Cross section Definition and 315 Threads

Hey folks, i am currently making myself familiar with the path integral in high energy physics by reading Lewis Ryder's QFT book. I do have a question however, since i do not really understand the connection between the path integral and the cross section of a process. Are they only related...

I am trying to write a program to numerically calculate RCS using geometrical optics (or some form of it). Basically my idea was to cast a bunch of rays from an emitting object (in my code it is a 1 m^2 plate), find where they intersect a surface, reflect the rays off of this surface and see if...

This was pretty cool. I had to draw the cross section of a quad seal (on CAD). It’s basically an O-ring with a cross section that looks like a deformed square with these lobes on the corners. It looks like this: http://www.daemar.com/images/Quad-Ring-PartingLine.jpg But I don’t have...

for the following cross section the ratio Eb/Ep=30 find the shear centre of the cross section ------------------------------------------- first of all i need to find the equivalent cross section, which will be the same except that the horizontal parts will be of length n*L=30*1=30cm...

Homework Statement Integrate the rutherford cross section over the backward hemisphere to get 4pi(sigma0(E)) Homework Equations Rutherford cross section is sigma0(E)/sin^4(theta/2) The Attempt at a Solution When I integrate this with the limits pi/2 to pi i get sigma0(E)*(8/3) i...

What is physically meant by: \frac{d \sigma}{d \Omega} Where \sigma is the cross section and \Omega is solid angle. I can't really picture it.

Hi guys, I am trying to calculate the macroscopic cross section (scattering and absorption) for high energy neutrons between 1 MeV and 10^7 MeV in Silicon. I am using the macroscopic cross section to determine the mean free path. To calculate the macroscopic cross section, i need to know the...

The Rutherford differential cross section \frac{d\sigma}{d\Omega} goes like cosec(\vartheta)^4 which means at \vartheta=0 the differential cross section is infinite, which is ok. My question is, given that the differential cross section is proportional to the probability per unit solid...

My professor told me that the neutrons in a reactor see the surface area of nuclei, and not the the projected cross section. That really doesn't make intuitive sense. Is he right?

i know that τ=VQ/(Ib) now I am looking for the maximum stress so i will find that at the point at the centre of the rectangle Q=A*\bar{y} A=0.5*d*b \bar{y}=0.25*d ===> Q=0.125d2b I=(b*d3)/12 τ=VQ/(Ib) τ=V*0.125d2b*12/((b2*d3) τ=1.5V/(bd) now d changes as a function...

I need to find the volume of this figure y=sinx, y=sinx + 2, x=4, x=-4 using the area of triangular cross sections. i don't really know where to start...how to find the formula for area of cross section etc. HELP!

in a given shaft with a circular cross section, the radius changes linearly find the maximum shear stress i used T*r/J and since J is dependant on r^4, i found that the cross section with the smallest radius will feel the largest stress. find the angle of twist at the end of the...

A 3.5 m long steel member with a W310 x 143 cross- section is subjected to 4.5KNm torque. Knowing that G=77GPa, determine (a) the maximum shearing stress along the line a-a, (b) the maximum shearing stress along the line b-b, (c) the angle of twist...

I was calculating the cross section for a particular decay and saw that I was off by a factor of half from the known value.. Now, the decay has two identical particles in the final state and I seem to remember having read somewhere that this requires a factor of half...but I am not able to...

The base of a solid is the triangular region bounded by the y-axis and the lines x + 2y = 4, x - 2y =4. Find the volume of the solid given that the cross sections perpendicular to the x-axis are isosceles right triangles with hypotenuse on the xy-plane. So what I did is: 2\int_{x=0}^2...

Hello I am reading this book: "[URL and the appearance of a classical word&f=false"]decoherence[/URL] I hope someone could help me. Please go to Appendix A1 Joos introduces the notation f(q,q'). What is the dimension of f from his notation? Next page he writes that \int f^2 d\Omega...

