[Halld-online] Notes from trigger workshop

[Alexander Somov]

Hi Elton,

Below are a few minor comments:

I think that both items have been discussed since quite time.

1. The system allows for multiple triggers. We have to discuss
whether merging event by increasing the readout window is the
right solution (though it seems to be possible). Generally, if the
pile up becomes an issue, one can think of increasing the drift
time (however adding flammable gas components is not desirable)

2. I am planning to do the bit-wise trigger simulation shortly.
During trigger summation, we will set up threshold on each individual
channel; this has to be simulated. The thresholds can be loaded to
the FPGAs after pedestal calibration. There are also discussions
that we can sum up energies for signals pulses only (at the FADC250
level) and send  the sums to the next trigger boards; rather than
summing energies for all channels.

We can organize a dedicated meeting and go through these items.


Cheers,
       Alex








On Thu, 15 Jul 2010, Elton Smith wrote:

>
> Hi Chris,
>
> Before I forget, I wanted to put down two of the items that came up during
> the trigger workshop, which I think deserve further discussion
> (resolution):
>
> 1. When multiple triggers fire (in short succession), what is the
> implication for duplicate data recorded in the event stream?
> 2. How are pedestals handled in the trigger summation scheme, and how are
> they handled during data extraction? (We will certainly need to develop a
> consistent scheme for determining pedestals and subtracting them from the
> raw samples).
>
> Thanks, Elton.
>
>
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton at jlab.org
> (757) 269-7625
> (757) 269-6331 fax
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