Tagged Questions

1answer
50 views

Decay/Counts/Number of Nuclei

I'm writing up a lab report and have a question about the following formula $$N = N_0e^{-\lambda t}$$ $N$ indicates the number of nuclei left after a time $t$ and $N_0$ indicates how much there was ...
2answers
103 views

Franck and Hertz graph function [closed]

I need a function whom graph is the following (the Frank and Hertz experiment graph): Currently I wrote the following function: ...
2answers
182 views

NMR Analysis of Ethylene glycol [closed]

I have the spectrum obtained by an NMR analysis of Ethylene glycol : I would like to explain the number of peaks in this spectrum, and assign them to the proton spins present in the molecule. I ...
1answer
122 views

What are the problems in analyzing an experiment with non-ideal collisions? [closed]

For a two-dimensional collision experiment, I must explain in one of the questions the problems in analyzing a non-ideal two-dimensional collision. As the question states: Suppose that the ...
1answer
237 views

Calculating Lyapunov exponents from a multi-dimensional experimental time series

Wolf's paper Determining Lyapunov Exponents from a Time Series states that: Experimental data typically consist of discrete measurements of a single observable. The well-known technique of phase ...
2answers
519 views

Does a muon detector on Earth's surface correctly measure the mean lifetime of a muon?

Just a simple question. Does a muon detector on Earth's surface correctly measure the mean lifetime of a muon? I would think the answer is no because most muons detected are created about 15 km above ...
1answer
118 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 ...
1answer
148 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 ...
0answers
89 views

Textbook about the handiwork of a HEP analysis?

I'm wondering if there is a textbook that describes the handiwork of a particle physics analysis. There are a bunch of books about theory, about the experimental aspects like detectors, and about ...
0answers
47 views

Converting impact speed to pressure magnitude

In explosive safety and stability testing, a drop test is commonly used to determine the sensitivity to impact. In the test, an impactor of known mass is dropped. The initial height varies throughout ...
0answers
69 views

What could be the distribution of an explosion energy of a mining-grade and seismic exploration explosives?

Seismic exploration involves the excitation of seismic waves using the industrially made explosive charges. What could be the distribution of explosion energy of such a charges? My guess is that it ...
2answers
167 views

1/r Counting Rate for Radiation Experiment

In an experiment performed in the lab, I want to justify that, when the width of the Geiger counter window is approximately the same size as the distance between the window and a mildly radioactive ...
0answers
23 views

Expression for combining several probabilities in a single discriminator

I'm doing an analysis of some experiment. Details are not very important, but I've stumbled on an expression that I cannot make sense of. I have several simultaneous measurements of a certain ...
1answer
69 views

Curve Fitting and Multiple Experiments

Say I do an an experiment 5 times, each of which gives you a list of data points. Do I fit a curve to each one separately and then average the parameters and their uncertainties? Or do I take the ...
0answers
113 views

Statistical analysis of data in Physics

Analysis of data is integral in bridging the gap between theory and experiment. My question is about the two major methods of approaching the analysis - Bayesian and Frequentist. How much do the ...
3answers
1k views

What does a curved natural log graph suggest?

Sorry if this is rather simple, but I've only just started learning about using logarithms in experimental physics. I did an experiment to test the amount of time it would take for an amount of ...
1answer
66 views

Interpreting the results

I have preformed the muon lifetime experiment at my uni's lab, and got the data. It's text file with 8190 numbers. My TDC unit was set so that the time gates were at 10 $\mu s$, and it has 8192 ...
1answer
1k views

Uncertainty in Acceleration given the uncertainty in position

I had a motion detector record the position of a dynamics cart and automatically plot Position vs Time and Velocity vs Time plots in Logger Pro on the computer. If the instrument uncertainty in ...
1answer
83 views

More points vs. precision

I have a dilemma. In my lab exercise, I was measuring spectra with HPGe detector of several sources (gamma spectroscopy). To determine the energy of the unknown spectrum I first needed to calibrate ...
1answer
148 views

Dealing with experimental data

I have some experimental data about a value $n$, now, I am supposed to give, in the ending, a single value with an error: $n=a\pm b$. I have originally 6 values of $n$, each one comes as an indirect ...
1answer
132 views

Data requirement to determine proportionality

A common result of theoretical analysis in physics is some sort of relation derived from physical parameters and typically expressed in the form of a non-dimensional parameter. These scale relations ...
3answers
117 views

How to find exponential values

I have a power equation for flow between two circular disks on a common axis as stator and rotor, which follows, $$P = \frac{n^a}{G}\tag{1}$$ Where: $P$ = power, $n$ = revolution (1200 rev/min), ...
1answer
132 views

Peak deconvolution [closed]

I need some help understanding how much information I can pull out of this data. I have a sample made up of two materials. Materials A and material B. Then I took a picture of the sample. The two ...
2answers
341 views

Microsoft Excel not graphing $x = y^{1/2}$

The experiment was relating the period of one "bounce" when you hang a weight on a spring and let it bounce. I have this data here, one being mass and one being time. The time is an average of 5 ...
0answers
221 views

How do I do error calculus right using gnuplot as an example?

Given is a set of measurements with their respective errors for example an energy spectrum. In gnuplot one is to fit a function $f(x;\{p_i\})$ depending on a variable $x$ and on fit parameters $p_i$. ...
1answer
334 views

Lab observation correct? As distance decreases, velocity increases, stderr decreases

The experiment goes like this: Allow a moving cart to move from the top of an incline plane ($x_0$) downwards. The time taken will be recorded by the picket fence (those things you see wired up). ...
2answers
563 views

Use of Monte-Carlo simulation in High-energy Physics

I've been doing some research into the analysis used in particle physics when determining the significance of a finding (e.g. the recent Higgs candidate was announced as a boson in the 125-126 ...
1answer
108 views

Variance of Nested Experimental Uncertainty

I have to find the uncertainty of a quantity $Q$ doing two mean values. For example for a set of parameters I measure ten times $Q$, I obtain a mean value $Q_1$ and variance ${\rm Var}(Q_1)$. Then for ...
1answer
313 views

Pendulum: Deduce proportionality from experiment

I know, very easy for all of you, but I'm a beginner in physics ... ;) I have to work with the mathematical pendulum. After some experiments (changing mass, chaning pendulum's length etc.), I could ...
2answers
417 views

What do “local” and “global” mean when talking about standard deviations in experimental particle physics?

I found the following sentence: The excess is most compatible with a SM Higgs hypothesis in the vicinity of 124 GeV and below, but the statistical significance (2.6σ local and 1.9σ global after ...
5answers
2k 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 ...
1answer
509 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 ...
2answers
371 views

How are the HEP experiments' invariant mass plots generated?

I am experimenting and playing around with some data, and I'm having trouble seeing how to generate invariant mass plots. The data I have has a bunch of events, and variables such as ...
2answers
646 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 ...
2answers
234 views

How to predict how much data to collect

The same question on CrossValidated Apologies if I'm being a bit vague in what follows, I've been asked to keep certain aspects of the experiment confidential for the time being. An analogous ...
2answers
2k views

Did the researchers at Fermilab find a fifth force?

Please consider the publication Invariant Mass Distribution of Jet Pairs Produced in Association with a W boson in $p\bar{p}$ Collisions at $\sqrt{s} = 1.96$ TeV by the CDF-Collaboration, ...