Slashdot Mirror

To whom it conCERNs.

The world seems to be more complex than just wired up.

CC.

Try http://jenni.web.cern.ch/jenni/BT.9Nov06.jpg

IAAPP and that part with black holes is pure fiction. A black hole is a singularity at level of space-time fabric. Quark Pluon Plasma is a state in which quarks and gluons are almost free because of high confined state. From what we know until _now_ one has nothing to do with the other.However, __IF__ they(black holes) will be produced, the evaporation time will be at level of ns. So .. the afirmation that: "one of the purposes of this huge facility is to generate small blackholes" is completly false. Better read at www.cern.ch and also http://aliceinfo.cern.ch/ (home page of ALICE experiment) which is an experiment dedicated to study of Quark Gluon Plasma

I was wondering what the magnetic field strength of this magnet would be, but the FA is a light on details. But there's a pamphlet!

Peak field strength for the barrel toroid magnet is 3.9 Tesla. And apparently it will take 30 days to cool the thing down with liquid helium to operating temperature.

Basically, the accelerator itself and therefore the particules are going through ATLAS. Collisions between particules (going in opposite directions) are setup to happen within the core of ATLAS. The objective is to build various layers of (different types of) detectors around this point of collision to search for specific particules with a very short lifetime generated by the collision.

http://atlas.web.cern.ch/Atlas/TCOORD/Activities/I nstallation/atlas_overview.gif

These differents layers of detection generate lots of data that is filtered to isolate a few 'interesting' events, which can then be processed by the computing Grid.

Romain.

There is about 1 GJ of energy stored in the magnet when it is at full strength. I don't remember my TNT converstions, but admitedly that is a lot. The energy is disapated through resistors and that heat is dumped into a LOT of mass all while actively cooling everything. Here is a pretty picture of the current as a function of time during the test (notice how fast it was shut down) http://jenni.web.cern.ch/jenni/BT.9Nov06.jpg/ The axis are in amps and minutes by the way. And yes, that is ~20,000 amps. As another intresting LHC note, the magnets in the accerator store ~11GJ of energy which is disapated into something like 50 tonns of steel. This is (breaking out the obscure unit conversions) the energy of something like 40 bullet trains traveling at full speed, or a nuclear aircraft carrier traveling at full speed. The energy stored in the actual beam of protons is also not anywhere near negligible and systems had to be designed to dump all of this energy as well.

> why do we need to bend the particles path

I am not a particule physicist, but the particules need be accelerated and are 'pushed' by the magnets before being collided, so they need to circulate many times around the accelerator in order to get sufficient speed.

"A beam might circulate for 10 hours, travelling more that 10 billion kilometres, enough to get to the planet Neptune and back again. At near light-speed, a proton in the LHC will make 11 245 circuits every second."

What is the LHC power consumption?

It is around 120 MW which corresponds more or less to the power consumption for households in the Canton (State) of Geneva."
http://public.web.cern.ch/Public/Content/Chapters/ AskAnExpert/LHC-en.html

> why does the magnet need to be super cooled?

To magnets are used also to maintain the beam within its path, and the requires huge amount of energy to create a magnetic field that is strong enough to prevent the beam to escape. These magnets are using a massive amount of power, and must be cooled down (a lot) do reduce their electrical resistance down to supraconductivity.

"In order to cool the magnets down to -193.16 C (pre-cooling), 10 080 tonnes of liquid nitrogen will be used. Afterwards, the refrigerators turbines will bring the helium temperature down to -268.7 C and fill the magnets with almost 60 tonnes of liquid helium. Once the magnets are filled, the refrigeration units will bring the temperature down to -271.3 C by lowering the saturation pressure - and therefore the temperature - of the liquid helium in a heat exchanger in contact with the static pressurized helium of the magnets' cold masses."
http://public.web.cern.ch/Public/Content/Chapters/ AskAnExpert/LHC-en.html

http://en.wikipedia.org/wiki/Large_Hadron_Collider
For reference, the LHC will also use a massive computing Grid: http://www.cern.ch/LCG/

Romain.

> why do we need to bend the particles path

I am not a particule physicist, but the particules need be accelerated and are 'pushed' by the magnets before being collided, so they need to circulate many times around the accelerator in order to get sufficient speed.

