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updated calculations - based on neutrino energy escaping and vapor inhalation risk Your math is close but not quite right. First - the number of tritium atoms. There are 1000/(16+3+3) = 45 moles (as you said) This means there are 45*2*$N_A$ = $5.5 \cdot 10^{25}$ atoms of Tritium Now the half life is 12.3 years or 4500 days, that is $3.9\cdot 10^8$s. ...

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The beryllium-7 nucleus is stable, but the beryllium-7 atom may decay by electron capture. This is because the reaction $$\rm ^7_4Be^+ + e^- \to {}^7_3Li + \nu_e + 0.861\,MeV$$ is energetically allowed. The equivalent reaction, with the electron on "before" side replaced with a positron on the "after" side $$\rm ^7_4Be \to {} {}^7_3Li^- + e^+ + \nu_e + ... 5 To begin, lets go over the basics again. Any ensemble of two body decays in which the parents and children have the same masses in each event has a delta-function energy spectrum, or violates at least one of energy- or momentum-conservation. The fact that the beta decay spectrum is broad and continuous implies that at least one of the pre-conditions is ... 5 There are no patterns. When a particle decays, the moment when it does so is absolutely random, chosen from the distribution$$ P_{\rm decay}(t\lt T\lt t+dt) = \frac{dt}{t_0}\cdot \exp(-t/t_0) $$For t=t_0, the beginning of time when we knew that the particle still existed, the exponential is equal to one and we see that the "probability of the decay per ... 4 A cloud chamber will show individual cosmic rays and individual alpha and beta particle tracks. An alpha particle may have say 5 MeV of energy, which is 8 \times 10^{-13} J The Sv unit is the biological effect of 1 Joule of radiation on 1 kg of matter. So a pSv is the biological effect of 1 \times 10^{-12} J on 1 kg.... so my answer to your ... 3 The electrons freed from the bounds of the fissioned nucleus will follow conservation of momentum and will move according to the kinetic energy they have. What will happen to them will depend on the medium they are in. Their kinetic energy will be too high for them to meet up with the fragments constructively, so there is very low probability the new nuclei ... 2 In astrophysics, rates of beta decay and electron capture can be influenced by environment, specifically the ambient density of free electrons. If the gas is dense enough, the Fermi energy of the electrons could be higher than the maximum possible beta decay electron energy. This would suppress beta decay and enhance electron capture. Take the example of ... 2 The alpha particles are emitted as bare nuclei, with charge +2. This is how alphas were originally distinguished from betas and gammas back when radioactivity was being discovered: the three species bent in different directions in a magnetic field. It's possible to distinguish between a two-body decay (to alpha and negative ion) from a three- or four-body ... 2 It's tempting to think of photoionisation as the photon coming in like a billiard ball and knocking out an electron. However this is a very misleading representation of the process. A gamma ray is poorly modeled as a photon or photon(s) because the energy in it is delocalised. If you wanted to use a photon description you'd have to treat the ray as a ... 2 This is to be read together with the checked answer. There are easy cloud chambers to be home made, like this one. It is easy to make, and the reason you should watch it is to realize that in a cloud chamber there will always be muon tracks ionizing the air vapor mix and creating seeds for a track. You will need a type of anti-coincidence to make sure that ... 2 It is the mass of material more than the thickness that determines the stopping power (which incidentally is a function of energy - so you can't simply state "40 cm reduces gamma flux one billion times" without specifying the energy). Lead has a positive coefficient of thermal expansion - so the same amount of lead will become slightly thinner at colder ... 2 There is some interesting data on the subject. People looked at the relationship between the prevalence of radon in counties in the US with the mortality due to lung cancer, and found a surprising relationship. Instead of the "more radon kills more people" correlation that was expected, there was an initial "dip" in the curve - as though "a little bit of ... 2 I thought I'd post the article - never a bad idea. (If it's not the article, let me know). http://www.scientificamerican.com/article/do-transuranic-elements-s/ I'm going to give a long answer, cause I think I see what you're going for, having read a few of your questions. Also, I appreciate your questions, I found them interesting. What this article ... 2 When you put the pot on the stove, the heat from the stove is somehow getting to the pot, which gets hot. The pot and the stove are obviously in contact with each other. Therefore conduction plays a role here. If you have an old pot, with a warped bottom, it will heat up slower, because the contact surface between pot and stove is smaller. When you hold ... 1 The radiation of a body is given by the Stefan-Boltzmann equation:$$E= \epsilon \sigma T^4$$Which means that if you can measure the radiated power E, the temperature is$$T=\sqrt[4]{\frac{E}{\epsilon \sigma}} If the emissivity is lower than you think, it follows that you see less emission that you would expect for a given temperature and you would ...

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Stoves and other hot objects heat up, but don't burn. Burning is very different. Burning is a chemical reaction. In the example of stoves, they work by conduction.

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Here's a simple mental picture to have of a how a burner on a stove heats up water in a pot (which is sitting on the burner). (In what follows, I will use the term "molecules" for both molecules and atoms.) Also, keep in mind that thermal conduction is different than electrical conduction. One (electrical conduction) concerns the flow of charge, so in this ...

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Is there some sort of pattern to which atoms decay at which time, or is it some miraculous property of quantum mechanics that somehow each atom knows when to decay? Atoms are dumb. They don't know anything. Radioactive decay is a memoryless process, a process that doesn't depend on history. Consider three atoms of radon 222. One was created a month ago ...

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You have just read reasonable answers of knowledgeable people, so now you know that "radioactive decay...- it's completely stateless (@Luaan)", "There are no patterns" (@Luboš Motl), and "Atoms are dumb" (@David Hammen). However, there is a bit more to it. Atoms may be dumb, but they happen to know quantum mechanics much better than we, mere mortals, do. So ...

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From an energy perspective, a free neutron sees a nucleus as a three-dimensional square well with a depth of a 5--10 MeV. The presence or absence of milli-eV thermal oscillations or eV-scale molecular bonds may change the details of the shape of that potential well, but in general the change is much less important than the uncertainty in the neutron's energy ...

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Oh, I love this subject. The term here is radiation hormesis, and it's basically off-limits for nuclear regulators (If it's true, it horribly complicates the risk analysis for the use of any radiation source). The classic study comes from Taiwan http://www.jpands.org/vol9no1/chen.pdf where a number of apartment buildings were built using rebar that had been ...

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The equation that you have is right, but actually a little more complicated than you need for this problem. A point source is infinitely small and you don't need to integrate over it . This problem can be handled without working through integrals formally. Consider a full sphere around the point (rather than the partial surface that you've got). In that ...

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You can pump heat from cold objects to hot objects if you pay some more energy (that's what your refrigerator is doing) and that doesn't violate second law of thermodynamics. You should note as you heat object, its thermal radiation will increase. Intensity (that is power per unit surface area) of thermal radiation is proportional to $T^4$ so when the ...

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Although there are different types of "radiation," their common effect is to transfer some/most of their energy to the material they "hit," resulting in the breaking of the atomic bonds and or structures of the material. When "enough" bonds and/or structures are broken, the material will fail. Since the electrical characteristics of electronic components are ...

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