Brute Force with a Gentle Touch: Vibration Isolation Techniques Used to Increase HD Target Polarization

The performance of statically polarized high-field/low-temperature targets is a strong function of the base temperature during polarization. At the Laser-Electron Gamma Source (LEGS) facility, highly polarized Hydrogen Deuteride targets are created in a dilution refrigerator/15 tesla superconducting magnet system, and converted to a frozen spin state. This allows them to retain polarization when placed in a beam at a lower field (0.7 T) and higher temperature (1.3 K). An increase in temperature from the 0 T state to the 15 T state of the refrigerator suggested eddy currents were primarily responsible for heating of the cold finger. Vibration-isolation techniques have been developed to reduce the level of eddy currents due to vibration inside the polarizing field. These techniques reduced the amplitude of vibration due to the pumping system by two orders of magnitude and lowered the cold finger temperature with field energized from similar to 17 mK to similar to 12 mK. The potential gain in polarization is substantial.