32,948 reputation
344108
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 43
visits member for 3 years, 9 months
seen 39 mins 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.


Aug
8
revised Can we “fill” an atom with alpha particles?
added 327 characters in body
Aug
8
answered Can we “fill” an atom with alpha particles?
Aug
7
comment Coupled Spring System (3 mass 3 springs)
I have no idea if the model is correct or not, but not finding simple sinusoids does not, in and of itself, point to a bug. There are a few regular modes, but finding them is an eigenvalue problem and I am unsure if you know that term and what it implies.
Aug
7
comment Coupled Spring System (3 mass 3 springs)
You aren't expecting simple sinusoids except in a few special cases.
Aug
6
comment How is viscosity described on the molecular level?
@alemi I really enjoy spurious correlations. They come up with the damndest things. And every time I see one I starting trying to build a change of inference that offers a possible explanation. In this case I thought "Hmmm ... old people trip and old people play golf..."*.
Aug
6
revised Does a photon in vacuum have a rest frame?
Fix a long standing problem that no one called me on...we read what we expect or something.
Aug
5
comment What is $c + (-c)$?
Also of interest: physics.stackexchange.com/q/16018 and the many duplicate and related questions it the sidebar of that one.
Aug
5
comment A question about special relativity theory
"Each set is designed so that if both touchers are touched simultaneously the lamp is turned on otherwise it remains off." This is ambiguous without clarification because these things happen at space-like separated points, so "simultaneous" is observer dependent. How is this "designing" accomplished? Do each pair of touchers send a signal back the the central box? Are they light-speed signals or something else? I know Einstein's thought experiments sound casual, but he was actually meticulous about this kind of thing and you need to be as well if you are to get unambiguous answers.
Aug
4
comment Theoretically, is there a way to hold a quantum entangled particle in a state by continuously observing it?
A useful search phrase for this trick on ordinary states is "quantum watched pot".
Aug
4
comment Neil deGrasse Tyson says that electrons “teleport” between energy levels?
Not my field of specialty, and I don't have the book the blogger references, but ... I'm fairly sure that those calculation are for an atom in the presence of an externally imposed electromagnetic field which is treated as a perturbation, meaning that we still label the states as the (pure) atomic they most resemble. But the Hamiltonian is changed so that there is a time-evolution operator between them; which is emphatically not the case for a pure, pristine, ground-state, hydrogen-like atom in an empty universe. So, there is a little bit of apples and oranges going on there.
Aug
4
answered Is time not a universal parameter, really, in special relativity?
Aug
4
revised How do we measure meson decay constants?
update citation to include reviewed publication of a preprint
Aug
4
revised Transmission/Equilibrium Question
fix a stupid algebra mistake
Aug
4
answered Is there inductance to a DC circuit?
Aug
4
comment What stabilizes neutrons against beta decay in a neutron star?
@ticster Can I say "yes"? I am far from a expert in the matter but I believe that the presence of neutrinos (which are not bound) in the reactions means that the situation is not the kind of continuous back-n-forth equilibrium that we usually envision in, say, a mixed phase or chemical reactions. But the ambient neutrino flux must allow some shuffling.
Aug
4
comment Time homogeneous Markov chain for Axelrod's model
I have to say, that I don't see this as a physics question. To be sure physicists were instrumental in bringing MCMC to a state sufficient to make it a major tool in numeric analysis, but it's just a tool and here you seem to be applying it to things that have no physics in them.
Aug
4
comment Why is Huygens' principle only valid in an odd number of spatial dimensions?
Er ... and yet we do demos that depend on the validity of Huygen's principle using surface waves on water. Are we just getting away with a fast one because the amplitude dies away to soon too see the violation? Or don't surface waves count as two-dimensional for the purposes of this discussion? (I guess this is related to Ben's "Edit".)
Aug
4
comment What other shielding material than lead is effective against gamma rays?
@Floris Well, that's an issue if you're building a product. The safety guys I had in mind are the lab EH&S group and they're not in the product business. Mind you, they do make us only use painted lead and handle it with "LEAD ONLY" leather gloves and all that, but compared to the fit they'd throw if you proposed a paraffin neutron absorber in an experimental hall lead is just a shrug and "make sure your crew has taken the training".
Aug
2
comment Mixed-Alloy materials
In addition to case-hardening mild steel tools on the forge, differential tempering and the welding together of parts made of different steels followed by differential tempering have been used and that is just listing the things that craft metal-worker have gotten up to over the years. With the rise of scientific metallurgy I imagine that a lot of things have been tried, but it is always going to come down to specifications and money. Do you actually need that and do you need it badly enough to pay what it costs?
Aug
2
comment I need to know how many pounds of force a 3 million pound object has moving at 1 mph
Your words "How many pounds of force does a [...] object have [while moving]?" expresses a fundamental misunderstanding about the nature of force (as the word is used in physics) that I've seen from students many times. It is possible that the concept you are looking for is "momentum".