A Cooling System for the Nab Detector Preamplifiers*

The decay of free neutrons enables precise studies of CKM unitarity, by measuring V_ud, and searches for beyond the Standard Model physics via weak scalar and tensor interactions. The goal of the Nab experiment, located at the Spallation Neutron Source at Oak Ridge National Laboratory, is to measure the electron-neutrino correlation coefficient, a, and the Fierz interference term, b, to a precision δa/a = 10^-3 and δb = 3×10^-3, respectively, via beta decay of cold free neutrons. The Nab experiment employs two identical, segmented silicon detectors and uses 22 printed circuit boards (PCBs) each with six channels that amplify and shape incoming detector signals. The combined power dissipation from all cards is estimated to be up to 100 W. Fully powering all preamplifier cards for extended periods of time will thus result in high temperatures, significantly reducing the efficiency, speed, and longevity of the operational amplifiers. Therefore, a self-regulating, reliable cooling system is necessary for continuous operation. I will present a design for a custom preamplifier liquid cooling loop, implementation into the Nab detector system, and preliminary cooling power test results.