Status of the Polarized 3He Target Patricia Aguar Bartolomé

Overview Magnetic Holding Field - Solenoid design - Numerical calculations - Solenoid test Target Cell Preparation Measurement of Polarization - Mechanical rail system - External holding field Patricia Aguar Bartolomé

Magnetic Holding Field Polarized targets require a magnetic holding field, B0, to provide a quantization axis. SOLENOID The strength and uniformity of the field play an important role in obtaining long polarization relaxation times. Depolarization effects due to field gradients should be smaller than the relaxation due to surface effects. Main constraints Produce magnetic holding field of 7G with a relative field gradient of 10-3 cm-1 for 6 bars in the target cell area. Appropriate outer radius to fit inside the Crystal Ball detector. Target cell dimensions determine the inner radius. The outgoing particles have to pass the coil minimization of the wire thickness. Patricia Aguar Bartolomé

Magnetic Field Calculation Numerical calculation of the field and gradients with a finite element code (FEMM) Geometric parameters for the solenoid Parameter Value Solenoid length 80 cm N0 windings 1457 Current 0.3 A Inner coil diameter 0.82 cm Outer coil diameter 0.83 cm Copper wire diameter 0.053 cm Coil wound on a CFK-tube with cross section of 82 x 1 mm2 and 120 cm length. B magnitude determined using the three axis magnetometer MAG-03 MS (Bartington Instruments Ltd.) Patricia Aguar Bartolomé

Solenoid Test Patricia Aguar Bartolomé

Target Cell Design 20 cm length and 6 cm diameter Non-magnetic materials in order to avoid depolarization of the gas - Quartz glass cell coated with Cesium - Aluminum caps - 50 mm Mylar windows metalized with Aluminum 3He gas target (P = 6 bar) First tests with prototype are in process Patricia Aguar Bartolomé

First T1 Measurement With Uncoated Cell Patricia Aguar Bartolomé

Measurement of Polarization Mechanical rail system to transport the target cell from the center of the solenoid to the center of the external holding field 1) 2) 3) 4) Patricia Aguar Bartolomé

External Holding Field Helmholtz coils needed to measure the polarization Parameter Value Coils diameter 160 cm Current 4 A N0 windings 150 Copper wire diameter 0.2 cm Patricia Aguar Bartolomé

Transporting Solenoid Solenoid to bring the target cell from the center of the CB to the center of the Helmholtz coils. Parameter Value Solenoid length 40 cm N0 Windings 800 Current 0.3 A Inner coil diameter 0.82 cm Outer coil diameter 0.83 cm Copper wire diameter 0.053 cm Patricia Aguar Bartolomé

Summary and outlook Conclusions A solenoid produced to provide the holding field for the 3He target was designed and tested First homogeneity measurements of the solenoid with the polarized gas give values of First measurement of T1 with uncoated cell gives 4h Future Fix the leak on the target cell prototype Measurement of T1 with coated cell Production of mechanical rail system Patricia Aguar Bartolomé