# Summer Science 2019 Summary

(Written by Jonathan Sheppard and Aaron Conover)

This summer, Jon Sheppard and Aaron Conover joined Merideth Frey’s physics research team through the Sarah Lawrence Summer Science Internship program. Last summer, the team focused on setting up the new TeachSpin equipment and optimizing the Halbach Mandhala design. They were successful in both endeavors. Thus, this summer, the attention has been on designing and creating a Radio Frequency transceiver and an easily manipulated gradient field (while also attempting to optimize all magnetic fields even further).

Jon took on the creation of the RF transceiver while Aaron got to work on the gradient field and its manipulation mechanism.

## RF Probe

Below is a diagram of the circuit Jon used in his design. This circuit is based on the tank circuit given in the book Experimental Pulse NMR: A Nuts and Bolts Approach by Eiichi Fukushima and Stephen B. W. Roeder.

In addition to the circuit, we also had to come up with the specifications of the inductor coil itself. To this end, we coded a Python script that, when given a few baseline numbers, would calculate the rest of the necessary values.

The tank circuit enclosure manifested itself in two variations. In the first attempt, we designed and used a 3-D printed enclosure. After a few drafts, we made one that we liked, and went forward with implementing the circuit within the enclosure. Pictured below is the final result.

But then we noticed a lot of background noise coming from the transceiver. In an attempt to lessen this noise, we tried to recreate the circuit in an aluminum box. We bought more variable capacitors so the first transceiver could remain intact, and we created a second with the aluminum enclosure. The first version of this metal upgrade wasn’t captured in a picture before we modified it yet again. However, in the second version (picture below), the only difference is we added a variable capacitor in parallel to our static matching capacitors.

We then tested these systems extensively. As stated previously, we noticed a lot of noise coming from the 3-D printed enclosure. When testing the aluminum enclosure, we noticed a similar amount of noise. In order to reduce this, we designed and built some rudimentary shielding, which brought our noise levels equal to that of the manufactured TeachSpin system.

For the final 3D print files we created, see the Thingiverse page.

After the new gradient was printed, we used a gaussmeter to collect specific values of magnetic induction across the inside of the gradient in all 3 configurations, along the 2D cross-sectional plane at the center of the magnets. This data, when processed, showed that, while not all of the configurations were ideal, the strongest central configuration conformed to our expectations of a quadrupolar magnetic field, and provides a linear gradient of ~11 Gauss/mm.