Fast, Large-Area Detector for Position and Energy Determination

To study nuclei and nuclear reactions, scientists collide stable and rare isotope heavy-ion beams like those generated at the Cyclotron Institute at Texas A&M University into targets of various elements and measure the resulting complex nuclear fragments of these collisions. The data collected from these nuclear reactions can provide information for research endeavors such as nuclear structure, nuclear astrophysics, and nuclear chemistry. Radiation detectors used in such experiments for energy, timing and position measurements should be fast and very radiation resistant. However, today’s common radiation detectors, like scintillators and silicon detectors are extremely sensitive to radiation damage by heavy ions preventing accurate measurements. In addition, the anticipated experiments with much higher intensity ion beams such as at the new generation FRIB facilities at Michigan State University will require even more radiation- tolerant detectors than currently exist. Diamond’s unique combination of material properties make it an ideal material for high energy applications and particularly for radiation detectors in nuclear physics, high energy physics, and nuclear energy. Diamond detectors have excellent radiation tolerance and have been found to withstand irradiation doses many times greater than silicon detectors. The high electron and hole mobility in the diamond material ensures very fast signal response, down to the sub-ns range. Large area detector-grade polycrystalline diamond (PCD) material is currently available and provides fast response and position determination, but PCD detectors are not suitable for energy determination, e.g. product identification. Single crystal diamond (SCD) detectors provide good energy resolution (~1%) but the size of today’s commercially available detector-grade SCDs is limited to about 4.5 mm. If SCD detectors could be made from large area electronic- grade SCD, they could replace silicon detectors in environments of high beam intensity while at the same time providing good spectral resolution. Applied Diamond Inc. proposes to make large area SCD material suitable for fabrication of radiation detectors used for energy and position determination and having fast time response. The large new area electronic-grade SCD mosaic material will represent a significant improvement over currently available large area electronic-grade PCD material. With performance similar to large PCD detectors for beam position measurements (but providing more sensitivity), it will also allow spectroscopic measurements for heavy ion identification (now only available with small SCD detectors). As part of the project, we will make fast, large area PCD and SCD resistive detectors for position determination with sub-millimeter resolution which are in high demand in the accelerator community. Also, we will make large area SCD detectors for spectroscopic measurements of alpha particles for nuclear nonproliferation and nuclear forensics applications.