much switch forms (transforming from one to another) as oscillate between mixed states. The particle in question ends up being, say, 90% electron neutrino (I'm pulling the numbers out of the air here), 8% mu neutrino, and 2% tau neutrino, in one of the theories. (Another one has a neutral charge neutrino in the mix too...) and the mixed state travels as a single packet of quantum potential. If it interacts at a particular time, the chances of the interaction being muon is X, electron being Y, etc. Except that if one of the neutrino types has mass, the packet is moving at a finite, though high, fraction of the speed of light, and the probability of interaction is affected by the phase of the different particles in the potential with respect to one another (which would be uniform if they were all massless and moving at the speed of light), and the phase is further affected by medium of transmission (matter versus vaccuum), which is why there is a statistical variation due to time of day and day of year... different distances traveled in different seasons, and different amount of matter traveled through. Course, although IUTBAP, IANCAP. This is from distant memory echoing through fog and cobwebs. YMMV.

I guess we'll never know...

[Anonymous Coward]

... what a Beowulf cluster of these would be like.

HAHAHAHA What does this mean?

[CrazyJim0]

All your base are belong to us!

Night and Day

[MarkusQ]

So the assertion (or hypothosis) is that the amount of neutrinos emitted from the sun's core is different during night than day??

No, the same number are emitted, but if they have to travel through the bulk of the earth before reaching the detector, it will effect how many you detect. That's true of photons too (you see a lot more of them durring the day, even though the sun emits at a ~constant rate), but here it is even more interesting; the neutrinos aren't being absorbed by the earth, they are being converted between two forms, one of which is easier for a particular detector to detect. So you can wind up detecting more at night!

--MarkusQ

Re:Night and Day

[pjbass]

I have to thank you. I'd mod you up for informative, but I obviously can't. That is something I didn't think of (in my intoxicated state) for why the level of neutrinos detected would be different during night than day. I guess all I have to say is I wish they differentiated what they meant there, instead of implying the sun emits "more" neutrinos during "day" than "night." I found it confusing. But then again, this might have been something lost in the Japanese-English translation. Thanks again!!

Re:Night and Day

[Anonymous Coward]

I don't think you're quite correct...
Consider the scale of all these things, just for interest:
From production at the core of the sun (solar radius ~7x10^8m) to emission from the surface takes a photon (travelling at speed of light) somewhere on the order of a couple hundred thousand years or so simply because it interacts with matter so readily.
On the other hand, a neutrino produced from the same reaction travels almost straight out on the order of a couple minutes.
The earth has a radius of ~6x10^6m, to astronomical accuracy ~7x10^6m. In terms of volume, the sun is ~10^6 times as large. If we assume earth and sun to have equal density (not true..ho well), you can see that an interaction between solar neutrinos and the earth is of the same order as that between solar neutrinos and a large convection cell in the sun's atmosphere.
Since an observatory is only looking at a small percentage of neutrinos on a relatively thin path between here and sun's core, I don't think you could establish any day/night difference, even with years of observations.

Re:Night and Day

[j-beda]

Generally, I think that this analysis is correct, the size of the earth compared to the radius of the orbit is pretty small. In fact I think that the eleptical deviations of the earth's orbit are larger than the size of the earth. Additionally, the volume of the sun from which the neutrinos are created is probably larger than the volume of the earth, so we already have a pretty large uncertainty in knowing where the neutrinos each were created in the first place.

However this does not necessarily mean that the earth has no effect on the situation. The detector itself might not be symmetric - maybe it is more or less accurate when pointing down compared to pointing up? Theories involving neutrino oscillations might have measurably different rates when the neutrinos pass through the earth than when they pass through empty space.

Re:Night and Day

[krlynch]

As you pointed out, the size and shape of the earth is miniscule compared to variations in the orbit. However, if neutrinos oscillate between different mass eigenstates during their travels, then you would expect the oscillation rate inside matter (i.e. the earth) to be different from the rate of oscillation outside matter (i.e. the vacuum of space), and from knowledge of the oscillation rate in one, you can predict the oscillation rate in the other (well, given some other information that doesn't concern us here...). The day/night variation would arise because the neutrinos from the sun that are detected during the day travel through less matter than do the neutrinos at night, which have to travel all the way through the earth first, and hence would have reached a different point in their oscillation. You would also expect to see a seasonal variation as the earth moves radially toward or away from the sun during the year, because the distance over which the neutrinos oscillate would change. Finally, from knowledge of the matter effects, you would also predict a difference in the number of neutrino events passing through the detector from teh top and from the bottom. It was actually the last effect which was the evidence for oscillations, if I'm not mistaken.