"A beam might circulate for 10 hours, travelling more that 10 billion kilometres, enough to get to the planet Neptune and back again. At near light-speed, a proton in the LHC will make 11 245 circuits every second."

What is the LHC power consumption?

It is around 120 MW which corresponds more or less to the power consumption for households in the Canton (State) of Geneva."
http://public.web.cern.ch/Public/Content/Chapters/ AskAnExpert/LHC-en.html

> why does the magnet need to be super cooled?

To magnets are used also to maintain the beam within its path, and the requires huge amount of energy to create a magnetic field that is strong enough to prevent the beam to escape. These magnets are using a massive amount of power, and must be cooled down (a lot) do reduce their electrical resistance down to supraconductivity.

"In order to cool the magnets down to -193.16 C (pre-cooling), 10 080 tonnes of liquid nitrogen will be used. Afterwards, the refrigerators turbines will bring the helium temperature down to -268.7 C and fill the magnets with almost 60 tonnes of liquid helium. Once the magnets are filled, the refrigeration units will bring the temperature down to -271.3 C by lowering the saturation pressure - and therefore the temperature - of the liquid helium in a heat exchanger in contact with the static pressurized helium of the magnets' cold masses."
http://public.web.cern.ch/Public/Content/Chapters/ AskAnExpert/LHC-en.html

http://en.wikipedia.org/wiki/Large_Hadron_Collider
For reference, the LHC will also use a massive computing Grid: http://www.cern.ch/LCG/

Romain.

> why do we need to bend the particles path

I am not a particule physicist, but the particules need be accelerated and are 'pushed' by the magnets before being collided, so they need to circulate many times around the accelerator in order to get sufficient speed.

"A beam might circulate for 10 hours, travelling more that 10 billion kilometres, enough to get to the planet Neptune and back again. At near light-speed, a proton in the LHC will make 11 245 circuits every second."

What is the LHC power consumption?

It is around 120 MW which corresponds more or less to the power consumption for households in the Canton (State) of Geneva."
http://public.web.cern.ch/Public/Content/Chapters/ AskAnExpert/LHC-en.html

> why does the magnet need to be super cooled?

To magnets are used also to maintain the beam within its path, and the requires huge amount of energy to create a magnetic field that is strong enough to prevent the beam to escape. These magnets are using a massive amount of power, and must be cooled down (a lot) do reduce their electrical resistance down to supraconductivity.

"In order to cool the magnets down to -193.16 C (pre-cooling), 10 080 tonnes of liquid nitrogen will be used. Afterwards, the refrigerators turbines will bring the helium temperature down to -268.7 C and fill the magnets with almost 60 tonnes of liquid helium. Once the magnets are filled, the refrigeration units will bring the temperature down to -271.3 C by lowering the saturation pressure - and therefore the temperature - of the liquid helium in a heat exchanger in contact with the static pressurized helium of the magnets' cold masses."
http://public.web.cern.ch/Public/Content/Chapters/ AskAnExpert/LHC-en.html

http://en.wikipedia.org/wiki/Large_Hadron_Collider
For reference, the LHC will also use a massive computing Grid: http://www.cern.ch/LCG/

Romain.

This was once featured on slashdot and for those confused, this is just a part of the world largest (longest) particle accelerator thing and one of the purposes of this huge facility is to generate small blackholes.

http://public.web.cern.ch/Public/Content/Chapters/ Spotlight/SpotlightATLAS-en.html

The first web page [was] http://nxoc01.cern.ch/hypertext/WWW/TheProject.htm l. Unfortunately CERN no longer supports the historical site

This is why I hate people. What self-respecting scientific establishment would fail to maintain such a significant piece of modern technological history? Without even so much as a C record and redirect to a maintained hosted copy? Such a notion should not be difficult for the inventors of the first web server, suck though it may have.

Although the blurb explicitly claims that this new bootloader is "more powerful" than NTLDR/boot.ini, in fact it sounds like this new loader is doing the same thing (starting grup/lilo/etc. from the windows boot loader) that people have been doing for ages with NTLDR. Here is an ancient HOWTO on how to do it.

Here's something that describes a theory and experiements by danish scientists. The statement that it is only in the US that people is arguing the global warming because of the oil industry is simply false and an easy way to discredit the research done by those who you do not agree with.

