An attempt at using TMA to improve the energy resolution of high-pressure Xe ionization chambers

Preliminary results of using TMA (trimethylamine) to improve the energy resolution of a high-pressure (>50 atm) Xe ionization chamber are presented. This work borrowed a technique which has been successfully applied to dope liquid Ar and Xe. However, problems related to the contamination of TMA were found to be more difficult to overcome. The maximum density of Xe at which the influence of impurities could be neglected was only 0.3 g/cm³ at a concentration of TMA of about 80 ppm. As in the case of liquid Xe, doping increases the collected charge and considerably improves energy resolution, but only at low fields