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Re: Understanding PDE information
Dear George,
That was exactly my point .A 1GeV photon does NOT deposit 1GeV in the
fibers but only a few percent of its energy(I cannot find now the number
but I have it from the MC's) and the rest in the inert material.That's why
I do not understand Elton's number.Maybe I am still missing something.
Cheers,Christine
> Hi Christina:
>
> I agree that once we decide to read a number of outer layer cells as a
> single cluster, then fine mesh PMT's have certain advantages over
> Planacon's.
>
> The number of photons surviving to the ends of the BCAL for several
> energies and cell geometries have been extracted by Blake and Rafael,
> independently, using the full geometry of BCAL and GEANT. I attach my
> review report for the meetings next week and you can see the
> simulations. The calculation for the total can also be verified very
> fast by:
>
> # photons at 1 GeV/end= 8000 ph/MeV x 1000 MeV x 12% x 9.3%x exp{-l/L} =
> 44,000/end
>
> 12%=fraction deposited in SciFi's
> 9.3%=capture ratio of double clad SciFi (both GEANT and GUIDEIT give the
> same result)
> l=2m (half the length)
> L=2.8m attenuation length.
>
> I hope this clarifies Elton's numbers.
>
> Pollous hairetismous,
>
> Giorgos
>
>>>> "Christina Kourkoumeli" <hkourkou@phys.uoa.gr> 04/18/07 4:58 AM >>>
> Dear all,
> I attach a table refering to the fine-mesh characteristics which were
> missing from Elton's documents.At this point I would like to see in the
> table a differentiation between the Planacon B-field sensitivity (up to
> 10degrees then the signal disappears) vs the fine-mesh (up to 45degrees
> small loss ,gain is anyway 10^7)
> One more thing which I did not understand reading Elton's document is
> where this 84000 phtons/side is coming from and how is divided
> evently(?)between readout cells.The number wich we always used was 8000
> phtons/MeV of DEPOSITED energy.So one has to run a MC to see how much is
> deposited per readout segmentation and this differs between
> segmentations
> by big factors due to the shower profile.It is obvious that the 20MeV
> shower doesn't reach the outer layer (even the 200MeV produces few tens
> of photons)Am I missing something?
> Cheers,Christine
>
>