These guys aren't saying that CO2 might not be one of the causes but that it might not be the biggest cause.

source: http://denmark.dk/portal/page?_pageid=374,931599&_ dad=portal&_schema=PORTAL

"Results from an experiment, called SKY (Danish for 'cloud'), show that the released electrons significantly promote the formation of building blocks for cloud condensation nuclei on which water vapour condenses to make clouds.

Hence, a causal mechanism by which cosmic rays can facilitate the production of clouds in Earth's atmosphere has been experimentally identified for the first time.

The Danish research team, headed by Henrik Svensmark, officially announced their discovery 4 october 2006 in Proceedings of the Royal Society A, published by the Royal Society, the national academy of science, United Kingdom."

The place they performed the experiments: http://en.wikipedia.org/wiki/Cern http://public.web.cern.ch/Public/Welcome.html


"Global warming caused by cosmic rays?

It is known that low-altitude clouds have an overall cooling effect on the Earth's surface. Hence, variations in cloud cover caused by cosmic rays can change the surface temperature. The existence of such a cosmic connection to Earth's climate might thus help to explain past and present variations in Earth's climate.

Interestingly, during the 20th Century, the Sun's magnetic field which shields Earth from cosmic rays more than doubled, thereby reducing the average influx of cosmic rays. The resulting reduction in cloudiness, especially of low-altitude clouds, may be a significant factor in the global warming Earth has undergone during the last century."

More info here:
http://en.wikipedia.org/wiki/Solar_variation#_ref- Svensmark1998_0

the problem is that those predictions are currently beyond our experimental powers. i believe the most near-term prediction could be supported if supersymmetric particles are observed at the large hadron collider when it's completed.

According to this safety report(PDF), commissioned by CERN, there is no perceivable threat.

Yeah.. I totally agree.

It's like this PC thing that everybody seems to be talking about nowadays..
I have no idea what the fuck it means.. Post-Communist? But why would somebody like to have one at home, then? Particle Collider? I've heard the one in Switzerland has a diameter of several miles, but my friend told me he has a PC at home and his flat isn't that large.

I'm confused.. ;-)

The pool of images is pretty small (or at least it was yesterday). A couple sites keep popping up (pictures of the aurora borealis, pictures of various galaxies and nebulae from NASA, etc.). The most annoying of these is a site with some time-lapse photos of the construction of the ATLAS experiment at CERN. The pictures show what looks like a construction site, with some blue-painted metal, and a large circular hole in one of the walls. You could figure out what it is by following the link below the photo after you're done playing the game. Just bypassing that step to hopefully reduce a little frustration :) IT'S "ATLAS" or "CERN"!!! Hopefully your partner will know that too. BTW, just wanted to point out that a good way to jump up the rankings is to get a partner who agrees with you to label every picture "foo", regardless of its contents.

Python is interpreted, not compiled. When you distribute a python app, you are distributing its source.

Actually, it's possible to compile Python into Java-style bytecode or native binary. See Psyco for example.

While it's true that Python is mostly used as an interpreted language, it's not a part of the language definition. Conversely, there are interpreters for languages like C++, I've used one as a part of the ROOT system. ROOT users often compile into native binaries when their code is getting into production level. The same goes for Matlab, for example.

On the other hand, I believe that distributing software as source is much better than the binary, even if you don't have a GPL-like permission to modify/distribute it further. I believe one reason why the www got mainstream is that pages were distributed as source, so people could learn HTML from each other.

The fact that the average cost of a kb/S in Africa is 4 to 8 USD ( ( http://event-africa-networking.web.cern.ch/event-a frica-networking/cdrom/Joint_Internet2_IEEAF_works hops/EnhancingAfricanResearchandEducationNetworks/ 20050505-AFRICA-STEINER.pdf ) as opposed to about 12 cents in the US, may have a lot to do with the relative
scarcity of African Wikipedists.

If it cost you 50 times as much every time you logged onto the net, you too might waste less time contributing to a free encyclopedia. Even if you weren't poorer, which most Africans likely are.

Well, actually I used to do work with (IT support, nothing fancy) for part of the SUCIMA http://accelconf.web.cern.ch/accelconf/d03/papers/ CT09.pdf team (Badano, Ferrando e Pezzetta).
Well, the monitor uses a CCD indeed. Problem with CCDs is that usually it's a destructive monitor (it destroys the particle beam), so you must do some tricks (read the pdf) if you want to keep it.

