1. MICE LH2 Absorber Safety Mary Anne Cummings Edgar Black (IIT) Abingdon, UK Oct. 30, 2003

2. Design considerations Emittance eqn: coolingheating So, minimizing beam heating term by minimizing and maximizing L R.  The design features of a cooling channel: 1)Hydrogen (lowest Z, highest L R ) for the cooling medium. 2)Thin windows for the hydrogen absorbers. 3)LH2 absorbers placed in large magnetic fields. additionally… 4) RF between LH2 absorbers to restore forward momentum : Muons through matter can actually focus!  xx zz P1P1 P2P2    absorber accelerator absorber P1P1  Multiple scattering RF cavity

3. Liquid Hydrogen Safety For safe operation, have designed with the redundant requirements: 1)LH2 and O2 separation 2)The avoidance of any possible ignition sources in the vicinity of the hydrogen. The four key features of the design with respect to safety are: 1)The window thicknesses specified based on safety factors of 4.0 for the absorber window and 2.5 for the vacuum window at maximum allowable working pressure (MAWP). 2)An argon-gas-filled jacket surrounding the vacuum chambers of the RF/coupling magnet modules and the hydrogen absorber/focusing magnet modules to minimize the possibility of oxygen leaking in and freezing on the absorber-system windows. 3)Separate vacuum volumes provided for the RF cavities, magnets, and LH 2 absorbers. 4)Hydrogen evacuation systems using valved vents into external buffer tanks.

4. MICE Cooling Channel Design Other safety concerns: 1)Magnet quenching, LH2 absorber stability 2)Any instrumentation must be “instrinsically safe” 3)Sufficient shielding from detectors/RF 4)Robust, simple failsafe systems Compact environment

5. Absorber/Coil Assembly Sufficient venting into evacuation tank Secure plumbing attachments Stable and repeatable placement of LH2 absorber inside magnet bore

6. Experiment Installation Accessibility in a compact, sealed environment Certification of Windows-Absorber-Coil Assembly Accurate component placement LH2 absorber Coil Hydrogen storage ISSUES:

7. Photogrammetry: Non-contact measurement of strain by calculating displacement Photogrammetry ~1000 points Strain gages ~ 20 “points” Shape measurement at FNALPressure tests at NIU LH2 Window R & D

8. Absorber window test results Discrepancies between photogrammetry and FEA predictions are < 5% Performance measurement (photogrammetry) 1. Room temp test: pressurize to burst ~ 4 X MAWP (25 psi) 2. Cryo test: a) pressure to below elastic limit to confirm consistency with FEA results b) pressure to burst (LN2 temp) ~ 5 X MAWP from ASME:UG 101 II.C.3.b.(i) Window # Test temp. FEA resultsTest results Minimum window thickness (mm) Rupture pressure (psi) Window thickness from CMM (mm) Measured rupture pressure (psi) 1293K0.13480.11442 2293K0.331170.33119 3293K0.345 1230.345120 480K0.331560.33*152 1. 2.3.4. Cryo test 4 burst tests:

9. Certification procedures Windows to be tested/certified independently: both vacuum and absorber Pressure tests of assembled absorber manifold Assembly inside vacuum containment vessel or magnet bore Survey of absorber position inside magnet Cryo pressure test after absorber installation Pressure test of vacuum vessel after installation Nitrogen/argon purge of absorber and vacuum before LH2 fill and vacuum area evacuation. Safety valve tests

10. Vacuum Windows FNAL Requirements: 1.Burst test 5 vacuum windows at room temp. to demonstrate a burst pressure of at least 75 psid (~5 bars) for all samples. (pressure exerted on interior side of vacuum volume). 2.Non-destructive tests at room temperature: a.External pressure to 25 psid (~1.7 bars) to demonstrate no failures: no creeping, yielding, elastic collapse/buckling or rupture b.Other absorber vacuum jacket testing to ensure its integrity Internal pressure: burst at 83 psi No buckling at 1 st yield (34 psi) Vacuum “bellows” window (34 cm diam):