# Tag Info

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There are basically three methods: Bombardment, decay, decay following bombardment. But really all positron emitters that exist on earth in practical quantities are man made: it always starts with bombardment of nuclei with protons, deuterons or alpha particles. Usually the "thing" that is made is the unstable nucleus - the actual production of the ...

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You can easily find the answer in Wikipedia, http://en.wikipedia.org/wiki/Positron_emission. One source of positrons are nuclear reactions. I just quote from there: "In 1934 Frédéric and Irène Joliot-Curie bombarded Aluminium with alpha particles to effect the nuclear reaction $$\ _2^4He + _{13}^{27}Al \to _{15}^{30}P + _0^1n,$$ and observed that the ...

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A negative energy particle running backwards in time is mathematically equivalent to a positive energy antiparticle running forwards in time. Since the time dependence of the wavefunction is of the form $exp[-iEt]$ for particles that run forward in time, then the simultaneous transformation $t \to -t$ and $E \to -E$ will give you:  exp[-i(-E)(-t) \equiv ...

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Annihilation lines are spectral lines caused by the collision of particle-antiparticle pairs. In the case of $e^-e^+$, the emission is at 511 keV. (source (arXiv link)) However, because it is caused by a collision of particles, rather than an absorption-emission of a photon, the peak is Doppler broadened. This means that the peak is spread out over a few ...

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I'm imagining a box made completely out of anti-matter so that your situation is realistic. Positrons are the antiparticle of the electron (i.e., the anti-matter equivalent). Meaning, in this case, they're identical to electrons except for charge. Photons, though, have no charge. So don't give a hoot whether a charged particle it's interacting with is ...

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This is not an answer, I just place here a picture for a comment on the covalent bond.

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Since the anti-proton and electrons are different particles there is no Pauli principle requiring them to stay apart. In effect we get a set of electronic orbitals and a set of anti-protonic orbitals. These will all be approximately hydrogenic, though their exact form will be perturbed away from the hydrogenic orbitals by the repulsion between negative ...

0

The relationship between energy, angular momentum, and shape of the orbital are all strongly dependent on the mass of the particle. This will be VERY different for antiprotons than for electrons. For example, for conventional atoms You can see the term $a_\mu$ appear in the denominator several times: that's the mass of the electron. Depending on the ...

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Before asking if two halogen atoms could share an anti-proton, ask if they can share an electron. As far as I remember the chemical bonds between two atoms are so as to form in both atoms a complete shell. For instance, in the molecule of salt, NaCl, the Na atom has a superfluous electron (see the electron shells of Na in the periodic table of elements, ...

2

According to the so called Feynman-Stueckelberg interpretation a negative energy solution of the Dirac equation corresponds to a positron which then runs apparently backwards in time. A negative energy solution corresponds to an electron running backwards in time, which is the same thing as a positron running forwards in time. A positron runnning ...

3

Not at first, but usually eventually. You should read the Wikipedia article on Annihilation, which is the name of the phenomenon of a particle's colliding with its anitparticle. Particles and antiparticles have opposite-signed, equal magnitude quantum numbers (such as spin and parity to name two). Collisions must conserve these quantum numbers, so the ...

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When a particle collides with its antiparticle, all of the mass in both is converted into electromagnetic energy (usually high energy gamma radiation). Whilst it is certainly possible to then convert this gamma radiation into heat so as to drive a turbine, it may be also possible to convert gamma radiation directly into electricity using a special type of ...

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For anyone with similar problems: The following observation has helped me immensly: We have in fact four particles directly related to an electron: A left-chiral electron $\chi_L$, with isospin $-\frac{1}{2}$ and electric charge $-e$, A right-chiral anti-left-chiral-electron $(\chi_L)^c=\chi_R$ with isospin $\frac{1}{2}$, electric charge $+e$ A ...

3

Roughly sketched, for the quantized Dirac field one has: $$\hat\psi(x)\sim \int d\mathbf{p}\, \sum_r \bigg[ u^{r}(p)\, \hat a^r_\mathbf{p}\,e^{-ipx}+v^{r}(p)\, {\hat b^r_\mathbf{p}}^\dagger e^{ipx}\bigg],$$ where $r=\pm1$ denotes helicity. The ${\hat a^r_\mathbf{p}}^\dagger$ operator creates a helicity-$r$ particle state when it ...

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Neutrino definitely have anti-particles. Another question whether an anti-particle differs from its "particle" or not. The charge conjugation operator may generally change a given "neutrino state" because a neutrino solution is not completely determined with just Dirac's equation.

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We then talk about a left-chiral electron we do it in an informal way, you are correct that a massive particle cannot be inherently chiral. To see this, let us remember that he handedness of an elementary particle depends on the correlation between its spin and its momentum (helicity). If the spin and momentum are parallel, the particle can be said to be ...

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Skobeltzyn recounts his research on particle physics in his text "The early stages of cosmic ray particle research", which has been mentioned in another answer. I found it in the book The Birth of Particle Physics edited by Laurie M. Brown and Lillian Hoddeson in 1985. It looks like he was the first one to try using Wilson chamber to detect tracks of ...

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You might want to look at D. SKOBELTZYN's paper The Angular Distribution of Compton Recoil Electrons Nature 123, 411-412 (16 March 1929) | doi:10.1038/123411a0; but it is behind a 'paywall' and only a short abstract is available for free. (FWIW, Nature, Lond., 1929, v. 123, No. 3098, p.411) EDIT (11/27/2014): See also: Dimitry V. SKOBELTZYN, THE EARLY ...

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According to Bazilevskaya's Skobeltsyn and the early years of cosmic particle physics in the Soviet Union paper (emphasis mine), Skobeltsyn demonstrated a series of photographs with the cosmic ray tracks at the Cambridge conference presided by Ernest Rutherford on 23–27 July 1928, where they made a strong impression on the audience. The comprehensive ...

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