Re: Moller electrons included?

[Alexander Somov <somov@jlab.org>]

Hello Richards,
Thanks a lot for details. Actually I was a bit surprised that
the default value of ILOSS  is 2 (if I understood it
correctly), i.e., generation of delta electrons is switched off.
It seems to be important for the drift chambers (and microscope
counters (?)). Anyway, I will repeat background estimates when
we finalize the tagger hall geometry.

By the way, do you have a 'realistic' position/size of the
tagger magnet (has Yang finalized it) ?

Thanks,
        Sascha


On Tue, 25 Nov 2008, Richard Jones wrote:

> Alex, please see my comments below.
> -rtj
>
> somov@jlab.org wrote:
>> Hello Elke, Richard,
>> 
>> The moeller scattering seems to be on everywhere
>> in geant (at least it's used for delta-ray production).
>> I will check tomorrow once again.
>> 
>> ---------
>> 
>> Regarding the diamond cristal simulation:
>> 
>> 1. My understanding is that moeller scattering is simulated
>> when we simulate an electron beam-halo background, i.e.
>> geant passes electrons through the diamond (producing
>> incoherent beam photons). Richard correct me if I am wrong.
>> (though I am not sure that ionization energy losses are
>> simulated properly ?)
>> 
> That is true, provided that the control cards are set up properly.  To get 
> this, you need ILOSS set to 1 (card LOSS) and a sufficiently low value of the 
> DCUTE variable (card CUTS) for the volumes of interest.  You can look in the 
> log output from the hdgeant run to see what these values are.
>> 2. It's not taken into account when we generate coherent
>> beam photon spectrum (on the cristal) using a beamgen generator.
>> Tagged electron parameters are simply analytically smeared in this
>> case.
>> 
> Yes, that's right.
>> Richard, I would like to discuss it once again to be sure that I am
>> understanding it correctly.
>> 
> As for background in the GlueX target, the answer is the same as given under 
> point (1) above.  Provided the cards are properly set up, it is.
>> Cheers,
>>        Alex
>>
>> 
>
>