Re: Additional data

["Fernando J. Barbosa" <barbosa@jlab.org>]

Hi Yves,

Just like I mentioned in my previous email.

Now, with regards to the trigger, and from your previous email, it is 
simple enough to understand. Actually that explains some of the 
questions I had about the spectrum on some of the plots as it seems to 
me that the threshold was a bit high. Now, triggering on a single straw 
is definitely "noisy" and requires a relatively high threshold to remove 
any background noise. This of course does not impact the dynamic range 
measurements for the ASIC but it makes it harder to understand if what 
we see is correct. For instance, it would be nice to see the Fe55 (5.9 
keV) spectrum with the Ar escape peak (3.2 keV) - a well known check. 
However, employing additional sources, like Sr90 (546 keV) could be used 
for scaling purposes or cosmics.

I would suggest using two adjacent staggered straws and from the trigger 
from the coincidence of the two. This would clean up the spectrum a lot. 
You could also look at timing resolution in this mode, if needed.

Gerard mentioned using the ADC in self triggering mode but that would 
make your analysis task a lot more difficult. But it would still work if 
looking at only the amplitudes. In other words, we need to understand 
the dynamic range from the peak amplitudes (ASIC dynamic range) but 
eventually we also need to show that the energy spectrum and resolution 
is as expected.

Regards,
Fernando




Yves Van Haarlem wrote:
> Hi Gerard,
>
>> Not that I understand the apparent spectrum here (can you explain 
>> it?), but I certainly _thought_ that is exactly what Yves is 
>> plotting. Isn't it? "Amplitude" = integral of the pulse ~= integral 
>> over a fixed time bracketing the pulse. Pedestal subtracted of course.
>>
>> Or are you plotting peak height here, Yves? That would probably allow 
>> for the strange shape of this curve. (??)
> I am plotting the peak hight. The pre-amp converts charge into 
> amplitude right?
>
> Cheers,
>     Yves
>
>
>
>
>
>>
>>>
>>> Thanks,
>>> Fernando
>>
begin:vcard
fn:Fernando J. Barbosa
n:Barbosa;Fernando J.
org:Jefferson Lab
adr:Suite #10, 12B3;;12000 Jefferson Ave.;Newport News;VA;23606;USA
tel;work:757-269-7433
version:2.1
end:vcard