BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Space-charge effects in liquid argon ionization chambers
DTSTART;VALUE=DATE-TIME:20140227T101000Z
DTEND;VALUE=DATE-TIME:20140227T103500Z
DTSTAMP;VALUE=DATE-TIME:20260510T113842Z
UID:indico-contribution-83@indico.inp.nsk.su
DESCRIPTION:Speakers: John Rutherfoord (University of Arizona)\nWe have un
 iformly irradiated liquid argon ionization chambers with betas from high-a
 ctivity Strontium-90 sources.\nThe radiation environment is similar to tha
 t in the liquid argon calorimeters which are part of the ATLAS detector in
 stalled at CERN's Large Hadron Collider (LHC). We measured the resulting i
 onization current over a wide range of applied potential for two different
  source activities and for three different chamber gaps. These studies pro
 vide operating experience at exceptionally high ionization rates.\nIn part
 icular they indicate a stability at the 0.1% level for these calorimeters 
 over years of operation at the full LHC luminosity when operated in the no
 rmal mode at an electric field of 1.0 kV/mm. We can operate these chambers
  in the normal mode or in the space-charge limited regime and thereby dete
 rmine the transition point between the two. This transition point is param
 eterized by a positive argon ion mobility of μ₊ = 0.08 ± 0.02 mm²/Vs 
 at 88.0 ± 0.5 K and 1.02 ± 0.02 bar. In the space-charge limited regime 
 the ionization currents are severely degraded and show signs of instabilit
 y.\nAt the highest electric fields in our study the ionization current is 
 still slowly rising with increasing electric field\, that is\, the current
 s don't appear to be approaching an asymptotic value.\n\nhttps://indico.in
 p.nsk.su/event/0/contributions/83/
LOCATION:
URL:https://indico.inp.nsk.su/event/0/contributions/83/
END:VEVENT
END:VCALENDAR