Wiki - "The first Web site built was at http://info.cern.ch/ [2] and was first put online on August 6, 1991. It provided an explanation about what the World Wide Web was, how one could own a browser and how to set up a Web server. It was also the world's first Web directory, since Berners-Lee maintained a list of other Web sites apart from his own."
http://www.thesecondchancemovie.com/_site/mediapla yer/index.php?id=9f72b0fbe5bde711a0696cac5b339a5e/

In a study by CERN (you know them as the inventor of the WWW) in 1996 they calculated an energy payback in around 6 years for Switzerland (which perhaps is the most beautiful place on earth but definitly not the most sunniest). In 2000 they updated their calculations and ended up with a number of appr. 4 years.
Solar cell technology has made a lot of significant advances in the last 10 year. Bank Sarasin, one of the biggest European advisor for ecological safe investments, concludes on page 30 that with modern solar cells energy payback comes after 1.5 to 2.5 years, depending on technology and country (1.5 years for the most modern, in production technology in Southern Europe, comparable to Florida; 2.5 years for middle Europe, comparable to New York).

One manufacturer of solar cells even claims 0.85 years with their "Dünnfilmtechnologie" (is flat film a suitable translation?), see on page 3 here (Enegierückzahldauer = amount of time for energy payback) .

So your 6 year number is definitly old.

Bye egghat.

The point of visualizing data is to learn something that you could not do with the raw data. In all of the cases shown in the article (yes, I acually read TFA), I didn't spot an example where it actually showed anything useful.

I don't think you can conclude so easily that a visualization is useless.

This plot gives a lot of information about the resonances involved in a particular annihilation process and their relative phases. [More info here.] But you have to know how to interpret it. Without training, you would not be able to tell whether it is meaningful or not.

Since when is this a new idea? I heard about people doing stuff like this years ago.

http://neuralnets.web.cern.ch/NeuralNets/nnwInHepH ard.html
http://www.particle.kth.se/~lindsey/elba2html/sect ion3_5.html
http://www.cs.ucl.ac.uk/staff/D.Gorse/research/pRA M.html
http://www.kcl.ac.uk/neuronet/about/roadmap/hardwa re.html

The OP may be trying to be funny, but in fact a modern Fortran (F90/95) is easy to do string manipulation in, has dynamic memory, is type-safe, and is arguably a much higher-level language than C.

*sigh* I was definitely serious. I have a background in scientific computing, which is how I've gotten to know Fortran's strengths. And I don't like the fact that the physics world is moving towards C++, though the tools involved (such as Root) are arguably better in some respects.

This is certainly not the first time that my 'insightful' and 'funny' intentions were confused... perhaps the 'me too' style of my original post didn't help much :-/

...but the W3C seems 15 years behind everything...

Dude, you clearly have no idea what you're talking about.
15 years ago the world wide web hadn't even been announced.
Care to check out this usenet post?
That's right, 15 years ago the only publicly accessible web server
was http://info.cern.ch/ and even this one wasn't
widely known outside of CERN at the time...

At timecode 1:39 he claims that the protons are travelling around the 27km at 50,000 times/second. This gives them a speed of 1.3m km/sec, over 4 times the speed of light ;). Impressive!

Apparently they travel 11,000 times a second around the 27km, reaching 0.999997828 the speed of light.

LHC Facts

If you'd like to pitch in yourself and help the LHC project, running LHC@Home is a great way! They use your CPU cycles to simulate particles traveling in the LHC. The server might be out of work units at the moment, but there are, of course, other cool projects that use the same BOINC client that you might not have heard of, like Einstein @ Home that helps the LIGO project searching for gravity waves.

Sadly CERN does not research anti-matter in the sense you are thinking of. Anti-matter is unlikely to ever be a source of power as you have to make it. At best you could use it as a battery but thats so far off right now its science fiction because its really really hard to make anti-matter. At CERN's current production rate (people have been making and studing anti-matter for a long time now), we'll have enough anti-hydrogen to fill a ballon in about 25,000,000 billion years

Antimatter and its production mechanisms is fairly well understood with the exception of the matter-antimatter asymmetry we observe in the universe today. And incidently the LHC will be the first particle physics collider (I think, with the exception of heavy ion colliders) that will not use anti-matter particles in either of its two beams. Its a proton-proton collider unlike the Tevatron which is proton-antiproton. It gets round the seeming lack of anti-matter because protons actually contain anti-matter in the form of sea quarks and at high enough energyies you end up probing them rather than the valence quarks.

