for questions about design, process, data, or analysis of experiments and observations.

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10
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3answers
634 views

What are the main algorithms the LHC particle detectors use to reconstruct decay pathways?

I am just starting to look into how we understand the data from particle collisions. My question is, what are the algorithms or ways that these detectors interpret the data? Are there standard ...
9
votes
2answers
981 views

Mechanical Equivalent of Heat

Recently I have been looking up James Joule's experiment regarding the mechanical equivalent of heat. After viewing some drawings of the apparatus, I assumed that the lines holding the weights would ...
8
votes
1answer
1k views

Can you tell just from its gravity whether the Moon is above or below you?

If you are on a place of Earth where the Moon is currently directly above or directly below you, you experience a slightly reduced gravitational acceleration because of Moon's gravity. This is what ...
8
votes
2answers
149 views

Can the question of a gravitationally accelerated charge radiation be tested experimentally?

I know that the question of radiation from a gravitationally accelerated charge has been discussed extensively at Does a charged particle accelerating in a gravitational field radiate?. Yet the ...
8
votes
3answers
967 views

How are the 4 km arms of LIGO measured so accurately?

The arms of the LIGO interferometer are 4 km long. Now, LIGO functions by measuring phase difference between two beams of light comming (as in Michaelson's Interferometer) to a sensitivity of $10^{-18}...
7
votes
2answers
408 views

How do the LASERs in LIGO realize that space has expanded as a gravitational wave passes by?

I read an article on LIGO, and I heard it mentioned that it is a nontrivial argument to say that the effect can be measured by interferometry. What happens to space as the wave passes? Does the light ...
7
votes
1answer
350 views

What are the different ways to measure the spatial curvature of the universe?

Just what the question asks. Assuming the Friedmann-Rovertson-Walker (FRW) metric, what measurements can be performed to determine the spatial curvature of the universe.
7
votes
3answers
3k views

Left and Right-handed fermions

Is there a simple intuitive way to understand the difference between left-handed and right-handed fermions (electrons say)? How to experimentally distinguish between them?
7
votes
1answer
885 views

How to prepare a desired quantum state?

Given a quantum state function, we can Fourier expand it in terms of stationary states of the Hamiltonian. So if we want to build that same quantum state approximately all we need to do is to ...
7
votes
3answers
329 views

What are the main differences between $p p$ and $p \bar p$ colliders

I know that it is somehow related to the parton distribution functions, allowing specific reactions with gluons instead of quarks and anti-quarks, but I would really appreciate more detailed answers ! ...
5
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2answers
4k views

What is the smallest length scale ever measured?

And, by the way, what is, or are, the measured values?
5
votes
4answers
189 views

Possibility of making an experiment in a classroom to simulate DNA diffraction

I am a TA in a structural chemistry class. The professor want me to show students how Watson and Crick determined the structure of DNA from X-ray diffraction results of DNA crystals. The professor ...
4
votes
1answer
789 views

How can Kaluza-Klein particles be told apart from winding modes at the LHC?

I`ve already asked this in the comments below this article http://profmattstrassler.com/articles-and-posts/some-speculative-theoretical-ideas-for-the-lhc/extra-dimensions/how-to-look-for-signs-of-...
4
votes
2answers
3k views

Strategies against 50 Hz mains hum on detector signals?

I'm having problems with a strong 50 Hz mains hum on signals created by photodetectors. I assume that they are due to ground loops and I realize that the best option would be to remove those. What are ...
4
votes
2answers
599 views

What are the easiest to get/make LN2 superconductors?

I am starting to build multistage Peltier cooler at the moment, and it should be able to reach -100C at least (but if I fail I can always get boring LN2). Doing some experiments with superconductors ...
4
votes
1answer
482 views

How do I calculate the experimental uncertainty in a function of two measured quantities

I am performing an experiment where I'm measuring two variables, say $x$ and $y$, but I'm actually interested in a third variable which I calculate from those two, $$z=f(x,y).$$ In my experiment, of ...
3
votes
1answer
141 views

How to determine the order of indications of a clock?

