39,602 reputation
355127
bio website inspirehep.net/…
location Duchy of Grand Fenwick
age 44
visits member for 4 years, 5 months
seen 1 hour 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.


1d
comment Where will the cloth fold?
This is your second "assume unphysical symmetry and then then try to disambiguate the situation with physics" question. The answer to these is always going to be the same: you will not actually have that level of symmetry and the system is sensitive to the atomic scale asymmetries that are present.
1d
comment Baryonic density in collision experiments
Unfortunately, I can't help you with the core answer. My impression was that searching for answers in this realm was a large part of RHIC's mission, but I haven't been near the right colloquia since their analyses started appearing.
1d
comment Baryonic density in collision experiments
Hmmm ... this question is a bit old, but the statement "Hence, barring inhomogeneities, LHC is essentially in the $\rho_B \approx 0$ regime." is completely wrong. The LHC collides two beams of protons or of heavy ions or one of each. It does not accelerate or collide any leptons or any anti-matter. LEP was a $e^+e^-$ machine. Was that what you were thinking of?
2d
comment In the time of the dinosaurs the Earth rotated once in 17 hours rather than about 24 hours, where did the rotational energy and angular momentum go?
To expand on David's comment about historical eclipse records: the East-West location of the affected areas on the surface of the Earth depend the integrated slowing between now and then.
2d
comment In the time of the dinosaurs the Earth rotated once in 17 hours rather than about 24 hours, where did the rotational energy and angular momentum go?
Thanks for running all those down, @David. I have to read that last paper as some kind of exposure therapy: just seeing Stan Peale's name as author still intimidates me a couple of decades after I took his course.
2d
comment Wu experiment and masses of neutrino
Presumably the OP is talking about en.wikipedia.org/wiki/Wu_experiment.
2d
comment What is a collider detector
tey, that just isn't any help. It's way too broad. We've been experimenting on those things for more than 40 years. Multiple generation of technology have come into being, supplanted their predecessors and been themselves replaced in that time. Whole books have been written on how they work. Worse a "detector" is generally a compound machine with several different technologies deployed in various places. Let's start small. Do you understand how a Geiger counter works? Or a photomultiplier tube? From there you can start to build upward.
2d
awarded  Nice Answer
2d
revised Will 1 gram of matter moving at relativistic speeds completely annihilate a larger quantity of stationary antimatter?
added 26 characters in body
2d
answered Will 1 gram of matter moving at relativistic speeds completely annihilate a larger quantity of stationary antimatter?
2d
comment Will 1 gram of matter moving at relativistic speeds completely annihilate a larger quantity of stationary antimatter?
Yet another reason why we shouldn't be teaching "relativistic mass".
2d
comment In the time of the dinosaurs the Earth rotated once in 17 hours rather than about 24 hours, where did the rotational energy and angular momentum go?
Its worth noting that the rate of slowing depends ocean levels and continental configurations (through the $Q$ of the tidal forcing). I don't recall if the value you quote is the current rate or the long term average.
May
1
comment A family stuck in time-travel
This is the plot of Heinlein's "All you Zombines" which was recently made into the movie Predestination. Related question on stack exchange sites: google.com/…
May
1
comment Why don't protons just bounce off each other in the LHC?
@Will The "never happens" value can be defined for an experiment just fine, even though it never goes away in theory. When the expectation for the number of such events observed drops far below one over the entire course of the experiment you are in "never happens" territory.
May
1
comment Why don't protons just bounce off each other in the LHC?
Of course, you can scatter protons coherently at high momentum-transfer it just makes up a very small fraction of the overall cross-section (falling as $1/t^2$). in my dissertation work we used values of $|t|$ up to $8.1 \,\mathrm{GeV}^2$, which is quite small by LHC standards but still represents a significantly smaller size than the naive proton.
May
1
comment Why is $c_p$ higher than $c_v$?
Think about the meaning of heat capacity: them about of energy needed to achieve a fixed change in temperature. The constant pressure system got less change in temperature out of the same energy, meaning that it needs more energy to get the same change in temperature.
Apr
30
comment Since nucleons are not elementary particles more, how we call nucleons and electrons together now?
Electrons are elementary particles.
Apr
30
comment Why don't protons just bounce off each other in the LHC?
A the right impact parameter they do, but they don't end up in the detector.
Apr
30
revised Why is $c_p$ higher than $c_v$?
edited body
Apr
30
comment What is the equation for the pressure at which neutrons can no longer be supported by neutron degeneracy pressure?
Do you understand what happens when electron-degenerate matter collapses to neutron degenerate matter? In particular the importance of the Fermi-energy to the question of which state is favored?