When antiparticles contact matter particles, they annihilate, releasing the mass as energy.
For positrons and electrons, this is a nice simple process of "two photons with a combined energy of just over 1MeV" (in the collision frame of reference they are equal in energy, 511 keV, and going in opposite directions); for protons and antiprotons, each quark does its thing separately so you get a whole mess of other things that are themselves unstable and I don't know the characteristic signatures of, only that they have one and you can look for it.
- "how do they actually know/analyze that they are making antimatter atoms ?"
That's answered in the OP paper: they detect the radiation from matter-antimatter annihilation that happens when the anti-atoms escape, and hit the experiment walls.
- "Central to the observations reported here is the antihydrogen annihilation detector[13] (Fig. 1a), situated coaxially with the mixing region, between the outer radius of the trap and the magnet bore. The detector is designed to provide unambiguous evidence for antihydrogen production by detecting the temporally and spatially coincident annihilations of the antiproton and positron when a neutral antihydrogen atom escapes the electromagnetic trap and strikes the trap electrodes. An antiproton typically annihilates into a few charged or neutral pions[14]. The charged pions are detected by two layers of double-sided, position-sensitive silicon microstrips. The path of a charged particle passing through both microstrip layers can be reconstructed, and two or more intersecting tracks allow determination of the position, or vertex, of the antiproton annihilation. The uncertainty in vertex determination is approximately 4 mm (1σ) and is dominated by the unmeasured curvature of the charged pions' trajectories in the magnetic field. The temporal coincidence window is approximately 5 µs. The solid angle coverage of the interaction region is about 80% of 4π."
- "A positron annihilating with an electron yields two or three photons. The positron detector, comprising 16 rows, each row containing 12 scintillating, pure CsI crystals[15], is designed to detect the two-photon events, consisting of two 511-keV photons that are always emitted back-to-back. The energy resolution of the detector is 18% full-width at half-maximum (FWHM) at 511 keV, and the photo-peak detection efficiency for single photons is about 20%."
As for the analysis, anti-particles are pretty much the same as their mirror particles save for some mirrored attribute(s), so charged antimatter particles carry the same charge as matter particles, but of opposite sign. An antiproton is negatively charged and an antielectron (positron) is positively charged.
Looking at particle tracks they'll see matching masses but curves in charged fields going in opposite directions.
Uncharged particles have some other mirrored attribute, so again "it's just like regular Alice only it's a mirror Alice wrt { X? }"
Create several thousand anti hydrogen atoms. Put them in a magnet trap. Open top and bottom of the trap. Detect collisions with wall. If more down. It's affected by gravity.
ben_w|2 years ago
As for how to detect:
When antiparticles contact matter particles, they annihilate, releasing the mass as energy.
For positrons and electrons, this is a nice simple process of "two photons with a combined energy of just over 1MeV" (in the collision frame of reference they are equal in energy, 511 keV, and going in opposite directions); for protons and antiprotons, each quark does its thing separately so you get a whole mess of other things that are themselves unstable and I don't know the characteristic signatures of, only that they have one and you can look for it.
perihelions|2 years ago
https://alpha.web.cern.ch/experimental-cycle
or at a more technical level
https://sci-hub.se/10.1098/rsta.2010.0026 ("Cold antihydrogen: a new frontier in fundamental physics")
- "how do they actually know/analyze that they are making antimatter atoms ?"
That's answered in the OP paper: they detect the radiation from matter-antimatter annihilation that happens when the anti-atoms escape, and hit the experiment walls.
- "Central to the observations reported here is the antihydrogen annihilation detector[13] (Fig. 1a), situated coaxially with the mixing region, between the outer radius of the trap and the magnet bore. The detector is designed to provide unambiguous evidence for antihydrogen production by detecting the temporally and spatially coincident annihilations of the antiproton and positron when a neutral antihydrogen atom escapes the electromagnetic trap and strikes the trap electrodes. An antiproton typically annihilates into a few charged or neutral pions[14]. The charged pions are detected by two layers of double-sided, position-sensitive silicon microstrips. The path of a charged particle passing through both microstrip layers can be reconstructed, and two or more intersecting tracks allow determination of the position, or vertex, of the antiproton annihilation. The uncertainty in vertex determination is approximately 4 mm (1σ) and is dominated by the unmeasured curvature of the charged pions' trajectories in the magnetic field. The temporal coincidence window is approximately 5 µs. The solid angle coverage of the interaction region is about 80% of 4π."
- "A positron annihilating with an electron yields two or three photons. The positron detector, comprising 16 rows, each row containing 12 scintillating, pure CsI crystals[15], is designed to detect the two-photon events, consisting of two 511-keV photons that are always emitted back-to-back. The energy resolution of the detector is 18% full-width at half-maximum (FWHM) at 511 keV, and the photo-peak detection efficiency for single photons is about 20%."
fhars|2 years ago
defrost|2 years ago
https://www.nature.com/articles/nature01096
As for the analysis, anti-particles are pretty much the same as their mirror particles save for some mirrored attribute(s), so charged antimatter particles carry the same charge as matter particles, but of opposite sign. An antiproton is negatively charged and an antielectron (positron) is positively charged.
Looking at particle tracks they'll see matching masses but curves in charged fields going in opposite directions.
Uncharged particles have some other mirrored attribute, so again "it's just like regular Alice only it's a mirror Alice wrt { X? }"
unknown|2 years ago
[deleted]
secult|2 years ago
Ygg2|2 years ago
jansan|2 years ago
The question was how this is done.