Hope College Department of Physics and Engineering
Research Experiences for Undergraduates
Project Title: Plastic Scintillator Neutron Detector Construction, Testing, and Application
Student Name: Justin Rieth
Student's home institution: Hope College
Research Advisor(s): Dr. P.A. DeYoung
Source of Support: Dean
Nuclear reactions often emit neutrons. Neutrons are particularly difficult to detect because they have no charge. The purpose of my research this summer was to construct a set of scintillating plastic neutron detectors (a neutron wall).
The detector wall consists of eight plastic bars aligned vertically next to each other. Light guides are fixed to the ends of the bars with an optical epoxy. Attached to these light guides are photo-multiplier tubes (PMTs). The bases plug onto the PMTs, which connect to electronics.
For a neutron to be detected it must interact with the nucleus of an atom in a detector bar. When this occurs, kinetic energy is transferred from the neutron to a proton. The proton then travels through the plastic, losing energy to electrons and promoting them to higher energy states. The electrons relax down by emitting photons. These photons travel to both ends of the detector bar and are focused by the light guides. These focused photons hit photo-cathodes in the PMTs, releasing electrons by the photoelectric effect. These electrons get multiplied and a useable signal is produced.
Using the time difference between when each photon reaches its end of the bar, the position where the neutron hit the bar can be found. To find the neutron's energy, we need the time of flight, which is the time it takes the neutron to travel from the its production point to the detector. After the distance from the target to where the neutron hit the detector is calculated, the neutron's velocity (and therefore energy) can be calculated.
When completed, the neutron wall will be integrated at the University of Notre Dame with one previously built by Hope REU Students. With two detector walls, versatility in experimental setup and efficiency in neutron detection will increase.
Publications and Presentations:
“Neutron-Decay Spectroscopy of Neutron-Rich Oxygen Isotopes.” M.Thoennessen, C.R. Hoffman, T. Baumann, D. Bazin, J. Brown, G. Christian, P.A. DeYoung, J.E. Finck, N. Frank, J. Hinnefeld, R. Howes, P. Mears*, E.Mosby, S.Mosby, J.Reith*, B. Rizzo*, W.F. Rogers, G. Peaslee, W.A. Peters, A. Schiller, M.J. Scott, S.L. Tabor, P.J. Voss, and T. Williams. ENAM08, book of abstracts page 30, (2008).
“ Determination of the N = 16 shell closure at the oxygen drip line.” C.R. Hoffman, T. Baumann, D. Bazin, J. Brown, G. Christian, P.A. DeYoung, J.E. Finck, N. Frank, J. Hinnefeld, R. Howes, P. Mears*, E. Mosby*, S. Mosby*, J. Reith*, B. Rizzo*, W.F. Rogers, G. Peaslee, W.A. Peters, A. Schiller, M.J. Scott*, S.L. Tabor, M. Thoennessen, P.J. Voss*, and T. Williams. Phys. Rev. Lett. 100, 152502 (2008).
“ Breakup of 6He Incident on 209Bi near the Coulomb Barrier.” J.J. Kolata, H. Amro, F.D. Becchetti, J.A. Brown, P.A. DeYoung, M. Hencheck, J.D. Hinnefeld, G.F. Peaslee, A.S. Fritsch, C. Hall*, U. Khadka*, Patrick J. Mears*, P. O’Rourke, D. Padilla*, J. Reith*, Tabatha Spencer, and T. Williams. Phys. Rev. C 75, 031302 (2007).
“ A Large Segmented Neutron Detector for Reaction Studies with Radioactive Beams Near the Coulomb Barrier.” J.J. Kolata, H. Amro, M. Cloughesy, P.A. DeYoung, J.P. Bychowski*, J. Reith*, and G. Peaslee. Nucl. Instr. And Meth. A557, 594 (2006).