Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
Autori: Frenje JA, Li CK, Seguin FH, Hicks DG, Kurebayashi S, Petrasso RD, Roberts S, Glebov VY, Meyerhofer DD, Sangster TC, Soures JM, Stoeckl C, Chiritescu C, Schmid GJ, Lerche RA
Editorial: REVIEW OF SCIENTIFIC INSTRUMENTS, 73 (7), p.2597-2605, 2002.
The response of CR-39 track detectors to neutrons has been characterized and used to measure neutron yields from implosions of DD- and DT-filled targets at the OMEGA laser facility [T. R. Boehly , Opt. Commun. 133, 495 (1997)], and the scaling of neutron fluence with R (the target-to-detector distance) has been used to characterize the fluence of backscattered neutrons in the target chamber. A Monte-Carlo code was developed to predict the CR-39 efficiency for detecting DD neutrons, and it agrees well with the measurements. Neutron detection efficiencies of (1.1+/-0.2)x10(-4) and (6.0+/-0.7)x10(-5) for the DD and DT cases, respectively, were determined for standard CR-39 etch conditions. In OMEGA experiments with both DD and DT targets, the neutron fluence was observed to decrease as R-2 up to about 45 cm; at larger distances, a significant backscattered neutron component was seen. The measured backscattered component appears to be spatially uniform, and agrees with predictions of a neutron-transport code. As an additional application of the calibration results, it is shown that the neutron-induced signal in CR-39 used in charged-particle spectrometers on OMEGA can be used to determine DD and DT yields ranging from about 10(10) up to 10(14). With further improvements in the processing and analysis of CR-39, this upper limit can be increased by at least two orders of magnitude.
Cuvinte cheie: instruments in physics, chemistry, and the life sciences