Some considerations about design and technology AE IS DT Science-Techno Tea meeting Diego Perini

Alexey Dudarevmagnets Johan Bremercryostats Thomas Eisel & Friedrich Haug refrigerator Tapio Niinikoski Lionel Metral DT colleagues: Bernard Cantin Francois Garnier Pierre-Ange Giudici Luc Kottelat Philippe Lenoir

What do we need for AEgIS? - Very cold region, 50 mK (dilution refrigerator) - Magnetic field to confine particles, 5T and 1T regions. Superconducting coils Cryostat - Positron accumulator - Traps, - Laser system, - Positronium target and supports, - Anti-H detector, - Deflectometer.

Very cold environment

Dilution refrigerator. The mixing chamber is inside a solenoid and in HV.

Mixing chamber and traps The need of having both electrical insulation and thermal conductivity At these temperatures Indium is superconducting.

Superconducting solenoids

Coils: Layout Precise magnetic field  main coils + correction coils Measurements after construction to understand the system 5T 1T 0T>0.7T

Coils: Homogeneity (%) 5 T region 1 T region

Böhler P506 - C 0.012, Si 0.23, Mn 12.05, P 0.005, S 0.001, Cr 19.18, Mo 0.86, Ni 10.90, Cu 0.04, Co<0.05, B<0.001, N 0.33

Superconducting coils NbTi superconductor embedded in Cu matrix At 4.2 K current passes through NbTi (superconductor, R ~ 0) In normal state (ex. In case of quench) resistivity of NbTi > Cu so the copper carries the current. Cu gives mechanical stability and is an heat sink. Thin filaments (some  m) since current flows skin-deep. Cables are produced by extrusion starting from billets. Winding is a delicate job – see Pierre–Ange’s presentation Number of filaments 42 Cu/Sc ratio 4.0 Wire dimensions (bare) 1.19 x 0.74 mm Insulated 1.25 x 0.80 mm +/ mm 5T 400 A

Cryostat

“Easy to open” structure Rails and stoppers

Services for the traps and the mixing chamber, laser system, mechanical supports, thermal screens. One have to Minimize the power dissipation at 50 mK. Detector 80K Target Mixing chamber 50 mK Coils 4.2K 200 mm The very crowded central region

Positron accumulator