FWIW Cern is in Switzerland, just outside of Geneva. Although the LHC ring is large enough to cross the border into France.

Les Horribles Cernettes are quite nerdcore in their own way. "I feel your attraction It's a strong interaction" seems quite the right words if you're the world's "one and only High Energy Rock Band".

Oh, and check the lyrics for liquid nitrogen too.

Les Horribles Cernettes are quite nerdcore in their own way. "I feel your attraction It's a strong interaction" seems quite the right words if you're the world's "one and only High Energy Rock Band".

Oh, and check the lyrics for liquid nitrogen too.

The US is helping quite a bit with the LHC, in addition to many other non-European countries. I'm not sure how you came up with the 20-year European lead on particle physics (maybe you pulled it out of your ass), but as with any other research facility I'm sure there will be plenty of US scientists making progress there. How many European scientists do you think are working with NASA on the Mars rover data? Quite a few. The US is already putting billions behind the LHC, doesn't seem obvious that US scientists would contribute significantly to LHC research once it's fully built? Major research is largely an international affair today; most mature scientists put patriotism aside (unless you think Harvard's being pro-Bush by researching with stem cells).

"Europe and Japan are doing advanced medical research" - such as? And the US isn't? Stem cells aren't the last word in medical science. The US stem cell situation sucks to be honest, but that's not enough to pass judgment on any nation's medical progress. I wouldn't be surprised if the 2008 presidential election changed things dramatically, possibly moreso than the 2004 election did. Why couldn't it?

Yes, the Hubble is dead. That's why there are multiple replacemetns being proposed. I'm intrigued by your claim that NASA's abandoning manned space travel; I suppose this whole Project Constellation business is a great hoax, and that Lockheed and Boeing are in on it too. Yes, the US wants to militarize space, but they're doing a lot more too. And the Taikonauts are a joke compared to the routine ISS missions by NASA.

Seriously, if you don't know what the fuck you're talking about, just shut up.

Over in the particle physics world, they're putting together some sort of grid for LHC. Seems to be a rather large undertaking.

So, does providing an apt repository for the nvidia
proprietary drivers (as CERN does for their scientific
linux version, which is a recompiled RHEL, as documented at
http://linux.web.cern.ch/linux/scientific3/docs/nv idia.shtml)
violate the GPL? CERN does the same for the ATI drivers.
Clearly they should be big enough (and probably have
enough real lawyers) to have addressed the GPL issues.

So instead of building something like a $1.000.000.000 LHC an $10.000.000 award is offered?

That sounds like an excellent idea, to save budget atleast.

it took me a week to compile firefox on my "standard" windows xp box, and the by-far-the-best online guide i found (http://pryan.org/firefox/TierMann/page/building/p ackages.html) after hammering google and the mozilla forums was out of date (referred to "microsoft sdk" instead of "microsoft platform sdk" thus messing up a lot of paths in the provided examples) still required tinkering (my activeperl installation conflicted with the cygwin perl, why i needed perl to compile a C++ app was not explained) and was not complete (a linker lib was missing, which i eventually found at the bottom of a swiss web page) a linker error occurred, which required a manual change in the source code) and the MOZ_CONFIG_BOOBAA system was never fully explained and i think i got a working config by pure happy chance.

and just to prove it this is the content of my c:/mozilla/setup/notestoself.txt

use: c:/mozilla instead of c:/home

(the compile path will then be c:/mozilla/mozilla !)

the "mozconfig" file needs to go in c:/mozilla/mozilla

some files are "missing" from the vc++ toolkit, namely lib.exe and supporting dlls, these can, bizzarely be snatched from the platform sdk's 64bit bin directory

make sure the INCLUDE paths point to "microsoft platform sdk/include" and not "microsoft sdk/whatever"

checkout:

make -f client.mk checkout MOZ_CO_PROJECT=browser

build:

make -f client.mk build

download msvcprt.lib from here:

http://root.cern.ch/root/Procedure/Procedure%20to% 20install%20the%20free%20Microsoft%20Visual%20C.ht m

LINK : fatal error LNK1104: cannot open file 'atlthunk.lib'

