filling in the unspecified details of elegant-sounding descriptions of experimental methods.

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1answer
25 views

Creating nanosecond pulses from a CW laser source

Experimental setup question. If anyone aware of a technique to create pulses of several nanoseconds at a around 10Hz repetition rate from a CW laser source?
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2answers
256 views

Are there any inventions/applications in our world based on QFT?

Are there nowadays any actual devices or experimental applications which are based on the quantum field theory and if so, how are they related to QFT? I could not find any similar question besides ...
2
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0answers
16 views

Creating a structural dynamic model using only modal test data

Short version: Suppose I excite a vibrational response in some structure and measure its mode shapes and natural frequencies. Is it possible to create a structural dynamic model of the structure ...
4
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2answers
57 views

Is circular masking a laser beam an acceptable way to get the beam diameter you require?

I am wondering what are the down sides to just masking a laser to get the beam diameter you require? For example if you have a collimated eliptical beam of say 2mm width and 4mm height, but you ...
2
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0answers
31 views

Determining the spatial imaging resolution based on a pinhole diffraction pattern

I aimed a 780 nm/1mW laser at a 1μm pinhole and took a picture of it using a lens and a CCD camera. The magnification of my imaging system is ~25 times. I wrote some code that takes the image of the ...
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0answers
25 views

How is it possible to combine various techniques in cold atom experiments?

I’ve been reading about laser-trapped cold atoms (6Li in particular, which is a fermion) and was amazed at the number of things to keep track of in the experiments, just to gain that degree of control ...
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1answer
92 views

X-ray diffraction on thin film

As far as I am concerned, when we perform an X-ray diffraction experiment using a Bragg-Brentano diffractometer using the "powder method" we have that the scattering pattern depends on only one angle ...
1
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1answer
35 views

How to stop particles from clustering on a water surface

For my experiment I have to obtain a water surface (1 m$^2$) seeded with floating particles. I found particles of the right size, density (and very acceptable price): expanded glass granulate. ...
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1answer
18 views

How to experimentally identify the exposed face of a crystal?

After depositing a material (e.g, TiO2) on a substrate, what methods can I use to check whether the material is crystalline, and what face (e.g, 001, 101, etc..) of the crystal is exposed?
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0answers
27 views

Can water seep in?

Today morning I was sweating a lot, and a drop of it directly fell on my iPhone's home button. Considering the height of fall to be approx. $30 cm$, I started wondering whether water could seep in. ...
2
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1answer
379 views

Is there a significant possibility of the LHC missing “exotic” particles or events?

In his popsci book, "Particle at the end of the universe", Sean Carroll says that the LHC, due to it's sheer information gathering capability, necessarily needs to completely discard most of the data ...
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0answers
16 views

Reverse polarity vs falling in Millikans experiment

There are multiple methods of hot to perform Millikans oil drop experiment. One of them lets the drop rise through an electric field (and measures the velocity) then lets if fall (without an electric ...
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1answer
55 views

What is the typical strength of the electric field in a particle accelerator?

I am working on a research project involving the closed orbits of hydrogen in the presence of an external electric field and I am curious what a reasonable approximation for the electric field ...
3
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1answer
156 views

What are the purposes of slits inside a spectrometer (Czerny-Turner)?

I am building a Raman spectrometer with a Czerny Turner configuration (with RamanPi). Why does the light source (A) appear to be converging into the entrance slit (B)? When a sample is excited by ...
3
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1answer
145 views

How I can launch light into PM fiber

A polarization maintaining fiber preserves the linear polarization of the light at the output, the light at the input must be linear polarized to see signal at the photodetector... However I can't see ...
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0answers
50 views

High resistance wire as a heating element

I'm redesigning one of the labs for our senior lab class at my university. It's a thermal conductivity experiment meant to measure aluminum's thermal conductivity in a thin (1.1 cm diameter) rod. I ...
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0answers
45 views

Kirchoff's voltage law doesn't seem to hold in an experiment conducted with series resistor, diode and signal generator

I've conducted an experiment to look at the electronic characteristics of a diode. This was done using a series diode, resistor ($R$) and signal generator. The signal generator was made to supply a ...
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2answers
97 views

How can we test relationship between frequency and peak current of an alternating current?

