135 reputation
4
bio website insectnation.org
location Cern, Switzerland
age 36
visits member for 2 years, 11 months
seen Jul 22 at 21:58

Particle physicist with a computational bent. Fun is maths, programming, graphic design, playing/listening music and climbing/mountaineering.


May
30
comment How do tracking detectors in particle accelerators create the pretty pictures we see?
@PurposeNation Exactly, they can measure all these things, but nowhere near the level of accuracy where the uncertainty principle is limiting. An optimistic estimate of tracker measurement accuracy would be 1 MeV/c uncertainty on the momentum measurement, and a spatial resolution of 1 micron; even that high level of precision is 5 x above the Heisenberg limit.
May
30
comment How do tracking detectors in particle accelerators create the pretty pictures we see?
@DavidZ No, detector simulation doesn't account for observer effects. As was mentioned in a comment on the question, the macroscopic length scales on which the detector elements interact with particles are such that it is a weak measurement: the detector is not significantly entangled with the hard process at the pp interaction. Significant correlations only occur within a nuclear radius of the primary interaction. There are quantum effects in e.g. how a charged particle interacts with silicon, but again each interaction is factorized/unentangled so effective interaction models can be used.
Mar
31
revised Why collide a moving particle with a particle at rest, rather than two moving particles?
Correct 'square' to 'square root' and correct the statements about LHC energy
Mar
31
suggested approved edit on Why collide a moving particle with a particle at rest, rather than two moving particles?
Mar
31
comment Why collide a moving particle with a particle at rest, rather than two moving particles?
For completeness, the LHC Run 1 actually finished (and took most data) with CoM energy of 8 TeV, not 7. The original question also asked about number of particles in a high-energy collision and the accuracy of the beam control: the LHC had roughly 10^11 protons in each of 2800 colliding bunches, each proton with 4 TeV of energy. The beams are 16 micrometres wide: colliding them is a technical feat! In each typical bunch crossing there are up to 60 pp interactions, to increase the luminosity; the downside is that overlaid uninteresting collisions (called pile-up) make event reconstruction hard.
Jan
23
comment What enables protons to give new properties to an atom every time one is added?
@Investor The change in quark flavour between proton and neutron crucially changes the nucleus charge by one unit. There has to be a corresponding change in the number of orbiting electrons, to achieve a neutral atom. The difference in electron configuration is what produces chemical (as opposed to nuclear) behaviour and the behavioural groupings of the Periodic Table (which have their roots in the electron configurations allowed by quantum mechanics).
Aug
23
comment Very basic question on spin
For fundamental particles it coincides (as also commented on your linked answer): systems will ill-defined spin are of course more complex. Fundamental particle are the relevant case for particle physics (cf. the original question) where the only composites are hadrons, and those are precisely treated such that every energy level is considered to be a distinct particle with a well-defined spin (and indeed all J^{PC} characteristics).
Dec
9
comment Why Cronin Effect Happens?
As mentioned, the leading twist term is a single partonic scatter, which will be of form 2 partons -> 2 partons. So that's why there is the comment about leading order preserving multiplicity: you need to go to higher orders to get a real parton emission which would increase the multiplicity. But the LO diagrams can still change kinematics. It's remarkably hard to find an introductory paper on higher-twist corrections in pQCD (in the OPE formalism), but this (e-)book gives some introduction that's easier than the state of the art papers: lpthe.jussieu.fr/~yuri/BPQCD/BPQCD.pdf
Aug
5
answered Why is there a size limitation on animals?
Oct
19
awarded  Editor
Oct
19
revised Why is $\int (dp/2\pi) |p \rangle\langle p| = 1 $?
Fixing LaTeX typos (and a few other punctuations things to pass the modified character threshold!)
Oct
19
suggested approved edit on Why is $\int (dp/2\pi) |p \rangle\langle p| = 1 $?
Aug
17
awarded  Supporter
Aug
3
awarded  Teacher
Aug
3
answered Very basic question on spin
Aug
3
awarded  Autobiographer