Re:Night and Day

[MarkusQ]

Since an observatory is only looking at a small percentage of neutrinos on a relatively thin path between here and sun's core, I don't think you could establish any day/night difference, even with years of observations.

To quote a teacher I once had, I would agree with you if not for the fact that you're wrong. The day/night neutino detection cycle isn't a theoretic effect they are trying to observe, it's an experimental effect they are trying to explain. The present best explanation is that they switch between two families (muon & tau) with different masses.

-- MarkusQ

anyone know...

[deglr6328]

...a site with large (desktop size) images of super-k? some of those pics on the homepage look like they'd make unbelieveably cool desktop backgrounds, if only they were bigger.

Re:anyone know...

[Brett Viren]

The main page, www-sk.icrr.u-tokyo.ac.jp has some
"press" sized pics, last I checked. Yes, here:
http://www-sk.icrr.u-tokyo.ac.jp/doc/sk/photo/hi gh .html

Re:anyone know...

[Anonymous Coward]

neat thx

Why TUBES ??

[green pizza]

I've been pouring over the details of this thing and something just doesn't sit right with me... the photomultiplier tubes. Why on earth would such a sensitive and crucial component be of an oldschool vacuum tube design? Did we learn nothing in the 1960s? I agree that it needs to rebuilt, but golly, use COTS (commercial, off the shelf) CCDs or similar.

Re:Why TUBES ??

[i_am_nitrogen]

Perhaps you missed the part where it says these are $30000 photomultiplier tubes. It would take an incredibly huge number of neutrinos emitting blue streaks to register on a CCD. These tubes are insanely sensetive to light I would assume, perhaps capable of detecting very small numbers of photons. Vacuum tubes are actually quite good for a number of things.. CRTs, vacuum fluorescent displays, guitary amplifiers... Plus, did it say they were vacuum tubes?

..whatever..

Re:Why TUBES ??

[dragons_flight]

Fine. You show them a better way to be able to detect SINGLE photon events, roughly measure their wavelength and do it with sub-nanosecond resolution and I'm sure they will be very interested.

Re:Why TUBES ??

[Anonymous Coward]

You have no idea what you're talking about, do you?

Re:Why TUBES ??

[markmoss]

If you want to count each individual photon, photomultiplier tubes are the only choice.

In a PMT, a photon hitting the first plate releases an electron. The first plate (cathode) is negatively charged, so the electron flies off towards the less-negative 2nd plate, picking up enough energy to knock several electrons loose. These hit the third plate, knocking out more electrons, and so on. After many plates, the pulse of electrons is large enough to be easily measured, so they are collected and output on a wire at the back of the tube (anode). You can either measure the average current to determine photons/seconds, or detect each pulse to determine when each photon arrived. The super-K uses the latter method, since it has to compare photon arrival times to find the position of the event which created a burst of photons.

The PMT has very high gain and a remarkably good signal to noise ratio. "Gain" is the number of electrons out for one freed electron in, and you just add plates (and increase the overall voltage) until you get what you need. "Noise" would be an electron spontaneously flying off from the cathode, and this is pretty rare.

Solid-state detectors also start with a photon energizing one electron to jump somewhere it wouldn't normally go. Then you need an amplifier. It's possible to build solid-state circuits that will amplify a single electron to a measurable pulse, but to make it that sensitive you must also make it possible for electrons to just tunnel through the first amplifier stage on their own, and this is indistinguishable from detected photons. So it's hard to sort out the signal from the noise.

Re:Why TUBES ??

[Anonymous Coward]

>If you want to count each individual photon, >photomultiplier tubes are the only choice.

Buzz, really really really good PMT's have absolute quantum efficiencies in the 60% range. Ones that mortals can afford are in the 30-50% range. (It's a trade off in the manufacturing process, the photo-cathode material needs to be thick enough to have good probability of absorbing incident photons, yet thin enough that the low energy electrons from the photo-electric effect can make it out.) You'll never reliably see each individual photon. You might, however get very good amplification of single photo-electrons and see peaklet's in the output for 1,2,3,... N photo-electrons.

Re:Why TUBES ??

[smoyer]

Other that the description of multiple "amplification" stages, how is this different that an APD (avalanche photo diode)? APDs have such a high gain that they are actually unstable for applications where there are an abundance of photons hitting the detector.

