filling in the unspecified details of elegant-sounding descriptions of experimental methods.
4
votes
1answer
46 views
Optics alignment of scanning microscope
I am facing a challenge in my project regarding optical alignment.
See the figure:
The challenge is with the vertical optical system alignment. I considered placing a mirror and check back if the ...
4
votes
0answers
72 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 ...
4
votes
1answer
87 views
How important is it, really, to clean vacuum parts?
In every lab I've seen, people are quite meticulous about cleaning parts that are to be used in ultrahigh vacuum, as well as the components of the chamber itself. The parts may be put in an ultrasonic ...
2
votes
0answers
138 views
Production vs. Collection, and Contaminants vs. Depositions, what might be missing in cold fusion research
I though cold fusion and LENR were discredited, but just a few days ago I found out that NASA is claiming LENR is real. So I thought if they're detecting something, what could it be, and why wasn't it ...
2
votes
1answer
61 views
Experimental measurement of volumetric flow rate
The other day I with my team had to measure the volumetric flow rate through a pipe only using a 2000 mm$^3$ volumetric flask and a chronometer. The end of the pipe discharged to the atmosphere. As we ...
2
votes
2answers
145 views
Multiple measurements of the same quantity - combining uncertainties
I have a number of measurements of the same quantity (in this case, the speed of sound in a material). Each of these measurements has their own uncertainty.
$$ v_{1} \pm \Delta v_{1} $$
$$ v_{2} \pm ...
3
votes
1answer
86 views
What algorithms are used for track reconstruction in cloud chambers?
In particular I'm interested in any algorithms that can separate multiple tracks from one another reliably.
0
votes
1answer
155 views
Experiment to measure initial speed of high speed tennis ball?
I want to devise a way to measure the initial speed of a tennis ball fired from a tennis ball cannon, but without using any speed-measuring devices. Just plan distance-measuring and physics formulas.
...
2
votes
3answers
119 views
Glass pipe cutting
I want to know how to quickly create the straightest possible breaks in glass pipes
I apologise if this is only borderline suitable for a physics forum - I just hope experts with a lot of experience ...
3
votes
2answers
65 views
Layman's method to sharpen a wire (STM-tip)
We use a platinum-irididum wire to fabricate our STM tips. And by "fabricate"
I mean to cut it with really sharp pliers or scissors.
Sometimes we get good tips but most of the time they are not usable ...
0
votes
1answer
52 views
How can I cheat an XRD sample (~10 mg) from a total 1g required? How can I use for the background.
How much can affect (in terms of hump) my X-ray diffraction pattern the "amorphous" glass or maybe someone can suggest me other material to compensate for the small amount of the sample.
Note: my ...
2
votes
0answers
51 views
Real World measurements related to phonon dispersion
I hope no one objects to the style of this question. Let me explain my motives in asking the question first.
Condensed matter physics is one of the most beautiful subjects around. But those who are ...
3
votes
2answers
96 views
Do I need to have an airtight container to siphon boiling water?
I'm attempting to siphon boiling water into another container for a school project. I have researched the physics of a siphon but I can't seem to make my boiling water siphon out of its initial pot.
...
0
votes
1answer
105 views
Repulsive Magnetic Hammering Experiment
I have been thinking about something thing...
I want to attach four or any number of magnets with arms to an axle..
Blue dots be magnets.
Its is not a wheel configuration, all arms can move ...
4
votes
1answer
74 views
Ways to create controlled small bubbles in water within plastic tubing
What is a practical way in an engineering or physics laboratory to create bubbles of a specified size in water within plastic tubing? The tubing is a few mm inner diameter. We'd like to make bubbles ...
1
vote
1answer
124 views
How do you calculate the equivalent absorbed radiation dose from activity, type of emission, and the energy of the emission?
I have a sample of U-238 of which my Geiger counter detects beta activity at 700 events per second. Based on the counter's efficiency of 98.6% for U-238, the activity would be about 710 becquerels, I ...
5
votes
2answers
157 views
statistics for photon counts in photomultiplier
It seems that a common statistical model for the count numbers of a photomultiplier is a Poisson distribution whose parameter $\lambda$ equals to the square-root of the number of counts.(e.g. ...
2
votes
1answer
86 views
Difference between Diamond anvil cell and Bridgman cell
In high pressure physics what is the difference between diamond anvil cells (DAC) and Bridgman cells? My understanding is that they are both forms of anvil cell but in the scientific literature I'm ...
0
votes
1answer
33 views
What is pulsed neutron diffraction?
I have tried a google search and checked my condensed matter books but I can't find out what pulsed neutron diffraction is and how it differs from inelastic neutron scattering.
3
votes
1answer
141 views
Rutherford's Gold Foil Experiment
Can anybody explain how Rutherford bombarded a 0.0004 cm thick gold foil? How did he put it in a photographic sheet? Wasn't the foil too thin to be held? How did he know that the atoms were deflected ...
5
votes
3answers
207 views
experimental technique for measuring temperature of an ant
I am taking a course on thermodynamics. I have a question from my text(halliday & resnick,physics-1). They asked me to measure temperature of an ant or an insect or a small body,like a small ...
3
votes
3answers
179 views
How to determine whether a large container is air-tight?
In constructing a kitchen-waste digester at home, I use a 50 Litre HDPE drum. The base of the drum is holed with a plug fitted to allow drainage when necessary.
The top has two openings - one for ...
0
votes
1answer
177 views
Calculational method for determining surface tensions from photograph of menisci?
How can I get from a photograph of a liquid surface to a value for the surface tension.
3
votes
0answers
90 views
Obtaining point of application of Ground Reaction Force with use of a hyperstatic load-cell array platform
I'm looking for the theory of an experiment that is giving me a hard time to perform.
