Argon

[kvjmistry]

This PR includes some updates to the NEXT100 geometry and argon properties relevant for the LPR argon run. I have also included some example configuration files with baseline parameters for running in the LPR mode.

Since the NEXT100 geometry had the drift velocities hard-coded. I have added a configurable parameter for this now.

[paolafer]

The optical material properties of some materials, such as the sapphire windows or the PMT windows, are not defined for energies greater than 10.3 eV and 10.7 eV, respectively, because the formulas we're using are not valid beyond that point. This could be a problem because we are simulating argon scintillation light up to 11.2 eV; if a photon at the end of the spectrum hits a material without optical properties for its energy, it will have an unexpected behaviour.

[kvjmistry]

The optical material properties of some materials, such as the sapphire windows or the PMT windows, are not defined for energies greater than 10.3 eV and 10.7 eV, respectively, because the formulas we're using are not valid beyond that point. This could be a problem because we are simulating argon scintillation light up to 11.2 eV; if a photon at the end of the spectrum hits a material without optical properties for its energy, it will have an unexpected behaviour.

I will see if I can find any references for relevant materials.

[kvjmistry]

The optical material properties of some materials, such as the sapphire windows or the PMT windows, are not defined for energies greater than 10.3 eV and 10.7 eV, respectively, because the formulas we're using are not valid beyond that point. This could be a problem because we are simulating argon scintillation light up to 11.2 eV; if a photon at the end of the spectrum hits a material without optical properties for its energy, it will have an unexpected behaviour.

I will see if I can find any references for relevant materials.

@paolafer I couldn't find much, it might be because the transmittance of 128nm light through sapphire and UV FS tanks very significantly at these wavelengths. The plot below is from the crab paper:

How is it best to deal with this?

[paolafer]

If the CRAB plot is the only piece of information we have at high energies, maybe we can add a few points more to those properties to match that transmittance values. We would need to do a small simulation and vary the refraction index and the absorption length to match the desired transmittance. What do people think?

[kvjmistry]

If the CRAB plot is the only piece of information we have at high energies, maybe we can add a few points more to those properties to match that transmittance values. We would need to do a small simulation and vary the refraction index and the absorption length to match the desired transmittance. What do people think?

I also found this paper which has the transmission and reflectance for quartz and sapphire for a few more thicknesses and angles of incidence. https://link.springer.com/article/10.1134/S0020441206030195

Transmittance is small (e.g. from CRAB measurements) or basically zero in these plots for FS and Sapphire. Reflectance ranges from 20-30% for FS, and 2-20% for Sapphire. I need to brush up on my optics, can we calculate the refractive index from these numbers or does it need to be done anlytically?

[paolafer]

I'm not sure about how to do it.

[soleti]

I think you should be able to calculate the refractive index starting from the reflectance at a specific angle using the Fresnel equations no?