Joe Sixpack Likes Antigravity

[i_am_nitrogen]

What this means to Joe Sixpack is that he's gonna have to wait for another year before he can swallow an antigravity pill to make his butt less sore from sitting on the same chair for 15 hours a day watching football. But seriously folks, is there any reason why your average Joe can't be interested in science? Why is it that science is so revolting? Perhaps its because in school our children are being taught (not by teachers, but by coaches and other students, and the mere fact that each sport individually receives three times as much money as music or physics at the average high school) that to be smart is to be stupid, and that to be stupid is to be cool. One study (sorry, don't have specific details) estimated that there could be as many as 2000 gifted individuals of the elementary-high school age in my state that are likely to never reach their full potential because of poor education limiting their opportunity to grow. Imagine where society would be if we spent half the money we're spending on this war on gifted education instead. We'd likely have a cure for cancer, AIDS, what have you. Wow, I really strayed from my Joe Sixpack joke topic!

Etre, ou n'etre pas?

Re:Joe Sixpack Likes Antigravity

[cronik]

According to hersay (a friend of mine in the atheletics department) the school district that I am in spent over 20,000 dollars to set up a football (American style) game. I was cool and all having two Palo Alto HS(s) playing football in the Stanford stadium, but the choir, band, and robotics (engr.paly.net) could have all been funded for a year off of that.

PS: sorry for not going with a html link, I'm too damn tired.

Re:Joe Sixpack Likes Antigravity

[Anonymous Coward]

Gifted students being overlooked by the Public School system in America is nothing new.

If it really bothers you, find out exactly how the details affect you and form a plan of action. It's not going to change any time soon.

Re:Joe Sixpack Likes Antigravity

[mmontour]

This site has some good "Joe Sixpack" antigravity (specifically, a live frog being levitated inside a solenoid). Nothing to do with neutrinos, though.

"Guitary"

[i_am_nitrogen]

Yes, I said guitary amplifiers, meaning amplifiers used for guitar-like, or therefore "guitary" purposes. Tube amps just sound so sweet! I love analog synths too.
Anyway... OT!

This is a tragedy

[Araneidae]

What the hell happened?
All the New York times article says is this:

"thousands of light detectors imploded in a chain reaction ... [it] must have had something to do with the [water] pressure ... [and] happened as the water tanks were being refilled after ... maintenance."

They've lost 70% of the detectors.
This was such a marvellous experiment: it will be a real shame if they don't bring it back soon.

probably no single stupid mistake

[mj6798]

Given that a lot of smart people were working on this for a long time, I doubt it was "titanically stupid mistake".

Here is a random guess at a scenario: someone dropped something or the detector was filled to quickly. The implosion of the first detector caused a chain reaction and caused nearby detectors to implode as well. You have to expect that these kinds of accidents happen.

I suspect that the people who built the device simply didn't expect a chain reaction of implosions. Maybe one can argue in hindsight that they "should have" thought of it, but it's not like people regularly build things that have thousands of vacuum tubes deep under water.

What would be stupid is if they anticipated the possibility of a chain reaction of implosions and decided "oh, we just aren't going to drop anything accidentally". We'll have to see whether anything like that eventually comes out. Until then, I'd hold my judgement.

Re:probably no single stupid mistake

[EasyTarget]

Given that a lot of smart people were working on this for a long time, I doubt it was "titanically stupid mistake".

Unlike, say, sending a probe all the way to Mars then having it burn up because two teams used different measurement units and forgot to convert them?

History is full of examples of very gifted and smart people making very simple but catastrophic mistakes, or totally failing to anticipate the consequences of their actions, this looks like another of them. At least nobody died in this one!

No matter how hard we (humanity) tries, things will go wrong, given the complexity of todays world it is probably unavoidable. But it is important that we at least learn.. And that is the good thing about this article, they are going to find the 'what' and 'why', and (if I read it correctly) make sure it does not happen again.

Re:probably no single stupid mistake

[SEWilco]

You're saying that a bunch of nuclear physicists didn't consider a chain reaction.

Re:probably no single stupid mistake

[Brett Viren]

The tank would have been closed durring filling, so nothing could have dropped in. The fill rate would certainly be close to the same as the first time it was filled (where no damage occured) and since the tank was more than half filled already when the event happened, I can't see how the fill rate would even come to play in this mystery.

The "cascade of implosions" was tested years ago, (but not in exactly the PMT configuration used in SK proper) and the neighboring PMTs were found to survive.