It has been suggested to me that $$\frac{V_{peak}^2}{I_{peak}^2}=R^2_{coil}+4\pi^2f^2L^2$$ where $L$ is a constant and $f$ is the frequency of AC. As a high school student I don't understand how can ...
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2answers
525 views

Sun spectroscopy - Home experiment

We let the sun light run through a 5x3x3cm triangular glass prism and we examined the formed 'rainbow' in search of Fraunhofer lines. However, even though we looked close enough (even with a ...
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1answer
85 views

How to make sure that two electrons collide head to head?

In high energy experiments, people smash particles into particles. But how to make sure that they really run into each other, instead of just passing by?
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2answers
519 views

How do I find the right lens for my laser?

I purchased this line laser recently and I'm running into a bit of an issue. The laser shoots out at a 120 degree angle which is perfect. However, once the laser spreads to about 4.25 inches, I need ...
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0answers
49 views

Errorbars for data series with variable number of points and several layers of uncertainty

I'm making a 2D plot of my microwave S Parameter data and want to represent the error bars correctly. Experimental Context: I measure S21, (Vout/Vin), as a function of frequency and drive power with ...
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0answers
38 views

Insulation for magnetic fields [duplicate]

How can I insulate conductors independently one off the other, where they pass through a magnetic field? Are there a techniques or alloys? There is a issue how to insulate copper wire where current ...
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2answers
56 views

Photon yield of NaI

We have to calculate the photon yield of the scintillator NaI. We have measured his pulse height spectrum but we have no idea how to solve this problem. Can someone explain it? The source that we used ...
1
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1answer
136 views

Measuring depth or height from sea level

How is the depth or height relative to sea level measured? Well, if it's near the ocean, it can be easily measured manually, but what if it is 100 km away from the sea? What method is used?
3
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1answer
215 views

Tunable Optical Band Pass Filter

Is there any cheap method by which to create tune-able optical band pass filter? I am working with a chemical process which will fluoresce when excited by a specific wavelength of light. As shown in ...
5
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1answer
152 views

How does one align a laser using two adjustable mirrors?

Suppose we would like to get a laser beam to pass through a particular point in space in a particular direction. At our disposal we have a laser, two adjustable mirrors (can rotate up/down and ...
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1answer
27 views

How do I make a Gaussian process generate a stream of events?

I would like to generate a stream of "random" gaussian events (on for event - off for no-event) that obeys a set standard deviation and mean. what algorithm could I use? thank you
1
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1answer
44 views

Uncertainty of approximately sinusoidal voltage measurement

Say one is interested in measuring the mean value an approximately sinusoidal voltage with an instrument that has an accuracy of 0.01 V, according to its spec sheet. 10 periods of the oscillation have ...
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0answers
180 views

Help understanding Fizeau's calculation of speed of light

While searching for different methods of calculating Speed of light, I came across one of the methods that Fizeau discussed below which I cannot fully understand. In short, in Fizeau’s apparatus, a ...
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0answers
34 views

Using GPS Satelites as dark matter detectors

Recently, two scientists have proposed a new way of detecting dark matter, using GPS Satellites. A part of the article is posted online: Hunting for topological dark matter with atomic clocks. Can ...
3
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1answer
98 views

How do we perform transverse measurements in a two level system?

In quantum mechanics any two level system can be mapped onto effective spin variables. If the system is defined by two energy levels, $|E_1\rangle$ and $|E_2\rangle$, the Hamiltonian is $$ H = ...
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0answers
26 views

How big can be gradient of magnetic induction (in lab)

I'm thinking about magnetic levitation and how big force can push a diamagnetic when we put it in inhomogenious magnetic field. As far as I know, force exerted on a diamagnetic is proportionald to ...
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0answers
62 views

How many measurements of a physical quantity should you do to get a representative value / distribution? [closed]

When we measure a physical quantity multiple times, we can calculate several values which should help us understand the whole measurement better: Standard deviation, variance, median, average, and so ...
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2answers
536 views

What is the relationship between radation intensity and count rate?

