Difference between revisions of "Test in d2n"
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| − | [ | + | [https://hallaweb.jlab.org/wiki/images/9/95/2008-033.pdf Studies of the Transmission of Gases for the Cerenkov Counters] |
| − | [ | + | [https://hallaweb.jlab.org/wiki/index.php/File:Gastransmission.xls.tar.gz Transmission data measured at Syracuse] |
Brad's note: | Brad's note: | ||
Latest revision as of 21:25, 4 January 2021
Studies of the Transmission of Gases for the Cerenkov Counters
Transmission data measured at Syracuse
Brad's note:
Here is a spreadsheet (gastransmission.xls) with transmission data measured at Syracuse on behalf of BTeV years ago. It shows essentially 100% transmission from 180--350nm. Unfortunately, I don't know the length of gas that was sampled, so a transmissability/absorption length can not be computed, but absorption is basically zero over this range.
Hall B measured a sample of the C4F8O we used for transversity/d2n in 2009. Their report is also attached (2008-033.pdf). The relevant figure is #22 (C4F8O). The transmittance plots are over 1.5m of gas at 1 atm. There is essentially no measured absorption from 200nm--500nm. NOTE: please do not be fooled/misled by figures 12, 14, 15, etc. The observed fall off in those plots is an artifact of the UV-glass PMT used for those data. Figure 22 has data taken after they borrowed a quartz-face PMT and you see it is basically flat up to the region where the PMT quantum efficiency starts to die (ie. 200nm for this particular tube). (See also: comment at bottom of p.6).
The Hall B data and the Syracuse data both support the conclusion that C4F8O is essentially 100% transparent down to 180nm over a nominal 1.5m of gas length.
I am not aware of measured transmittance/absorption data below for wavelengths below 180nm.
