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Status of the Polarized 3 He Target . Patricia Aguar Bartolom. Overview. Magnetic Holding Field - Solenoid design - Numerical calculations - Solenoid test Target Cell Preparation Measurement of Polarization - PowerPoint PPT Presentation

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Introduction

Patricia Aguar BartolomStatus of the Polarized 3He Target Overview Magnetic Holding Field

- Solenoid design - Numerical calculations - Solenoid test

Target Cell Preparation

Measurement of Polarization

- Mechanical rail system - External holding field Patricia Aguar BartolomMagnetic Holding Field Main constraints 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. Produce magnetic holding field of 7G with a relative field gradient of 10-3 cm-1 for 6 bars in the target cell area. Polarized targets require a magnetic holding field, B0,to provide a quantization axis. 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.SOLENOIDPatricia Aguar BartolomMagnetic Field Calculation

Numerical calculation of the field and gradients with a finite element code (FEMM) Geometric parameters for the solenoid 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 BartolomParameterValueSolenoid length80 cmN0 windings1457Current0.3 AInner coil diameter0.82 cmOuter coil diameter0.83 cmCopper wire diameter0.053 cm Solenoid Test

Patricia Aguar BartolomTarget 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 BartolomFirst T1 Measurement With Uncoated Cell

Patricia Aguar BartolomMeasurement of PolarizationMechanical rail system to transport the target cell from the centerof the solenoid to the center of the external holding field

1)2)3)4)Patricia Aguar BartolomParameterValueCoils diameter160 cmCurrent4 AN0 windings150Copper wire diameter0.2 cm

Patricia Aguar BartolomHelmholtz coils needed to measure the polarizationExternal Holding Field

Transporting Solenoid

Patricia Aguar BartolomParameterValueSolenoid length40 cmN0 Windings800Current0.3 AInner coil diameter0.82 cmOuter coil diameter0.83 cmCopper wire diameter0.053 cm Solenoid to bring the target cell from the center of the CB to the center of the Helmholtz coils.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 Bartolom