1. Freezing studies Retrofitting the fezzes in Malargue
Pablo Bauleo and David Warner
Physics Department
Colorado State University
Fort Collins, CO 80523

2. A little bit of history
Insulation
Ice layer
Ice formation around the dome and thaw-freezing cycles produces mechanical decoupling of RTV from dome
Test performed on small tank in a walk-in freezer
Thermal insulation around the fez and between fez and PMT prevents ice formation around the dome
“Deep” freezing tests (up to 9 cm of ice) develops a thin ice layer of a few millimeters around the dome
No mechanical decoupling of RTV with this configuration
Freezing studies Colorado State
P. Bauleo and D. Warner

3. Insulation used in Argentina
Inner ring
Outer ring
Due to delay in IR production of about 280 tanks have been deployed without any thermal insulation
Field mod calls for easy and fast retrofit
Freezing studies Colorado State
P. Bauleo and D. Warner

4. Retrofit kit “Tea cozy” design around the fez (replace the inner ring)
Larger OD in outer ring to push the ice away
Tests performed in small tank with walk-in freezer in Ft Collins
Thick ice layer (7-8 cm) outside the insulated area  No ice around the dome
Super thick ice layer (12-14 cm) outside the insulated area  1 cm of ice around the dome
Freezing studies Colorado State
P. Bauleo and D. Warner

5. Plans Finalize engineering details Get quote from vendor in Argentina
Take a prototype to Malargue in November and make sure does not interfere with HV/base heat dissipation in summer
Retrofit the tanks!
As part of regular maintenance visits
Retrofit campaign?
Keep up the momentum and experience on freezing test for Auger North
Freezing studies Colorado State
P. Bauleo and D. Warner