Feminist Friday
 

Discuss.

I don't get it

Time to go to a Vail resort! :rock_dj:

What?

[QUOTE=The Law;3630561]What?[/QUOTE]

[IMG]https://media.giphy.com/media/glmRyiSI3v5E4/giphy.gif[/IMG]

[QUOTE=Rev. Rob Large;3630562][IMG]https://media.giphy.com/media/glmRyiSI3v5E4/giphy.gif[/IMG][/QUOTE]

You aren't doing anything. Drop some knowledge.

Physics with Samir!

Yesterday was the birthday of one of the co-discoverers of, what is now known as, Cerenkov radiation seen here as the eerie blue glow in the water surrounding the fuel cells:

[IMG]http://www.geek.com/wp-content/uploads/2014/07/cherenkov-glow-2.jpg[/IMG]

One of the fundamental laws of physics is the Law of the Conservation of Energy. This law states that, in a closed system, all energy is conserved over time--everything going in must come out. When the brakes are applied on a moving vehicle, the energy "spent" to slow the car down (friction) is converted to heat and sound (a fact I know all too well in my car), and thus energy before and after the braking event is conserved.

In the case of highly radioactive material, vis a vis fuel cells in a pool of water of a nuclear reactor, the particles emitted by the material are travelling faster than the speed of light in that medium. When those particles start colliding with the surrounding medium, in this case the water, and with each other, they are slowed down and the excess energy from these collision events is given off as photons/light.

Now, I know what you’re thinking: “But, Rob, most nuclear reactors use uranium-235 as a fuel source and that is an alpha-emitter. Alpha particles are massive and slow, and can’t possibly travel faster than a massless photon!”, and you’d be correct. The Cerenkov radiation observed in most nuclear reactors is not from the emitted alpha radiation, but from the neutrino events associated with the beta radiation from the U-235 decay chain. The muon-neutrinos and electron-neutrinos interact with the protons in the surrounding medium giving off the excess energy after conversion to a muon and neutron or an electron and neutron, respectively, as a photon observed as Cerenkov radiation. Which leads me to my next topic: neutrons. Neutrinos are boring—tiny little charge-less leptons that don’t interact with anything. Neutrons, however, are far more interesting. Yes, they are charge-less like neutrinos, but they are far more useful. Since about half of the daughter decay products of U-235 are a result of beta-decay, nuclear reactors are sources of enormous neutron flux. This leads to one of the hazards surrounding nuclear power plants: neutron activation.

Neutron activation is when you take a stable isotope, hit with a neutron and create a whole new isotope, typically radioactive since you took a stable atom and made it unstable by adding a neutron. This can create some nasty radioactive stuff like tritium/hydrogen-3 (naturally-occurring H-2 undergoes neutron capture) and phosphorous-32 (naturally-occurring sulfur-32 undergoes neutron-proton reaction—gains a neutron, but loses a proton). Neutron activation, however, can also be very beneficial. It can be used as a non-destructive means to identify unknown materials or isotopes. When you bombard an unknown material with neutrons, the resultant activated (radioactive) material can be analyzed with gamma spectroscopy and identified since the gamma radiation signatures of most (if not all) radioactive isotopes are well known and readily identified. Then working backward from the activated material we know we have, we can then identify the material prior to activation.

Now, for the more industrious of you, I know what you’re thinking: “If we can produce a material simply by bombarding it with neutrons, can we create gold through neutron activation?” The answer is “YES, we can!” But, if you pull out your chart of the nuclides and look at the target isotope need to produce gold—it is platinum. Yes, currently, platinum is trading less than gold. But, if you take the most abundant isotopes of platinum (Pt-195 at 33.8%, Pt-194 at 33%, Pt-196 at 25.2% and Pt-198 at 7.2%) and neutron activate them, you will yield the following: Pt-195 will yield Au-196 which will decay back to stable Pt-196 and stable mercury-196 so nothing gained there; Pt-194 will yield radioactive Au-195 and Pt-196 will yield radioactive Au-197, both of which eventually will decay down, but will remain gold; Pt-198 will yield Au-199 which will decay to mercury-199. So starting with pure platinum that goes for about $1000 an ounce and bombarding it with neutrons, you will ultimately yield an alloy of gold, platinum and lead that I doubt one could sell and offset the cost of the target material AND the neutron source. “Well, what about silver?” To get silver through neutron activation—again, we refer to our chart of the nuclides—one would need palladium for the target material, a far more valuable commodity. lol

