Cross section Definition and 315 Threads

Hello It seems to me that the nuclei have a flat elastic scattering cross section of neutrons, for neutron energies from eV to MeV. http://www.nuclear-power.net/wp-content/uploads/2015/11/Elastic-Scattering-Cross-section-light-elements-min.png I thought that maybe it was caused because the...

I'm trying to figure our the relation between cross section, scattering angle and KE? I'm doing a few exercises where I've been given kientic energy and scattering angle and have to calculate the cross section. Cross section is in units of Barns (m2), and KE is 1/2 kg*m2*s-2, but I can't seem...

Hi folks, I'm working on Fluka nowadays which you can found from here if you are not familiar. It's a very useful and widely used Monte Carlo simulation package. My main goal is to be able to perform total cross section calculation with it. So far, please consider I'm a rookie, I've done some...

Will someone explain this step to me?

Given a rectangular prism that is composed of various horizontal layers made of different materials, how can one calculate the modulus of elasticity? Currently the materials used and their respective ratios have not been specified. We wish to determine this information using the results of...

Homework Statement Calculate the ratio ##R = \frac{\sigma_{had}}{\sigma_{\mu+\mu-}}## for energy around ##10~GeV##. At sufficiently high energies, the ##e^+e^- \rightarrow \mu^+ \mu^-## reaction can proceed via the ##Z^0## boson. Assuming vertex factors for EM and weak interaction are the same...

Homework Statement [/B] (a) Find the ratio of cross sections. (b) Find the cross section for electron-neutrino scattering by first writing down relevant factors. Homework EquationsThe Attempt at a Solution Part (a)[/B] These represent the neutral current scattering for the muon-neutrino and...

I am going over the optical theorem (specifically from Sakurai) and I just have a simple couple of questions. The optical theorem says \sigma_{total}=\frac{4\pi}{k}\text{Im}(f(0)) Where ##f(0)## is the scattering amplitude in the forward direction. (Which I am assuming means the direction...

Hi All, I have a question about resonance cross sections. I have been doing the design work on the reactor I want to propose for testing at Oak Ridge National Labs, and have run into a problem. It is an accelerator driven reactor transmuting thorium into uranium, then burning the uranium by...

I was studying my notes and specifically for the ##e^+e^- \rightarrow \mu^+ \mu^-## process, cross section is given by \sigma = \frac{4\pi}{3} \left( \frac{\alpha \hbar c}{W} \right)^2 where ##\alpha = \frac{g_{EM}^2}{4\pi}## and ##W## is the centre of mass energy. Is this the same for...

I was reading about control rods in a nuclear reactor. The carbon rods slow down the neutrons so they can interact better and induce fission. Is the reason that they don't interact when raveling fast is this because the have a smaller de broglie wavelength?

Homework Statement (a) Explain the results. (b) Why is the cross section much higher? Suggest the dominant decay product pair.[/B] Homework EquationsThe Attempt at a Solution [/B] Part(a) For a centre of mass energy of ##170GeV##, you produce pairs of oppositely charged ##W^{\pm},W^{\mp}##...

In one of my classes, I should give a talk about pair production cross section in front of the class and so I'm now searching for resources. But I can't find a place where the differential cross section for pair production process is given. Anyone knows somewhere I can find it and , preferably...

Hydrogen - Halpha cross section i need the absorption cross section for the absorption of an H-alpha photon by a hydrogen atom, in the correct state of course, which I'm pretty sure is neutral hydrogen, n=2. I am needing this for a project, so i also need a reliable source where this comes...

Hi, I was just wondering if someone could help clarify how pi - theta = phi? That is the link to the youtube video I was watching, the guys pretty good check him out if you want to learn how to derive the differential scattering cross section.

Hai all, I need some help in understanding the calculation of total ionization cross section. As per the literatures, for a gas capable of multiple ionization, the total cross section is a charge-weighted sum of partial ionization cross sections. To be more elaborate, consider the case of...

