Improvement of charge resolution for trans-iron nuclei (Z ≥ 30) in CR-39 plastic nuclear track detectors using trajectory tracing technique S. Ota1,2, N. Yasuda3, L. Sihver4,5,6, S. Kodaira3, S. Naka1, Y. Ideguchi1, and N. Hasebe1 1Research Institute for Science and Engineering, Waseda University, Tokyo, Japan 2Advanced Science Research Center, Japan Atomic Energy Agency, Ibaraki, Japan 3National Institute of Radiological Sciences, Chiba, Japan 4Chalmers University of Technology, Goteborg, Sweden 5Roanoke College, Salem, Virginia, USA 6Texas A & M University, Texas, USA
Received: 31 Oct 2010 – Revised: 03 May 2011 – Accepted: 16 Jun 2011 – Published: 15 Nov 2011
Abstract. Charge identification of trans-iron nuclei (nuclear charge: Z≥30) using CR-39 plastic nuclear track detector (PNTD) is essential as a part of an effort to our future measurements of the projectile charge changing cross sections for galactic cosmic ray nuclei, but extremely hard. Therefore, an improvement method of the charge resolution (δZ) for 350 MeV/n Ge in CR-39 PNTD using the trajectory tracing technique with averaging the signals of nuclear tracks for each ion was studied. Eight sheets of CR-39 PNTDs were aligned and exposed to Ge beam behind a graphite target to produce projectile fragments. Average of the nuclear track data was taken over 16 detector surfaces for each ion, then the δZ of Ge was successfully improved from 0.31 charge unit on single surface to 0.15 charge unit in rms, which is good enough for making the precise cross section measurements and no other experiments using CR-39 PNTDs or the other passive detectors have achieved such a good δZ for the trans-iron nuclei with Z/β < 50 (β: relativistic velocity). This method will be very important for our future cross section measurements toward the study of galactic cosmic ray origin.
Citation: Ota, S., Yasuda, N., Sihver, L., Kodaira, S., Naka, S., Ideguchi, Y., and Hasebe, N.: Improvement of charge resolution for trans-iron nuclei (Z ≥ 30) in CR-39 plastic nuclear track detectors using trajectory tracing technique, Astrophys. Space Sci. Trans., 7, 495-500, doi:10.5194/astra-7-495-2011, 2011.