[BDXlist] Catania measurements: Data vs MC comparison

[Andrea Celentano]

Hi Elton,
I was quite surprised too to see the very good agreement. However, there 
are no "ad-hoc" or "tricky" solutions here to reproduce the absolute rate.
  The main ingredients are:

- For the data, a single run only (1435, ~ 9 h) was analyzed.
- For the MC, the parametrization of the cosmic rays flux is from 
1509.06176. This give the absolute flux of cosmic rays. The 
parametrization was already in the code, but events were not generated 
properly. A full description on how the flux should be used to generate
events can be found, for example, in

edelweiss.in2p3.fr/Publications/Docs/PhDThesis_Kluck2013.pdf

see in particular Sec 5.3. I have repeated all the calculations and I 
implemented the procedure in the code. I plan to describe this at next 
BDX meeting (or the week after).
Also note that in this thesis, even if in a different contest, a data vs 
MC comparison for cosmic-rays is also shown (see Fig. 6.2). The 
situation here is very different from BDX (and much more complicate: 
here they simulate the muons-induced neutrons within the Modane 
undeground cavern), and the result is again very good. (Note that here 
they base the MC on an ad-hoc measurement of the muon flux out of the 
Modane cavern, but without any annual effect included).

I think that there may be factors at the 10% level that may still be 
hided under the error bars or that, just by chance, somehow compensate.

I am more than happy to share all the codes I used to anyone who's 
interested in repeating the analysis (simulation, reconstruction, 
analysis): it is always good to have multiple checks! Meanwhile I plan 
to analyze further data, and to also compare different observable 
(first, the "all-events" energy deposition in each crystal of the matrix 
as done for the old one).

Cheers

Andrea



On 03/03/2017 22:08, Elton Smith wrote:
> Hi Andrea, I agree with Marco, the comparison looks amazingly good 
> (too good?). Especially I am impressed by the absolute normalization. 
> I did not think that the cosmic-ray rates could be taken to be better 
> than about 10%, unless variations due to longitude, etc were taken 
> into account. (Are there seasonal/location variations?)
>
> Thanks, Elton.
>
> Elton Smith
> Jefferson Lab MS 12H3
> 12000 Jefferson Ave STE 4
> Newport News, VA 23606
> (757)269-7625
> (757)269-6331 fax
>
> On 3/3/17 11:24 AM, Marco Battaglieri wrote:
>> Dear Andrea,
>> the comparison of the 16 channels of the calorimeter looks wonderful!!
>> Whit this result in hands we can really think to write a paper about 
>> the prototype  including the comparison withthe  MC.
>> What about the 'old' crystal? do you have any results?
>> Cheers
>> Marco
>>
>> Andrea Celentano wrote:
>>> Dear all,
>>> just want to share with you the newest result from Catania Data vs 
>>> MC comparison: the comparison has been made by selecting events with 
>>> signals from 4 crystals in a column in the matrix above threshold 
>>> (to select vertical cosmic rays): note that in data (blue) and mc 
>>> (Red) histograms the scale is absolute (Hz/MeV), i.e. no "ad-hoc" 
>>> normalization has been used.
>>> Main issues that have been fixed in MC are:
>>>
>>> 1) Distribution of primary cosmic rays and their normalization - 
>>> according to the proper definition of "flux" as "fluence 
>>> differential wrt time"
>>> 2) Spread induced in the charge collection due to the finite 
>>> crystals attenuation length.
>>>
>>> I'll talk more about these results next Tuesday meeting, but I'd 
>>> like to share this good result with you.
>>>
>>> Bests
>>> Andrea
>>>
>>>
>>>
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>>
>>
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