[Halld-tracking-hw] New preamp - resending table
Fernando J. Barbosa
barbosa at jlab.org
Fri Apr 9 10:28:13 EDT 2010
Hi Yves,
Your table is correct.
Thanks and best regards,
Fernando
Yves Van Haarlem wrote:
> I think the formatting got weird up in previous mail:
>
> HV-board-ch || old-cable ch# || new cable ch# || fADC ch#
>
>
> 24 || 1 || 1 || 1
> 23 2 2 2
> 22 3 3 3
> 21 4 4 4
> 20 5 5 5
> 19 6 6 6
> 18 7 7 7
> 17 8 8 8
> 16 9 17 !
> 15 10 18
> 14 11 19
> 13 12 20
> 12 13 21
> 11 14 22
> 10 15 23
> 9 16 24
> 8 17 9 ! 9
> 7 18 10 10
> 6 19 11 11
> 5 20 12 12
> 4 21 13 13
> 3 22 14 14
> 2 23 15 15
> 1 24 16 16
>
>
>
> /--------------------------------
> / Yves Van Haarlem
> _--~~--_ /
> /~/_| |_\~\ / Carnegie Mellon University
> |____________| / Department of Physics
> |[][][][][][]|:= / Wean Hall room 8404
> __| __ |__ \ Pittsburgh, PA 15213
> | ||. | == | | \ USA
> (| ||__| == | |) \
> | |[] [] == | | \ Tel.: +1 412 268-6949
> | |____________| | \ +1 412 641-9252
> /__\ /__\ \ Fax.: +1 412 681-0648
> ~~ ~~ \-----------------------------------
>
> On Fri, 9 Apr 2010, Yves Van Haarlem wrote:
>
>> Hi Fernando,
>>
>> I have a suggestion below,
>>
>>>> My other concern is over the mapping of the preamp channels through
>>>> the
>>>> cable. We are now using the new preamp and new cable with the old HV
>>>> board. The correspondence between the numbering on the HV board
>>>> and the
>>>> preamp channels has changed. Is this now the final mapping?
>>>>
>>>> Previously we were using the cable with channels 1-8 and 17-24
>>>> feeding into
>>>> the shaper unit, which has 16 channels total, and then into two
>>>> 8-channel
>>>> fADCs. The chamber prototype is configured so that the missing 8
>>>> channels
>>>> correspond to the straws along 2 sides of the chamber; the two
>>>> groups of 8
>>>> channels in use correspond to two blocks of 8 straws, one above the
>>>> other.
>>>> With the new cable it seems that we now have access to the 8
>>>> channels which
>>>> were missing before (along the edge), but since we only have 16
>>>> channels
>>>> from the shaper, we have lost access to one block of 8 straws.
>>>> This makes
>>>> cosmic ray tracking much slower, since we are looking for tracks
>>>> passing
>>>> through at least 4 straws. This is hard to explain without a
>>>> diagram but
>>>> the effect is that the configuration of our available channels is
>>>> much less
>>>> as efficient than before. This will be solved when we have a
>>>> 72-channel
>>>> fADC; alternatively we could just use the old cable until the new
>>>> fADC is
>>>> available.
>>>
>>> The old preamps (also designed for 24-channels) had only two chips
>>> installed
>>> (on top) because the ASIC package was not reliable for assembly on
>>> the bottom
>>> (it had a removable lid in case we needed to probe the die). The
>>> preamp card
>>> has channels 1-8 from one chip on top, 9-16 from bottom chip and
>>> 17-24 from
>>> the second chip on top. Because of the 16-channel readout on the
>>> shaper, the
>>> cable (old cable) was modified at the ERNI connector (connects to
>>> preamp) to
>>> read channels 1-8 and 17-24. This is the reason for what you observe
>>> with the
>>> new cable. This won't be the case with the 72-ch fADC125 because it
>>> reads
>>> from all 24 channels on a preamp card. Yes, please you use the old
>>> cable with
>>> the new preamp and shaper for your immediate tests and then use the
>>> new cable
>>> when the 72-ch fADC125 becomes available (late April).
>>
>> Once it is decided which group of 8 channels goes where on the cable
>> (between HV-board and fADC), could you modify the labeling of the
>> channels
>> on the HV board so that channel 1 -> 24 on the HV-board corresponds to
>> channel 1 -> 24 on the fADC (or 25 -> 48; or 49 -> 72). We might avoid a
>> lot of confusion in the future.
>>
>> The difference in mapping between old and new cable in a table:
>>
>>
>> Ch# on HV board || ch# on old cable || new cable || fadc#
>> 24 || 1 || 1 || 1
>> 23 2 2 2
>> 22 3 3 3
>> 21 4 4 4
>> 20 5 5 5
>> 19 6 6 6
>> 18 7 7 7
>> 17 8 8 8
>> 16 9 17 !
>> 15 10 18
>> 14 11 19
>> 13 12 20
>> 12 13 21
>> 11 14 22
>> 10 15 23
>> 9 16 24
>> 8 17 9 ! 9
>> 7 18 10 10
>> 6 19 11 11
>> 5 20 12 12
>> 4 21 13 13
>> 3 22 14 14
>> 2 23 15 15
>> 1 24 16 16
>>
>>
>> So the possition of two chips have been swapped on the cable, was this
>> deliberate?
>>
>>
>> Best regards,
>> Yves
>> _______________________________________________
>> Halld-tracking-hw mailing list
>> Halld-tracking-hw at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/halld-tracking-hw
>>
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