Parameters

[xiaoyangliuy]

Hi,

I am using XMIM-SIM to simulate XRF spectrum from synchrotron light source. I have several questions about some parameters:

1. I am simulating monochromatic synchrotron beam, should I simulate with discrete energy? I am trying to simulate total number of photons (10^12 photons/s), but I cannot put this much number in Number of photons per discrete line. What is the meaning of this parameter in the simulation? Does this value needs to be the sum of Horizontally polarized intensity and Vertically polarized intensity?

2. I am wondering in Geometry section, I changed sample orientation vector to simulate the samples at varying angle. Do I need to consider the sample thickness in Sample orientation vector? For instance, if my sample is 3nm at 45 deg, should I use y=-0.707107 or y=-0.707107*3nm?

Thank you for your advice.

[tschoonj]

Hi,

In response to your questions:

I am simulating monochromatic synchrotron beam, should I simulate with discrete energy? I am trying to simulate total number of photons (10^12 photons/s), but I cannot put this much number in Number of photons per discrete line. What is the meaning of this parameter in the simulation? Does this value needs to be the sum of Horizontally polarized intensity and Vertically polarized intensity?

Yes, you need to simulate this with a single discrete energy. . This value is indeed the sum of both horizontally and vertically polarised beam components, and since you are dealing with synchrotron radiation, I expect that the former will be much, much larger than the latter. You can calculate each from the total intensity you already have, combined with the degree of linear polarisation, which is going to be a value close to 1. Ask the beam line for its exact value.

I am wondering in Geometry section, I changed sample orientation vector to simulate the samples at varying angle. Do I need to consider the sample thickness in Sample orientation vector? For instance, if my sample is 3nm at 45 deg, should I use y=-0.707107 or y=-0.707107*3nm?

The sample thickness is measured along the sample orientation vector, so the thickness does not change if this vector is changed.

[xiaoyangliuy]

Hi,

Thank you for the explanation.

For the first question: For the Number of photons, I expect it to be ∼3.5 × 10^9 photons/s at the sample. Should I put this value in? Then the Horizontally and vertically polarized intensity is ~97% and 3% of 3.5 × 10^9, separately. Do I need to put 0 in Number of photons per interval?

For the second question: now I understand the thickness is along the sample orientation vector. Why the thickness does not change when the vector change? If the sample is 3 nm thick, when the vector is (0,0,1). Then the sample rotate to 45 deg, the vector is (0,-0.707,0.707), the thickness should be 3nm/cos45?

Thank you.