Given the description of a clock $\mathcal A$, as (1) a set $A$ of all (more than 2) distinct indications of this clock, in no particular order (where the individual indications contained in set $A$...
3
votes
5answers
481 views

How do we know that time dilation applies to objects other than light?

Here is a traditional derivation of time dilation: There's a train with a lamp in the ceiling, moving at velocity v with respect to an observer. In the frame of the observer, the path taken by the ...
2
votes
2answers
345 views

Real World application of Topological Quantum Field Theory

What is a "killer-app" for the formalism of topological quantum field theory in "established real world physics"? To be more precise, I'm looking for an actual physical experiment, state of matter or ...
2
votes
1answer
174 views

Reference request for the terminology and usage of different types of plasmas

I'm looking into discharge models, specifically for combustion prcesses, and I'm swamped by the number of different types of plasmas and their respective treatments (thermal plasmas, non-thermal ...
1
vote
3answers
687 views

Experiment demonstrating interference patterns of neutrons

The question is about experiments (and references) that demonstrate interference patterns of neutral (chargless) particles (fermions), especially neutrons. Like double-slit experiments for neutrons (...
13
votes
1answer
577 views

Could LEP II have discovered a 125GeV Higgs?

LEP II eliminated the Higgs up to 114.5GeV. If it had been run for longer could it have detected a Higgs at 125GeV? I Googled for this without any luck, though I did find a comment that LEP II topped ...
10
votes
1answer
275 views

Are oscillations of electron chirality experimentally observable?

Is there any plausible experiment by which chirality oscillations in electrons could be observed experimentally, such as through some analogy to neutrino oscillation experiments?
9
votes
5answers
7k views

What experimental proof has been found of Einstein's theory?

As a casual science reader, I've always found the implications of relativity (inconsistent clocks after near-light-speed travel and various space-time paradoxes) to be confusing and magical-sounding. ...
7
votes
3answers
356 views

why there is no accuracy of the measured value of $G$?

With the advancement of Modern Technology still there is no accuracy of the measured value of $G$ Gravitational Constant, why!?
7
votes
2answers
2k views

What is the most counter-intuitive result in physics? [closed]

I think that relativity and quantum mechanics would provide some good examples.
6
votes
0answers
161 views

What is the largest number of bosons placed in a BEC?

What is the record for the largest number of bosons placed in a Bose-Einstein condensate? What are the prospects for how high this might get in the future? EDIT: These guys reported 20 million ...
6
votes
3answers
937 views

How are the masses of unstable elementary particles measured?

I am interested in knowing how (Q1) the particle's masses are experimentally determined from accelerator observations. What kind of particles? They must be as far as we know elementary and unstable (...
5
votes
2answers
347 views

Accuracy of various optical instruments

I understand that this may not be the type of question allowed here, but I'm not sure. Feel free to close this if you feel that it shouldn't be here I'm planning on carrying out a certain set of ...
5
votes
6answers
6k views

How to guess the correct fitting function to some data?

Imagine we are plotting some date points $\left(x_i,f(x_i)\right)$ that we obtained experimentally, and that we want to know what $f(x)$ is. The way to do this is to use some software and try to fit ...
5
votes
2answers
1k views

What is meant by “combinatorial background” in experimental high energy physics

My guess is that they find a certain tracks coming from a certain source by "combintaorially" selecting all track pairs and finding their invariant mass. If this is true, of which I am not sure, how ...
4
votes
0answers
90 views

A theoretical model for evaporation occurring when wind is blowing over the surface of water

I've recently done an experiment in which I was studying the variation of the cooling rate of hot water in a draft (wind). The air was blow directly over the surface of the water (kept in a ...
4
votes
1answer
185 views

Have general relativistic effects of all of the components of the stress-energy tensor been measured?

The stress-energy tensor is: Have general relativisic effects of all of the components of the stress-energy tensor been measured? I've heard that the accelerating expansion of the universe is due to ...
4
votes
3answers
599 views

Energy of the electron-muon reaction

Lets see the reaction: $e^- \mu^- \to e^- \pi^- \nu_\mu \;\;\;\;\;\;\;\;\;\;\; {(1)}$ I suppose, that this reaction occurs as follows $e^- \mu^- \to e^- \mu^- \pi^+ \pi^- \to e^- \pi^- \nu_\mu$ Is ...
4
votes
3answers
558 views

What factors determine whether wind resistance will have an important effect?

