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Forum: Processes Involving Optical Photons
Re: None No reflection at reflector surface (Athreya Shankar)
Re: Question Re: No reflection at reflector surface (Athreya Shankar)
Date: 02 Jun, 2011
From: Gumplinger Peter <Gumplinger Peter>

> I initially planned to use a Mylar reflector, but all the photons got absorbed,

> when they touched the Mylar layer.why does that happen?

Your code:

G4MaterialPropertiesTable* mptMylar = new G4MaterialPropertiesTable();

G4double AbsorptionLengthMylar = 100.*cm;

G4double refractiveIndexMylar = 1.640;

mptMylar->AddConstProperty("RINDEX",refractiveIndexMylar);

mptMylar->AddConstProperty("ABSLENGTH",AbsorptionLengthMylar);

is the cluprit for this. The code expects that the refrective index and the absorption length are functions of wavelength/energy, e.g. it does not search if the wavelength dependent property is not found to then try the list of constant properties in the G4MaterialProertiesTable. You can specify the same value for all energy entries.

> I would like to use diffused reflectors, most probably TiO2. for

> the reflective surface

I suggest instead of using dielectric_dielectric and groundfrontpainted that you use dielectric_metal and ground for the TiO2 surface, but both will work.

I have scanned over your code, it is rather lengthy for you to expect me to check every detail, I didn't see any real errors except the Mylar definition. Also, if you have only one type of scintillation (slow or fast) you don't need to specify the YIELDRATIO.

(A volume placed inside another (the mother) automatically subtracts from the 'mother'. There is no need to define a G4SubtractionSolid.)

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