35,911 reputation
350122
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 4 years, 1 month
seen 7 hours ago

Experimental nuclear and particle physicist. These days I'm teaching, but I've spent a lot of time on nucleon structure in fixed target electron scattering and neutrino oscillations using reactors and beam sources.


Nov
30
comment Determine the number of grays absorbed by human emitted by Uranium 238
You are not going to find a neat formula because this is not a neat problem. The ore spits out at least alpha, beta and gamma radiation. If there is any U-235 in there (which there is if it is a natural sample as implied by "ore" then it also spits out neutrons. Each type of radiation comes in several different energies and most have to be treated individually (you are probably safe lumping the alphas together unless the sample has the crumbly dusty character of the few samples of raw, high-content pitchblend I've actually seen up close).
Nov
30
comment Why is a thought experiment a valid way to prove anything?
Galileo did, however roll a heck of a lot of balls down ramps. That is he had already done the investigation in slightly less ideal conditions.
Nov
28
comment Why does U-235 split into barium and krypton in nuclear reactors?
There are many isotopic combination among the products of these fissions. Your book has simply picked a common one to use as an example.
Nov
28
answered Will light leak into a side glow optical fiber?
Nov
28
comment Are atoms made of protons, electrons and neutrinos?
It doesn't not depend on who you ask. Nucleons are not made of neutrinos and other things, so there is no sense in which an atom has neutrinos as constituents. Decay does not generally expose the make up of the decaying particle; it is often a transformation of wone kind of thing into another kind of thing.
Nov
28
comment Can someone prove that the $\tilde{E}$ and $\tilde{H}$ fields in a waveguide looks as pictured?
"Can someone prove [...]" As usual you use the proposed structure of the fields to make a observable prediction (say what the cut-off frequency for the mode would be) and then subject it to experimental test under conditions where different modes give different observables.
Nov
27
comment Has confinement been experimentally observed?
@innisfree The fact of substructure at least was well established in the 1950s when the proton form factors (polarized and unpolarized) were measured. The knowledge of the hadron spectrum had to have come from somewhere before Gell-Mann and Zweig could work on the date.
Nov
27
comment Kirchoff's loop law
Do you think I object to your answer? I don't and in fact voted for it, but I thought there was room for another approach to the problem.
Nov
27
comment Kirchoff's loop law
If there is an externally imposed, changing magnetic field then (a) you can't formally define a "potential" anymore and (b) If you're going to fake it (which you can and generally should) you have to include a EMF from the induction or KLL doesn't work. See WetSavanna... answer on the linked question.
Nov
27
answered Kirchoff's loop law
Nov
27
comment Has confinement been experimentally observed?
@innisfree If you insist on the language of QCD, then you can't have it until you have that same language, but the observation that (a) nucleons have substructure and (b) you can't seem to knock the pieces loose is what prompted the need to deduce the sub-component properties from the hadron spectrum. Those facts are the observation of confinement.
Nov
27
comment Do electrons get accelerated or decelerated by the atoms of the anode during X-rays production?
There is no unique definition of acceleration vis a vis deceleration. The observer's frame of reference can change one into the other.
Nov
27
comment Has confinement been experimentally observed?
Like every other observed fact at the most fundamental level it is simply the way the universe appears to work. Some observations in science can be explained in terms of more basic observations (and learning to do that is one of the pillars of the discipline), but at some level everything is built on a foundation of observation.
Nov
27
comment Has confinement been experimentally observed?
Er ... it was a phenomenological observation before it was part of any theory.
Nov
26
comment Does “normal torque” exist?
The floor exerts friction on the ruler spinning in contact with it and friction always points in the direction opposed to relative motion. The results is a perfectly ordinary torque.
Nov
25
comment Condition for formation of interference pattern
No time to write an answer now. This is a way of arguing about the spacial coherence of the light.
Nov
25
comment What does the Atomic Form Factor means?
"they have fallen out of fashion as a research tool" Hmmm ... well, they've remained important in the transition energy regime (a few GeV scale) exactly because it is hard to do accurate calculation above the nucleon mass but below the perturbative QCD scale. Also in applications like weak-axial scattering where a small signal must be extracted from a large vector background from electromagnetism.
Nov
24
comment How to rebut denials of the existence of photons?
This is really the core of (at least one of) Lamb's point. He doesn't argue against QED, but rather that the word in consistently abused in ways that are not consistent with a modern understanding of quantum optics.
Nov
24
comment What are the hypothetic cases when entropy of a closed system may decrease?
Describe a system in which there is no way to have a change from a micro-state of maximum entropy to another such state. Then anytime the system is in a micro-state of maximum entropy, any change causes a momentary decrease. I believe that a 1-D Ising model is such a system.
Nov
24
comment How to rebut denials of the existence of photons?
@KyleKanos The flip side is---of course---www-3.unipv.it/fis/tamq/Anti-photon.pdf (the paper that user31748 references) and arxiv.org/abs/1204.4616