Home » Groups » STAR Protected

gas flow study, 6A

Updated on Wed, 2012-02-29 13:10. Originally created by balewski on 2012-02-29 10:29.

 We have switched to high gas flow around 2 pm on Tuesday, Feb 29. The purpose was to increase removal of the oxygen drifting in to detector due to diffusion.

The estimate of quadrant gas volume is 1.6L  ( 1/4 of disc Rout=40cm, d=1.3 cm).
The high-flow (60mm on the gauge) should pump 100cm^3/min in to quadrant. Assuming all goes through the quad it would replace gas in a quadrant within 15 minutes.
Assuming the reality  is 10x worse, the replacement  would take 3 hours.
Lets tripple that, and count only events taken since midnight, i.e. 10 hours after the gas flow increase. 

In parallel we reduced flow in 6A to conclude  if  recently we see pulses in this quad becasue of better gas flow or softwrea change.

Only production runs data were processed.

 
'LowFlow' set (see fig 1)
runs 13059026,37,38, total 54 fgt_test triggered events. 
this set uses nominal flow not exceeding 40mm reading on all quadrants, except for 6A we have the max possible flow >65 mm reading

'HighFlow' set, 
runs 13060008,9,12, total 68 fgt_test triggered events. 
this set uses 2x nominal flow (as accurate as we could achieve that) , except for 6A we reduced the flow to 40 mm reading. 
 
The conclusions are:
*for 6A the 'pules' are gone for the lower flow. This quad needs max possible flow in 2012. 
* for all other quads, the spectra look very similar for both flow 

 

Fig 1. 'LowFlow' spectra, input=55k events.  6A has high flow in this data set and it counts like other quadrants.

 

Fig 2. 'HighFlow' spectra, input=68k events.  6A has low flow in this data set and it counts almost nothing.

Groups: