[Halld-online] Notes from trigger workshop

[C. Cuevas]

Hi,

We should definitely plan a dedicated meeting for these topics and I 
plan to send a summary of the workshop soon.  This year I found that 
there were not any new trigger system requirements that surfaced during 
the discussions, but several people had questions about the details of 
how each board performs specific functions.  (i.e. pedestal subtraction, 
global trigger 'windows', managing multiple triggers, SubSystem timing 
alignment, etc.) 

Let's plan on dedicating the regular Friday trigger meeting time to 
discuss these and other trigger topics on 23-July-2010.  

Regards,
-Chris
~~~~~~~~~~~~~~~~~~

By the end of the fiscal year we

Alexander Somov wrote:
> 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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