Boundary conditions Near Detector Hall Alan Bross US

Boundary conditions: Near Detector Hall Alan Bross US DUNE Near Detector Effort Workshop 18 April, 2019

Current baseline hall design • The figure to the left shows the current layout – LAr has original concept for cryostat ~ 8 m in beam direction – The magnet for the MPD is now much (~2 m) smaller in beam direction • Bucking coils now same diameter as field coils – 3 DST-S is in separate alcove 2 4/17/19 A. Bross | Near Detector Hall

On axis 3 4/17/19 A. Bross | Near Detector Hall

Off axis Max off axis position is 30. 5 m from on axis 4 4/17/19 A. Bross | Near Detector Hall

The real concern is the span • Given the average geotechnic data for the Fermilab side, our engineers were comfortable with a span of ~ 19 m. • The boring data are now in hand • Well…… 5 4/17/19 A. Bross | Near Detector Hall

Geo-tech data at ND hall location Interpretation of data from Kennedy Hartsfield • • • Hall width = 63’ Dirt = 83. 50’ Weathered rock = 16. 50’ Good rock = 38. 75 Width/Good ≃ 1. 6 – Rule of thumb: want ≲ 1 • Note: – Original hall width ~ 56’ 6 4/17/19 A. Bross | Near Detector Hall

Mitigation • Change roof profile – Kennedy used a very conservative design for the reference design (21’) • Even a flat roof is possible – Kennedy is guardedly optimistic that even with these data, the reference hall design can be made to work • Some “mitigation & exercise risk” will have to be take ($1 -5 M) • Detailed work on the design will not begin until the outside A&E firm is brought on board (mid-July) – First report in mid-October – This is very late for our process, or course – Some feedback earlier • NEED TO WORK HARD TO MINIMIZE DETECTORS’ LENGTH IN BEAM DIRECTION – Can we get another 2 m? • Take a close look at LAr cryostat • MPD system optimization 7 4/17/19 A. Bross | Near Detector Hall

Magnet: Space frame • Working to make the HPg. TPC’s pressure vessel as small as possible – And < 0. 5 X 0 in thickness • Put all of ECAL outside and nest within spaceframe – Could save ~ 1 m 8 4/17/19 A. Bross | Near Detector Hall

New PV design: Bhabba Atomic Research Center 9 4/17/19 A. Bross | Near Detector Hall

Magnet structural system 10 4/17/19 A. Bross | Near Detector Hall

Reminder: LAr Fiducial, veto definitions • So, open area in center of magnet system is good match to Argon. Cube – Push side coils to 3 m from 2. 5 m? • However, – The support structure has increased the overall diameter (including assumptions on coil strongback and cryostat 11 4/17/19 A. Bross | Near Detector Hall