Change AllocStdCallThunk and FreeStdCallThunk at line 287 of PSDK/include/atl/atlbase.h to the new macros: /* Comment it
PVOID __stdcall __AllocStdCallThunk(VOID);
VOID __stdcall __FreeStdCallThunk(PVOID);

#define AllocStdCallThunk() __AllocStdCallThunk()
#define FreeStdCallThunk(p) __FreeStdCallThunk(p)

#pragma comment(lib, "atlthunk.lib")
*/
#define AllocStdCallThunk() HeapAlloc(GetProcessHeap(),
                                                            0, sizeof(_stdcallthunk))
#define FreeStdCallThunk(p) HeapFree(GetProcessHeap(), 0, p)

http://public.web.cern.ch/Public/Welcome.html 'nuff said.

There's that, of course, but don't forget computing grids. It's a scientific network afterall. Look at the european Geant network and how crucial it is for the CERN's grid projects. When you have petabytes of data, hundreds of scientists in many places, a single data center just won't cut it. A fast network, which allows multiple high-throughput (latency and jitter aren't important) connections to petabytes of storage and teraflop supercomputers is a very nice thing. For some scientific projects it's a must.

Just look what EU is doing: EGEE. As an application see e.g. LCG. Without a fast network this just would not be possible.

Since you asked: http://www.cern.ch/

I may be wrong here, but from what I remember from high school LEDs produce light by making an electrical arc over a _very_ short distance.

No, LEDs work by using a voltage to push charge carriers in a semiconductor diode above the "bandgap" of the diode (the energy level at which the diode starts to conduct, which is determined by the type of semiconductor material used).

One part of the diode has positive charge carriers, the other has negative charge carriers, like so: +V ---{ p | n }--- V- Because like charges repel, the positive voltage pushes the positive charge carriers to the p-n junction in the center and the negative voltage also pushes the negative charge carriers to the p-n junction. The energy released when the positive and negative charges combine in the p-n junction comes out as light of a frequency (color) determined by the bandgap voltage.

This is a quantum process: Energy = Planck's constant * frequency (or E = h*f, often written E=h*v - that's a nu, not a v).

Sparks require a voltage that is higher the farther apart the electrodes are, and the highest frequency light produced does depend on the voltage, but sparks produce broad rather than monochromatic spectra with energy emitted down to very low frequencies.

**
As an aside, one can measure Planck's constant using LEDs:

Since the energy per charge carrier is the voltage times the charge (Electron-volts, which can be converted to Joules by multiplying by the factor coulombs per electron, 1.6E-19) and the wavelength is known from the manufacturer's data sheets and can be converted to frequency by:

frequency(Hz, 1/s) = speed of light(3E8 m/s) divided by wavelength(m, usually listed in nm = 10E-9m), given LEDs of known frequencies one can measure Planck's constant.

h = E/f = [V*(1.6E-19 Coulombs)*(wavelength in nm)*(1E-9 m/nm)]/(3E8 m/s) or

h (in Joule-seconds) = 5.3E-37 giga-coulomb-seconds * voltage * wavelength in nm.

Other factors make this an inaccurately low measure - the voltage needed to light the LED is lower than E = hf would indicate. (Perhaps it's the high energy tail in the distribution of thermal electron energies?)

A potentially more accurate way to get h is to note that in E = h*f, when E is graphed against f, then h is the slope of the line. Variations in eye sensitivity and LED efficiency also introduce inaccuracies here, but green and orange LEDs seem to give a slope very close to the correct number.

(Also note that you need single-color diodes - the "yellow" diodes commonly found are really red+green in a single package.)

See CERNs page on Jules Hoult's high school lab lesson plan:
lab sudent worksheet
results results graph

I may be wrong here, but from what I remember from high school LEDs produce light by making an electrical arc over a _very_ short distance.

No, LEDs work by using a voltage to push charge carriers in a semiconductor diode above the "bandgap" of the diode (the energy level at which the diode starts to conduct, which is determined by the type of semiconductor material used).

One part of the diode has positive charge carriers, the other has negative charge carriers, like so: +V ---{ p | n }--- V- Because like charges repel, the positive voltage pushes the positive charge carriers to the p-n junction in the center and the negative voltage also pushes the negative charge carriers to the p-n junction. The energy released when the positive and negative charges combine in the p-n junction comes out as light of a frequency (color) determined by the bandgap voltage.

