[Eg6_analysis] Data Acquisition System

[Nathan Baltzell]

Hello Everyone,

Here's a report on RTPC pedastal/noise:

http://clasweb.jlab.org/rungroups/lowq/wiki/index.php/RTPC_Pedestal_Investigation

Let me know your comments and suggestions.

-Nathan



On Thu, 31 Jan 2013 11:16:39 -0600, Dupré Raphaël
<raphael.dupre at gmail.com> wrote:

> Hello guys,
>
> The system of data acquisition is set up such that it stocks the data  
> over
> a long time. When the trigger signal arrives the DAQ system takes data  
> for
> 8.5 micro seconds more and keeps values from -1.5 to 8.5 relative to the
> trigger. TDC slots are of 100 ns and there you have 100 of them with the
> trigger time at TDC = 15.
>
> Pedestals for the ADC values are calculated from a larger window taken  
> from
> previous data. I do not remember the time window used for these  
> pedestals,
> but it is probably documented somewhere (it might be interesting to try  
> to
> find it). Finally the DAQ send some data, the data are sent by clusters  
> of
> consecutive TDCs. In order to define a cluster you need to have 3 (?)
> consecutive hits with ADCs higher than 45 (?). Then the cluster is  
> defined
> by all these consecutive hits plus the 3 before and the 3 after in term  
> of
> TDC, so you have a minimum size of clusters of 9 (except on the edges of
> the time sample). These additional 6 hits can be of any ADC value and can
> eventually be used in order to make an additional pedestal, either by  
> using
> a mean value of them or the 2 extremes (or any other combination that  
> would
> be most appropriate) and subtract this to all the hits of the cluster.
>
> I am not completely sure of the final values we used in the run, so the
> numbers followed by a "(?)" should be checked. It should be straight
> forward to find them by looking into data.  The minimum size of clusters
> will give the number of consecutive hits needed and the ADC distribution
> has a discontinuity at the threshold level.
>
>
> Best,