He flow and helium enviroment between the beamline Be window and the target cell.

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User name jpchen

Log entry time 01:57:10 on October 31, 2008

Entry number 245646

Followups:

keyword=He flow and helium enviroment between the beamline Be window and the target cell.

The BigBite analysis of reference cell Nitrogen run shows that there are significant amount of events upstream of the target cell (see log entry 245533). It was speculated that there are air instead of expected He in between the Be window and the target cell. To check out if this is the case, Ed Folts turned down the exhaust fan to allow He from cooling jet to stay there longer. The data taken shows the same patten ( see entry 245617). I tried a run with increase cooling jet flow from 36.9 to 97. Still no much change (see entry 245630). It seems not from air, but is He? Our concern is if there are air, then it could cause the Be window to go bad. We should monitor it (check it every time the target enclosure is opened).

A copy of this log entry has been emailed to: folts@jlab.org,jiang@jlab.org