What factors determine whether or not wind resistance will have an important effect on the trajectory of a projectile?
3
votes
1answer
788 views

Fitting to a high density scatter plot

I am trying to do a crude particle identification, using a Bethe Bloch tenchnique. Here is a plot I made from the data that I have From what I've read, the standard method to identify charged ...
3
votes
0answers
180 views

List of cross sections?

Sometimes I need to look up a certain cross section, say the inclusive Z production cross section at $\sqrt{s}$ = 7 TeV. Is there a place where 'all the' cross sections are tabulated (...
3
votes
1answer
265 views

Rutherford Experiment - practical and theoretical questions

I performed the Rutherford experiment the other day, using Au thin foil of $2\,\mathrm{\mu{}m}$, a source/gun of α particles (241Am) and a detector/counter. α particles were shot from the source ...
3
votes
1answer
2k views

What is a Pseudoscalar particle?

Can someone explain to me what is a pseudoscalar particle? And how do experiments figure out that what they're dealing with is a scalar or pseudoscalar?
2
votes
1answer
914 views

Enlightening experimental physics books/resources

Most book recommendations I've seen are usually geared toward theoretical understanding. It would be nice to know at least one or two classic experimental physics books. e.g. from Carl Brannen's ...
2
votes
1answer
368 views

What is 'tilt locking' of a laser cavity?

In another question, jasonh mentions a scheme for locking a laser to a resonant cavity called 'tilt locking': The signal is used for locking the frequency of a laser to a high finesse cavity. The ...
2
votes
1answer
158 views

With the LHC about to restart as max energy, are there absolutely no hints or tantalizing signs of Supersymmetry in previous data?

Over the last couple of years I've seen several articles talk about hints or bumps in the data that might point to Supersymmetry. An article in NewScientist from Summer 2012 discussed the discovery of ...
2
votes
2answers
282 views

Can we have light through out the house with out light being switched on for all the time?

Optical fibres are used to transmit light from one place to the other along curved path in a more effective manner. The optical fibres consist of thousands of strands of a very fine quality glass or ...
2
votes
0answers
43 views

Can a value of “length, in meters” be attributed to a pair of ends which are rigid (but not at rest) to each other? [duplicate]

The definition of the SI base unit "metre" [1] doesn't seem to rule out explicitly that a certain value of "length, in meters" could be attributed to a pair of ends which are rigid to each other, but ...
1
vote
1answer
88 views

Alpha scattering, observations and conclusions

For Rutherford's alpha scattering experiment where he fired alpha particles at a thin sheet of metal to determine the size of the nucleus, please can someone give me the direct link between his ...
1
vote
3answers
533 views

What is the reason behind specific values for charge of electrons, protons?

Why do things like protons and neutrons have specific values. Also speed of light is a speed in which even if you go towards it, the speed does not vary. But why does light have to travel at speed?
1
vote
1answer
43 views

Is there a rigorous, explicitly geometric, general characterization for whether a given clock had been “good”, or not?

In MTW, "Gravitation", there is a brief section (p. 26 and Fig. 1.9) discussing that clocks may be characterized, trial by trial, as having been "good" in the trial under consideration, or having been ...
1
vote
2answers
200 views

Which error propagation equation to use for a function of 2 variables?

So I have been taught two formulas for error propagation: For $Z=A+B$, $\sigma_Z=\sqrt{(\sigma_A^2+\sigma_B^2)}$ and for Z=AB or Z=A/B $(\dfrac{\sigma_Z}{Z})^2=(\dfrac{\sigma_A}{A})^2+(\dfrac{\...
1
vote
1answer
186 views

Examples to illustrate temperature dependant radiation by examples of temperature to color relation

I'm looking for a set of examples to illustrate the relation of temperature and color of "glowing" bodies. It should allow to build an intuitive understanding of this relation, so it's not about ...
1
vote
1answer
517 views

Numerical aperture of a lens

Using a laser setup, I was asked to determine the aperture of a given lens and then use some geometrical arguments and compare the theoretical value from the manufacturer and the experimental value. ...