If you know that the radioactive source is, for example, Cesium-137, is it possible to extrapolate a relationship between the count rate and radiation intensity? If it is not possible, what is the ...
4
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2answers
68 views

How do you measure neutron energy?

I think you can detect a neutron event with a scintillator (neutron to photon), photomultiplier tube (photon to electric signal) system, but how would a fusion neutron's energy (2.45 MeV) be typically ...
2
votes
1answer
137 views

How to measure trajectory regularity? [closed]

I have two animal running trajectories. A regular one with repeated back and forth running between point A and B, like the one on top in the figure. The other one is very irregular, animal paused and ...
3
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1answer
267 views

Experimentally measuring coherence length of laser

So I am trying to figure out the coherence length of my laser source. I am using a mach zehnder interferomter (image attached). I have theoretically calculated $L_c$ to be somewhere between 800-1200 ...
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0answers
46 views

What is the error on measuring the phase of a sine wave?

Let's say I have a wave, with frequency $\omega$ and phase $\phi$, of the form: $$y(t) = 1 + A \sin(\omega t+\phi)$$ where $A < 1$. I have measured this wave N times, and we can assume these ...
15
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0answers
527 views

Are the fast axes on Thorlabs quarter-waveplates mislabeled?

Some members of my lab are performing a polarization-sensitive experiment where they need to use a quarter-waveplate (QWP) with the fast axis in a specific direction. In the process of carefully ...
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4answers
1k views

Experiment - Measuring final velocity of a parachute

I'm working on a project that involves a scale parachute. It is vital for the project to get a good measurement of the speed it has when it lands. We still haven't built the parachute, but we need a ...
17
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6answers
1k views

Which experiment gave scientists reason to believe nuclear fission/fusion produced energy?

Every piece of knowledge in science has a beginning lying in someone's experiment. I would like to know which experiment gave scientists the reason to believe nuclear fission/fusion existed and was ...
0
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2answers
126 views

Layer thickness measurement

I am interested to measure the thickness of the coating on a mirror (e.g. in the picture below). What are the available and best way of measuring it? What will be the solution in case of multiple ...
1
vote
1answer
108 views

Collection Efficiency of Photon

I am currently reading this paper: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.116802#references In the second column of text in page 2, the author makes various claims about the ...
4
votes
1answer
239 views

How do you measure a particle's postion or momentum?

This question is about the Uncertainty Principle $$\sigma_x \sigma_p ~\ge ~\frac{\hbar}{2}.$$ Looking at the maths, I understant why the uncertainty in the poistion increases as the uncertainty in ...
2
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2answers
89 views

How do you know which atoms are in a specific piece of matter?

If you have a piece of matter in front of you, how can you know of which atoms it consists? And starting from nothing, how can I discover all the elements (or just a lot of them) of the periodic ...
0
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1answer
155 views

Dead time in data acquisition

I am creating a data acquisition software, based on Sparrow's Kmax. There I would like to add a feature that will show the system's dead time. I have already a text field that shows the real time and ...
3
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1answer
113 views

Why apply voltage on an Si detector only on atmosphere or high vacuum

The general instruction when using a silicon detector is to either apply voltage only in atmospheric pressure or in high vacuum. Not in between! I can't find a physical answer to it. Why is it so ...
3
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0answers
55 views

Alternative ways to take particle tracks photographs in a cloud chamber

I know that the most common type of particle tracks photography is in photographic plates, but i'm using a cloud chamber and I would like to know if there are alternative ways to take photographs of ...
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3answers
409 views

Error propagation estimations for sine and cosine

My lab manual gives this: $B$ is a function of $A$, Greek are uncertainties... $$B + \beta = \sin(A + \alpha) = \sin(A)\cdot\cos(\alpha) + \sin(\alpha)\cdot\cos(A)$$ --> because $\alpha$ is ...