1. LBNF Cryo + Detector schedule Filling scenarios (Cryostats #1 and #2) Mohammed Elrafih, Elaine McCluskey, David Montanari, Marzio Nessi, Bob O’Sullivan Mar 9, 2016

2. Problem definition 1)To fill Cryostat #1 we need to have Cryostat #2 ready to be able to eventually transfer the LAr, should that be needed. 2)To be ready with Cryostat #2, we need to have the detector installed and the cryostat closed. 3)This means that the filling of Cryostat #1 can only happen after the second detector is installed in Cryostat #2  long delay on the present schedule ( 14 months). 4)Can we challenge any or all the 3 assumptions above?

3. Problem definition 1)To fill Cryostat #1 we need to have Cryostat #2 ready to be able to eventually transfer the LAr, should that be needed: -To qualify the cryostat we will follow the rules of the safety MOU between CERN and Fermilab. -According to that, full qualification of the cryostat takes place when it is full. -Can we take the risk of not having to empty the cryostat? -At which stage of the filling might we decide to move the liquid from Cryostat #1 to Cryostat #2 instead of just boiling off the LAr? -To move LAr from Cryostat #1 to Cryostat #2, Cryostat #2 must be ready to accept LAr: it needs to have been purged and cooled down (4 mo activity).

4. Problem definition 2)To be ready with Cryostat #2, we need to have the detector installed and the cryostat closed: -Filling of Cryostat #1 can only start when Cryostat #2 is closed with the detector installed (see slide 6), it has been tested and the necessary authorization obtained, purged and cooled down. -Installation of detector ~ 11 months. -Closing of cryostat + leak test ~2 months. -Cryo test + safety authorization ~4 months. -Purge and cool down ~4 months. -Alternatively, we might decide to close Cryostat #2 before detector installation and then reopen it. In this case we need to duplicate activities and add the following to the schedule of Cryostat #2: -2 months to close it and 2 months to reopen it. -4 months to do the cryo test and obtain safety authorization. -4 months to do the purge and cool down. -If we close Cryostat # 2 before the installation of the detector, then the installation of Detector #2 can start only 7 months after the completion of filling of Cryostat #1 (see slide 7).

5. Cryostat #1 Beneficial occupancyJul-20 Start cryostat installationJul-20 Completion cryostat installationDec-21 Start detector #1 installationJan-22 End detector #1 installationNov-22 Cryostat #1 closedJan-23 Completion of cryo test + safety authorizationMay-23 Completion of cryogenic system safetySep-22 Start of purge and cool down #1Jun-234 months Start of filling #1Oct-23145 Calendar days Completion of filling #1Feb-24 Cryostat #2 Beneficial occupancyAug-20 Start cryostat installationJan-21 Completion cryostat installationDec-22 Start moving equipment to setup detectorDec-223 months Start detector #2 installationMar-23 End detector #2 installationFeb-24 Cryostat closed #2Apr-24 Completion of cryo test + safety authorizationAug-24 Start of purge and cool down #2Sep-244 months Start of filling #2Jan-25210 Calendar days Completion of filling #2Jul-25 1) Current schedule (take the risk) Note: we assume that we can speed up the cryogenic safety review process at Fermilab

6. Cryostat #1 Beneficial occupancyJul-20 Start cryostat installationJul-20 Completion cryostat installationDec-21 Start detector #1 installationJan-22 End detector #1 installationNov-22 Cryostat #1 closedJan-23 Completion of cryo test + safety authorizationMay-23 Completion of cryogenic system safetySep-22 Start of purge and cool down #1Jun-234 months Start of filling #1(would be ready in Oct 2023)Jan-25145 Calendar days Completion of filling #1May-25 Cryostat #2 Beneficial occupancyAug-20 Start cryostat installationJan-21 Completion cryostat installationDec-22 Start moving equipment to setup detectorDec-223 months Start detector #2 installationMar-23 End detector #2 installationFeb-24 Cryostat #2 closedApr-24 Completion of cryo test + safety authorizationAug-24 Start of purge and cool down #2Sep-244 months Start of filling #2Jun-25210 Calendar days Completion of filling #2Dec-25 2) Fill Cryostat #1 when Cryostat #2 is ready Note: we assume that we can speed up the cryogenic safety review process at Fermilab. Wait 14 Months 14 months delay