Homework Statement I want to find the ionization cross section in a mass spectrometer for the gas Argon. The value obtained should be in the 2x10-16 cm2 range. Homework Equations Q = ionization cross section I = K(V,B)xNxQxdxIe Where I = (0.17 x 10-11, K(V,B) =1, d = 0.1 cm, and Ie = 5 x...

Homework Statement I am making an old exam of a particle physics course, and i know how to calculate the cross section for example for bhabha or moller scattering. now one of the questions on the old exam is: Explain why e-+ e+ -> γ is zero, but i am not sure why this is, can someone explain...

1) Alpha particles can react with 48-Ca to produce protons. Consider a beam of alpha particles of current 20nA fired at a think target of Ca of thickness $$1mg/cm^2$$. A detector subtending a solid angle of 4*10^-3 steradians, records 20 protons per second. Determine the total cross section (in...

I am trying to calculate differential cross-section for partonic collisions (QCD) like q + q \rightarrow q +q q + \bar{q}\rightarrow q + q g + g \rightarrow g + g I can't find those calculations done anywhere, just the results and maybe some middle tips, that's all. As you may know those...

Homework Statement Why does ## \frac{ e^+ + e^- \rightarrow \mu^+ + \mu^- }{e^+ + e^- \rightarrow \tau^+ + \tau^- } \rightarrow 1## at high energies? Would it be the same if it was ## \frac{ e^+ + e^- \rightarrow \mu^+ + \mu^- }{e^+ + e^- \rightarrow e^+ + e^- }##? Homework EquationsThe...

I'm looking at deep inelastic scattering of a low-energy inelastic electron scattering from a stationary proton target. I am given ##E## and ## \theta ## where ##\theta ## is the scaterring angle. ##E=4.879 GeV , \theta=10^{0} ## I am given a figure of cross section...

I have a result for the differential cross section d\sigma/d\eta dP_T^2, but I want to obtain the corresponding differential yields dN/d\eta dP_T^2. How to relate yields to cross section?

Homework Statement In this problem, you will estimate the cross section for an earth-asteroid collision. In all that follows, assume that the Earth is fixed in space and that the radius of the asteroid is much less than the radius R of the earth. The mass of the Earth is M_e, and the mass of...

The electrons flow on the outer surface of the resistor, why then does the resistance of a resistor depend on it's cross sectional area and not on it's perimeter?

Homework Statement I'm finding conflicting statements. One says that current is measured as the amount of charge per time that enters through a cross sectional area. Another says that current is measured as the amount of charge per time that passed through a point. Could someone clarify this...

1. The problem statement, all variables and given/known I have to prove an equation for the differential cross section of compton scattering of an electron and a photon (electron (P) + photon(K) ⇒ electron(P') + photon (K') ) where P and so on are the inital and final four momenta. Given is...

1. Situation: I have no specific exercise in mind but just the general form. ''A beam of protons is colliding with a plate of a given particle density ##\rho## and thickness ##l##. The cross section is ##\sigma##. What should the thickness of the plate be such that the intensity of the outgoing...

Greetings, i need the absorption cross section for the absorption of an H-alpha photon by a hydrogen atom, in the correct state of course, which I'm pretty sure is neutral hydrogen, n=2. I am needing this for a project, so i also need a reliable source where this comes from. Thanks beforehand...

Hello, hello, I ask you to tell me the difference between the "absorbance" calculated from the dielectric function, and the "absorption cross section" calculated from Real-time TDDFT. is that they can give the same appearance spectrum? Thank you very much

I am looking for a realistic explanation of the double-slit experiment in terms of wave packets (instead of stationary waves). First of all this results in using the scattering cross section, i.e. the probability current (not the density). Then, I guess, there is a kind of time average. So one...

This isn't a homework problem. I am preparing for a particle physics exam and although I understand the theoretical side of field theory, I have little idea how to approach practical scattering questions like these. THE PROBLEM: Dark matter might be observed at the LHC with monojet and...

Hello. I'm trying to calculate the total collisional cross section of the hydrogen atom impacted with the proton. (ion of the hydrogen plasma) I've found many good papers but they're showing specific cross section, for example, total cross section when n = 1 state is direct-excited to n =...

