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[Daniel Brandenburg <dbrandenburg.ufl AT gmail.com>]

Hi all, 

maybe just a little clarification:

Gene, in our meeting a week ago about the forward tracking we discussed difficulty with the silicon. Specifically I talked about the resolution in R and you guys mentioned that rasterizing the hits was study and found to be important. 

Jason, we talked about the global efficiency some time ago now. We did several studies of the lambda decays with the older fast sim (with different resolution etc.) and with the newer ones for Si and sTGCs. We found that the lambda daughters (true global tracks, not just primary tracks without the primary vertex included in fit) had a very low reconstruction efficiency ( maybe 10%, I dont remember exactly) - we talked about this and how the tracker does the track following etc. 

So my comment is not so much that those plots are wrong but that it is definitely not the performance we see with the current detector resolutions. I hope that is clear.

Since i was not active with the forward tracking before last year I understand that a lot was done before I was active. I want to make sure we fully understand this issue before we get further along. 

Best,

Daniel

On Wed, Jun 26, 2019 at 9:16 AM Zhenyu Ye <yezhenyu2003 AT gmail.com> wrote:

Hi Jason, Gene,

I was told by Daniel Brandenburg that you made the point to him very recently that more radial segmentations are absolutely needed for Forward Silicon Tracker. This would contradict to the statement in page 41 of the proposal https://drupal.star.bnl.gov/STAR/system/files/ForwardUpgrade.v20.pdf

“In addition, we increased the radial segmentation from 8 to 16, 32, and 64 and found no significant improvement on the momentum resolution or tracking efficiency.”

Can you please help me understand why you believe more radial segmentations are needed for FST?

Jason, I was also told by Daniel that the global track efficiency for those plots is wrong. Can you please tell me what is wrong with them?

Thanks,
Zhenyu