Funds from this grant support the third iteration of an effort by researchers at JILA/University of Colorado, Boulder to build advanced instrumentation capable of detecting new fundamental particles through precision measurement of the distortions these particles cause to the distribution of electric charge in an electron.К A team led by JILA Fellows Eric Cornell and Jun Ye will attempt to use laboratory-generated electric fields to trap and hold molecular ions, which can then be measured to detect deformations in their electrical charge. Held still, ions can be monitored for thousands of times longer than if they were in motion, thereby increasing the probability of a successful detection of a charge-distorting particle. Cornell and YeХs third-generation experiment will seek to improve on their prior efforts in several ways. First, they will switch from hafnium fluoride (HfF+) to thorium fluoride ions (ThF+) as the primary ion used for detection. This will result in greater sensitivity, as thorium is known to be more sensitive to the sorts of electrical distortions the group is attempting to measure. Second, Cornell and Ye will redesign their experimental apparatus to boost the number of ions that can be measured at one time from a few thousand to a few hundred thousand. Taken together, the improvements are expected to increase the sensitivity of their experiments by a factor of 10. This project will produce high-profile publications, talks at major conferences, public lectures, and training for six Ph.D. students.