7. 3) Closing #2 before detector #2 is installed Cryostat #1 Beneficial occupancyJul-20 Start cryostat installationJul-20 Completion cryostat installationDec-21 Start detector #1 installationJan-22 End detector #1 installationNov-22 Cryostat #1 closedJan-23 Completion of cryo test + safety authorizationMay-23 Completion of cryogenic system safetySep-22 Start of purge and cool down #1Jun-234 months Start of filling #1(would be ready in Oct 2023)Nov-23145 Calendar days Completion of filling #1Mar-24 Cryostat #2 Beneficial occupancyAug-20 Start cryostat installationJan-21 Completion cryostat installationDec-22 Cryostat closedFeb-23 Completion of cryo test + safety authorizationJun-23 Start of purge and cool down #2Jul-234 months Completion of filling #1Mar-24 Cryostat #2 openedMay-24 Start moving equipment to setup detector (?? Needed ??)Jun-244 months Start detector #2 installationOct-24 End detector #2 installationAug-25 Cryostat #2 closedOct-25 Start of purge and cool down #2Nov-254 months Start of filling #2Mar-26210 calendar days Completion of filling #2Sep-26 Note: we assume that we can speed up the cryogenic safety review process at Fermilab 1 month delay

8. Summary (with alternate option *) Cryostat #1 Filled Cryostat #1 filled If #2 Parallel operation (*) Cryostat #2 Filled Cryostat #1 filled If #2 Parallel operation (*) 1) Take the risk (current schedule)Feb-24Jul-25 2) Fill cryostat #1 when detector #2 is installedMay-25Jan-25Dec-25Aug-25 3) Close cryostat #2 before installing detector #2Mar-24Feb-24Sep-26Apr-26 This gives an early detector to debug This gives more time to install #1 4) Take the risk (current schedule) and use Cryostat #3 as buffer (Cryostat #3 available in Dec-23). Fill of Cryostat #1 would start in Dec-23 instead of Oct-23 (2 months delay). This assumes that we can do the cryo test, obtain safety approval, and purge and cool down cryostat #3 in parallel to fill #1. We would also need to evaluate what cryogenics still needs to be done to be ready for that (e.g. internal cryogenics has to be installed). 4a) If Cryostat #3 is not available, we may have to wait for #2 to be ready. In column “#2 Parallel operation (*)” we assume that: Purge and cool down of cryostat #2 can be done during the filling of #1 (4 months). The activity “Move equipment to setup the detector” can be done in parallel to cryostat #1 ops (4 months) in scenario 3 only.

9. Final remarks If we need 2 cryostats ready, we have to assume that the problem is not in the design of the cryostats (we have to assume that cryostat #2 is ok, if we want to transfer LAr to it). Scenario 2 (Fill cryostat #1 when cryostat #2 is ready) gives more time for detector #1 installation. An alternate scenario (4) takes scenario 1 and uses cryostat #3 as buffer. Cryostat #3 is ready 2 months after cryostat #1 is ready to be filled (potential 2 months delay on completion of filling of cryostat #1). This assumes that we do the cryo test, obtain the safety approval, and purge and cool down cryostat #3 in parallel to the filling #1. If cryostat #3 is not available, we may have to wait for cryostat #2 to be ready (scenario 4a). In all scenarios we have 2 detectors ready by ~mid 2025-mid 2026. In scenarios 1, 3 and 4 we have Detector #1 operational in early 2024. Reopen a cryostat (scenario 3) might not be as easy as it sounds and requires duplication of several activities: closing of the cryostat, purge and cool down.

10. Transfer time of liquid from #1 to adjacent Up to 25% better to evaporate it, cost of LAr lost ~$4M ??