Giving particle detectors a lift

In particle colliders that reveal the hidden secrets of the tiniest constituents of our universe, minute particles leave behind extremely faint electrical traces after they are generated in enormous collisions. Some detectors in these facilities use superconductivity — a phenomenon through which electricity is carried with zero resistance at low temperatures — to operate.

For scientists to more accurately observe the behavior of those particles, these weak electrical signals, or currents, should be multiplied by an instrument able to turning a faint electrical flicker right into a real jolt.

Scientists on the U.S. Department of Energy’s (DOE) Argonne National Laboratory have developed a brand new device that acts as a “current multiplier.” This device, called a nanocryotron, is a prototype for a mechanism that might turn up a particle’s electrical signal high enough to a level where it temporarily turns off the superconductivity of the fabric, essentially making a type of on-off switch.

“We’re taking a small signal and using it to trigger an electrical cascade,” said Tomas Polakovic, one in all Argonne’s Maria Goeppert Mayer Fellows and an creator of the study. “We will funnel the very small current of those detectors into the switching device, which will be then used to change a much larger current.”

To organize the nanocryotron for a collider experiment will take some more work due to the high magnetic fields involved. While today’s particle detectors can withstand magnetic fields of several tesla in strength, this switch’s performance degrades in high magnetic fields.

“Finding ways to make the device work in higher magnetic fields is vital to incorporating it right into a real experiment,” said Argonne graduate research assistant Timothy Draher, one other creator of the study.

To make this possible, the researchers plan to alter the geometry of the fabric and introduce defects, or tiny holes. These defects will help researchers stabilize small superconducting vortices in the fabric, the movement of which might result in an unanticipated disruption of superconductivity.

The nanocryotron was created through the use of electron beam lithography, a type of stenciling technique that uses a beam of electrons to remove a polymer film to reveal a selected region of interest. That region of interest is then etched using plasma ion etching.

“We mainly just strip away the parts which can be exposed, abandoning the device that we wish to make use of,” Draher said.

In keeping with Argonne physicist Valentine Novosad, one other creator of the study, the brand new device also could function the idea for a type of electronic logic circuitry.

“This work is particularly essential for collider experiments, similar to people who will probably be performed on the Electron-Ion Collider at Brookhaven National Laboratory. There, superconducting nanowire detectors, positioned near the beams, would require microelectronics proof against magnetic fields,” said Argonne Distinguished Fellow and group leader Zein-Eddine Meziani.

The work was funded by DOE’s Office of Science, Office of Nuclear Physics. Work to perform reactive ion etching of the superconducting movies within the experiment was carried out on the Center for Nanoscale Materials, a DOE User Facility.