Does anyone (intend to) work on free-orbit experiment with laser interferometry X-rays (FELIX)?

As the title says, is the FELIX experiment intended to be conducted in the foreseeable future?

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Magnetic monopoles imaged through neutron scattering experiment

I am writing a report about a magnetic monopoles, in the report I am trying to write about the observations made during an experiment using a neutron scattering technique. The experiment mean that the monopoles were considered to exist in spin ice. I am clear about spin ice, however, an image is associated with the experiment, but I do not understand what it means:
enter image description here

What are the axis labelled as (if they are axis), what does the colour represent, and what does h,h,0 and 0,0,1 mean?


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Capacitor and Pith Ball experiment

Suppose I first charge a capacitor so that one plate is positively charged and another negatively. Now I remove the charging source and ground only one of the terminals say negative terminal, will there be a net positive charge in the capacitor that can be detected by a pith ball? Can a capacitor be used as static electricity generator?

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Don’t understand why Rutherford was shocked by results of gold foil experiment

The way Rutherford’s classic gold foil experiment is generally presented doesn’t make sense to me.

As many of you know, Rutherford famously described himself as being utterly shocked at the results brought to him by Geiger in 1909: “It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you.” [Rutherford, Ernest; Ratcliffe, John A. (1938). Forty Years of Physics. In Needham, Joseph; Pagel, Walter. Background to Modern Science. Cambridge University Press.]

Simply put, it makes no sense to me that he should have been so surprised. Rutherford wrote the following in 1908: “We can conclude with certainty from these experiments that the α particle after losing its charge is a helium atom. Other evidence indicates that the charge is twice the unit charge carried by the hydrogen atom set free in the electrolysis of water.” [Ernest Rutherford & Thomas Royds, Philosophical Magazine 17, 281-286 (1909).]

Thus, at the time of the gold-foil experiment, Rutherford believed (correctly) that his “15-inch shells” (the α particles) were helium atoms that had lost negative charge. So essentially Rutherford, using particles that he knew to be highly concentrated atomic-scale matter derived from atoms (α particles), was shocked to find that atoms contained highly-concentrated atomic scale matter (?!).

I’m not saying he should have known specifically about the nuclear model of the atom prior to the experiment. I am saying he shouldn’t have been utterly shocked to find that atoms contain something that can deflect alpha particles, given that he knew alpha particles themselves were simply atoms whose negative charge had been removed.

To use Rutherford’s own metaphor, it’s as if he were saying: “I went to an armory and obtained some artillery shells. I then fired these at another armory, and was shocked to find, as a result, that armories contain artillery shells.”

I.e., if Rutherford already knew this about helium ions, why wouldn’t he expect other atoms would also have their positive charges concentrated as well? Was his thinking that neutral atoms were accurately described by a plum pudding model, yet once you removed the electrons the positive charge would collapse into a small space? If anything, given that he didn’t know about nuclear binding, it would seem he should have expected the opposite—that removing the negative charges would cause the positive charges to expand and become even more diffuse.

Can someone familiar with the history of these experiments resolve this?

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SkillRep – experiment in computing a skill focused reputation

Update: Now offline/closed. See the answer, below.

Reputation, on the Stack Overflow Site, is mostly a measure of a user’s contribution.

That’s fine but sometimes, when looking at a user you encounter on SO, you’re more interested in his skills.
You don’t want a score coming from questions or polluted by a high-scoring answer to a trivial but very popular question.

SkillRep is both

1. a site ranking all users with (a little) less pollution on scoring. The About section explains how the “skill rep” is computed.

enter image description here

2. an extension for Chrome displaying the rank and skill reputation of all users directly in the Stack Overflow site.

enter image description here

Incidentally it’s written in Go. Curious coders might want to have a look at how querying the SE API or serving JSON can be done in Go (it’s fairly simple).

Obviously this shouldn’t be taken too seriously.

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Run One Experiment mutiple times at the same time

Hi, how can i run one experiment multiples time at the same time in
azure, because each time takes like 25 min and if it is possible to
run like multiple at 1 time it would save a lot of time.

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How fast a quantum state updates in a quantum experiment when the experimental setup itself changes. Are there known experiments on this?

