Transcript E906PreAmp20091007

E906 Pre-Amplifier Card
2009/10/07
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E906 Wire Chambers
• Station1 MWPC:
– build a new E906 MWPC.
– 4500 channels in total.
• Station2 DC:
– recycle old E866 DC3.
– 1200 channels in total.
• Station3 DC:
– recycle old E866 DC2 and build a new E906 DC.
– 1600 channels in total.
2
Constraints
• If preamp card is directly plugged into the
card-edge socket of the wire chamber, a
width of less than 15 cm is required to
meet the space of E866 DC.
• High channel density of MWPC.
• Due to the heavy work load of Da-Shung
and available manpower, only one kind of
form factor/design is feasible/likely.
• ?
3
Geometry
> I have a preliminary estimate of the pre-amp card size, is probably
> 30cm wide, 14cm depth.
>
The size is somewhat larger than we expected.
How firm is this estimate and is there any ideas to reduce the size?
If we use such card for the old chambers
(as a 8-ch card by omitting 8 out of 16 ch),
since the space between two card-edge sockets on the chambers is only ~15 cm, a card
interferes with neighboring ones when cards are directly
inserted into the sockets.
One solution is using an extension cable and arranging cards properly.
>PCB thickness (1.6mm)? PCB shape ... PCB install/remove mechanism?
>
These details haven't been well considered yet.
We would like to ask Da-Shung to provide a first design for us.
We can get a realistic picture from such design, and consider these details.
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Geometry
Below is our current thoughts.
- PCB thickness (1.6mm)?
If the card-edge connection is adopted, the PCB thickness should be
equal to that of the old card, 1.6mm. Otherwise no constraint.
- PCB shape (square)?
We don't find any reason to select non-square shape.
- Channel density (16ch/30cm)?
As I wrote above, the size is too large to fit the space between
neighboring card-edge sockets on the old chambers.
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Geometry
- PCB max high/low? (Can do surface mount on Top/bottom side?)
- Keep-out area? (Do have any place need to avoid?)
- Through-hole location? Drilling diameter?
- Is it ground hole? How many (4 or 6)?
- PCB install/remove mechanism?
No answer yet. What is the "max high/low"?
Does the "ground hole" mean a hole shorting two PCB sides?
PCB max high/low: the height constraint for the electronic parts or
connectors on PCB.
Ground hole: the holes to be drilled on PCB for the purpose of
positioning.
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Cabling
> Now it seems that the signal input with flat-cable, twist-pair for
> differential output. But if there has a topology for cabling on the
> chamber side, then we can find out the way to shorten the distance;
> try to avoid the use of more expensive shielded cable.
>
On the old chamber, your view are right. At the input side, a flat cable runs inside the Al
frame from sense wire to card-edge socket.
On the new chamber, below is the current idea although it hasn't been fixed yet.
A socket for preamp card is placed at a distance of 5-10 cm from
sense-wire end, and is tied to sense-wire end with a shielded cable.
The cost of shielded cable is more expensive as you said, but is not
significant in comparison with that of the chamber itself. And it is
safe to use shielded cable at this raw-signal line no matter how it is short.
Da-Shung’s point here is to take into account uniform cable length and easy bundling of
cables.
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Channel Inputs
> Each input signal needs a ground return signal which should be
> firmly connected to High-voltage power system on the chamber side.
> One thing to be noted that the group return of each channel should
> NOT be connected to the other on the pre-amplifier card.
>
We don't understand what part you are pointing.
Could you explain in details or with drawings?
(Please see next page.)
> How to make one receptor and cable assembling using two different plugs?
> Or can just use only one? Is it easy to get from the market (cheap)
> or not (expensive)?
In the current idea proposed by Wen-Chen, only one shape of plug+socket is used for
both the "8 ch/card" case and the "16 ch/card“ case.
> Is it applying high voltage on the input channels?
No. Input channels (= sense wires) are at ground level. Other wires
are not at ground level, but their HVs are supplied via other cables.
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E866 Old PreAmp
Such kind of grouping of grounding should be avoided.
9
Power Supply
> Then, how to apply power to each card?
> The use of rail-mounted power supply, or the use of wire connectors?
Not determined yet.
> AC power? or DC?
DC as commonly used.
> we may need at least +/-7 V DC power for the +/-5V requirement.
We think the use of "+/-7 V" is OK.
> Unless the signal line has a shielding, otherwise,
> it is not recommend that the power line goes together with the
> signal transmission line.
We agree, even if the signal line has a shielding.
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Questions
> 3. Da-Shung prefers the scheme of a short cable connection to the
> detector instead of direct contact. The concern is the rigidity and
> possible distortion of the card which might affect the robustness in
> the connection.
>
We understand the defect of the direct contact. It has a tradeoff with
the defect of adding an extra cable length and an adapter board for
the old chamber. How do you think which is bigger?
We consider that the connection scheme with cable is probably the only
way to be flexible and possible.
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Questions
- How is the acceptable size of the preamp card for the St. 1 MWPC?
It should be the strongest constraint in all the chambers.
- How realistic is the idea that all cards are of 16 ch/card and
one card is used for 2 x 8 ch on the old chambers with a split cable?
It can be better than the current idea
(a card for the old chambers is of 8 ch/card by omitting 8 out of 16 ch)
in terms of two facts;
- The card-edge connection is not so reliable, and
- A card with a larger-than-15-cm width and the card-edge plug
cannot be directly inserted into the card-edge socket on the old
chambers.
- How to host or position preAmp cards and provide the LV power
supply? Is VME 3U a good choice?
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