You'll find this data at the NNDC useful for answering part of your question:
http://www.nndc.bnl.gov/chart/reColor.jsp?newColor=235ufy"
The colors show the relative frequency in which a given nuclide appears as a product of thermal fission of U-235. Notice that for thermal fission, the...
It's not in the decay chain, but it is in the denominator of the equation used to find the fraction of U-235 in natural uranium:
frac(U-235) = N(235) / [N(235) + N(238)] (Ignoring the really small amount of U-234)
That's why most of the times I saw this type of question in basic physics...
Your equation is right, although that .77 should either be .77% or .0077. I get something around half the value you reported when I plug the half-life and 1 Billion years into my calculator.
One thing you're not accounting for is the decay of the U-238 though. Does the problem say to ignore...
I think it's doable, it's just a matter of finding the right program, staying motivated, and being willing to make sacrifices.
The right program is key because since you're a nine-to-fiver you need a program that offers classes in the evenings. The NE department at my school does really well...
Thanks, D H. I'll take a look at the exponential and see if it does any better. Another thought that occurred to me was that what I'm looking at may be the convolution of two different Gaussians - one with a small maximum and a very broad distribution and a second with a very large peak and a...
Hi, I'm finishing up my PhD in NE, so I'll try to offer you some insight. I do agree with your assessment of the workforce... getting older all the time, so there should be a lot of positions coming up. It's a subject that is mentioned frequently at conferences I go to. I got in for some of...
Hi, thanks for the quick response.
The mean is zero. The data I'm modeling is essentially the angle a neutron scatters in the x-y plane, which is going to be a symmetric function. f(theta) is the number of counts I get in a detector at angle theta. The incoming particles I modeled are all...
I need to fit a tail-heavy "Gaussian" curve
Hi, it's been a long time since I've been around PF.
Homework Statement
This isn't a homework problem per se, but I've been trying to fit some scattering data using a Gaussian function using a least squares approach and it's not working so...
Cool problem. I would approach it this way: The microscopic cross-section is ~ the area presented by a single nucleus, so in this case \sigma = \pi*(3x10-15 m)2 = 2.83 x 10-29 m2
Once you have that, you can calculate the macroscopic cross section using \Sigma=N\sigma and then you can use...
Your book didn't really do you any favors on the k thing. Since the amount of radioactive material remaining decreases as time increases, the first equation should properly be written as:
\frac{dm}{dt}=-kt
The minus sign on the kt represents the fact that m is decreasing as time increases...
timm3r,
Draw a triangle with one vertex at the center of the sphere, the 2nd at the top wall of the cylinder, and the 3rd straight down from the second so that it forms a 90 degree angle with the first two. What is the length of the 3 sides of the triangle? That should give you your...
Are you saying I should model u_{hom} and u_{part} as:
u_{hom} = \sum \limits_{n=1} ^ {\infty} A_{n} \exp(-j_{n0}^2 t) J_{0}(j_{n0}r)
(There is no n=0 solution for the homogeneous case)
and
u_{part} = c + \sum \limits_{n=1} ^ {\infty} A_{n} \exp(-j_{n0}^2 t) J_{0}(j_{n0}r) = c
(there's only...
Halls,
The A_{n}'s are zero in that case.
I should point that I goofed up when I wrote the homogeneous solution above. The n=0 case shouldn't be an eigenvalue (so no constants in the solution.) I must have been working on too many problems at once and gotten them mixed up. I edited my...
I've got a nonhomogeneous BVP I'm trying to solve. Both my book and my professor tend to focus on the really hard cases and completely skipp over the easier ones like this, so I'm not really sure how to solve it. It's the heat equation in a disk (polar coordinates) with no angle dependence...
Halls, thanks for the reply.
I'm not sure where you're getting that. This is the heat equation (u = temperature,) not the wave equation. It's 1st order in t -> 1 IC required. The 2 IC's I posted are for 2 different problems where everything is the same, save for the IC's.
Hmm...