Top stringer in a drift chamber for CLAS12 project

A top stringer work instructions

The top stringer is responsible for

1- Dropping a wire that has from the top feed through to the bottom feed. The wire should have an additional length that has a range of 10-12" relative to the top end of the bottom feed through.

2- crimp the pin that holder the wire in the top feed through.

3- Observe if any changes take place inside the chamber through the stringing time.

The top stringer has tools to drop that wire such as chains (hand made), a wire cutter, a crimper, torch, and a feeler gauge. A left is used to help the top stringer to reach the top of the chamber which is placed to take advantage of the gravity to vertically drop the wire inside it.

Procedure to drop the wire

The chamber location is in a clean room, before following the next procedure, the stringer is expected to follow all the clean room instructions that include safety instructions to be in a clean and safe working environment for him (her) and the other co-workers.

The top stringer is going to :

1- locate and Raise up the left to a height that helps to see the all the top and top feed through rows that he is going to string distinguishing their locations. (The rows are numbered for accuracy).

2- Be sure that the stringing machine is in an appropriate location (the bottom stringer helps to relocate if needed), and the wire is stretched around the machine's pulleys.

3- Feed the free end of wire gently into a rubber snot, then the sharp end of chain in a depth that prevent any of them to separate as they are dropped inside the chamber.

4- Extend the wire by pressing the bottom of the machine until the top of the chain passes the top feed through and with a distance of 1-2" (or shorter if possible) from the inside end of the top feed through.

5- Wait until the chain is stable.

6- Increase the length of the wire until the wire reaches the inside end of the bottom feed through.

7- Two ways to feed the wire inside the bottom feed through:

a- By holding and extending wire closer to the machine, then feeding the wire slowly in the feed (specially for sense wires).

b- Feed the wire in the bottom feed through directly. (for guard and field wires).

Feeding the wire continues until the chain disappears, then stop.

It is recommended to feed wire all over the feed through continuously until the chain comes of it to avoid having the chain stopped inside it.

At this moment, if the wire passes the feed through, it will be stretched the stringer won't observe any wire bending inside the chamber.

8- Extend the wire to have additional length of 10-12" outside the bottom feed through. Counting is used to reach the desired length.