RE: EVENTBIN as a function of the radius

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Wed, 25 Jan 2012 20:25:20 +0100

Dear Georgios,

> If I divide the sphere in 2 volumes and score each of them apart, I
> would expect that their sum (top-right plot) it would be equal with the
> singular one... But it is not...
> What is the reason for that?

actually the two energy deposition spectra are expected to be
*statistically* equal (as indeed they seem to be from your plot), but
cannot be identical since the further region boundary affects the tracking
and alters the random sequence. The quality of their convergence is (as
usual) a function of the number of histories.

> My issue is how to get the energy deposition e-by-e and also as a
> function of the radius of the sphere.
> I tried to use the comscw.f routine and define the radius from XA,YA,ZA
> but the results that I obtain with eventbin are shifted towards smaller
> values and are distorted...

Your EVENTBIN by region gives the total energy deposited in a (gas) region
over a primary history, with the ~8keV spike corresponding to the
energy of the X-ray emitted by copper atoms as yourself remarked. In
comscw you intercept single energy deposition events, i.e. the 3.2keV
(argon K-edge) of the Auger electron and the 4.8keV of the photoelectron.
So the energy deposition spectrum from comscw is clearly different, unless
you add together all the contributions from the same primary history (e.g.
flagging them by the history number, NCASE in (CASLIM)). By the way, note
that you get the two mentioned lines (3.2 and 4.8keV) only because, due to
a - unfortunately quite common - sign error in the EMFCUT card implying
the default electron threshold of 100keV, you do not have electron
transport. Otherwise you would get from comscw an energy deposition
spectrum obviously more continuous and pushed towards even lower values.
Now, if you aim at an event-by-event cumulative scoring as a function of
the position (radius), why not a cartesian or cylindrical EVENTBIN - OK,
not optimal for a spherical geometry, but still useful - with boundary
contamination prevented through a comscw accepting only energy deposition
in the gas?

Best regards

Francesco

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854

> On Mon, 16 Jan 2012, Georgios Tsiledakis wrote:
>
>> Dear experts,
>>
>> I am trying to calculate the energy deposition E/M inside the gas of a spherical detector
>> on event-by-event basis using the EVENTBIN card.
>> Please have a look at the attached picture.
>> If I define the sphere as a singular volume I am getting the top-left plot.
>> If I divide the sphere in 2 volumes and score each of them apart, I would expect that
>> their sum (top-right plot) it would be equal with the singular one... But it is not...
>> What is the reason for that?
>> My issue is how to get the energy deposition e-by-e and also as a function of the radius of the sphere.
>> I tried to use the comscw.f routine and define the radius from XA,YA,ZA but the results that
>> I obtain with eventbin are shifted towards smaller values and are distorted...
>>
>> Any feedback is appreciated
>>
>> Thanks a lot
>>
>> Georgios
Received on Thu Jan 26 2012 - 17:37:58 CET

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