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Interesting information, Evaristo.<br>
<br>
Taking samples 75 ns apart is out of the question. We must use multi
mode.<br>
<br>
When switching from 3->6 samples, the readout time APV25->VME
will go from ~10 us to ~20 us . If we read out at the L2 trigger
rate, this should be fine.<br>
<br>
The data per channel to be moved to the DAQ will increase from 43
bits/channel to 55 bits/channel at 12 bit resolution. If we drop the
resolution to 10 bits/sample, we can stay within the 48 bits/channel
that I have assumed for the 3-sample readout. The total event size
from the trackers would then be unchanged at 90 kB/event.<br>
<br>
Like Evaristo suggests, I think we can defend these considerations
as a later "optimization strategy" and not get too deeply into
details at this time.<br>
<br>
Ole<br>
<br>
On 5/16/2011 8:03, Bogdan Wojtsekhowski wrote:
<blockquote
cite="mid:52940.96.238.76.231.1305547431.squirrel@webmail.jlab.org"
type="cite">
<pre wrap="">Hi Evaristo,
It is in agreement with Igor Rachek. However, I am wondering
if the two rejection parameters (see GEM analysis section of
the Response to TR2) could be calculated in VME module (which
require 4 sample) and than only three of them moved to CPU.
Could you provide a timing diagram and a calculation of the
readout time?
</pre>
<blockquote type="cite">
<pre wrap="">Dear all,
looking more carefully at the APV25 manual, there are some restrictions
on the number of samples we can get and the distance between samples:
- in peak mode we can get from 1 to 32 samples in step of 1, each
sample separated by at least 2 clocks period (and therefore, if I
understood correctly, the samples are separated by 75 ns).
- in multi mode we can get from 3 to 30, in step of 3, each sample
separated by 25 ns.
Therefore if we want exactly 4 samples, we must run in peak mode; but in
this case the distance between samples should be 75 ns.
On the other hand, we can get 6 samples at 25 ns sampling, but we
require larger transfer time.
Take into account that shaping time and other parameters of the pulse
can be modified within certain extends.
Therefore I would suggest to assume 3 samples in the TRD, which already
provide reasonable results, and study and optimize later the number of
samples taking into account all pros and cons.
Evaristo
On Fri, 2011-05-13 at 15:03 -0400, Vahe Mamyan wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Dear all,
Please find attached new results of g20 analysis.
A new variable is introduced (Bogdan) to filter background. This new
variable uses 4 samples instead of 3 used
in previous analysis. This new variable is defined as
R_new = ((amp[2] + amp[1] + amp[0] -Ao/(1.1*1.1*1.1) -Ao/(1.1*1.1)
-Ao/1.1 ))^2 / ( (amp[2] -Ao/(1.1*1.1*1.1)) * (amp[1] -
Ao/(1.1*1.1)) );
where amp[0], amp[1], amp[2] are strip signal integrated in the
following intervals 0-25, 25-50, 50-75 ns respectively
and Ao is the strip signal integrated -25-0 ns. R_new is used in
addition to R=(1.1 * amp[1] - amp[0])/ ( 1.2 * amp[2] - amp[0]).
Vahe
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</blockquote>
<pre wrap="">
--
Evaristo Cisbani office : +39 06 4990 2847
Istituto Superiore di Sanita` lab : +39 06 4990 2347
Department of Technology and Health fax : +39 06 4990 2137
and Istituto Nazionale di Fisica Nucleare Roma - gruppo Sanita`
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</blockquote>
<pre wrap="">
</pre>
</blockquote>
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