I have an instrument composed of a rigid horizontal square plate rigidly supported under each corner by a ...
0
votes
1answer
108 views
How to choose a $\alpha$, $\beta$, $\gamma$ measurement detector?
There are many different detectors for different radiation,such as NaI,HpGe,CsI for $\gamma$ detection,and ionization chamber,proportional counter,Geiger counter for $\alpha$, $\beta$ detection,but ...
1
vote
1answer
116 views
Calibrating an electronic temperature sensor based on power consumption
I'm working with an electronic temperature logger that is being affected by heat generated internally.
How does one come up with a calibration equation to calculate a more accurate reading of ambient ...
4
votes
1answer
263 views
How the bond angle of a water molecule is measured?
How the angle of a water molecule is measured?
The bond angle for water was first determined by vibrational and rotational analysis of its infrared absorption spectra. How is bond angle extracted?
4
votes
0answers
150 views
Parity and Helicity of the Higgs Boson
I have been studying how the spin and parity of the new boson discovered at the LHC will be studied and have run into some confusion. The Standard Model Higgs is expected to be a scalar (i.e. have ...
4
votes
2answers
235 views
Vector Boson Fusion
I have been reading about the production mechanisms for the Higgs at the LHC. It is always mentioned that for Vector Boson Fusion, the initial quarks cause jets that are back to back and with a higher ...
0
votes
1answer
104 views
Increase the signal-to-noise ratio of photomultiplier
It is a GRE physics problem.
A technique would most likely increase the
signal- to-noise ratio of a photomultiplier tube is to
operate the tube at a lower temperature
operate the tube at higher ...
0
votes
2answers
78 views
Image contrast as function of exposure for a CCD detector
In a laser interferometry experiment, we project a pattern of interference fringes onto a CCD sensor. For best results, we want good contrast between the bright and dark fringes, and we carefully ...
2
votes
1answer
67 views
random triggers
I understand that a small proportion of events at the LHC that would not trigger on any deterministic trigger are saved on what might be called a random trigger, so that, amongst other uses, proposed ...
3
votes
1answer
92 views
What's an efficient way to produce graphite on TEM-Grids?
I am trying to produce graphene with few layers(<10) on a TEM-Grid. Until now I've been trying this with the scotch-tape-method with slight modifications. Unfortunately it requires a lot of time ...
4
votes
2answers
179 views
What has been measured at the Higgs experiment and what do we know now?
Explained at the level of a 5$^{\text {th}}$ semester physics student (i.e. pre QFT, but far beyond the level of a news article for non-physicists, which avoids all details and only deals in ...
0
votes
1answer
401 views
Franck-Hertz Experiment explanation
Can anyone explain to me how the Franck-Hertz experiment works? (in term of electric current and voltage changes) I am getting all confused.
More specifically, why is an accelerating grid (or mesh ...
3
votes
1answer
122 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 ...
2
votes
1answer
100 views
Amount/flow rate of N2 needed to cool substrate
I'm trying to cool a substrate inside a vacuum chamber with liquid nitrogen. The substrate holder is a block of copper suspended from the top of the chamber via nylon screws (for thermal insulation). ...
0
votes
1answer
125 views
How was Dorsey able to measure speed of light with 3 significant digits?
How was Dorsey able to measure speed of light with 3 significant digits in the year of 1907?
4
votes
2answers
186 views
How does one get the value of acceleration of gravitation on earth accurately by experiment without electronic device?
How does one get the value of acceleration of gravitation on earth accurately to 5 significant digits by experiment without electronic device?
2
votes
1answer
117 views
Good algorithm for in-experiment 1-D optimization?
I'm running an experiment -- for the question, it doesn't matter which one, but I'm measuring an optical intensity $I$ as a function of two parameters: reflection angle $\theta$ and wavelength ...
1
vote
1answer
171 views
How does the Double Slit Experiment work in detail?
What is the best detailed description/visualisation of the experiment available?
Describing what is actually measured, how the data is analysed, correlated and interpreted when for example large ...
2
votes
1answer
460 views
Inductor with controlled temperature coefficient
Let's assume we have an air-spaced inductor made of copper wire.
As temperature changes, due to thermal expansion of physical dimensions of the coil, its inductance changes too.
1) Is there a way to ...
4
votes
2answers
933 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 ...
1
vote
1answer
525 views
Oil drop experiment--How was the result so accurate?
I remember while learning about Millikan's oil drop experiment and being pretty skeptical about the setup. I know that there is a lot of controversy regarding manipulation of data, but the fact is; he ...
3
votes
2answers
253 views
What is the highest accuracy of measuring time differences achievable today?
I was wondering if it would be possible to shorten the distance between detectors when measuring the speed of neutrinos to, say, 7m rather than the current ~700km? In this way the distance traveled ...
6
votes
2answers
202 views
How is the distance between Geneva detector and the Gran Sasso one measured?
Does anyone know how is the distance between detectors in the now famous neutrino experiment measured? Also, how was the time of flight measured?
11
votes
1answer
199 views
Cleaning Already Mounted Microspheres on an AFM
I am running an experiment that uses a microsphere (Diameter ~ 50um) mounted onto the end of an AFM cantilever. I run several experiments in a row, but somewhere during a sequence, the microsphere ...
2
votes
1answer
131 views
Measuring concentration
I am trying to measure the concentration of a Volatile Organic Compound (VOC) inside a liquid using Gas Chromatography (GC). The liquid contains particles that cannot be sent to a GC, so I am using ...
12
votes
2answers
20 views
Why are binary objects so critical to astronomy?
There are a lot of astronomical objects out there to study but binary objects seem to get more attention. Why is this? What makes binary objects (stars, Kuiper Belt Objects, black holes, galaxies, ...
12
votes
4answers
3k 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.
