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seen Oct 21 at 19:24

Oct
10
comment How detectors in particle colliders can differentiate neutrons from antineutrons?
because anti-quarks in the anti-neutrons annihilate with the quarks in the protons and neutrons in the carbon nuclei while at such low energies, a neutron essentially behaves like an (unbreakable) ball
Sep
29
comment How can I measure the speed of a figure skater's spin?
the stroboscope (or camera flash which has such a function) probably only works well if she can spin for a enough time while you adjust the stroboscope's frequency...
Sep
29
comment why are two higgs doublets required in SUSY?
see also physics.stackexchange.com/questions/116598/…
Sep
26
comment Why more than one Higgs?
Is there a typo here we don't want the theory to be renormalisable ?
Sep
7
comment Is the photoelectric effect a type of nuclear decay?
good point, so 'photonuclear reaction' is probably more adequate.
Sep
6
comment Is the photoelectric effect a type of nuclear decay?
The article on induced gamma emission I linked starts with the sentence: "In physics, induced gamma emission (IGE) refers to the process of fluorescent emission of gamma rays from excited nuclei". That's what the original poster was looking for as an analogy to the photoelectric effect, isn't it ?
Aug
20
comment How does one experimentally determine chirality, helicity, spin and angular momentum?
actually, the original poster asked for fundamental particles which usually means that they are not composite.
Aug
20
comment How does one experimentally determine chirality, helicity, spin and angular momentum?
in fact, at least in the Standard Model to talk about chirality makes only sense for the fermions (or the sfermions in the MSSM which have spin 0), because chirality is defined by how the corresponding field/particle transforms under $SU(2)_\mathrm{L}$
Aug
18
comment What is the total kinetic energy per second of the particles accelerated by the LHC
Note that the 4 Terawatts counts each particle about 11'000 times (the number of revolutions per second). You could not exploit this power: if you were to fully absorb the energy of the particles (e.g. at the beam dump), the machine would be empty after one revolution.
Aug
18
comment Can lightly-ionized atoms be accelerated to relativistic speeds with current technology?
the ions in these accelerators are fully ionized, not lightly (for lead, this would be Pb 82+), the force exerted on the fully ionized ions is much larger than on the singly ionized while the mass (to be accelerated) of both is more or less the same.
Jul
24
comment What will be the goal of (V)LHC after receiving upgrades?
175-200 TeV will certainly not happen in 2019. The energy limitation of the current LHC comes from the maximum field the dipole (bending) magnets can produce. To go to higher energies, one needs to either dig a longer tunnel or do extensive research & development to build large scale magnets achieving higher magnetic fields or both (this is called FCC-hh, there is also a similar Chinese project). Given the large cost of such a project, studies are currently going on to reduce cost and a decision whether or not to build such a machine will not be taken until we have more results from LHC.
Jun
18
comment What is the symmetry associated with the local particle number conservation law for fluid?
see also the question on the symmetry associated to the conservation of mass here: physics.stackexchange.com/q/2690
Jun
18
comment What is the symmetry which is responsible for conservation of mass?
see also physics.stackexchange.com/questions/24596/… on the discussion of the converse Noether's theorem
Jun
13
comment Uncertainty principle - momentum so precise that uncertainty of position is outside light-cone?
how can we talk about particles for which we are not certain they are somewhere in the universe ?
May
5
comment Distance and time measurement in the famous Superluminal Neutrinos Experiment
see mi.infn.it/~psala/Icarus/nugsweb/cngs_und.jpg on your question 1 ('Ginevra' is where CERN is). The maximum depth of the path is 10km underground... Digging a tunnel of 700km length may technically be possible but is too expensive (not to mention the time it would take to complete...)
Feb
27
comment What will happen if we will be able to produce a quark-gluon plasma and the we cool it down?
yes, the quark gluon plasma also contains antiquarks. Even an ordinary proton contains anti quarks in what is called the 'sea'. These are created when a gluon splits into a quark/anti-quark pair and normally 'recombine' quickly but they can interact with the quarks/gluons/antiquarks of another proton in a collision. So even if no quark gluon plasma is created in a particular proton-proton (or Lead ion-Lead ion) collision, antiparticles (such as antiprotons) can be produced.
Feb
27
comment What will happen if we will be able to produce a quark-gluon plasma and the we cool it down?
yes, the purpose of colliders is to have energies (or better: energy densities) similar to those shortly after the big bang (in the lab) to study the relevant physical processes which led to the formation of the universe we know today.
Feb
27
comment What will happen if we will be able to produce a quark-gluon plasma and the we cool it down?
yes, exactly. Protons and neutrons are baryons (but in principle other baryons could be formed as well but these are typically short lived as are the mesons).
Feb
27
comment Is there any way to annihilate matter without the use of anti-matter?
The experimental lower limit on this decay mode of the proton (see pdg8.lbl.gov/rpp2013v2/pdgLive/… ) is $8.2 \cdot 10^{33}$ years (the corresponding publication is here: inspirehep.net/record/814697 ) . This is $5.9\cdot 10^{23}$ larger than the estimated age of the universe (13.8 billion years).
Feb
19
comment Why does the Sun turn red near sunset?
yes, redshift from Doppler effects are negligible (40'000 km / day is about $1.5 \cdot 10^{-6}$ of the speed of light). If the redshift were responsible for the sunlight turning red in the evening one would expect it to be affected equally by blue shift in the morning...