Re:probably no single stupid mistake

[JabberWokky]

Unlike, say, sending a probe all the way to Mars then having it burn up because two teams used different measurement units and forgot to convert them?

When, pray tell, did *that* ever happen? I recall the rather recent example of the Mars Lander, which crashed due to cumulative drift of significant digita due to repeated conversion of units back and forth, but no Mars probe that burned up "because two teams used different measurement units and forgot to convert them?"

--
Evan

Re:probably no single stupid mistake

[Steve Hamlin]

"NASA's Mars Climate Orbiter was lost in space last week because engineers failed to make a simple conversion from English units to metric, an embarrassing lapse that sent the $125 million craft fatally close to the Martian surface, investigators said yesterday."

Washington Post

**********

"In September 1999, the Mars Climate Orbiter presumably burned up in the Martian atmosphere because propulsion engineers failed to convert English and metric units.

Three months later, its sibling spacecraft the Mars Polar Lander likely crashed because a software glitch shut off the descent engines prematurely, sending it on a fatal plunge into the red planet."

CNN

Re:probably no single stupid mistake

[JabberWokky]

CNN (and dozens of news agencies including Reuters and possibly the Washington Post) go on and on about this anthrax virus that is going around. Damn shame there's no such thing. But there *is* a bacteria named anthrax that's being mailed.

If you believe that news is accurate...

BUT - in this case it was... I just read the Official Mishap Investigation Board Phase I Report... turns out that the problem was a small program called SM_FORCES that was to read a table of pound-second figures, while the table provided for the flight was in newton-second figures. Read the whole thing here.

--
Evan "Not too proud to admit when he's wrong"

Re:probably no single stupid mistake

[EasyTarget]

It's cool, I was going from memory of the reports at the time, so I would not have been at all surprised if a different explanation had arrived later (and cumulative errors actually sounds more likely to me, I've seen similar effects in feedback modelling systems I once worked with).

It just seemed like a fairly relevent example of the great and good cocking up.. There are others, but of course it's the failures that we remember, and we forget the vast majority of times when everything goes perfectly (because the same people got it right). Perhaps the real lesson here is that success needs more recognition..

PS. 100% with you on the quality of news reporting (look here), Always amazes me that the the news media are so quick to critisize errors in others, when they are the least accurate of all..

Re:probably no single stupid mistake

[mj6798]

The problem there wasn't the fact that people used wrong units in that one case. The problem was that (1) the US hasn't standardized on the metric system along with the rest of the world, and (2) that the NASA engineers didn't have software engineering procedures in place that required the presence of units on all data. Those are on-going, deep-rooted problems, and they are going to cause crashes and other problems over and over again until they get addressed.

Re:probably no single stupid mistake

[mj6798]

Unlike, say, sending a probe all the way to Mars then having it burn up because two teams used different measurement units and forgot to convert them?

You can't rely on people remembering to convert units--they will make these mistakes. The problem is that the US hasn't converted to the metric system, and that NASA software apparently does not use type systems and data files containing units throughout. Those aren't stupid mistakes, they are on-going, deep-rooted problems, and they will cause more crashes, guaranteed.

Why use PMTs over solid-state light detectors?

[sigwinch]

When you want to sense the raw quantity of light arriving (i.e., you don't care about direction, image, and color), PMTs are ludicrously good. They are absurdly linear over the range of one photon/year to millions of photons/second. (Solid-state detectors are notoriously nonlinear.) PMTs have a tremendous dynamic range. PMTs can measure the time of arrival of individual photons to the nearest nanosecond. (Solid-state devices tend to be much slower.) I don't know for sure, but I strongly suspect that large PMTs are vastly more reliable than equivalent solid-state detectors.

The real kicker is cost. Solid-state devices cost on the order of $1,000,000 per square meter of active area! PMTs are on the order of $100,000 per square meter. If you want hundreds of square meters of active area -- like in a neutrino observatory -- PMTs are the only way to go.

I know it felt funny when you wrote this....

[Cplus]

...but my major love of /. back in the day was that people who knew a little bit about the topic would chip in and we'd all learn more. My problem with /. today is that every jerkass with a wisecrack speaks up. Please Taco, we need a dumbass filter, now more than ever.

I expect that my comment will be modded down, as it is entirely offtopic, but I pray, with /. in mind that the parent gets modded down first and that others cry out against the idiocy that is running rampant on our beloved site.

Perhaps we should have two sections to every story, a 'for play' section and a 'for real' section where those that are informed can spread the knowledge.

