Start Counter Status, August 20, 2014

All 50 scintillators have been fully wrapped. The best 30 scintillator paddles have been selected and fully tested at all 12 locations on the test stand. The average timing resolution across the entire length of of the best 30 paddles is approximately 360 ps. In the nose region, the time resolution measurements indicate that the Start Counter will provide a timing resolution less than 350 ps with the best resolution at the tip of the nose corresponding to a timing resolution on the order of 275 ps. The complete testing of the worst 20 paddles is ongoing.

A test assembly was successfully performed. We were able to assemble 30 scintillators in accordance with the nominal Start Counter design. Since then the Rohacell support structure has been painted black and any gaps filled with black caulking for light tightening purposes.

Shimming studies are complete. These studies indicate that the we will require approximately 30 mils (762 um) of shimming for each scintillator paddle. The material to be used is Kapton polyimide heavy duty film. We will utilize one 10 mil strip (0.5 in x 13 in), and one 20 mil strip (0.5 in x 13 in).

Today we begin the final construction of the Start Counter. This is set to be completed by Friday of this week. The following week we plan to do the final wrapping of the start counter with 80 gauge bundling wrap, test all 30 channels of the readout system, and prepare the Start Counter for transportation to Jefferson Lab. We currently plan to have the Start Counter delivered to JLab September 2nd.

Once the Start Counter is delivered to Jlab we will commence with light tightening and final testing prior to mounting to the target and commissioning of the Start Counter.

If you have any questions or comments regarding this update please do not hesitate to contact me.

-Eric