This is a quantum process: Energy = Planck's constant * frequency (or E = h*f, often written E=h*v - that's a nu, not a v).

Sparks require a voltage that is higher the farther apart the electrodes are, and the highest frequency light produced does depend on the voltage, but sparks produce broad rather than monochromatic spectra with energy emitted down to very low frequencies.

**
As an aside, one can measure Planck's constant using LEDs:

Since the energy per charge carrier is the voltage times the charge (Electron-volts, which can be converted to Joules by multiplying by the factor coulombs per electron, 1.6E-19) and the wavelength is known from the manufacturer's data sheets and can be converted to frequency by:

frequency(Hz, 1/s) = speed of light(3E8 m/s) divided by wavelength(m, usually listed in nm = 10E-9m), given LEDs of known frequencies one can measure Planck's constant.

h = E/f = [V*(1.6E-19 Coulombs)*(wavelength in nm)*(1E-9 m/nm)]/(3E8 m/s) or

h (in Joule-seconds) = 5.3E-37 giga-coulomb-seconds * voltage * wavelength in nm.

Other factors make this an inaccurately low measure - the voltage needed to light the LED is lower than E = hf would indicate. (Perhaps it's the high energy tail in the distribution of thermal electron energies?)

A potentially more accurate way to get h is to note that in E = h*f, when E is graphed against f, then h is the slope of the line. Variations in eye sensitivity and LED efficiency also introduce inaccuracies here, but green and orange LEDs seem to give a slope very close to the correct number.

(Also note that you need single-color diodes - the "yellow" diodes commonly found are really red+green in a single package.)

See CERNs page on Jules Hoult's high school lab lesson plan:
lab sudent worksheet
results results graph

I may be wrong here, but from what I remember from high school LEDs produce light by making an electrical arc over a _very_ short distance.

No, LEDs work by using a voltage to push charge carriers in a semiconductor diode above the "bandgap" of the diode (the energy level at which the diode starts to conduct, which is determined by the type of semiconductor material used).

One part of the diode has positive charge carriers, the other has negative charge carriers, like so: +V ---{ p | n }--- V- Because like charges repel, the positive voltage pushes the positive charge carriers to the p-n junction in the center and the negative voltage also pushes the negative charge carriers to the p-n junction. The energy released when the positive and negative charges combine in the p-n junction comes out as light of a frequency (color) determined by the bandgap voltage.

This is a quantum process: Energy = Planck's constant * frequency (or E = h*f, often written E=h*v - that's a nu, not a v).

Sparks require a voltage that is higher the farther apart the electrodes are, and the highest frequency light produced does depend on the voltage, but sparks produce broad rather than monochromatic spectra with energy emitted down to very low frequencies.

**
As an aside, one can measure Planck's constant using LEDs:

Since the energy per charge carrier is the voltage times the charge (Electron-volts, which can be converted to Joules by multiplying by the factor coulombs per electron, 1.6E-19) and the wavelength is known from the manufacturer's data sheets and can be converted to frequency by:

frequency(Hz, 1/s) = speed of light(3E8 m/s) divided by wavelength(m, usually listed in nm = 10E-9m), given LEDs of known frequencies one can measure Planck's constant.

h = E/f = [V*(1.6E-19 Coulombs)*(wavelength in nm)*(1E-9 m/nm)]/(3E8 m/s) or

h (in Joule-seconds) = 5.3E-37 giga-coulomb-seconds * voltage * wavelength in nm.

Other factors make this an inaccurately low measure - the voltage needed to light the LED is lower than E = hf would indicate. (Perhaps it's the high energy tail in the distribution of thermal electron energies?)

A potentially more accurate way to get h is to note that in E = h*f, when E is graphed against f, then h is the slope of the line. Variations in eye sensitivity and LED efficiency also introduce inaccuracies here, but green and orange LEDs seem to give a slope very close to the correct number.

(Also note that you need single-color diodes - the "yellow" diodes commonly found are really red+green in a single package.)

See CERNs page on Jules Hoult's high school lab lesson plan:
lab sudent worksheet
results results graph

My favourite is ALICE. Straight down to the
rabbit hole.

Cheers!

Nick.