Consider the following Sagnac interferometer setup:

enter image description here

where $B$ is a beam splitter which can be raised and lowered with an adjustable frequency $f$, $D$ is a detector which does not click when $B$ is up and clicks when $B$ is down. $S$ is an electron beam source which fires single electrons with some classical velocity $v << c$

I am trying to model the hypothesis on whether there is a finite speed that the quantum state updates as the experiment setup changes due to raising and lowering $B$. If there is a finite speed $u$, then a delay between the appearing and disappearing of the clicks registered and the raising/lowering of $B$ should be observed

Let $lvert ⟳rangle$ and $lvert ⟲rangle$ be the clockwise and anticlockwise state of the electron respectively. When $B$ is down, we have $lvert ⟲rangle$ arriving the detector which produces a click. When $B$ is up, we have instead $lvert ⟲rangle + lvert ⟳rangle$ arriving at $D$ which does not produce a click. Thus when $B$ is send to oscillate at a frequency $f$, we have the following state in the system:

$$sqrt{frac{f+1}{f+2}}lvert ⟲rangle + sqrt{frac{1}{f+2}}lvert ⟳rangle$$

Thus as $f to infty$, contributions from $lvert ⟳rangle$ vanishes and $D$ will be always clicking. Likewise when $f to 0$, we have equal contributions from $lvert ⟳rangle$ and $lvert ⟲rangle$ thus $D$ will not click. For all intermediate values of $f$, we end up with a scenario where $D$ clicks $frac{f+1}{f+2}$ of the time and does not click $frac{1}{f+2}$ of the time.

  1. How does the deterministic oscillation of $B$ lead to a probabilistic outcome on whether $D$ will click, is it due to the Heisenberg uncertainty principle that relates the status of $D$ clicking with the oscillation frequency?

  2. How can I incorporate $v$ into my state description?

  3. Are there known literature examples that investigate this phenomenon?

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Basic Intro to Quantum Chemistry. Two Slit Experiment and Bohr Model

We just learned about the 2 slit experiment in Quantum Chemistry today, where electrons behave as waves when nobody is looking and behave as particles when they are being observed.

So, what would happen If I were to observe an atom (such that all it’s electrons now behave as particles instead of waves) for a long period of time?

I know that real atoms have wave electrons, but when you observe them, don’t they “turn” into particle electrons and obey Newtonian law like the 2 slit experiment? So what keeps the electrons from falling into the nucleus when you observe them? I was considering how the earth doesn’t “fall” into the sun because of a momentum perpendicular to the centripetal force, but the mass of an electron is so much smaller than the nucelus, I’m not sure it will work.

If anyone can give a simple explanation that would be great, I asked the professor and he only said the the Bohr model was inaccurate and it’s difficult to observe electrons.

Thanks in advance.

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Coulomb’s law: Torsion balance experiment

I have read about Coulomb’s torsion balance experiment for the first time from an online pdf article. I interpret it as follows:

enter image description here

Black ball $-$ neutral

Red ball $-$ positive charge

Blue ball $-$ negative charge

At point $P$, there is no spring force and the positive charge is immobile. As soon as the positive charge is mobilized, it attracts the negative charge and the positive charge-neutral system rotates towards negative charge. It rotates until the positive charge reaches point $Q$ where the elastic spring force $(vec{T})$ equals the electrostatic force in the direction of elastic spring force $[F_e(hat{T})]$.

$(vec{T})$ can be found by measuring torque on positive charge-neutral system $(tau)$ which can be found by measuring the angle in which the positive charge-neutral system rotated $(phi)$ and applying the angular form of Hooke’s law:

tau &=-kphi\
T l &=-kphi\
T &=-dfrac{kphi}{l}\

Thus we can find $[F_e(hat{T})]$ and consequently using trigonometry, we can find $vec{F}_e$. With $(phi)$ and $(l)$, we can also find the distance between positive and negative charges $(r)$. Thus we can get the relation between them.

Is there any mistake in my interpretation?

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Individual differences in response time (RT) experiment – searching for the right test

Given a distribution of response times to different categorical variables, what’s the best way to test for individual differences?

or more specifically:

There are 100 people pressing buttons in 10 colors, with more than 200k presses collected altogether.
I want to test for individual differences in response-time (RT) to the buttons, what’s the best way to do this?

(remember there are differences in response time in-between the different colors).

So far I thought of:

  1. ANOVA – calculate a general (weighted) mean RT and compare to individual people.
  2. The distribution level: compare the mean distribution of RT to individual distributions using:

    • chi-squared for goodness of fit
    • Kullback–Leibler divergence test
    • Kolmogorov–Smirnov test
  3. Find a cool bayesian way to do it (which?)

  4. Use a mixed-effect regression model, and calculate the marginal contribution of the people (R square test).

please help me decide – what’s the best practice here?
I’d love to learn about another way I didn’t think of that would do the trick.

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