[QUOTE=Rev. Rob Large;3630573]Yesterday was the birthday of one of the co-discoverers of, what is now known as, Cerenkov radiation seen here as the eerie blue glow in the water surrounding the fuel cells:

[IMG]http://www.geek.com/wp-content/uploads/2014/07/cherenkov-glow-2.jpg[/IMG]

One of the fundamental laws of physics is the Law of the Conservation of Energy. This law states that, in a closed system, all energy is conserved over time--everything going in must come out. When the brakes are applied on a moving vehicle, the energy "spent" to slow the car down (friction) is converted to heat and sound (a fact I know all too well in my car), and thus energy before and after the braking event is conserved.

In the case of highly radioactive material, vis a vis fuel cells in a pool of water of a nuclear reactor, the particles emitted by the material are travelling faster than the speed of light in that medium. When those particles start colliding with the surrounding medium, in this case the water, and with each other, they are slowed down and the excess energy from these collision events is given off as photons/light.

Now, I know what you’re thinking: “But, Rob, most nuclear reactors use uranium-235 as a fuel source and that is an alpha-emitter. Alpha particles are massive and slow, and can’t possibly travel faster than a massless photon!”, and you’d be correct. The Cerenkov radiation observed in most nuclear reactors is not from the emitted alpha radiation, but from the neutrino events associated with the beta radiation from the U-235 decay chain. The muon-neutrinos and electron-neutrinos interact with the protons in the surrounding medium giving off the excess energy after conversion to a muon and neutron or an electron and neutron, respectively, as a photon observed as Cerenkov radiation. Which leads me to my next topic: neutrons. Neutrinos are boring—tiny little charge-less leptons that don’t interact with anything. Neutrons, however, are far more interesting. Yes, they are charge-less like neutrinos, but they are far more useful. Since about half of the daughter decay products of U-235 are a result of beta-decay, nuclear reactors are sources of enormous neutron flux. This leads to one of the hazards surrounding nuclear power plants: neutron activation.

Neutron activation is when you take a stable isotope, hit with a neutron and create a whole new isotope, typically radioactive since you took a stable atom and made it unstable by adding a neutron. This can create some nasty radioactive stuff like tritium/hydrogen-3 (naturally-occurring H-2 undergoes neutron capture) and phosphorous-32 (naturally-occurring sulfur-32 undergoes neutron-proton reaction—gains a neutron, but loses a proton). Neutron activation, however, can also be very beneficial. It can be used as a non-destructive means to identify unknown materials or isotopes. When you bombard an unknown material with neutrons, the resultant activated (radioactive) material can be analyzed with gamma spectroscopy and identified since the gamma radiation signatures of most (if not all) radioactive isotopes are well known and readily identified. Then working backward from the activated material we know we have, we can then identify the material prior to activation.

Now, for the more industrious of you, I know what you’re thinking: “If we can produce a material simply by bombarding it with neutrons, can we create gold through neutron activation?” The answer is “YES, we can!” But, if you pull out your chart of the nuclides and look at the target isotope need to produce gold—it is platinum. Yes, currently, platinum is trading less than gold. But, if you take the most abundant isotopes of platinum (Pt-195 at 33.8%, Pt-194 at 33%, Pt-196 at 25.2% and Pt-198 at 7.2%) and neutron activate them, you will yield the following: Pt-195 will yield Au-196 which will decay back to stable Pt-196 and stable mercury-196 so nothing gained there; Pt-194 will yield radioactive Au-195 and Pt-196 will yield radioactive Au-197, both of which eventually will decay down, but will remain gold; Pt-198 will yield Au-199 which will decay to mercury-199. So starting with pure platinum that goes for about $1000 an ounce and bombarding it with neutrons, you will ultimately yield an alloy of gold, platinum and lead that I doubt one could sell and offset the cost of the target material AND the neutron source. “Well, what about silver?” To get silver through neutron activation—again, we refer to our chart of the nuclides—one would need palladium for the target material, a far more valuable commodity. lol[/QUOTE]

**** man. Thank the gods you are teaching the youth.

Getting tired after lunch

[IMG]https://lh6.googleusercontent.com/-meV_SdVrToA/U47Mx2yqpgI/AAAAAAAAAoU/zI0rtmCVCgM/2014-06-04[/IMG]

Need sleep....