Hi For example in e-e- -> e-e- scattering (electron-electron scattering) the differential cross section goes to infinity as theta goes to zero. Consequently the cross section is infinite. But how can we measure and interpret the cross section/differential cross section and interpret it as a...

Does anybody know how to calculate cross section of the photodissociation of CH?

Hi all I found http://en.wikipedia.org/wiki/Cross_section_(physics)#Relation_to_the_S_matrix" on wikipedia: {d\sigma \over d\Omega} = (2\pi)^4 m_i m_f {p_f \over p_i} |T_{fi}|^2 Has it the dimension of a surface? (I only see M*M) It is the first time I read this formula about...

I am reading some material on laser physics and quantum physics, there involes something called absorption cross section, collision cross section, differential cross section and so on quite often. I try to google the definition online but many website or book just give the formula instead of...

Here's the question: How can we describe a sudden change in the cross sectional area of a super conductor carying a current i from bigger A1 to smaller A2, such that the current density J after change is higher than Jc ? I have one scenario in my mind, the tempreture rises in the...

Hello, I am curious about fusion reaction cross sections, and fusion power in general, and have been trying to self-teach myself in this area. I saw some emprical data for cross section curves in a paper that I read recently, and thought I understood enough of what made the curve (cross...

I know the formulas for the length and velocity forms of the photodetachment cross section for an electron with energy \hbar\omega are, respectively, \sigma_{L}(\omega)=\frac{4\pi^{2}\alpha a_{0}^{2}\omega}{3}\sum_{f}|\langle\Psi_{f}|\sum_{j=1}^{n}z_{j}|\Psi_{i}\rangle|^{2} and...

How to deal with non uniform cross section bending? How does one approach a solution for bending of a shaft having multiple diameters. I have one particular shaft in mind that has 11 diameters to get to the midpoint. I know the deflection at the midpoint, and I would like to calculate...

Not technically homework, just something I wanted to see if I could do. Homework Statement Find the differential cross section for the interaction between an electron and a photon via compton scattering. Basically, I'm just after calculating the matrix (s-matrix?/amplitude?) for the s-channel...

Hi.. I've got a problem about moment inertia. I don't understand about looking the distance of centroid (y). I am still confucing about the formula of "y" in Moment Inertia. Can you shows me about the formula of y or if any thread for this before, I am glad to see it too.Thanx's for your help...

Hello, how do the angular distributions of Bhabha Scattering e^+ e^- \Rightarrow e^+ e^- and Muon pair production e+ e- \Rightarrow \mu^+ \mu^- differ? Regards, Phileas Fogg

Hello Ive come across some approximate cross section formulas during a course of particle physics. And in a reaction like A + B --> R --> C + D the cross section should be something like \sigma = K\frac{\Gamma_R^{AB}\Gamma_R^{CD}}{(s-m_R^2)^2+m_R^2\Gamma_R^2} Where K is a constant (depending...

Well I'm supposed to draw Thomson cross section in polar plot by MATLAB software. Have I done it right? I mean does this figure that I got seem to be in polar plot or not? t = 0:.01:2*pi; r = 2.8179e-13 x = t,0.5*power(r,2)*(1+power(cos(t),2)) polar(t,x) Thanks

So here's a crazy question...I was trying to think it through and have come up with nothing. Is it possible to bend a laser beam's cross section? For instance, if you are using a diode bar (which has a beam cross section resembling a line) is there a simple way to bend it into a...

How to determine the darcy friction factor for irregular cross section tunnels hi, I needed to calculate the f value for tunnels with these cross section area but I am not sure what are method available to calculate these shapes. Two of those cross section areas are already provided as...

Suppose we consider a beam of neutrons incident upon a thin target with an intensity of 10^12 neutrons/(cm^2.s). Suppose further that the total cross section for the nuclei in this target is 4 b. Using this information, determine how long one would have to wait, on the average, for a given...