Thank You

Re:yeah but...

[Shimbo]

there is still no fucking formal explanation, Mr. Man.

Well no. It will be looked into by 'committees' - reading between the lines, some sort of board of inquiry will be set up. When you decide to do a formal investigation, you don't preannounce the results even if you have a damn good idea what happened. You make sure your investigation process is transparent and fair to anyone whose career might suffer. These things take time to do properly.

PMT?

[tomknight]

Hey, they're spending $30m got restore PMT?

Man, those guys are masochists....

Tom.

Re:PMT?

[tomknight]

Fuck me, I can't type for toffee. I really should have used preview then.

I meant "...to restore...", not "...got restore...", of course. Ah, the ebb and flow of karma.

Tom.

Mod THIS up.

[SilverWeed]

I totally agree.

Further speculation

[jutus]

Further speculation...

Could it be possible that the tank was filled to capacity, and then some? Resulting in pressure high enough to implode the PVT's?

I'd think they'd have pressure gauges and/or backflow sensors. Who knows.

In any case, shit happens. Best of luck to the SuperK team in the rebuilding.

sell them some real estate in anartica

[Anonymous Coward]

I guess somebody done noticed it last time, but why don't they just make a cheap
ice one?

K2K

[ErfC]

Incidentally, K2K is sort of the other half of Super-K's job. It's an experiment where the KEK accellerator creates a neutrino beam and fires it through Japan (through the ground, through towns, farmers' fields, through the Japanese people...) at Super-K. The nice thing about neutrino beams is that you know what you're starting with and you can control the rate.

(I imagine it's probably also kind of hard to aim, since neutrinos are so hard to see in the first place... They have a "front detector" at KEK which gives them an idea of how many neutrinos they're starting with, and I think where they're shooting them. KEK and Super-K are 250 km apart, so even a slight miss can have a big impact on whether they hit Super-K or not, I think.)

Re:K2K

[krlynch]

I imagine it's probably also kind of hard to aim, since neutrinos are so hard to see in the first place...

Actually, it is (relatively) easy to aim, as long as you are done aiming before the neutrinos are produced... neutrino beams are made by accelerating protons into targets, which produces beams of charged pions, which are collimated and sent down a beam pipe pointing directly at Super-K. Some fraction of the pions (checking... checking... 99.9877% ) of the pions decay to a muon and a muon neutrino, going in the same direction as the pion (i.e., pointed directly at Super-K). All the muons and undecayed pions are stopped at the end of the beam pipe, and don't contribute to the beam. The hardest part of aiming is digging the tunnel in the right direction, but GPS makes that relatively easy these days.

Re:K2K

[caffeinated_bunsen]

(through the ground, through towns, farmers' fields, through the Japanese people...)

More like through the ground, under towns, farmers' fields, under the Japanese people. I'm not sure how far underground the KEK is, but I know the Super-K is quite a ways down, and then there's that whole curved earth thing. The beam doesn't reach the surface until somewhere in the Sea of Japan, I think.

Re:K2K

[Eric Sharkey]

I imagine it's probably also kind of hard to aim, since neutrinos are so hard to see in the first place.

It's not that hard. Don't think of it as aiming a gun. Think of it as aiming a flashlight. As the neutrino beam travels, it spreads out into a cone. The further away you get the "dimmer" the beam gets because the neutrino density goes down, but as long as you can generally aim the beam with some coarse precision, it doesn't matter how far away your target is, you can hit it.

Thursday update

[Tsar]

PhysicsWeb has this story providing additional detail about the accident, and their recovery plans.

the story so far

[lcarey]

my modern physics prof is working on the project. He looks like he hasn't slept in the past two days. They were refilling the cylinder, it was ~2/3 full, and one tube blew. shockwave. the surrounding tubes blew. everytube that was underwater at that time blew.It was a problem that they'd considered before, worried about, then forgotten as nothing worked. They'd emptied the detector in order to replace defective tubes, and apparently one/many of the new tubes had a problem. In three years they excpect to be back up and running.

Re:um oh

[Anonymous Coward]

too bad they decided to compress them so hard they're basicly ruined.

No, it isn't possible

[autopr0n]

It's been stated quite clearly that the tank was half full when it 'detonated' for lack of a better term...

Re:No, it isn't possible

[angst_ridden_hipster]

Ah, bit the pessimists assert that it was half empty at the time of 'detonation'.

*sigh*

[autopr0n]

Don't they teach math in highschool anymore?

