ENA particles enter the instrument through the ring shaped collimator encircling a signal processing unit in the sensor head. The collimator defines the range of directions from which incoming particles can enter the instrument at any given moment, channeling them toward a ring of ultra thin carbon foils that convert the neutral ENA particles into positively charged ions.

An electrified deflector shield surrounds the entire sensor head preventing charged solar wind particles from entering the collimator.

Once the ENAs have been ionized, they enter an electrostatic energy analyzer or ESA.

This part of the instrument consists of two electrically charged plates that guide ions within a specific energy range through the analyzer's U-shaped gap and into the time of flight or TOF detector system. The ESA is stepped through a set of 9 voltage settings to select ions within 9 different energy ranges.

The TOF detector uses the time it takes for a particle to travel between a pair of ultra thin carbon foils to determine the particle's velocity.

The combination of velocity from the TOF measurement and energy from the ESA allows the signal processing unit to distinguish between true heliosphere ENAs and unwanted background particles. The part of the sky that the ENA arrived from is determined by the direction that the instrument was pointing at the instant the ENA entered the collimator.

Learn more about imap-hi

Using the energy levels of the converted ENAs and the direction they entered IMAP-Hi’s collimators, scientists can create a map using color-coded pixels that shows the origin of the particle through the heliosphere and its energetic level. Using the ToF sensor data, scientists like IMAP-Lo lead Herb Funsten can also map the type, or species, of particle it was originally, helping us to understand in more detail the composition of the heliosphere protecting our solar neighborhood. Comparing the data from IMAP-Hi and IMAP-Lo, scientists are better able to understand why some particles to accelerate as they journey through our solarhood.

Meet the Team  

The IMAP-Hi team is led by Herb Funsten and deputy leads Daniel Reisenfeld and Frederic Allegrini. The team consists of over 50 engineers and scientists collaboratively working together across four institutions: Los Alamos National Laboratory, Southwest Research Institute (SwRI), the University of New Hampshire, and the University of Bern, Switzerland. The team is comprised of a diverse spectrum of young to senior professionals and has a long history in the development of instruments that detect energetic neutral atoms (ENAs) from the Earth’s magnetosphere to the interstellar boundary.

My experience on IMAP has taught me a lot about working with people and how important it is to work together face-to-face. COVID was hard, and it was a tough setback for all of us on IMAP. I really now appreciate the magic that happens when you get a bunch of really smart engineers, scientists, and technicians in the same room. Zoom meetings come nowhere close. 

- Dan Reisenfeld, Deputy Lead, IMAP-Hi