Actually....there is a better argument that it actually does not exit.

http://cdsweb.cern.ch/search.py?recid=622019

I find it amazing that that not one mention of Peter Lynds is on any of these pages, since he seems to be the main proponant of a fairly new theory about time/space/movement which has been getting some press lately.

http://cdsweb.cern.ch/search.py?recid=622019

Abstract:

It is postulated there is not a precise static instant in time underlying a dynamical physical process at which the relative position of a body in relative motion or a specific physical magnitude would theoretically be precisely determined. It is concluded it is exactly because of this that time (relative interval as indicated by a clock) and the continuity of a physical process is possible, with there being a necessary trade off of all precisely determined physical values at a time, for their continuity through time. This explanation is also shown to be the correct solution to the motion and infinity paradoxes, excluding the Stadium, originally conceived by the ancient Greek mathematician Zeno of Elea. Quantum Cosmology, Imaginary Time and Chronons are also then discussed, with the latter two appearing to be superseded on a theoretical basis.

Hell, do we even have the capabilities to smash two high energy protons together?

Well particle accelerators have been smashing high-energy protons together for a long time... but can we smash them hard enough to create micro-black-holes? No. ... not yet, anyways. But that's why the Large Hadron Collider is being built! This is the frontier of particle physics.

I'd be interested to know how they intend to measure the micro-black holes.

The LHC has been in the works for a long time, and should come online sometime in 2007. This instrument will be able to probe these questions, and set limits on the possibility of micro-black hole production, as well as extra dimensions.

You did fine. ;)

I'm glad I was able to explain at least something clearly. Maybe there is hope for me yet...

It indeed seems that the CMS home page is written for physicists or physics students. It basically tells nothing a non-physicist or non-engineer would like to know. This is quite sad.

The CERN public pages seem to be more newbie-friendly.

The purpose of these experiments and the importance of the results to our understanding of the universe is indeed important to explain... Not only because it might be good for also non-physicists to know something about these things but also because (if told correctly) it is a very intriguing and nice story, that is, very good PR! We foolish physicists are wasting an excellent tool that could be used to increase the public awareness and interest in basic research. And naturally the politicians making decisions about funding are mostly non-physicists too...

200TB of Xserve RAID storage (link includes pictures)

Text of the article:

The University of Wisconsin - Madison has deployed 35 5.6TB Xserve RAID storage arrays in a single research installation as part of an ongoing scientific computing initiative.

The Grid Laboratory of Wisconsin (GLOW), a partnership between several research departments at the University of Wisconsin, have installed almost 200TB, or 200,000GB, of Xserve RAID arrays.

As a comparison, 200TB of storage is enough to hold 2.75 years of high definition video, 25,000 full length DVD movies, 323,000 CDs, 20 printed collections of the Library of Congress, or over 1000 Wikipedias.

The GLOW storage installation is physically split between the departments of Computer Sciences and High Energy Physics. Each Xserve RAID is attached to a dedicated Linux node running Fedora Core via an Apple Fibre Channel PCI-X Card and is either directly accessed via various mechanisms, such as over the network via gigabit ethernet, or aggregated using tools such as dCache.

The storage is primarily used to act as a holding area for large amounts of data from experiments such as the Compact Muon Solenoid (CMS) and ATLAS experiments at the Large Hadron Collider at CERN.

200TB of Xserve RAID storage (link includes pictures)

Text of the article:

The University of Wisconsin - Madison has deployed 35 5.6TB Xserve RAID storage arrays in a single research installation as part of an ongoing scientific computing initiative.

The Grid Laboratory of Wisconsin (GLOW), a partnership between several research departments at the University of Wisconsin, have installed almost 200TB, or 200,000GB, of Xserve RAID arrays.

As a comparison, 200TB of storage is enough to hold 2.75 years of high definition video, 25,000 full length DVD movies, 323,000 CDs, 20 printed collections of the Library of Congress, or over 1000 Wikipedias.

The GLOW storage installation is physically split between the departments of Computer Sciences and High Energy Physics. Each Xserve RAID is attached to a dedicated Linux node running Fedora Core via an Apple Fibre Channel PCI-X Card and is either directly accessed via various mechanisms, such as over the network via gigabit ethernet, or aggregated using tools such as dCache.

The storage is primarily used to act as a holding area for large amounts of data from experiments such as the Compact Muon Solenoid (CMS) and ATLAS experiments at the Large Hadron Collider at CERN.