1. Status of the Polarized 3He Target
Patricia Aguar Bartolomé

2. 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

3. 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 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

4. 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

5. Solenoid Test
Patricia Aguar Bartolomé

6. 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

7. First T1 Measurement With Uncoated Cell
Patricia Aguar Bartolomé

8. 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

9. 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

10. 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

11. 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