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

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2
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1answer
48 views

What is the minimum sample sizes to show the error bar in an experiment?

In scientific experiment, people often try to show an error bar based on the standard deviation around a mean (average) value. My question is twofold: How to estimate the minimum but adequate ...
0
votes
0answers
10 views

Methods for producing Molecular C60 (A.K.A Buckminsterfullerene) [on hold]

I wanted to know about how to produce molecular C60 - also known as Buckminsterfullerene/buckyballs. I read online that vaporising graphite in helium gas was how scientists initially discovered ...
0
votes
2answers
232 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 ...
3
votes
1answer
73 views

Measuring very long half lives accurately

There are already some questions about long half life times for radioactive elements, explaining how to calculate the half life time. Now I am wondering: When you have some radioactive material and ...
10
votes
3answers
309 views

Measuring the effective mass

Intro: To avoid any terminology confusion, this is asked in the context of Solid State Physics and semiconductors. The canonical definition given for the effective mass is that it is related to the ...
0
votes
0answers
36 views

How are optical lattices created, and how big can they be?

I am asking about the basic concept and the schematics of the laser configuration. How are atoms forced to stay in optical lattices? What lasers (power, wavelength, etc.) are used, and how are they ...
1
vote
0answers
8 views

Anoxic sample containers

I am preparing pure Si samples, etching the oxide layer, in an argon glovebox, and I have to transfer them to the AFM. We don't have any sample containers in the lab, so I have to buy some. I wasn't ...
0
votes
0answers
18 views

What is needed to be taken into consideration when measuring torque in dynamic mode?

Let's consider a DG generator connected with a hydraulic turbine through a shaft. To the stator of the generator it's attached a arm connected to a load cell. The load cell is measuring the force that ...
1
vote
0answers
22 views

Sine wave in my residuals graph [closed]

We had a physics experiment where we should have had a linear relation between 2 measured values, we got a pretty good fir however our residuals plot has a kind of a sine wave behaviour. We were told ...
2
votes
1answer
56 views

Why does one use different materials for cathode and anode in the photoelectric effect experiment

All photoeletric lab experiments I have seen so far have a setup where you have different materials for cathode and anode. However this raises some experimental difficulties since you have to take ...
1
vote
1answer
42 views

Are residuals supposed to have error bars?

Hopefully I'm asking this in the correct section. So I've got a graph with a linear trend of data and a best fit line plotted. The data points on the main graph obviously each have their own error ...
1
vote
1answer
36 views

What is an absolute frequency reference (Frequency combs)?

So I am currently studying for my bachelors thesis which is all about frequency combs. I am reading a lot of articles about them but I just keep coming across things that the people who wrote the ...
4
votes
1answer
31 views

Why is 2-terminal sensing less accurate than 4-terminal sensing if the internal resistance of leads is known?

I have a pretty good understanding of 2-terminal vs. 4-terminal (kelvin) sensing measurements. I understand that in the 4-terminal measurement, current is supplied by 2 terminals that are separate ...
5
votes
2answers
376 views

Einstein's original papers predicting gravitational waves? [closed]

I came across the original handwritten papers in which Einstein predicted gravitational waves1: and since LIGO announced they've detected a signal confirming the predictions I was wondering if ...
4
votes
1answer
32 views

What's the difference in the film between sputtering deposition and an ebeam evaporator?

I know the differences between the two deposition techniques, but what about the difference in the properties of the resulting films? All things being equal (such as substrate temperature), would ...
6
votes
1answer
2k views

Liquid nitrogen and liquid helium

In cryogenics, liquid nitrogen and liquid helium are often used as coolants. Other than their low boiling point of 77K and 4.2K respectively, what properties make them suitable as coolants? Are there ...
22
votes
0answers
776 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 ...
3
votes
1answer
35 views

Machine readable database of gamma lines

Friends of mine did a lab experiment where they recorded $\gamma$-spectra in the range from 0 to 1500 keV with a soil sample. The data contains some background and a couple sharp peaks at different ...
3
votes
2answers
62 views

How to measure transverse current-current correlation at arbitrary wave vector and frequency

Let $\hat J^{\mu}(t,\boldsymbol r) \equiv (c \hat \rho(t,\boldsymbol r), \hat{\boldsymbol J}(t,\boldsymbol r))$ be the density-current operator at spacetime coordinate $(t,\boldsymbol r)$, in the ...
1
vote
3answers
27 views

Measuring Activity

The formula for Activity of a radioactive substance is $ \frac{dN}{dt}=A=λN $. If we have an initial number $N(0)$ of some Radionuclide, which has a halflife of, say, 12 hours, is there any ...
1
vote
1answer
101 views

Double slit experiment mechanism

Can someone explain the mechanism that sets in motion the electrons in the experiment? Is it an electro-magnetic force? If so, I think it's not right to describe the motion of the electron as a ...
1
vote
2answers
33 views

Gamma spectroscopy - Fitted Singlet

I'm using some gamma acquisition and analysis software. When I ask the software to do some sort of Nuclide Identification, almost every single peak in the generated output is marked with "F". ...
15
votes
4answers
10k views

How to prolong life of liquid nitrogen in hosehold vacuum flask?

I need to do some work with liquid nitrogen at home. The main question is how to store it without buying huge vacuum flask specifically for liquid nitrogen. I've tried to use usual steel household ...
1
vote
0answers
25 views

Procedure for wrapping a superconducting coil around a cylindrical shell?

I don't know if experimental physics questions are allowed on this site - please direct me to the proper SE if it doesn't belong here. I need to wrap a few layers of superconducting wire (~80 ...
0
votes
1answer
36 views

measure barometric pressure using boiling water

I have set a cup of water in a bell jar, with a thermometer. I am able to lower the pressure until the water boils and I am able to measure the temperature of the water simultaneously. I then looked ...
0
votes
0answers
19 views

Interferences while using two ToF cameras

Im using two time-of-flight (ToF) cameras, a DS325 from SoftKinetic and a Creative Senz3D, at the same time with the DepthSense-SDK and the Point-Cloud-Library (on Ubuntu 15.04). But I got strong ...
0
votes
1answer
36 views

prototyping a cyclotron , a charging problem

I'd like to model a cyclotron but not with subatomic particles but with a small metallic ball but the problem is i need to charge the metallic ball with certain amount of charge and i must know it to ...
0
votes
1answer
42 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?
12
votes
2answers
400 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 ...
4
votes
2answers
117 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
votes
0answers
24 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 ...
0
votes
1answer
184 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 ...
2
votes
0answers
39 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 ...
1
vote
0answers
32 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 ...
0
votes
1answer
20 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?
9
votes
2answers
961 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 ...
1
vote
1answer
46 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. ...
2
votes
1answer
398 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 ...
1
vote
0answers
40 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. ...
0
votes
0answers
28 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 ...
0
votes
1answer
205 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 ...
10
votes
2answers
2k views

Methods to stabilize and maintain extremely low humidity in a lab environment

My atomic physics lab is in a building that experiences huge swings in humidity levels during the year due to the monsoon season Our building provides temperature, but not humidity control. Using ...
3
votes
1answer
963 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 ...
1
vote
1answer
244 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
votes
1answer
430 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 ...
5
votes
1answer
304 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 ...
20
votes
4answers
13k views

How do astronomers measure the distance to a star or other celestial object?

How do scientists measure the distance between objects in space? For example, Alpha Centauri is 4.3 light years away.
1
vote
0answers
54 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 ...
12
votes
2answers
749 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 ...