Does anyone know anywhere where I can find reliable up-to-date cross section infromation? In particular I'm looking for the absorption cross section of Gadolinium-157 for thermal neutrons. Everywhere I look seems to give a different value ranging fro 70000barns up to 450000barns.

why is the cross section of photon - proton less than the electron- photon cross section for the same photon energy??

Is there a difference between (1-\gamma^5) and (1-\gamma_5) ? I see the two used interchangeably when calculating cross section.

Cross section means the effective size of a nucleus for capturing a neutron, am I right? But what makes the cross sections for different nucleus different? I am a bit puzzled, why the cross section for Boron(for example) is so high?

I need to use this libraries with confidence. Any articles that involves benchmarking of these cross sections?

Hi all, I'm trying to teach myself high energy physics and was wondering if anyone knew a good reference site on calculating cross sections. I'm specifically trying to calculate the cross section for \nu _{\mu} + e^- \rightarrow \mu ^- + \nu_e using the 4-fermi interaction. Are there any good...

Problem Determine the differential and total cross sections for scattering from a "hard sphere" of radius R ("hard" means impenetrable). Relevant Formulae \sigma (\Omega) d \Omega = \frac{number \ of \ particles \ scattered \ into \ solid \ angle \ per \ unit \ time}{incident \ intensity}...

What does it mean when they say s wave cross section, p wave cross section .. ?

Homework Statement I've been asked to find the cross section of a hydrogen atom in thermal equalibrum at 6000K for a photon which induces a transition from the ground state to the first excited state. The density of states for n=2 is 4x the density of states for n=1 i.e. g(E2) = 4*g(E1)...

Let's say that we have Na at room temperature. The concentration of Na becomes plus one percent due to impurities. I'm interested in finding the mean free path and collisional cross section due to these impurities. I'm not sure on how Matheissen's rule could be applied, if we don't know what the...

Homework Statement b) The Large Hadron Collider (LHC), a 14 TeV proton-proton collider, will produce about a million Z0 per year. Explain why the cross section of such a process can be approximately written as: d\sigma / d\Omega = F_{q/p}(X_{1})F_{q'/p}(X_{2})d\sigma '(qq' \rightarrow...

I'm extracting data from a Monte Carlo sim. and i need to extract the differential cross-sections of the resultant protons and neutrons in momentum and rapidity space. ie \frac{d\sigma}{dy} ; \frac{d\sigma}{dp} and \frac{d^2\sigma}{dydp} where I know the values of y and p...

I'm writing a paper on Thorium utilization in nuclear reactors. In this connection I'm looking for figures which describe the neutron capture and neutron fission cross sections over a wide energy range (not only thermal). There are probably some online resources unbeknown to me, any hints?

I'm calculating an ionization cross section in partially ionized plasma, with taking into account of correlation effects. I'm trying to do it with help of variation phase method. Please, help me to find some link to useful articles.

Homework Statement The total cross section of a S wave is given by the following equation Sigma=(pi/k)*(b^2)/((E-En)^2+(b/2)^2)) prove that b is the width of the resonance. Homework Equations Nothing that is the only thing The Attempt at a Solution I already solved the question...

For my diploma thesis I must provide a calculation that reproduces the results given on page 46 of the paper hep-ph/0309342 . For those who do not want to look it up, I briefly explain what it is about: It concerns the two-body scattering processes (1) N + V => L + H, (2) N + L => V + H, (3) N...

In a scattering experiment, an aluminium foil of thickness L = 10E-6 m is placed in a beam of intensity of 6E12 particles per second. The differential scattering crosss section is known to be of the form. \frac{d\sigma}{d\Omega} = A + Bcos^2 (\theta) where \theta is the...

If I show something that a cross section is proportional to: 1 / (16p^2 sin^4( x) + 8mpsin^2 (x) + m^2) does it imply that the cross section is proportional to 1 / sin^4 (x) as well?