Meson Production Targets at PSI G Heidenreich Paul

Meson Production Targets at PSI G. Heidenreich Paul Scherrer Institut 5232 Villigen PSI Switzerland

2 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Accelerator Facilities at PSI • P-beam: 590 Me. V, 1. 8 m. A (1 MW DC) • 2 meson production targets: - Target “M“ (5 mm graphite) Target M - Target “E“ (40 or 60 mm graphite) • Spallation neutron source SINQ • Proton therapy • Two new project under construction - Ultra Cold Spallation Neutron Source UCN - PROSCAN (250 Me. V cyclotron for proton therapy) Target E 3 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

590 Me. V Ring Cyclotron 4 New copper RF-cavities will allow a beam current of up to 3 m. A in future 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Meson production targets used at PSI 1974 -80 < 100 A Target M Target E Be, Graphite *) 190 mm 0. 9 g/cm 2 Be, Graphite *) 190 mm 22 g/cm 2 Pyrolitic graphite**) 22 g/cm 2 1980 -89 since 1990 250 A 0. 5 - 2 m. A Graphite *) 320 mm 0. 9 g/cm 2 *) rotating wheel target 5 Graphite *) 280 mm 18 g/cm 2 Graphite *) 450 mm 10 g/cm 2 (60 mm) or 7 g/cm 2 (40 mm) **) static target 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Target-M design Target M: P P-BEAM Mean diameter: 320 mm Target thickness: 5. 2 mm Target width: 20 mm Graphite density: 1. 8 g/cm 3 Beam loss: 1. 6 % Power deposition: 2. 4 k. W/m. A Operating Temperature: 1100 K Irradiation damage rate: 0. 12 dpa/Ah Rotational Speed: 1 Turn/s Drive-motor 6 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Exchange of Target-M Operation of the remotely controlled shielded flask Dose rate 7 ~10 m. Sv/h 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Design of the proton channel between target-E and the beam dump BEAM DUMP 8 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Working platform / Operation of the remotely controlled shielded flask 9 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Design of Target station E BACKWARD SHIELDING TARGET CHAMBER INFLATABLE ALL-METAL SEAL COLLIMATOR 2 & 3 Beam losses: 22/18 % p TARGET E: 6/4 cm Beam losses: 18/12 % FORWARD SHIELDING 10 SHIELDING COLLIMATOR 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Target-E design Drive shaft TARGET CONE Mean diameter: 450 mm Graphite density: 1. 8 g/cm 3 Operating Temperature: 1700 K Irradiation damage rate: 0. 1 dpa/Ah Rotational Speed: 1 Turn/s Target thickness: 60 / 40 mm 10 / 7 g/cm 2 Beam loss: 18 / 12 % Power deposition: 30 / 20 k. W/m. A SPOKES To enable thermal expansion of the target cone BALL BEARINGS *) Silicon nitride balls p-beam Rings and cage silver coated Lifetime 2 y *) GMN, Nürnberg, Germany 11 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Drive motor & permanent-magnet clutch vacuum Ball bearing air pressure Permanent-magnet clutch DC-motor Record of the drive torque for the rotation 12 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

The design of the spokes allow the isotropic shrinkage of the graphite. Anisotropic dimensional changes causes deformation of the shape and hence leads to a radial wobble. Linear dimensional changes [%] Lifetime of the rotating polycristalline graphite target cones due to irradiation-induced dimensional changes 1100 K Irradiation induced isotropic shrinkage of polycristalline graphite as a function of neutron fluence and temperature. 1650 K 1 dpa 1022 p/cm 2 10 Ah Beam axis 13 1 2 3 4 5 6 * 1021 [n/cm 2] Radial deformation rate [mm/Ah] 0 W. Delle, Juelich 1980 Radial deformation rates of the graphite cones as a function of proton current for different graphite grades *). *) SGL Carbon Mean proton current [m. A] 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

A new design of graphite wheel The gaps allow unconstrained dimensional changes of the irradiated part of the graphite. 14 In operation since 2003 Integrated beam current: ~25 Ah Irradiation damage rate: ~2. 5 dpa 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Temperature & stress distribution (2 m. A, 40 k. W) 600 K 1700 K 5 MPa 15 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Maintenance of the target-insert in the hot-cell Exchange parts: horizontal drive shaft 16 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Operational limits of the rotating graphite & beryllium cones for target-E 3 m. A operation of Target-E D = 0. 45 m Temperature (K) e* = 0. 7 Safety factor syp/s I(m. A): Proton current C Be 17 D(m) : Mean target diameter e* : effective emissivity Evaporation rate (mg/g/year) 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Lifetime of the pyrolitic graphite targets due to irradiation-induced dimensional changes Operational parameters: Proton current: Peak current density: Peak temperature: Swelling of the target after irradiation 100 A 1000 A/cm 2 1800 K 1022 p/cm 2 p p Dimensional change (%) Lifetime limits: Proton fluence: 1022 p/cm 2 Integrated beam current: 50 m. Ah Irradiation-induced swelling: ~ 10 % Irradiation damage rate: ~ 1 dpa 70 60 50 40 30 20 10 0 -10 -20 -30 —— —— 1273 - 1423 K 1473 - 1573 K 1800 K ~ 1 dpa 0 2 4 6 8 10 12 * 1021 N/cm 2 Neutron Fluence J. Bokros et. al, Carbon 1971, Vol. 9, p. 349 18 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich

Thank you for your attention ! 19 2 nd High-Power Targetry Workshop, Oak Ridge, TN, October 10 -14, 2005 / G. Heidenreich