Homework Statement What is the cross section if the density of atoms in a material is 10^26 metres-3, and 0.04% of a beam of neutrons is stopped in a 2 cm slab of the material ? Homework Equations Sigma = event rate per nuclei / incident flux The Attempt at a Solution I have...

I have a question regarding the calculation of the cross section in muon pair production from electron positron annihilation. After some calculations the textbook comes to the conclusion that the differential cross section is approximately equal to: (1+cos(theta)^2)alpha^2/(4*s) where alpha...

Homework Statement The question asks for resistance R of a disk with radius r and fixed width w, whose cross sectional area is variable. Unlike in the picture below, the resistor is not connected to the circuit on the flat ends, but on the cylindrical sides. Homework Equations...

How do I calculate radar cross section given the diameter of a spherical object and the radar's frequency in GHz? Thanks

I'm trying to find specific reaction cross section 18O(p,n)18F in proton + O-18 TENDL (ENDF format). # p + 18O : (p,n) Total # Q-value =-2.51902E+00 # E-threshold= 3.64964E+00 # # energies = 45 # E xs 1.000E+00 0.00000E+00...

A long piece of sheet metal w inches wide is to be bent into a SYMMETRIC form with three straight sides to make a rain gutter. A cross section is shown below. \_____/ The base is w-2x and the angled side lengths are both x with a theta between top horizontal. A. Determine dimensions that...

As we know RCS is measure of how detectable an object is with a radar. But I don't understand one thing. If we take a sphere as an example, we can see that RCS is the largest in forward direction (forward scattering). If the sphere is to big (radius>>lambda), still this forward scattering is...

What are three different ways that i can produce a hole with a square cross section in a plate with a thickness of at least 1"?

Hi, I'm doing a project to see the feasibility of transmuting tungsten into platinum on a small scale (maximum output of 1 kg per month). However, some of the cross section data that I need seems to be hard to find. Now because I am new to this, I don't know if its because no body has...

Hi all, I think that the off shell decay dosn't decrease the decay cross section, I mean if a particle X decays into a jet pair has mass for example Mjj ~ 130 GeV, being X has mass M ~ 130 GeV so decay in resonance or on shell into jj or being MX even much greater ~ 2000 GeV , this...

Hi all I was trying to understand the Born-Bethe approximation related to cross sections for atomic and molecular collisions. All the stuffs that i got are explaining in complicated way which am not able to follow. Can anyone explain in simple terms what the theory explains? It will be of...

Homework Statement Using the Eikonal approximation (1) Determine the expression for the total scattering cross section of a particle in a potential V(r) (2) Using this result, compute the total scattered cross section for the following potential. V(r)= \begin{cases} V_0, \text{for } r < a \\...

What does "cross section area" mean when dealing with stress/strain? Homework Statement For clarification, here is an example problem: A circular steel wire 2 m long must stretch no more than 0.25 cm when a tensile force of 400 N is applied to each end of the wire. What minimum diameter is...

Hi, I am self-teaching Quantum Elctrodynamics, and have come across something which I do not understand. I would appreciate feedback from anyone on this specific issue from Atchison & Hey, "Guage Theories in Particle Physics" pg 238-239: In calculating the u-channel electron-muon...

Homework Statement For a laser, assume single mode operation, only lifetime broadening due to A21 and A1. Write out the rate equations for the atomic densitions N1 and N2 and the flux \Phi. Then there's a diagram where there's 2 stats. Pump rate is P, stimulated emission between 1 and 2 is...

Dear Forum ： I'm looking for proton-proton inelastic cross section in MeV. There are lots of results in GeV, TeV. But I can not find the results in MeV in ENDF nor TENDL. https://www-nds.iaea.org/exfor/endf.htm ftp://ftp.nrg.eu/pub/www/talys/tendl2011/proton_html/proton.html Please advise...

Homework Statement See the problem attached in this post. Homework Equations See the problem attached in this post. The Attempt at a Solution I set my limits of integration with respect to z axis and got an upper limit of 2 since that's the vertex point/height of the pyramid...