Repair estimates top $30M...That comes out to approximately $300 million per day! Or we will spend what is required to fix the SuperK in 12 hours

No. $300/$30million = 1/10. We will spend the equivalent of the super-k repair in 1/10th of day, or 2.4 hours, or two hours, 24 minutes, not twelve. Of course, the cost of the war in Afghanistan is not constant, but that's not the point.

Haha

[autopr0n]

I hope this is meant as a joke, really. It's been modded as funny so..

Anyway, these PMTs are sensitive enough to detect a single photon, I doubt you'd be able to find a CCD that could do that.

scoop on what happened -insiders info

[paraquat]

I have heard from people close the the community several things.
1. The detectors that imploded/ did not implode
where seperated by the water line. I.E. Those under water imploded and the above the water line did not implode.
2. There is about 3 meters of broken glass in the bottom of the tank.
3. Nobody is sure of what will happen to funding or the experiment. (I realize this contradicts the the main thread explanation)

4. there was about 20 million in damage just in destroyed tubes. This is not counting water which was very expensive, near the theroetical purity of water. Or the cleanup and redisign cost.

_____________
Now for some speculation/opinion
1. It is the opinion of some people in the field that this could have possibly been prevented, by baffles, and partitions.
They either did not fully consider the affects of what could happen or they dismissed it.

2. This was a pretty prestigious experiment.
Liken this to Fermilab exploding in the US or
CERN in europe. This was one of the biggest if not the biggest experiment of its kind in the world. Also the most sensitive. (vs say Homestake)

3. Because of the prestige for the Japanese scientific community there is a very good chance funding to bring it back will come through.

4. Unless the tank itself is leaking. These tanks were not designed to survive a catastrophic event like this. If it leaks it probably will not be repairable. and the experiment is over

5. The tank will need to be drained and the glass removed, About 3 meters deep worth, and they will need to design a baffle system to keep this from happening again before they star again.

6. this could have been prevented acording to people in the community and was a known danger.

9. This suddenly makes funding for other competing projects in other place more available. Which is good for the other places. They may be secretly glad.

10. This is great for Hamamatsu, because they make the tubes and may get and order to replece them.

Re:scoop on what happened -insiders info

[paraquat]

p.s.
I forgot to add the general feeling, is that it was a single imposion due maybe to water pressure that touched off imposions in all of the tubes.

idiot poster

[Anonymous Coward]

Additionally - the tank will again be flooded with the same amount of water, and correspondingly, water pressure. With only half the amount of sensors - wont these sensors each have more pressure placed on them? Wasnt a collapse because of water pressure what caused the initial sensor implosion chain reaction?

NO! - the # of pmt's does not have anything to do with the pressure placed on each PMT - it's simple physics. Reducing the # of PMTs only has an effect on the granularity of their measurements - they may miss some events because of a lack of coverage - the more PMTs the easier it is to catch every event.

So reducing the # of PMTs should not cause more PMTs to implode - but you've obviously forgotten all of your basic physics principles

Learn how to spell, dude!

[Anonymous Coward]

Wow, painful to read your post.

Re:Learn how to spell, dude!

[Anonymous Coward]

FFS chill out, guys? Nobody's perfect, and the post was easily comprehensible. Who gives a crap about a few characters here and there? Ever heard of diversity of life?

Mystery solved

[leonbrooks]

http://www.electric-universe.de/ (warning: contains flash)

http://www.kronia.com/

...there are more, but those should be enough.

.

Re: You try doing some of this stuff

[Kris_J]

History is full of examples of very gifted and smart people making very simple but catastrophic mistakes, or totally failing to anticipate the consequences of their actions, this looks like another of them.

Just to clear things up, the reason why history isn't quite so full of ordinary people making stupid mistakes that that it's far more common and usually doesn't involve innovative projects -- thus rarely of historical note. Just thought I'd put that in to make the scientists feel a little less like everyone's favourite chew toy.

New Sign

[Wanker]

I bet when it's all fixed they have a new sign in 1000-point lettering which says:

NO FLASH PHOTOGRAPHY

Whoops. ;-)

"thier"

[Anonymous Coward]

Please! You can not just swap "i"and "e" at random. That word, "thier", looks as peculiar as a face with its nose drawn rotated a quarter turn, so its nostrils face left (or right) instead of down.

Something is terribly wrong in our methods of teaching reading, when our perceptions are sabotaged by mis-teaching to the point that we can't see how strange that misspelling looks.

Enby in Waltham