MCNP: Can I input the X-Ray tube voltage in MCNP source specification?

In summary, the question addresses whether the X-ray tube voltage can be specified directly in the source definition for MCNP (Monte Carlo N-Particle Transport Code) simulations. It clarifies that while MCNP does not allow direct input of tube voltage, users can define the energy spectrum of the emitted X-rays using appropriate energy bins or distributions that correlate with the desired tube voltage. This allows for accurate modeling of X-ray interactions within the simulation framework.
  • #1
Anisur Rahman
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TL;DR Summary
Source Specification
Can I input the X-Ray tube voltage in MCNP source specification?
 
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  • #2
Anisur Rahman said:
TL;DR Summary: Source Specification

Can I input the X-Ray tube voltage in MCNP source specification?
One would put in energy or energy spectrum for a photon source. I am not aware that voltage for an X-ray tube is an input.
 
  • #3
An electron falling through a potential difference of 1V gains 1eV of kinetic energy.

So an X-ray tube powered at 100kV would be simulated with a beam of electrons of energy 0.1 MeV (SDEF ERG= are in MeV) directed at a target.
 
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  • #5
Alex A said:
An electron falling through a potential difference of 1V gains 1eV of kinetic energy.

So an X-ray tube powered at 100kV would be simulated with a beam of electrons of energy 0.1 MeV (SDEF ERG= are in MeV) directed at a target.
Even if the current value (mA) differs?
 
  • #6
mariem said:
Even if the current value (mA) differs?
The current determines the number of particles (mA/e) per sec, were e is the unit charge.

The accelerating potential determines the energy per particle.

The total energy/sec or power would be the number of particles/sec * energy/particle, and the total energy or dose deposited would be related to the integral over time of the (particles/sec * energy/particle).
 
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  • #7
Yes, as @Astronuc says the intensity is the other part of the problem. Almost all answers output by MCNP are per source particle. So no one would attempt to simulate one mA-second (a milli coulomb) of electrons. Enough particles are simulated to get a statistically useful answer and then the results which are per source particle are multiplied by the real world source activity to get flux or dose rate answers, or the total number of real world particles to get dose.

It also means that if you are simulating a 1mA tube and a 10mA tube (the same tube at the same voltage) that only one simulation needs to be done because these situations are the same. Only the maths done afterwards differs.
 
  • #8
Where can I input the electron source intensity in MCNP? How many particles will I have for an X-ray tube set at an intensity of 10 mA?
 
  • #9
Do you understand coulombs, do you understand unit charge (the charge on an electron)?
 

FAQ: MCNP: Can I input the X-Ray tube voltage in MCNP source specification?

Can I input the X-Ray tube voltage directly in MCNP source specification?

No, MCNP does not allow direct input of the X-Ray tube voltage in the source specification. Instead, you need to define the energy spectrum of the X-rays generated by the tube, which can be derived from the tube voltage using separate software or analytical methods.

How do I define an X-Ray spectrum in MCNP?

To define an X-Ray spectrum in MCNP, you need to use the SDEF (source definition) card along with the SI (source input) and SP (source probability) cards. These cards allow you to input the energy distribution and probability of each energy bin, effectively creating a custom energy spectrum for your X-ray source.

What tools can I use to generate an X-Ray spectrum from a given tube voltage?

There are several tools available to generate an X-Ray spectrum from a given tube voltage, including SpekCalc, XOP, and IPEM Report 78. These tools take into account the tube voltage, anode material, and filtration to produce an energy spectrum that can be input into MCNP.

Can I simulate the effect of different anode materials in an X-Ray tube using MCNP?

Yes, you can simulate the effect of different anode materials by adjusting the energy spectrum to reflect the characteristic X-rays and bremsstrahlung radiation produced by different anode materials. This requires generating or obtaining the appropriate energy spectrum for each anode material.

How do I include filtration effects in my X-Ray spectrum for MCNP simulations?

Filtration effects can be included by modifying the energy spectrum to account for the attenuation of X-rays as they pass through the filters. This can be done using attenuation coefficients for the filter materials and applying them to the initial spectrum, which can then be input into MCNP.

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