posted October 5, 2001

NSF Grant for Neutron Detector

The National Science Foundation has awarded a grant to Hope College as part of a coalition of 10 colleges and universities building a highly efficient large- area neutron detector, the Modular Neutron Array (MoNA).

Hope received $93,626 for its portion of the project, which is based at Michigan State University and should be completed by October of 2002. Hope's work is guided by Dr. Paul DeYoung and Dr. Graham Peaslee, who co- lead the college's "nuclear group": student-faculty research in nuclear physics and nuclear chemistry.

In addition to Hope and Michigan State University, the institutions participating in the MoNA collaboration are: Ball State University, Central Michigan University, Concordia College at Moorhead, Florida State University, Indiana University South Bend, Millikin University, Western Michigan University and Westmont College. The project totals approximately $1 million.

The MoNA detector will be a key instrument in the study of rare isotopes at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. Peaslee, who conducted post-doctoral work at Michigan State University before joining the Hope faculty, noted that the NSCL is the most advanced rare isotope user facility in the nation. The laboratory is used by more than 500 scientists from the United States and abroad.

A recently completed upgrade of the facility that was funded by the National Science Foundation offers unprecedented possibilities in the search and investigation of very neutron rich nuclei. The study of such nuclei will help scientists better understand how the basic elements of the universe are synthesized inside of stars.

The MoNA detector will be made of a large number of individual detector modules arranged in layers. Each of the layers will be constructed and tested by one of the undergraduate institutions in the collaboration. The layers will then be brought to the NSCL, where they will be assembled into the final MoNA detector configuration.

The MoNA project is involving a large number of undergraduate students from the collaborating colleges and universities and giving them the opportunity to take part in cutting-edge research at the forefront of nuclear physics.

"It's a huge opportunity for us to have the cyclotron only 90 minutes up the road," said Peaslee, who is an associate professor of chemistry and geological/environmental sciences. "Over the last seven years we've done a lot with the national lab at MSU. This project provides another strong research opportunity for our students."

The 144 individual two-meter long detector modules in MoNA will be arranged in nine layers of 16 detectors each, covering an area two meters wide by 1.6 meters high. The individual detectors are horizontal blocks of plastic scintillator fitted with photo-multiplier tubes on each end. The detector is position-sensitive and features multi-hit capability. The detection efficiency for single neutrons between 50 MeV and 250 MeV is around 70 percent.

Compared to the present capabilities, the instrument increases the detection efficiency by a factor of seven for single-neutron events and a factor of 50 for two- neutron events. The increase will allow the investigation of very neutron-rich nuclei that can only be produced with small intensities and therefore are out of reach with the present neutron detection capability.