CONSTRUCTION AND TEST OF A TRANSVERSE SUPERCONDUCTING HOLDING MAGNET 15th CB Meeting Mainz March 8th, 2010 Henry G. Ortega Spina

March, 2010Henry G. Ortega Spina A2-Collaboration CONTENTS Motivation Frozen Spin Mode Simulation Construction Tests & Results Conclusions & Outlook

March, 2010Henry G. Ortega Spina A2-Collaboration Spin polarized targets needed to complete nuclear physics experiments, in particular to study internal structure of nucleons in detail. Information about polarization observables inferred from differential cross section of photoproduction. MOTIVATION

March, 2010Henry G. Ortega Spina A2-Collaboration Beam Target Photoproduction of pseudoscalar meson with polarized beam and target

March, 2010Henry G. Ortega Spina A2-Collaboration “Internal” superconducting holding magnets for longitudinally and transversally polarized targets. Design and construct an “internal” superconducting holding coil for transverse polarization. MOTIVATION

March, 2010Henry G. Ortega Spina A2-Collaboration Frozen Spin Target scheme: cooling down, high magnetic field and optical pumping. Spins direction chosen beforehand with holding magnets. “External” holding magnets are very large and provide strong fringe field. First “internal” holding coil discussed in 1980 (Niinikoski, 1980 ) and developed in 1992 (Dutz et al., 1995 ). FROZEN SPIN MODE

March, 2010Henry G. Ortega Spina A2-Collaboration The Mainz Frozen Spin Target Copper: T= 300 K  70 K HTS: T= 70 K  4 K NbTi: T= 4 K  1.5 K

March, 2010Henry G. Ortega Spina A2-Collaboration Microwave system NMR system Magnet

March, 2010Henry G. Ortega Spina A2-Collaboration “Racetrack” coil: magnetic field highly non-uniform and not appropriated for a cylinder. “Saddle” coil: winding must fit to the so-called overlapping ellipse or “cosine” shape of current distribution. SIMULATION

March, 2010Henry G. Ortega Spina A2-Collaboration Ideal case for dipole magnet: 4 -layer dipole: N 1 =N 2 = 138 N 3 =N 4 = 78 SIMULATION

March, 2010Henry G. Ortega Spina A2-Collaboration B y (G) vs. X (cm)B y (G) vs. Y (cm) SIMULATION

March, 2010Henry G. Ortega Spina A2-Collaboration SIMULATION

March, 2010Henry G. Ortega Spina A2-Collaboration SIMULATION

March, 2010Henry G. Ortega Spina A2-Collaboration SIMULATION

March, 2010Henry G. Ortega Spina A2-Collaboration Copper/scandium wire with 54 Nb-Ti filaments embedded in it. Cu:Sc= 1.35 : 1 Alloy composition: Nb 47 wt.%Ti Diameter= mm It achieves currents up to 50 A at 4.2 K and 1 T. CONSTRUCTION

March, 2010Henry G. Ortega Spina A2-Collaboration CONSTRUCTION 17 cm 10 cm

March, 2010Henry G. Ortega Spina A2-Collaboration

March, 2010Henry G. Ortega Spina A2-Collaboration Copper holderInsertCryogenic Hall generator

March, 2010Henry G. Ortega Spina A2-Collaboration TESTS & RESULTS First test in a helium dewar and magnetic field in the centre of the target region. Field homogeneity could not be analyzed. Different currents applied and Hall voltage measured with the probe. TESTS & RESULTS

March, 2010Henry G. Ortega Spina A2-Collaboration TESTS & RESULTS Magnetic field obtained from the Hall voltage (black) with a mean loaded sensitivity of 0.95 mV/kG.

March, 2010Henry G. Ortega Spina A2-Collaboration TESTS & RESULTS

March, 2010Henry G. Ortega Spina A2-Collaboration TESTS & RESULTS Transverse holding coil implemented within the Mainz FST and tested under beam conditions in December ( 2009 ) and February ( 2010 ). Stable temperature around 30 mK and holding field corresponding to 30 A (~ 0.4 T) at 1.5 K. Butanol target polarization greater than 80 % and relaxation time of 1000 hours. TESTS & RESULTS

March, 2010Henry G. Ortega Spina A2-Collaboration TESTS & RESULTS

March, 2010Henry G. Ortega Spina A2-Collaboration Positive DNP Negative DNP Holding field

March, 2010Henry G. Ortega Spina A2-Collaboration After many attempts a transverse holding dipole magnet has successfully been constructed. Magnetic field was measured in the centre of the target cell region. The obtained values were very close to those given by the computer simulation. The transverse holding coil was implemented in the cryostat of the Mainz FST and satisfactory tested observing no quenches or polarization loss. New measurements with transverse polarization throughout this year and data analysis in a near future. CONCLUSIONS & OUTLOOK

Jen ĉio! Koran dankon por via atento! Speciala danko al Oleksandr Kostikov

March, 2010Henry G. Ortega Spina A2-Collaboration GAUSSMETER Lake Shore cryogenic Hall generator HGCA-3020 Operating temperature range: 4.2K-375K Diameter: 6.35mm Active area: 0.8mm GAUSSMETER

March, 2010Henry G. Ortega Spina A2-Collaboration ELLIPSE GAP WIDTH

March, 2010Henry G. Ortega Spina A2-Collaboration Energy levels of particles with spin are splitted in the presence of an external magnetic field. Spin polarization is the asymmetry in the populations of the levels. FROZEN SPIN MODE