38,883 reputation
354126
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 44
visits member for 4 years, 5 months
seen 3 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.

Been reading Zemansky & Dittman's book on thermodynamics recently. Quote: ``The concept of temperature is rich in interpretations and levels of abstraction.'' Nice.


Apr
8
comment Finding equivalent resistance in complex circuit
This statement is true but it is not an answer to the question.
Apr
8
comment Why aren't orbitals symmetric?
I don't have time, but a complete answer would include the fact that selected sets of the orbitals do sum to a spherically symmetric distribution. And in particular all closed shells are spherically symmetric. This is essentially impossible to see in the visualizations because of the information they throw away. Just another reason to treat visualizations with a certain wary regard.
Apr
8
comment Do we actually measure distances in light years?
@Rob en.m.wikipedia.org/wiki/Moving_cluster_method Doesn't get a lot of press, and never been very accurate but independent of the AU and these day we can range some of those clusters by parallax.
Apr
8
comment Do we actually measure distances in light years?
Only I don't think it is quite true that all the long range measures rest on parsec because the ballistic clusters give us a cross-check.
Apr
8
comment Do we actually measure distances in light years?
@RobJeffries I think the question is "Given that all the long range distance techniques rest ultimately on the back of parallax measurements, isn't in more proper to quote distances in terms of parsecs than light-years?" I don't really think that Emilio claims that there is a problem with speed of light measurements; rather he questions the philosophical reasonableness of assuming them to be good when we have an alternate rules (parsec) which doesn't depend on it.
Apr
8
comment Why are neutron stars mostly composed of neutrons?
In light of some of your earlier questions I think that it is worth noting that you need (need!) to understand the energetics of degenerate gasses for this to be clear. But it is not obvious to me how comfortable you are with these systems.
Apr
7
comment The Interior of A Nucleon
The question that @Mobin suggests is clearly not a duplicate. This question concerns the distribution and behavior of partons within a single nucleon, not of nucleons within a nucleus.
Apr
7
comment Do we actually measure distances in light years?
The proper motion and Doppler shift of ballistically coupled clusters gives us a second, distinct rung for distances larger than the solar system but smaller than the galaxy. And I believe that that rung is independent of the parsec. It is possible that this is the core of a good answer, but I am now at the limit of what I recall on the matter.
Apr
7
comment The Interior of A Nucleon
As a tagging matter, nucleon structure spans the boundary of nuclear and particle physics and makes only the most modest of contribution to atomic physics.
Apr
7
comment The Interior of A Nucleon
Various related questions: physics.stackexchange.com/q/118782 physics.stackexchange.com/q/56005 physics.stackexchange.com/q/132378 physics.stackexchange.com/q/19886
Apr
7
awarded  Good Answer
Apr
6
comment How to treat an exercise about the rotational acceleration during a throw?
The way to understand this is the same as the way to understand any other basic dynamics problem: draw the free-body diagram(s), label the forces, apply $\sum \vec{F}_i = m\vec{a}$ and $\sum \tau_i = I \alpha$, solve the system of equations and interpret the results. In your case you can even neglect the linear motion portion of the problem and concentrate entirely on the rotational part.
Apr
6
comment Optimal “Blow up” Configuration
Presumably related to Maximum Momentum of Neutral Pion.
Apr
6
comment How can we test relationship between frequency and peak current of an alternating current?
@AlfredCentauri Hmmm ... yes, I see. That said, there shouldn't be a problem in treating it that way as long as you avoid going to DC (where the various divergences will need to be handled with L'Hopital's rule.
Apr
6
revised Does my green laser pointer emit three distinct frequencies, or is my measurement flawed?
edited tags
Apr
6
answered Is it possible for a planet to be “axially locked”?
Apr
5
answered Why particles don't lose mass when they radiate
Apr
5
comment How can we test relationship between frequency and peak current of an alternating current?
Suchal, it is really just a matter of picking the right tools. A good oscilloscope will allow you to simply measure $V_{peak}$, $I_{peak}$ and $f$.
Apr
5
comment How can we test relationship between frequency and peak current of an alternating current?
@pyramids Your comment is possibly wrong or possibly just coming through very badly, but a driven circuit will always run at the driving frequency and not at it's natural frequency (a fact that always surprises me and is very important in a number of applications). This question is presumably getting at the resonant behavior which tells us that the size of the signal in the circuit is dependent on the how closely the driving frequency matches the natural frequency.
Apr
5
revised Why can't a high intensity beam be injected into the LHC when the machine is empty
edited tags