Cool Down Prescription for Clio


May 2010

Vacuum Pumpdown: 2-3 days before run

Before cooling, Clio should be put on the turbopump. When the vacuum gets down to about 7e-4 Torr, it is good enough for a typical Clio AO run.

Cooldown: 12 hours before beginning of night


The Clio needs 12 hours to completely cool down to a stable temperature. The detector is operational 6 hours after cooldown. If possible, it is thus preferable to begin cooldown the day before the Clio run starts.

Only the outer vessel is filled for the first fill, and this takes typically 10 minutes to get the cooling down going. Fill until the liquid spurts out of the tube.

Look for the vapor to stop exiting from Clio after about 30 minutes. This is an indication the liquid has boiled off. Refill the outer vessel a second time. It should be empty after around 3 hours from the start of your cooldown. Refill a third time.

When the outer vessel temperature is 150 degrees or below, you can fill the inner vesel. The limit of 150 degrees is important, as this is the temperature that the getter in the dewar activates. Do not fill the inner vessel if the outer vessel is above 150 K! If the detector is the coldest surface in the dewar, the detector will attract all residual vapours!

Example Refrences


Fill Vessel Time from start Optics Temperature (Channle B)
1st outer start 280 K
2nd outer 30 min 220 K
3rd outer+inner 3 hours 140 K
4th outer+inner 6 hours 90 K


Past Clio Cooldown information
Fill Vessel Temperature just before filling
1st outer chamber 283K at 18:19 2008 Mar 19
2nd fill outer 224K at 18:48 2008 Mar 19
3rd fill outer 150K at 21:14 2008 Mar 19
4th fill outer 150K at 21:14 2008 Mar 19
OUTER AT 150 K, can fill INNER
5th fill outer 130K at 21:37 2008 Mar 19 DETECTOR = 321K, INNER = 84K OUTER = 130K
6th fill inner 21:37 detector at 231K, inner at 84K
7th fill inner and outer topped up slightly at 00:40 2008 Mar 20

Fills at 11.30am 2008 Mar 20, but INNER not needed. OUTER requires only small topup. Inner vessel on pump at about 2.45pm, temperature change is 10 degs in about 10 mins to 65K.

Oct 2009 Cooldown

Dewar at 3.9e-6 Torr at disconnection from the pump.

Fill Vessel Temperature just before filling
1st outer chamber 298K at 22:10 2009 Oct 02
2nd outer chamber 245K at 22:30 2009 Oct 02
3rd outer chamber 175K at 23:40 2009 Oct 02
4th outer chamber 120K at 01:10 2009 Oct 03
5th inner OUTER AT 150 K, can fill INNER

Temperature of INNER is 80K at 1:30am.